2012r09enpiarc.rmto.ir/doclib/انگلیسی/روسازی راه... · 2016-03-05 · luc rens...

www.piarc.org2012R09EN

Reduction of constRuction timeand cost of Road pavementsPIARC Technical Committee D2Road Pavements

The World Road Association (PIARC) is a nonprofit organisation established in 1909 to improve international co-operation and to foster progress in the field of roads and road transport.

The study that is the subject of this report was defined in the PIARC Strategic Plan 2008 – 2011 approved by the Council of the World Road Association, whose members are representatives of the member national governments. The members of the Technical Committee responsible for this report were nominated by the member national governments for their special competences.

Any opinions, findings, conclusions and recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of their parent organizations or agencies.

This report is available from the internet site of the World Road Association (PIARC)http://www.piarc.org

Copyright by the World Road Association. All rights reserved.

World Road Association (PIARC)La Grande Arche, Paroi nord, Niveau 292055 La Défense cedex, FRANCe

International Standard Book Number 2-84060-253-9

statementsReduction of constRuction time and cost of Road pavements2

2012R09EN

Reduction of constRuction time and cost of Road pavements

This report has been prepared by Working Group 1, lead by Technical Subcommittee D2c Concrete Roads of the Technical Committee D2 – Road Pavements of the World Road Association.

Working Group Members contributing to this report:

Ralf Alte-Teigeler (Germany),Randolf Anger (Germany),Anne Beeldens (Belgium),Diego Calo (Argentina),Raymond Debroux (Belgium),Stefan Höller (Germany),Carlos Jofré (Spain),Katalin Karsai (Hungary),Franci Kavcic (Slovenia),Solomon Kganyago (South Africa),Hennie Kotze (South Africa),Beata Krieger (Germany),Anne-Séverine Poupeleer (Belgium),Justine Rasoavahini (Madagascar),Luc Rens (Belgium): Working Group Coordinator,Thierry Sedran (France),Juan J. Orozco (Mexico),Bryan Perrie (South Africa),Johannes Steigenberger (Austria),Tim Smith (Canada),Suneel Vanikar (United States of America). Other Contributors:

Rudolf Bader (Germany),Betty Bennet (United States of America),Rudi Bull-Wasser (Germany),Tibor Bors (Hungary),Laszlo Gaspar (Hungary),Karin Keglevich (Austria),Lars Keller (Germany),Nick Kong Kam Wa (South Africa),Becca Lane (United States of America),Franz Lecker (Austria),Junichi Noda (Japan),Bernd Nolle (Germany),Reinhard Pichler (Austria),Arno Piko (Austria),

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Peter Schöller (Austria),Kurt Smith (United States of America),Shiraz Tayabji (United States of America).

The Technical Subcommittee D2c was chaired by Mr. Raymond Debroux (Belgium) and Anne-Séverine Poupeleer (Belgium), Thierry Sedran (France) and Mr. Juan J. Orozco (Mexico) were the english, French and Spanish speaking secretaries, respectively.

The english Version of this report has been edited by Luc Rens (Belgium) and translations into French has been made by Raymond Debroux and Thierry Sedran and Spanish translation has been made by Juan J. Orozco (Mexico) respectively.

The french version of this report is published under reference 2012R09FR, ISBN 2-84060-254-7.

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coNtENts

executive summaRy .......................................................................................................................8intRoduction .......................................................................................................................................91. inventoRy and analysis of methods to Reduce constRuction

time and cost ................................................................................................................................111.1. inventoRy .................................................................................................................................111.2. evaluation cRiteRia ...........................................................................................................121.3. analysis ....................................................................................................................................131.4. case-HistoRies........................................................................................................................17

2. conclusions and Recommendations ..............................................................................203. appendices ........................................................................................................................................21

3.1. concRete pavement – ppp easteRn Region ...............................................................213.1.1. Concrete pavement on the main route...............................................................................223.1.2. Concrete pavements in secondary facilities ......................................................................233.1.3. Construction period ..........................................................................................................233.1.4. Traffic opening ..................................................................................................................243.1.5. Bibliography .....................................................................................................................24

3.2. ReconstRuction of HigHway a1 Regau – seewalcHen, using Recycled concRete ...............................................................................................24

3.2.1. Concrete pavement construction .......................................................................................253.2.2. Construction period ..........................................................................................................27

3.3. inlay in continuously ReinfoRced concRete on tHe motoRway a10 BRussels - oostende (2002, 2003 and 2009) ....................27

3.3.1. Tendering conditions .........................................................................................................283.3.2. Organisation of the worksite .............................................................................................283.3.3. Adequate technical choices ...............................................................................................30

3.4. tHe ReHaBilitation of tHe antweRp Ring Road (2004-2005) ...............................313.4.1. Introduction .......................................................................................................................313.4.2. Tendering conditions .........................................................................................................323.4.3. Organisation of the worksite .............................................................................................323.4.4. Adequate Technical Choices .............................................................................................333.4.5. References ........................................................................................................................34

3.5. cold in-place Recycling in canada ..........................................................................343.5.1. Materials Savings .............................................................................................................353.5.2. Cost Savings ......................................................................................................................353.5.3. Time Savings .....................................................................................................................363.5.4. Performance ......................................................................................................................363.5.5. Summary ...........................................................................................................................363.5.6. References .........................................................................................................................37

3.6. RemovaBle uRBan pavement ..........................................................................................373.6.1. Preliminary survey and potential market ..........................................................................383.6.2. The concept .......................................................................................................................383.6.3. The Saint Aubin project (summer 2007) ...........................................................................39

Reduction of constRuction time and cost of Road pavements5

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3.6.4. The Nantes project (summer 2008) ...................................................................................403.6.5. Main conclusions ..............................................................................................................423.6.6. To know more about RUP .................................................................................................42

3.7. Recycling of a concRete suRface and use of Rc-aggRegate in a gRavel Base couRse in tHe fRamewoRk of tHe complete ReconstRuction of tHe motoRway BaB a11 Between BeRlin and szczecin (stettin) (2009) ........................................................43

3.7.1. Preparatory work and development ..................................................................................443.7.2. Crushing and sizing ..........................................................................................................443.7.3. Gravel base course construction ......................................................................................453.7.4. Summary and Outlook.......................................................................................................46

3.8. fast tRack – ReHaBilitation of concRete slaBs on HigHway and aiRpoRt pavements in one woRking sHift using fast setting concRete .....46

3.8.1. Material requirements .......................................................................................................473.8.2. Machinery – mobile mixers ...............................................................................................483.8.3. Organisation of the worksite .............................................................................................49

3.9. Renewal of fatigued and woRn concRete Roads using an ultRa-HigH-peRfoRmance concRete oveRlay - a field tRial using a Heavy veHicle paRking lane .........................................................................51

3.10. innovative and economical paving metHod foR compact aspHalt pavements ..............................................................................543.10.1. General ...........................................................................................................................543.10.2. Laboratory Tests .............................................................................................................57

3.11. ReconstRuction of tHe Runways noRtH and soutH at fRankfuRt aiRpoRt witH waRm mix aspHalt ..................................................573.11.1. The Projects .....................................................................................................................583.11.2. The Reconstruction ..........................................................................................................593.11.3. The construction Process ................................................................................................593.11.4. The Personnel Placement and the Construction equipment ...........................................603.11.5. The “breaking-up” Nights ..............................................................................................603.11.6. The “paving” Nights .......................................................................................................61

3.12. Hot on Hot aspHalt paving in geRmany..................................................................633.13. tHin wHitetopping oveRlay oveR a defoRmed aspHalt pavement

of a HigHly tRafficked uRBan inteRsection .......................................................643.13.1. Selection of the site for TW trial section .........................................................................653.13.2. Preliminary laboratory test results .................................................................................653.13.3. The construction of the trial section ...............................................................................663.13.4. Quality control ................................................................................................................673.13.5. Conclusions .....................................................................................................................68

3.13. low-cost cement concRete pavement tHat allows eaRly opening to tRaffic ...............................................................................................683.13.1. What ................................................................................................................................683.13.2. Why .................................................................................................................................68


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3.13.3. How .................................................................................................................................693.13.4. Plan, progress and success .............................................................................................693.14.5. Lessons learned ...............................................................................................................69

3.15. waRm mix aspHalt in japan ............................................................................................723.15.1. Simulation of the WAM’s benefit .....................................................................................723.15.2. Other benefits of WAM ....................................................................................................733.15.3. Summary .........................................................................................................................733.15.4. References .......................................................................................................................74

3.16. pavement ReconstRuction of tHe mexico–QueRetaRo HigHway (tepalcapa – palmillas) ...............................................................................743.16.1. Organization of the worksite ...........................................................................................753.16.2. Stabilized base ................................................................................................................753.16.3. Concrete slab construction .............................................................................................763.16.4. Technical highlights ........................................................................................................77

3.17. mecHanical placement of dowels and ReinfoRcing BaRs in concRete pavements....................................................................................................773.17.1. Introduction .....................................................................................................................773.17.2. Mechanical insertion of dowels ......................................................................................783.17.3. Mechanical steel placement (tube-feeding) in continuously

reinforced concrete pavements ........................................................................................813.17.4. References .......................................................................................................................84

3.18. RepaiRs of a continuously ReinfoRced concRete pavement in soutH afRica ....................................................................................................................853.18.1. Introduction .....................................................................................................................853.18.2. Background ....................................................................................................................853.18.3. Concrete mix design .......................................................................................................863.18.4. Construction aspects ......................................................................................................883.18.5. Conclusion ......................................................................................................................913.18.6. References .......................................................................................................................91

3.19. Rapid inteRsection ReconstRuction in wasHington state .........................913.19.1 Urban Intersection Reconstruction: State Route 395/Kennewick Avenue .............................. 923.19.2. Pavement Design ............................................................................................................933.19.3. Mix Proportioning ...........................................................................................................933.14.4. Staging ............................................................................................................................943.19.5. Construction ....................................................................................................................953.19.6. Opening to Traffic ...........................................................................................................953.19.7. Summary .........................................................................................................................953.19.8. References .......................................................................................................................96

3.20. inteRmittent RepaiRs of jointed concRete pavements using pRecast concRete panels .................................................................................963.20.1 Introduction ......................................................................................................................963.20.2. The technique ..................................................................................................................973.20.3. The New Jersey repair project ........................................................................................983.20.4. References .....................................................................................................................100


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for many different reasons, road authorities who want to build, rehabilitate or repair a pavement wish to do this in the shortest possible construction time and for the lowest possible initial cost. these reasons can be related to their limited available resources, to the benefit for the road users by a minimal disruption of the traffic flow or to a policy of environmental friendliness or road safety.

construction time and construction cost, however, are often conflicting parameters. achieving a shorter construction time may require extra craftsmen and machines which increases the cost of the project. on the other hand, lower cost may provide lower performing equipment and less experienced staff, which may result in a longer execution time. in addition, once the work is finished and paid, it is expected that the construction can fulfil its function during the assumed lifetime. in other words, the reduction of time or cost must not compromise the quality of the work. indeed, a reduction of construction time and/or a reduction in construction cost may not always lead to a better project. therefore one should rather speak of optimising time and cost for a given quality. in some cases, it may even be the wish of the owner to accept a higher cost and/or construction time in order to obtain a better end result such as a road with a longer design life and less maintenance.

the methods that can contribute to an optimised worksite can be subdivided into three domains: tendering conditions, organisation of the worksite and adequate technical choices. these methods must not have a negative environmental impact or, even preferably, should be an improvement with regard to the life-cycle environmental assessment (co2, energy, water, waste, and so forth). the methods can be analysed with regard to several indicators of cost, time, quality, economy, society and environment in order to detect the strong and weak points of them.

the publication describes a list of methods, analyses them and gives a number of case-histories, illustrating the different techniques that are available and their use worldwide. they confirm the difficulty of combining reduction of time and cost concurrently and also teach us that these issues have gained a lot of importance and that research and developments are still going on in these fields.

as a final conclusion and recommendation, the issue of “reducing” construction time and cost should rather be considered as “optimising”. indeed, the objective is to find a well-balanced solution that meets all of the goals taking into account the different priorities and specific conditions of the project. a “best solution” can only be achieved when each party takes up his responsibility in the construction process. each player, from the designer and calculator to the craftsman on the worksite must be aware of the importance of his contribution. He must always remember that every idea, initiative or action has an impact on the final result and that he can make a difference.

ExEcutivE summaRy


2012R09EN

whatever be the type or size of a construction work, the same two questions always arise:

“How long will it take?” and “How much will it cost?”.

in most cases the client is hoping to get an answer that ensures the shortest possible construction time and the lowest possible initial cost. the same is true for road authorities who want to build, rehabilitate or repair a pavement. there are a large number of reasons why they want to do so:

• due to limited resources and particular budget requirements or in order to respect the yearly allocated budget, they are looking for the lowest bid;

• to keep the traffic flowing and to get the maximum availability of the road that would lead to minimum disruption, minimum societal costs and maximum benefits for the road users;

• it is good for their image;• in the case of private companies, they want to maximise their benefits;• good mobility facilitates and improves logistical operations and the economy of

the country or region;• reduced construction time means fewer traffic jams, reduced fuel consumption

and air pollution and is therefore also better for the environment.

“Reducing construction time and cost” has been chosen as one of the issues to be studied within the technical committee d2 - Road pavements of the world Road association.

construction time and construction cost, however, are often conflicting parameters. achieving a shorter construction time may require extra craftsmen and machines which increases the cost of the project. on the other hand, lower cost may provide lower performing equipment and less experienced staff, which may result in a longer execution time.

in addition, once the work is finished and paid, it is expected that the construction can fulfil its function during the assumed lifetime. in other words, the reduction of time or cost must not compromise the quality of the work, which can be measured by means of performance indicators. indeed, a reduction of construction time and/or a reduction in construction cost may not always lead to a better project. not only should the reduction of time and cost not result in a loss of quality; on the contrary, enhanced overall quality should be the goal. therefore one should rather speak of optimising time and cost for a given quality. in some cases, it may even be the wish of the owner to accept a higher cost and/or construction time in order

iNtRoductioN


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to obtain a better end result such as a road with a longer design life and less maintenance.

Hence, it was agreed to amend the wording of the issue to:

“Identify methods for reducing the time and cost of construction for different types of road pavements without affecting the quality”.

in addition, the chosen method must not have a negative environmental impact or, even preferably, should be an improvement with regard to the life-cycle environmental assessment (co2, energy, water, waste, and so forth).


2012R09EN


1. inventoRy and analysis of methods to Reduce constRuction time and cost

1.1. inventoRy

the methods that can contribute to an optimised worksite, from different viewpoints: of the designer, the contractor, the authority, the road user; can be subdivided into three domains:

• tendering conditions;• organisation of the worksite; and• adequate technical choices related to :

– general aspects,– concrete pavements,– asphalt pavements.

these methods may concern both construction of new roads as well as rehabilitation and maintenance works.

for each of the domains, an inventory of possible methods has been made.

tendering conditions• bonus – penalties;• reduction of construction time by the bidder;• performance based specifications;• public private partnership;• allowing subcontracting – Requiring specialised craftsmen or equipment;• technical suggestions by the bidder;• criteria in the evaluation of the bidding (references, work capacity, pre-qualifications

of the bidder, soundness of financial situation, reputation, quality procedures);• lane rental;• market situation “supply and demand”;• quality of the technical design.

organisation of the worksite• traffic management;• quality plan – quality control;• night work;• working 24 hrs a day;• working during the weekend or 7 days a week;• public awareness and communication;• space management on the worksite.

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adequate technical choicesGeneral aspects• design optimisation;• overlay- inlay (concrete, asphalt);• on site recycling (concrete, asphalt, soil treatment or in situ pavement recycling

using cement, hydraulic road binders, lime, bitumen, etc.).

Concrete pavements• fast track (rapid hardening concrete);• equipment: wireless paving, dowel bar inserter, etc.;• modular techniques;• bridge decks.

Asphalt pavements• compact asphalt;• warm mix asphalt.

1.2. evaluation cRiteRia

Referring to the difficult balance between construction time, construction cost and quality of the work, an analysis will be made of the selected methods in order to define their strengths and weaknesses. indicators for these strengths and weaknesses will relate to the final goals (cost, time, quality) but also to the different aspects of sustainable construction (economic, social and environmental considerations).

a number of possible indicators or criteria are given in the following list:

• cost-benefit analysis;• initial cost;• life-cycle cost;• user delay costs;• construction time;• hindrance to road users;• hindrance to residents;• technical quality and service life of the pavement;• acceptance by the public;• traffic flow;• environmental impact;• impact on health & security for the workers;• universal solution or limited solution due to development of the country, climatic

conditions, necessary investments by the authorities or contractor.

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Reduction of constRuction time and cost of Road pavements1.

3. a

na

lysi

s tab

le

1 -

an

aly

sis

of

th

e m

eth

od

s fo

R R

ed

uc

ing

co

nst

Ru

ct

ion

tim

e a

nd

co

st

gro

up o

f m

etho

ds

met

hod

for

redu

cing

co

nstr

ucti

on ti

me

and

cost

stre

ngth

– p

osit

ive

asse

ssm

ent

Wea

knes

s – n

egat

ive

asse

ssm

ent

methods related to the tendering conditions

Bon

us –

pen

altie

sa

syst

em o

f bon

us a

nd/o

r pen

altie

s can

be

rela

ted

to a

shor

ter c

onst

ruct

ion

time

and

can

be v

ery

effe

ctiv

e de

pend

ing

on th

e am

ount

s al

loca

ted.

whe

n bo

nuse

s and

/or p

enal

ties b

ecom

e to

o im

port

ant,

the

cont

ract

or w

ill b

e fo

cuse

d on

ly o

n th

e co

nditi

ons h

ow to

obt

ain

the

bonu

s or t

o av

oid

the

pena

lty,

bein

g in

this

cas

e th

e co

nstr

uctio

n tim

e. c

ontin

uing

the

wor

ksite

in b

ad w

eath

er

cond

ition

s or i

n le

ss fa

vour

able

tech

nica

l con

ditio

ns m

ay le

ad to

a d

ecre

ase

in

qual

ity o

f the

fina

l wor

k. e

ven

whe

n th

e co

ntra

ctua

l req

uire

men

ts a

re m

et, t

he

cons

eque

nces

may

onl

y ap

pear

aft

er a

num

ber o

f yea

rs. t

his c

an h

owev

er b

e co

unte

red

by a

n ad

equa

te b

onus

syst

em fo

r qua

lity

aspe

cts.

a b

onus

/pen

alty

syst

em w

ill a

lway

s hav

e an

adv

erse

eff

ect o

n th

e ov

eral

l pric

e of

th

e w

ork,

eith

er b

y th

e su

m o

f the

bon

us th

at h

as to

be

paid

, eith

er b

y th

e ri

sk o

f the

pe

nalty

whi

ch is

cal

cula

ted

by th

e co

ntra

ctor

in h

is b

id.

lane

rent

alit

can

be c

onsi

dere

d as

a p

artic

ular

form

of

bonu

s sys

tem

and

hen

ce is

an

ince

ntiv

e fo

r the

co

ntra

ctor

to w

ork

fast

er.

see

“Bon

us-P

enal

ties”

.

Red

uctio

n of

co

nstr

uctio

n tim

e by

th

e bi

dder

(cos

t+ ti

me

bidd

ing)

the

cont

ract

or is

the

best

pla

ced

part

y to

stud

y an

d fi

x th

e tim

e ne

cess

ary

to c

ompl

ete

a jo

b. it

is

als

o an

ince

ntiv

e fo

r the

con

trac

tor t

o m

ake

use

of th

e be

st a

vaila

ble

tech

niqu

es a

nd

equi

pmen

t, to

use

inno

vativ

e te

chni

ques

and

/or

proc

edur

es a

nd to

eng

age

extr

a st

aff i

n or

der t

o re

duce

the

cons

truc

tion

time

in a

reas

onab

le

way

.

in a

syst

em w

here

the

low

est “

cost

+tim

e” b

id w

ill g

et th

e jo

b, th

e co

mpa

nies

will

co

nsid

er th

e m

ost f

avou

rabl

e co

nditi

ons i

n or

der t

o re

ach

the

shor

test

con

stru

ctio

n tim

e in

thei

r bid

. dur

ing

exec

utio

n ho

wev

er, t

he c

ondi

tions

may

not

be

optim

al a

nd

the

cont

ract

ing

com

pany

will

sear

ch fo

r oth

er w

ays t

o re

spec

t the

con

stru

ctio

n tim

e as

set i

n th

e bi

d.

perf

orm

ance

bas

ed

spec

ific

atio

nsth

is w

ay o

f ten

deri

ng a

llow

s the

con

trac

tor t

o m

ake

use

of h

is e

xper

ienc

e an

d kn

ow-h

ow in

th

e be

st p

ossi

ble

way

to d

eliv

er a

pro

duct

that

co

mpl

ies w

ith th

e re

quir

ed p

erfo

rman

ces.

the

cont

ract

or m

ay se

ek fo

r the

low

er b

ound

arie

s of t

he re

quir

emen

ts w

hat m

ight

re

sult

in a

low

er li

fetim

e of

the

pave

men

t. ex

tra

war

rant

y pe

riods

shou

ld th

eref

ore

be c

onsi

dere

d.

publ

ic p

rivat

e pa

rtne

rshi

pin

typi

cal d

Bfm

(des

ign-

build

-fin

ance

-m

aint

ain)

con

trac

ts, t

he p

artie

s inv

olve

d ar

e lo

okin

g fo

r roa

d st

ruct

ures

that

allo

w a

goo

d co

st/b

enef

it ra

tio o

ver t

he lo

ng te

rm, i

nclu

ding

th

e m

aint

enan

ce p

hase

(pre

fera

bly

30 +

yea

rs).

invo

lvem

ent o

f thi

rd p

artie

s for

the

fina

ncin

g of

the

proj

ect i

nclu

de a

dditi

onal

cos

ts

on th

e lo

ng te

rm (f

inan

cing

ban

ks, i

nsur

ance

com

pani

es, m

anag

emen

t bur

eaus

, et

c.).

13

2012R09EN


tab

le

1 -

an

aly

sis

of

th

e m

eth

od

s fo

R R

ed

uc

ing

co

nst

Ru

ct

ion

tim

e a

nd

co

st

gro

up o

f m

etho

ds

met

hod

for

redu

cing

co

nstr

ucti

on ti

me

and

cost

stre

ngth

– p

osit

ive

asse

ssm

ent

Wea

knes

s – n

egat

ive

asse

ssm

ent

methods related to the tendering conditions

allo

win

g su

bcon

trac

ting

– R

equi

ring

sp

ecia

lised

cra

ftsm

en

or e

quip

men

t

wor

k th

at is

don

e by

spe

cial

ists

can

be

achi

eved

in a

bet

ter a

nd fa

ster

way

.m

ore

com

pani

es in

volv

ed le

ads t

o hi

gher

adm

inis

trat

ion

cost

s. sp

ecia

lized

cr

afts

men

and

tech

niqu

es m

ay b

e m

ore

expe

nsiv

e in

initi

al c

ost i

nves

tmen

t.

tech

nica

l sug

gest

ions

by

the

bidd

er o

r “V

alue

-eng

inee

ring

”

the

free

dom

for c

ontr

acto

rs to

incl

ude

tech

nica

l sug

gest

ions

the

bid

will

enc

oura

ge

them

to d

evel

op a

nd m

ake

use

of in

nova

tive

tech

niqu

es a

nd a

pplic

atio

ns a

nd a

llow

s the

m to

be

nefi

t fro

m c

ompa

ny-o

wne

d te

chni

ques

. th

ese

may

hav

e a

posi

tive

impa

ct o

n co

nstr

uctio

n tim

e, p

rice

and/

or q

ualit

y of

the

wor

k.

not

all

the

com

pani

es h

ave

the

sam

e ex

perie

nce,

staf

f, m

achi

nes,

etc

. whi

ch m

ay

lead

to u

nfai

r com

petit

ion

betw

een

them

. the

ben

efit

may

be

pres

ent f

or th

e co

ntra

ctor

but

not

nec

essa

rily

for t

he ro

ad o

wne

r.

crit

eria

in th

e ev

alua

tion

of th

e bi

ddin

g

the

best

pos

sibl

e co

ntra

ctor

can

be

chos

en

taki

ng in

to a

ccou

nt a

num

ber o

f crit

eria

such

as:

- bid

ding

pric

e,- r

efer

ence

s,- p

requ

alif

icat

ion,

- sou

ndne

ss o

f fin

anci

al si

tuat

ion,

- rep

utat

ion,

- qua

lity

proc

edur

es.

even

a c

ompa

ny w

ith g

ood

refe

renc

es m

ay h

ave

unde

rgon

e re

stru

ctur

ing

and

de

fact

o no

long

er m

eet t

he re

quir

emen

ts. o

r goo

d re

fere

nces

may

be

obta

ined

th

roug

h th

e w

ork

of s

ubco

ntra

ctor

s tha

t do

not w

ork

any

long

er fo

r thi

s com

pany

.

mar

ket s

ituat

ion

“Sup

ply

and

dem

and”

in ti

mes

whe

re o

nly

few

wor

ks a

re b

eing

te

nder

ed, p

rices

will

go

dow

n be

caus

e of

to

ughe

r com

petit

ion.

whe

n th

ere

is a

hig

h de

man

d fo

r con

trac

tors

(per

iods

of h

igh

conj

unct

ure)

, bid

ding

pr

ices

will

go

up.

Qua

lity

of th

e te

chni

cal d

esig

na

wel

l-tho

ught

and

com

plet

e de

sign

lead

s to

a fa

ir co

mpe

titio

n w

ith a

min

imum

of a

dditi

onal

w

orks

dur

ing

exec

utio

n.

Bad

des

igns

lead

to s

pecu

latio

n du

ring

tend

erin

g pr

oced

ures

and

will

cau

se e

xtra

co

sts d

urin

g ex

ecut

ion.

14

2012R09EN


tab

le

1 -

an

aly

sis

of

th

e m

eth

od

s fo

R R

ed

uc

ing

co

nst

Ru

ct

ion

tim

e a

nd

co

st

gro

up o

f m

etho

ds

met

hod

for

redu

cing

co

nstr

ucti

on ti

me

and

cost

stre

ngth

– p

osit

ive

asse

ssm

ent

Wea

knes

s – n

egat

ive

asse

ssm

ent

methods related to the organisation of the worksite

traf

fic

man

agem

ent

Bet

ter t

raff

ic f

low

, low

er so

ciet

al c

osts

.ex

tra

man

agem

ent c

osts

.

publ

ic a

war

enes

s and

co

mm

unic

atio

nin

crea

ses t

he a

ccep

tanc

e by

the

publ

ic.

extr

a co

sts f

or c

omm

unic

atio

n ca

mpa

igns

thro

ugh

the

diff

eren

t med

ia.

Qua

lity

plan

– q

ualit

y co

ntro

lB

ette

r qua

lity

lead

s to

low

er li

fe-c

ycle

cos

ts.

extr

a co

sts f

or q

ualit

y co

ntro

l, ex

tra

adm

inis

trat

ion.

nig

ht w

ork

less

traf

fic

disr

uptio

n, lo

wer

soci

etal

cos

ts,

bette

r acc

epta

nce

by th

e pu

blic

.R

isk

for l

ower

qua

lity

of th

e fi

nish

ed jo

b.ex

tra

cost

s for

the

irre

gula

r hou

rs. i

ncre

ased

soci

al p

ress

ure

on th

e w

orke

rs (f

amily

lif

e, h

ealth

).

wor

king

24

hrs a

day

sh

orte

r con

stru

ctio

n tim

e.ex

tra

cost

s for

the

irre

gula

r hou

rs. i

ncre

ased

soci

al p

ress

ure

on th

e w

orke

rs (f

amily

lif

e, h

ealth

).

wor

king

dur

ing

the

wee

kend

or 7

day

s a

wee

k

shor

ter c

onst

ruct

ion

time.

extr

a co

sts f

or th

e ir

regu

lar h

ours

. inc

reas

ed so

cial

pre

ssur

e on

the

wor

kers

(fam

ily

life,

hea

lth).

spac

e m

anag

emen

t on

the

wor

ksite

a g

ood

orga

nisa

tion

of th

e tr

affi

c on

the

wor

ksite

can

redu

ce ti

me

and

cost

.po

ssib

le e

xtra

cos

ts fo

r tem

pora

ry ro

ads o

n th

e w

orks

ite o

r oth

er in

fras

truc

ture

.

methods related to adequate technical choices

Rel

ated

to g

ener

al a

spec

ts

des

ign

optim

isat

ion

opt

imis

atio

n =

mee

ting

the

requ

ired

sp

ecif

icat

ions

at t

he b

est p

ossi

ble

pric

e or

in th

e be

st p

ossi

ble

time.

inve

stig

atio

n of

the

actu

al

situ

atio

n is

an

impo

rtan

t iss

ue in

the

optim

isat

ion

appr

oach

.

opt

imis

atio

n =

less

rese

rve

in th

e de

sign

and

hen

ce h

ighe

r var

iabi

lity

in th

e pe

rfor

man

ces.

ove

rlay-

inla

yu

sing

the

exis

ting

stru

ctur

e as

a s

ub-b

ase

for

the

new

road

mea

ns:

- les

s dem

oliti

on w

orks

;- l

ess u

sage

of v

irgi

n m

ater

ials

;- l

ess t

rans

port

and

ther

efor

e le

ss d

amag

e to

ad

jace

nt o

r acc

ess r

oads

.in

gen

eral

it c

an b

e co

nsid

ered

as a

cos

t- an

d tim

e-ef

fect

ive

solu

tion.

a g

ood

know

ledg

e of

the

exis

ting

stru

ctur

e is

nec

essa

ry in

ord

er to

be

sure

it is

ab

le to

with

stan

d th

e ne

w d

esig

n lo

ads.

this

can

be

base

d on

mea

sure

men

ts w

ith

fwd

and

geo

rada

r and

taki

ng o

f cor

es.

the

high

er p

rofi

le o

f the

road

is n

ot a

lway

s pos

sibl

e be

caus

e of

exi

stin

g in

fras

truc

ture

(brid

ges)

and

bui

ldin

gs.

15

2012R09EN


tab

le

1 -

an

aly

sis

of

th

e m

eth

od

s fo

R R

ed

uc

ing

co

nst

Ru

ct

ion

tim

e a

nd

co

st

gro

up o

f m

etho

ds

met

hod

for

redu

cing

co

nstr

ucti

on ti

me

and

cost

stre

ngth

– p

osit

ive

asse

ssm

ent

Wea

knes

s – n

egat

ive

asse

ssm

ent

methods related to adequate technical choices

Rel

ated

to g

ener

al a

spec

ts

on

site

recy

clin

gle

ss u

se o

f vir

gin

mat

eria

ls.

less

tran

spor

t.en

viro

nmen

tally

frie

ndly

.c

heap

er th

an c

onve

ntio

nal m

etho

ds.

extr

a qu

ality

con

trol

requ

ired

.R

ecyc

led

mat

eria

ls m

ay n

ot a

lway

s be

suita

ble

in n

ew c

oncr

ete.

a m

inim

um a

nd

max

imum

size

of t

he w

orks

ite a

re c

onst

rain

ts fo

r the

inst

alla

tion

of a

cru

shin

g an

d si

evin

g un

it on

site

.

Rel

ated

to c

oncr

ete

pave

men

ts

fast

trac

k (r

apid

ha

rden

ing

conc

rete

)sh

orte

r con

stru

ctio

n tim

e, e

arlie

r ope

ning

to

traf

fic.

long

term

dur

abili

ty m

ust b

e en

sure

d. d

iffi

culti

es m

ay b

e en

coun

tere

d w

ith

wor

kabi

lity

of th

e co

ncre

te m

ix. m

ater

ial p

rices

may

be

high

er.

equi

pmen

t: w

irel

ess

(or s

trin

gles

s) p

avin

gsa

ving

labo

ur c

osts

.H

ighe

r saf

ety

on th

e w

orks

ite.

Bet

ter s

urfa

ce e

venn

ess.

Rel

iabi

lity

of g

ps-s

yste

ms.

equi

pmen

t cos

ts.

equi

pmen

t: do

wel

bar

in

sert

er (j

pcp)

; m

achi

ne p

lace

men

t of

long

itudi

nal

rein

forc

emen

t (c

Rcp)

plac

emen

t by

mac

hine

of d

owel

s or

long

itudi

nal r

einf

orce

men

t can

be

time

and

cost

ef

fect

ive.

the

exac

t pos

ition

of t

he d

owel

s or s

teel

bar

s mus

t be

ensu

red.

nee

d fo

r ext

ra d

evic

es o

n th

e sl

ipfo

rm p

aver

.

mod

ular

tech

niqu

esR

apid

con

stru

ctio

n an

d op

enin

g to

traf

fic.

no

need

for c

urin

g on

site

. Hig

h qu

ality

con

cret

e.ex

pens

ive

syst

ems.

dif

fere

nt ty

pes o

f tec

hniq

ue; s

kille

d la

bour

is re

quir

ed.

Brid

ge d

ecks

Bet

ter t

rans

ition

bet

wee

n pa

vem

ent a

nd b

ridge

de

ck w

ith th

e sa

me

mat

eria

ls. c

ost-e

ffic

ient

by

savi

ng a

spha

lt pa

vem

ent.

surf

ace

reha

bilit

atio

n is

mor

e di

ffic

ult.

methods related to adequate technical

choices

Rel

ated

to a

spha

lt pa

vem

ents

com

pact

asp

halt

pave

men

ts (“

hot o

n ho

t” a

spha

lt pl

acin

g)

Red

uctio

n of

con

stru

ctio

n tim

e by

layi

ng

surf

ace

and

bind

er c

ours

e in

one

ope

ratio

n.sa

ving

on

the

thic

knes

s of t

he w

eari

ng c

ours

e.

Red

uctio

n in

ove

rall

cost

.

nee

d fo

r a s

peci

al p

avin

g m

achi

ne o

r a m

odif

ied

conv

entio

nal p

aver

.

war

m m

ix a

spha

ltR

educ

tion

of c

onst

ruct

ion

time

and

traf

fic

clos

ure

time

due

to h

igh

perf

orm

ance

s at l

ower

te

mpe

ratu

re. R

educ

tion

of fu

el c

ost a

t the

as

phal

t pla

nt. R

educ

tion

of c

o2 e

mis

sion

.

incr

ease

of a

spha

lt m

ixtu

re p

rice.

16

2012R09EN


it always seems to be possible to work either faster or cheaper but reducing both the cost and the time of a road project without affecting the quality of the end result, on the contrary, hardly seems possible. the challenge is to optimize the cost-time-quality relation for a specific project. from the table above, the following observations can be made:

• some of the methods aim at reducing construction time but they are requiring a higher cost for investment, materials or labour. this is both applicable to concrete and asphalt pavements;

• for some procedures, the apparent cost saving is partly countered by other, often hidden costs, some of which may only appear after construction through the lesser performance of the pavement;

• automated execution methods (gps based, specific equipment, etc.) can be cost- and time-effective but only if there is a sufficient return on the investment for the equipment and if the systems function properly with a very high degree of reliability;

• the success of the measures that are taken is very dependent on the human factor: efforts, skills and attention of the workmen and operators of the machines; availability and motivation of the people, especially for work in shifts, at night and during the weekend.

1.4. case-histoRies

a total number of 20 case-histories have been collected, most of which are briefly describing a worksite or project where one or more of the methods, discussed in the previous paragraph, have been applied.

15 case-histories are related to concrete pavements and 5 to asphalt or bitumen based applications. all of them have been evaluated in the same way and the following table gives for each of them the methods that were used for reducing construction time and cost.

the examples are described in appendix in the order of their presentation in the table.

17

2012R09EN


table 2 – case-histoRies pResneted in appendix

cou

ntry

case-historyapplied methods for reducing construction

time and cost

aus

tria 1 - public private partnership in the eastern

Region of austria.• public private partnership.

2 - Reconstruction of highway a1 Regau – seewalchen using recycled concrete.

• Recycling on site,• traffic management measures.

bel

gium

3 - inlay in continuously reinforced concrete on the motorway a10 Brussels-oostende (2002, 2003 and 2009).

• cost+time bidding,• phases in the planning allowed keeping the traffic at

maximum capacity,• technical choice of inlay,• high quality pavement concrete allowing opening

to traffic after 6 days of curing,• use of automatically guided slip form paver by means

of total stations.4 - the rehabilitation of the antwerp Ring Road

(2004-2005).• Reduction of construction time by the bidder,• working 7 days a week,• concreting works 24 hours a day,• optimisation of the worksite traffic flow,• plants on the worksite,• lcca and multi-criteria analysis,• maximum recycling on the worksite,• gigantic traffic management measures,• large communication campaign.

can

ada 5 - cold in-place recycling in canada. • on-site recycling technique.

fran

ce 6 - Removable urban pavement • modular system.

ger

man

y

7 - Recycling of a concrete surface and use of recycled concrete aggregate in a gravel base course in the framework of the complete reconstruction of the motorway BaB a11 between Berlin and szczecin (stettin) (2009).

• Recycling,• plants on site,• traffic management,• space management on the worksite.

8 - fast track rehabilitation of concrete slabs on highways and airport pavements in one working shift using fast setting concrete.

• Rapid hardening concrete mix,• night work,• special equipment (mobile mixers),• organisation of the worksite.

9 - Renewal of fatigued and worn concrete roads using an ultra-high performance concrete overlay – a field trial using a heavy vehicle parking lane.

• Rapid hardening concrete mix.

10 - innovative and economical paving method for compact asphalt pavements.

• compact asphalt.

11 - Reconstruction of the Runways north and south at frankfurt airport with warm mix asphalt.

• warm mix asphalt,• night work,• organisation of the worksite.

12 - Hot on hot asphalt paving in germany. • compact asphalt.

18

2012R09EN


table 2 – case-histoRies pResneted in appendix

cou

ntry

case-historyapplied methods for reducing construction

time and cost

hun

gary 13 - thin whitetopping overlay over a deformed

asphalt pavement of a highly trafficked urban intersection.

• overlay technique,• rapid setting concrete mix.

Japa

n 14 - low-cost cement concrete pavement that allows early opening to traffic.

• Rapid hardening concrete mix,• night work.

15 - warm mix asphalt in japan. • warm mix asphalt.

mex

ico

16 - pavement reconstruction of the mexico-Queretaro highway (tepalcapa – palmillas).

• inlay,• weekend work,• phasing,• traffic management,• subcontracting,• equipment: wireless paving, dBi, plants on site.

spai

n 17 - mechanical placement of dowels and reinforcing bars in concrete pavements

• equipment.

sout

h a

fric

a 18 - Repairs of a continuously reinforced concrete pavement.

• Rapid hardening concrete mix,• night work,• technical suggestions.

u.s

.a.

19 - Rapid intersection reconstruction in washington state.

• Rapid setting concrete mix,• weekend work,• staged construction process,• public Relations campaign.

20 - intermittent repairs of jointed concrete pavements using precast concrete panels.

• use of precast technology,• night work.

some of the observations from the case-histories:

• for most of the projects, the starting conditions are fixed by the client or by society and they determine the modus operandi, e.g. the time window that an airport must be operational leads to an execution split over more than 600 nights while an uninterrupted rehabilitation obviously would require a shorter construction time but was not possible. the same is true for the renovation of heavily trafficked roads where at all times a number of lanes must be kept open or where repairs must take place over night;

• preparation and organization of the worksite, mainly a task for the contractor, appears to be one of the key elements in the success of other measures. or inversely, innovative materials or techniques are doomed to fail when the procedures on the worksite are not strictly defined and followed;

• innovation in the use of materials tends to solve the weak points in the use or behaviour of the material. for concrete pavements, special mixes aim at higher strengths of the young concrete while for asphalt the aim is mixes that can be

19

2012R09EN


produced and laid at lower temperatures. Both developments have mainly the same objective: reduction of the construction time, reduction of the hindrance to road users and an overall positive environmental impact.

the case-histories provide a good illustration of the different techniques that are available and of their use worldwide. they confirm the difficulty of combining reduction of time and cost concurrently and also indicate that these issues have gained a lot of importance and that research and developments are still going on in these fields.

2. conclusions and Recommendations

a number of tools are available to influence the construction time and cost for a specific project. these tools, which are related to tendering procedures, organisation and technical issues, have been discussed and evaluated. even though the conditions can be very divergent for different projects, a long-term vision should be sought.

other decision-support tools such as lca (life cycle assessment) for the environmental impact and lcca (life cycle cost analysis) for the economic impact can help in making the right decision. entire life cycles – from cradle to cradle – including the usage phase should be considered. the negative consequences of a reduction of time or cost on the long-term behaviour or on the long-term environmental impact should be as low as possible. therefore all the methods, described in this document, should be used cautiously; e.g., a contractor should not keep on paving in bad weather conditions only because of the bonus he will get for a shorter construction time. Bonuses for time reduction should go along with bonuses/penalties for quality of the work. in the case of performance-based specifications, an extended warranty period should be provided. the duration of this warranty period should be different for asphalt and concrete, due to the different lifetimes of the respective pavements. for dB(f)m contracts (design – Build – finance – maintain), the considered maintenance period should also be over a long enough period (30+ years) in order to encourage long-life pavements requiring a minimum of maintenance throughout their lifetime.

as a final conclusion and recommendation, the issue of “reducing” construction time and cost should rather be considered as “optimising”. indeed, the objective is to find a well-balanced solution that meets all of the goals taking into account the different priorities and specific conditions of the project. for larger projects, this can become a difficult exercise and one could use a multi-criterion analysis in order to come to the best fitting solution with regard to the criteria: cost, construction time, quality, environment, etc. this “best solution” can only be achieved when each party takes up his responsibility in the construction process. each player, from the designer and calculator to the craftsman on the worksite must be aware of the importance of his contribution. He must always remember that every idea, initiative or action has an impact on the final result and that he can make a difference.

20

2012R09EN


3. appendices

3.1. concRete pavement – ppp easteRn Region

Karin Keglevich, Reinhard Pichler; Arno Piko, Austria

the ppp (public private partnership) project eastern Region is one of the biggest building sites in central europe these days. the project includes the construction of approx. 52 km of a highway (a5) respectively of expressways (s1 east, s1 west and s2) as well as several provincial roads.

21

2012R09EN


the project includes the following civil engineering structures:

• 76 bridge structures;• 3 tunnels: 4,5 km antipollution tunnel in the stetten area;

2,4 km tunnel tradeberg; 0,5 km antipollution tunnel eibesbrunn;

• 18 tank constructions;• 25 basins including 42 pumping stations;• 81 km of noise protection measures;• 2 service stations.

3.1.1. concrete pavement on the main route

in general the main route (motorway and expressway) has been constructed as a dual carriageway with two lanes in each direction. furthermore some parts have been manufactured with three lanes in each direction and a hard shoulder throughout the whole section. the road surface of the carriageway with approx. 102 km has been paved with a noise-reducing washed concrete. thereby an aggregate size with a maximum of 8 mm and surface treatment with gunny cloth was used.

according to the austria guidelines (Rvs 8.17.02 [1]) the concrete pavement is placed in two layers green-to-green with slip-form. the subconcrete has been paved with 21 cm while the surface concrete has a thickness of 4 cm.

22

2012R09EN


the amount of the expressway concrete pavement is approx. 634.000 m² and the motorway area approx. 726.500 m².

in addition approx. 42.000 m of cast-in-situ concrete step barriers with a height of one meter are constructed in compliance with Rvs 08.23.06 [3] throughout the whole route.

3.1.2. concrete pavements in secondary facilities

particularly 20 roundabouts at junctions and intersections on provincial roads as well as slowdown areas on cross-roads are implemented with concrete pavements. consequently an area of 35.000 m² was built.

in general, concrete pavements of secondary facilities (roundabouts and junctions) are manually paved with a thickness of 25 cm by using a superplasticizing agent (concrete grade c 30/37 / B7 / xm2 according to Rvs 08.17.03 [2]). a few structures were paved with a slip-form paver in single-layer construction.

3.1.3. construction period

in september 2008 the road works started, the paving construction was finished in august 2009.

23

2012R09EN


3.1.4. traffic opening

the sections s2 and s1 east had been opened to traffic in november 2009, while the sections s1 west and a5 is going to complete in february 2010.

3.1.5. bibliography

• [1] Rvs 08.17.02 Betondecken – Deckenherstellung; edition 1 march 2007.• [2] Rvs 08.17.03 Kreisverkehrsanlagen mit Betonfahrbahndecken Markblatt;

edition 1 february 2009.• [3] Rvs 08.23.06 Straßenausrüstungen – Rückhaltesysteme – Leitwände aus

Beton; edition 5 april 2005.

3.2. ReconstRuction of highWay a1 Regau – seeWalchen, using Recycled concRete

Franz Lecker and Peter Schöller ÖBA – Österreichische Betondecken ARGe (Austrian Concrete Pavement Consortium), Austria

the building site of highway a1 includes approx. 10 km and ranges form the junction Regau to seewalchen. the construction costs of this highway section are approximately 40 million euros (net).

the road construction works included removal of the old concrete structure, extension of the carriageway, construction of the new concrete pavement including secondary facilities as well as the complete traffic management. thus the challenging construction period of 17 months was the limiting factor.

in addition, the aforementioned project contains the renewal of 14 bridge structures (12 new structures) and several noise barriers.

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3.2.1. concrete pavement construction

the road surface of the subject highway section consists of approx. 238,000 m2 of concrete pavement slabs.concrete pavement slabs in austria are paved in two lifts, wet on wet according to the austrian guidelines (Rvs 8.17.02). at this project the lower concrete course is 20 cm thick, made partly with recycled concrete aggregates (32 mm maximum aggregate size) that do not need to be highly wear resistant. furthermore the upper concrete course is 5 cm thick and contains smaller (8 to 11 mm maximum aggregate size) aggregates with high wear resistance.

Basically the application of recycled concrete in new layers is very common on austrian highways and the performance is equal to new paved concrete materials.

the surface was executed with noise-reducing exposed aggregate texture.

concRete paving convoy (junction scHöRfing)

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concRete paving convoy – aReal view (a2 lassnitzHöHe)

suRface tReatment (left) and concRete finisHeR (RigHt)

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3.2.2. construction period

construction phase 2: Renewal direction salzburg (july 2008 – june 2009).

construction phase 3: Renewal direction vienna (july 2008 – june 2009).

due to the adverse weather conditions at the beginning of last year it was impossible to start in spring. nevertheless the project team was able to stay on the time schedule and finished in time.

3.3. inlay in continuously ReinfoRced concRete on the motoRWay a10 bRussels - oostende (2002, 2003 and 2009)

ir. Chris Caestecker – ir. Tim Lonneux, Ministry of the Flemish Community, Roads and Traffic Agency, Belgium

a part of the a10 motorway between groot-Bijgaarden and ternat, has been rehabilitated in 2002 and 2003 by the technique of an inlay in continuously reinforced concrete. the goal was to finish the work in the shortest possible period, without loss of quality and with all three traffic lanes kept open all the time in both carriageways on this very busy motorway.

therefore, several measures were taken: in the tendering documents, in the technical options and in the worksite organisation.

the a10 Brussels - oostende is a part of the motorway e40 and has to cope, on a typical day, with an average traffic intensity of 57,000 vehicles in each direction. in the province of flemish-Brabant, the existing asphalt pavement had been a source of problems. Rutting was discernible on the right-hand and middle lane. on the middle and the left-hand lane, reflection cracks appeared due to the underlying concrete slabs. moreover the section of road was badly affected as the result of the earlier stabilisation of the concrete slabs with bitumen. in some places the bitumen was pushed up through the top layer, with oily areas resulting in an uneven road pavement.

in order to obtain a road surface that would not need frequent repairs or any major maintenance works for the next 40 years, it was decided to opt for a new pavement in continuously reinforced concrete.

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Because of the high volume of traffic and the daily structural queues in the direction of Brussels, it was economically unwarrantable to close a lane during the works. the goal to finish the project in the shortest possible time and the extra condition that the 3 traffic lanes in both directions would have to be kept open all the time, necessitated a number of measures in different domains.

3.3.1. tendering conditions

the call for tenders (2003) was organised in an innovative way. the allocation of the works was defined according to two parameters: on the one hand the cost as mentioned in the bid and on the other hand a social cost amounting up to €50.000 /day. following formula applied:

p = n x 50.000 + min which: p = allocation amount;m = amount of the bidding;n = construction time in calendars days, mentioned by the contractors in their bid.

obviously, this formula resulted in a considerable reduction of the construction time, proposed by the contractor. in addition, the contractor could obtain a bonus of € 25.000 for each day that he needed less than the construction time mentioned in the bid. on the contrary, for each day delayed, the penalty amounted € 50.000.

the construction time set by the contractor was 126 calendar days. the works have been completed in a record time, from june 26th, 2003 until october 26th, 2003, that is in 122 calendar days.

3.3.2. organisation of the worksite

in order to keep three traffic lanes available for both carriageways, the work was split in different phases (see figure 1, following page):

• phase 1: construction of emergency strips along the existing hard shoulder;• phase 2: Breaking up of the central reserve. using the existing hard shoulder, the

traffic is put on 2 x 3 lanes towards the outside with a width of the right lane of 3 m and a width of 2,75 m for the other two;

• phase 3: Rehabilitation of lanes 2 and 3 towards Brussels. the heavy traffic towards Brussels stayed on the existing hard shoulder; the other two lanes were diverted to the other half of the highway;

• phase 4: Rehabilitation of the hard shoulder and the slow lane towards Brussels. two lanes were again diverted to the other side, one lane used the newly laid most left lane in the direction of Brussels.

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the same scenario was repeated in the other direction.

phase 1

figuRe 1 - RepResentation of tHe 4 pHases of tHe woRks and tHe tRaffic management

safety barriers work zone

phase 3

phase 2

phase 4

the replacement of the existing central reserve, consisting of two safety barriers and a green zone in between them, by one single safety barrier (us type f) was a key factor in finding the space for a continuous traffic flow.

a typical problem with this kind of works is the queue created by curious drivers, passing along the worksite. in order to avoid this phenomenon, it was decided to screen off the construction zone from the traffic by means of screens.

the short construction time forced the contractor to work in a continuous way, 24 hours a day and 7 days a week, so weekends and holidays included. during the night, the worksite was illuminated by lighting balloons, fixed on the slipform paver.

the smooth proceeding of the concreting works requires a steady supply of the pavement concrete. for that reason, two computer controlled concrete batching plants, with a capacity of 120 m³/hr each, were located on site.

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3.3.3. adequate technical choices

counting on the solid structure of old concrete slabs or lean concrete beneath the degraded asphalt layers, the road authorities choose for the solution of an inlay. this means that a part of the existing asphalt depth is milled off, providing in the same time a new longitudinal and transverse road profile, and is overlaid with the new road structure consisting of a new intermediate asphalt layer of 6 cm thickness and a 23 cm continuously reinforced concrete pavement (cRcp), which is a typical Belgian road structure for motorways.

the technique of inlay or the use of the existing structure as a base has several important advantages, compared to a complete rehabilitation of the road structure: • less transport of materials;• less use of new materials;• reduced construction time;• reduced construction cost.

the specifications of a high quality pavement concrete mix (400 kg of cem iii/a 42,5 per m³, water cement ratio below 0,45) made it possible that each phase of the new road could be opened to traffic only 6 days after completion of the last work. the average compressive strength after 5 days on 3 test cores amounted to 50 mpa with a standard deviation of 1.6 mpa.

different from a classic wire guided machine, the slipform paver was steered by a set of 3d total control stations: two to control the paver and the third to ‘leapfrog’ the trailing total station when necessary and to check the as-built measurement.

the 250.000 m² of motorway were concreted in only 122 days and the total cost amounted up to € 20 million, bonus and vat included. in spite of the speed of work and the night work, the quality could be maintained thanks to thorough quality control systems and an ultra modern machine park. the extraordinary dedication on behalf of the contractor in maintaining 2x3 lanes operational during all sequences of the works and the continuously ongoing activities on the worksite resulted in numerous positive reactions from the road users. taking into account the reduced user delay costs and the long design service life of the new pavement, we can conclude that a very life-cycle cost-effective solution was found for this ambitious rehabilitation project and that the hindrance for the society was limited in the best possible way.

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3.4. the Rehabilitation of the antWeRp Ring Road (2004-2005)

3.4.1. introduction

the R1 is an urban motorway located at approximately 3 km from the centre of the city. the 14 km long ring road comprises the j.f. kennedy tunnel in the southwest and the merksem viaduct in the northeast. several fully directional interchanges provide the link with 6 radial motorways tying into the R1. due to the vicinity of the ring with regard to the city centre local access and exit ramps are provided as well.

in 2003, after 35 years of service, the maximum traffic intensity on the R1 was nearing 200.000 vehicles per day, of which 25 % trucks, what made it to one of the most trafficked motorway links in europe. this situation had led to the need for a complete structural rehabilitation of this motorway. it consisted not only of a pavement renewal but also the renovation of 170 km of sub-surface drainage pipes and storm sewers, manholes, road appurtenances, bridges, utility tunnels for pipes and cables, etc.

this project was unique in the history of Belgian road construction, due to its size (a total cost of approximately 100 million euro) but also due to the comprehensive approach that was put first during the study and realisation. in addition to the pure technical works, a lot of attention also was paid to the establishment of an ambitious programme of “Less Disturbance” measures in and around antwerp and to a maximum recycling of the broken up materials, in favour of the environment. this comprehensive approach made it possible to execute the works in a record period of two times approximately five months.

the original pavement on the motorway consisted of asphalt on a base of lean concrete or unbound coarse aggregates. after a thorough comparative study of the different alternatives, the main part of the existing pavement was replaced with a new pavement structure consisting of 23 cm continuously reinforced concrete

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(cRcp) supported by a 5 cm thick bituminous asphalt inter-layer, 25 cm of cement stabilised asphalt rubble and 15 cm recycled crushed lean concrete. a fine textured exposed aggregate concrete surface was applied in order to obtain an excellent skid resistance combined with a reduction of the rolling noise.

the original pavement in concrete slabs in the kennedy tunnel was replaced with a new pavement of the same type with a similar foundation as for the cRcp.

3.4.2. tendering conditions

the international importance of the R1 along with the extremely high average daily traffic volumes necessitated to keep the construction period as short as possible. this construction period was limited to 140 calendar days during construction period 1 for the outer Ring and to 150 calendar days during construction period 2 for the inner Ring.

in addition to these short construction periods a working time of 16 hours per day, 7 days a week was imposed for the rehabilitation works on the mainline. the rehabilitation works in the kennedy tunnel had to be carried out continuously, 24 hours a day, 7 days a week.


a separate temporary haul road was built over the entire length of the project. this road was also intended for use by emergency vehicles and crossed the ramps of the interchanges by means of temporary grade separations. the creation of this road was a key-factor for the contractor allowing him to reduce the construction period.

in order not to overload needlessly the surrounding roadway network, the provision of a screening and a batching plant on the construction site itself had to be foreseen. these plants were utilized to recycle the broken up materials and to supply the concrete.

a continuous blinding screen on the median ensured a visual separation between all through traffic detoured on one carriageway and the construction operations on the other carriageway.

the selected regulation of traffic during execution necessitated a well thought-out phasing and organization of the works and resulted in a construction method of the cRcp, which was phased both longitudinally and transversally.

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3.4.4. adequate technical choices

choice of the type of pavement

considering the limited space because of the requirement to maintain traffic on at least 1 lane and due to the relatively small radii of the alignment curves it was immediately decided to use asphalt for the pavement of the ramps of the interchanges.for the new pavement on the actual Ring Road a thorough comparative study was made of the type of new pavement structure to be used, i.e. asphalt pavement versus continuously reinforced concrete pavement (cRcp).

at first a life cycle cost analysis was made. this involves an economic appraisal. subsequently a multi criteria analysis was made in order to take into account in the appraisal the non-budgetary aspects as well.

the lcca indicated that, at the moment of initial construction, an asphalt pavement is less expensive than a cRcp. on the long term, taking also into account future rehabilitation and re-construction costs, the net present value over an infinite horizon appeared to be comparable and slightly beneficial for cRcp.

upon performing the multi criteria analysis besides economical aspects other aspects were considered as well such as amongst others noise, recycling, comfort, safety, execution time, winter maintenance, etc. a score is assigned to each type of pavement for each of the criterions. furthermore, a weight factor is allocated to each criterion, taking in account the particular circumstances of the R1.

this analysis resulted in an overall score of cRcp that was slightly better than that of an asphalt pavement. Because of the small difference in the scores a sensitivity analysis was performed subsequent to the mca. this revealed that the overall score for the asphalt pavement alternative would become better than that of the cRcp only when the criterion of the execution time is assumed to have absolute priority.

Based on this comparative study the decision was made to renew the pavement on the actual Ring Road using cRcp with the exception of the asphalt pavement on the viaduct. indeed, the longer lifetime and the very little maintenance required finally tipped the balance in favour of cRcp. the scale of the works and of the accompanying traffic alleviating measures was so enormous that this kind of intervention, with such a socio-economic impact, should not be repeated too soon.

Recycling

it was a major purpose of the rehabilitation project to apply recycling of broken-up materials to the maximum possible. this was a logical consequence of the very large

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quantities of broken-up and recyclable materials, of the envisaged short construction period, and last but not least, of the decision not to create additional traffic flows by hauling broken-up materials and by supplying new materials.

due to these circumstances a detailed study was made of the opportunities for recycling. the envisaged service lifetime of the new pavement structure, the very large quantities of recyclable materials and the experiences in Belgium and abroad were taken into account in this study.Recycling in itself is not new but the large scale that was at stake was new and unique in Belgium.

the existing asphalt pavement was recycled:

• partly in the new bituminous pavement mixes;• partly in the new base of cement bound asphalt rubble (cBaR) consisting of a

homogeneous mix of sand, aggregates (in this case asphalt rubble), batching water and a binder. Belgian standard specifications only provide cement as a binder for the use in base layers. a cement content of 4% (of the dry mass) allows achieving the required compressive strength of 3 mpa after 7 days. after 28 days, the compressive strength must reach 5 mpa. in order to arrive at a continuous gradation and at a maximum density of the base after compaction, it was necessary to add 15 to 20 % sand.

3.4.5. References

• “Accompanying measures for the rehabilitation of the Antwerp ring road”, griet somers, accessibility manager, “Less Disturbance” contact point, flanders Region, Belgium & patrick debaere, project leader, flemish authorities, Belgium, piaRc-magazine Routes-Roads, n° 329, 2006.

• “Rehabilitation of the Antwerp Ring Road. Innovative approaches and techniques”, manu diependaele, engineering Bureau tecHnum & luc Rens, feBelcem, paper at the 10th international symposium on concrete Roads, Brussels, 2006.

3.5. cold in-place Recycling in canada

Betty Bennett and Becca Lane, Ontario Ministry of Transportation, Canada

the ministry of transportation of ontario (mto) has an active pavement recycling program that is strongly promoted and monitored for performance and cost-effectiveness. over the past 21 years, mto has successfully in-situ recycled over 7,200,000 m2 of hot mix asphalt (Hma) pavement. this has been achieved using cold in-place Recycling (ciR) with asphalt emulsion and more recently, cold in-place Recycled with expanded asphalt mix (ciReam).

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the mto is committed to using technologies to help build a more sustainable transportation system that supports today’s needs while protecting the environment for future generations. the increasing cost of fuel together with the development of improved in-place processing methodologies has accelerated pavement recycling in ontario.

the placement of ciR and ciReam consists of processing the existing pavement surface material through an in-situ screening/crushing machine and either infusing the reclaimed asphalt pavement with asphalt emulsion (ciR) or expanded asphalt cement (ciReam). the material is placed to the desired profile with a hot mix paver, compacted to the desired density, and overlaid with a single lift of Hma. these technologies support a “zero waste” approach to pavement rehabilitation where the existing road material is reprocessed and reused in place, without offsite transportation. essentially, no resources are wasted and the need for additional pavement materials is minimized.

to date, mto has completed 52 cold in-place Recycling (ciR) and 17 cold in-place Recycled expanded asphalt mix (ciReam) contracts that equate to approximately 1,920 lane-km of pavement recycling.

an analysis was carried out to compare ciR and ciReam with a conventional rehabilitation strategy consisting of milling the existing asphalt surface to a depth of 100 mm, paving 130 mm of Hma in three lifts and compacting to the desired density.

3.5.1. materials savings

for a 1 km section, ciR/ciReam consumes 920 tonnes of aggregate compared to 2,400 tonnes required to mill and place a three-lift overlay. this equates to a 62% savings in aggregate consumption. when multiplied by the quantity of ciR and ciReam placed since 1989 (7, 200 000 m2), aggregate savings are in the order of 1.5 million tonnes.

3.5.2. cost savings

Table 1 compares the costs of ciR and ciReam with a conventional pavement rehabilitation strategy over a 1 km section.

table 1 - cost compaRisonciR / ciReam mill & overlay

depth - milling - 100 mmdepth - ciR 100 mm -width 7.5 m 7.5 msurface course 50 mm 40 mmBinder course - 90 mmprice $100,000 / km $173,000 / km

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a cost savings of 42% is realized with the use of ciR and ciReam.

3.5.3. time savings

ciR and ciReam are moving operations that are capable of milling and placing several kilometers of roadway per day. in addition to being highly productive processes, road safety is improved by reducing traffic disruptions and driver inconvenience.

3.5.4. performance

the performance of ciR/ciReam contracts are continually monitored and compared to traditional rehabilitation methods using internationally recognized performance measures such as the pavement condition index (pci) and international Roughness index (iRi).

Figure 1 illustrates the performance trends of ciR/ciReam compared to a traditional rehabilitation technique (mill and overlay).

93.0 92.9 92.4 91.3 89.7 87.9 86.0 83.7 81.5 79.2

77.6 75.379.881.883.685.286.387.087.287.3

40.050.060.070.080.090.0

100.0

1 2 3 4 5 6 7 8 9 10

Age

PCI

Avg. PCI (Mill & Overlay) Prediction

Avg. PCI (CIR/CIREAM) Prediction

figuRe 1 - pavement condition index (pci) compaRison

the conventional mill and overlay rehabilitation strategy is smoother to start resulting in a marginally better performance. However, the life cycle cost analysis (lcc) over a 30 year period reveals that the ciR/ciReam is the more cost effective solution in terms of life cycle costs, which include initial construction, maintenance and future rehabilitation treatments.

3.5.5. summary

the mto is committed to using technologies to help build a more sustainable transportation system that supports today’s needs while protecting the environment

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for future generations. the increasing cost of fuel together with the development of improved in-place processing methodologies has accelerated pavement recycling in ontario.

in addition to the environmental, social and economic benefits of recycling in terms of aggregate consumption, greenhouse gas emissions and performance there are also significant per-lane kilometer cost savings and time efficiencies realized when compared to conventional pavement rehabilitation techniques.

3.5.6. References

• alkin, a., lane B., kazmierowski, t.j. Sustainable Pavements – environmental, economic and Social Benefits of In-situ Pavement Recycling, ontario ministry of transportation, tRB january 2008

• lane, B., and t.j. kazmierowski. Implementation of Cold in-place Recycling with expanded Asphalt Technology in Canada. in transportation Research Record: journal of the transportation Research Board, no. 1905, tRB, national Research council, washington, d.c., 2005.

3.6. Removable uRban pavement

T. Sedran and F. de Larrard, Laboratoire Central des Ponts et Chaussées (LCPC), France

Concrete slabs

6/10mm granular material

SECTM

Subbase

Cast‐in‐place soft polymeric joints

Void

210

30

600

Rup in saint auBin

urban pavements have many functions, and incorporate many different types of utility networks (telecommunications, water, power electricity, etc.). as a perfect coordination between all operators is very difficult to achieve, these pavements are subject of frequent works, sometimes soon after construction or maintenance. these works are quite bothering for the human environment, causing noise, air pollution and traffic jams. in that context, lcpc has leaded a R&d

program between 2003 and 2009 in france aiming at developing a new Removable urban pavement (Rup). in this original generic concept the pavement can be opened and closed within some hours, with a very light site equipment, restoring the initial aspect of the street and all its functional abilities. two cities have experienced such a Rup. the results are presented in [eRlpc 2009] and a technical guide was produced by the project partners to help the future owners making the prescription for such a pavement [cud 2008].

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more information on http://heberge.lcpc.fr/cud/

3.6.1. preliminary survey and potential market

preliminary to the project, about 40 city authorities were interviewed to identify the potential advantages of a Rup technology, according to the average customer opinion. the three most significant were:

• reduction of user and neighbour annoyance caused by maintenance work operations thanks to the reduction of construction time;

• easy access to underground networks;• sustainable management of the pavement (possibility to repair or to change the

functions of the pavement, with an easy reusing of the modular elements).

in the context of contemporary urban developments, four potential markets were identified through this survey: downtown streets, boulevards and urban highways; new residential areas, and tramway lanes.

3.6.2. the concept

precast hexagonal concrete slabs are put on a thin gravel bed laid on an easy-to-dig base material:

• hexagonal shape is selected since the risk of angle failure is greatly reduced compared to rectangular shape. the size of the slabs is limited to allow and easy removing with light site equipment;

• gravel bed is used to level the concrete slabs and also facilitates the water drainage;• a specific compacted cement-treated material was developed as a base material

and called structural excavatable cement treated material (sectm). treatment is used to give a good cohesion to the material and ensure vertical borders during excavation. the binder is pure portland cement because a rather quick strength development is desirable, to allow a rapid opening to traffic and to avoid long term strength gain which would overcome later excavation works. the cement content (generally around 25 kg/m3) is adapted to reach a compressive strength at 28 days lower than 2.5 mpa to ensure excavation and a tensile splitting strength at 28 days higher than 0.16 mpa to ensure the bearing capacity of the base.

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Concrete slabs


SECTM

Subbase


Void

210

30

600

excavation of sectm

then, when necessary targeted concrete slabs can be removed and the underlying base dig to reach the network to be maintained. after the intervention, the hole can be filled again with classical self levelling trench filling materials (also called controlled low strength materials, clsm) and the slabs rapidly replaced on the pavement.

3.6.3. the saint aubin project (summer 2007)

saint aubin-lès-elbeuf is a city located near Rouen in department of seine-maritime in the west of france.

the project consisted in a 90-m long straight street in an industrial area rehabilitated as a residential one. in order to facilitate their removing, independent slabs were selected as well as 70 cm border length for the slabs, which gives a weight less than 800 kg for each slab. this weight was low enough for easy handling but high enough to avoid unauthorized removing and slab faulting under trucks wheels.

three-dimensional finite element computations were carried out in order to evaluate the stresses induced by the traffic in the slabs and the base course. allowable stresses were determined using the classical french pavement design fatigue approach and adapted dimensions were then selected.

Concrete slabs


SECTM

Subbase


Void

210

30

600

saint auBin Rup design. dimensions aRe given in mm

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constRuction of tHe saint auBin Rup.

Removing of a slaB on saint auBain Rup

3.6.4. the nantes project (summer 2008)

nantes is a city located in department loire atlantique in the west of france.

the project consisted in a 12 x 7 m, corresponding to approximately 155 slabs, in an industrial zone near a material stocking area, submitted to significant lorry traffic. Because the owner had a vacuum tool with a limited capacity, a maximum weight of 250 kg per slab was needed in this project. it leads to select slabs with a border length of 46 cm. yet, with smaller slabs, the effect of stress diffusion from the truck wheels to the base course is minimized and risk of slab faulting is increased. that is why the slabs were equipped with keys to connect them to each others. to avoid failure of these keys, steel fibers were added to slab concrete.

three-dimensional finite element computations were carried out in order to design the structure shown below.

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concrete slabs

2/4 mm gravel

SECTM

Platform (E > 50 MPa)

190

30

2 x 200

joints filled with 0/2 mm sand

120°

nantes Rup design. dimensions aRe given in mm

concrete slabs

2/4 mm gravel

SECTM


190

30

2 x 200


120°

nantes Rup undeR constRuction and finalized

due to the presence of the connecting keys, the removing of the slab is slightly more complicated but has proved to be rapidly feasible.

concrete slabs

2/4 mm gravel

SECTM


190

30

2 x 200


120°

Removing of tHe connected slaB Rup. all slaBs inside a 120° diHedRal must Be Removed to ReacH any inneR point of tHe pad

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3.6.5. main conclusions

• the two experimental Rup behave well under traffic since their construction;• calculations have been carried out to compare cost of Rup and classical urban

pavement (cup) which consists in a granular untreated material layer covered by a thin asphalt concrete wearing course:

• construction cost of Rup is 3 to 4 times more than a classical pavement;• construction + maintenance cost on a 30 year lifespan is comparable for Rup

and cup. in fact during its life, urban pavement is opened frequently. each opening work would result in a certain cost, proportional to the duration of the task. this duration was taken at 2.5 days for a cup, to be compared with 0.5 day for a Rup;

• lower duration of maintenance tasks on Rup limits the annoyance to the neighbourhood and the number of days of traffic interruption. so a total calculation including social cost is clearly favourable to the Rup solution.

• the Rup concept is a free open technology. a technical guide [cud 2008] available on http://heberge.lcpc.fr/cud/ gives tables to design such pavements on the basis of the traffic and the size of the slabs.

3.6.6. to know more about Rup

• [de larrard et al. 2006] de larrard f., Balay j.m., sedran t., laurent g ., leroux a., maribas j ., vulcano-greullet n., sagnard n., masson j.m., Belouard R., Development of a removable urban pavement technology, 10th international symposium on concrete Roads, Bruxelles, 18-22 september 2006.

• [de larrard et al. 2007] de larrard f., Balay j.-m., sedran t., masson j.-m., durame p., Belouard R., pommelet p., cante d., laurent g., leroux a., maribas j., petit g., vulcano-greullet n., metais g., mancina l., sagnard n., Bruny s., le lez c., grin l., abdo j., Brissaud l., Removable urban pavements: a new neighbour-friendly technology, congrès de l’association mondiale de la Route, aipcR, paris, september 2007.

• [de larrard et al. 2008] de larrard f., masson j.-m., pommelet p., laurent g., leroux a., maribas j, sagnard n., pellevoisin p.., grin l., Removable urban pavements: the only sustainable technologies for modern cities?, transport Research arena, ljubljana, april 2008.

• [cud 2008] “Chaussées Urbaines Démontables - Guide Technique 2008”, technical guide, published by ceRtu, de larrard ed., december 2008, available on http://heberge.lcpc.fr/cud/ , in french.

• [eRlpc 2009] “expérimentations sur les chaussées urbaines démontables” (experimentations on removable urban pavement), etudes et recherches des lpc, eg 22, de larrard ed., 138 p., june 2009, http://heberge.lcpc.fr/cud/, in french.

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3.7. Recycling of a concRete suRface and use of Rc-aggRegate in a gRavel base couRse in the fRameWoRk of the complete ReconstRuction of the motoRWay bab a11 betWeen beRlin and szczecin (stettin) (2009)

Rudolf Bader, Bietigheim, Stefan Höller, Bergisch Gladbach, Germany

in 2009, the complete reconstruction of a 3.8 km long section of the motorway BaB a11 between Berlin and szczecin (stettin) took place. the a11 was built in 1936 and slab had a thickness of 20 cm. Reinforcement was used within the individual concrete panels. the formation of the longitudinal and transverse joints were carried out without dowels or tie-bars, the transversal joints partly in the form of expansion joints. Base courses or frost-protection layers were

not applied. the concrete slab was being constructed between pre-installed side forms, whereas the paving process was done by using a so-called paving train operated on rails, positioning the slab directly on the in-situ compacted sand.

after 69 years of intense use and weather exposure, the surface was severely damaged at certain spots, which consequently called for a complete renovation. the new concrete slab was built on a gravel base course whereas the old pavement was being recycled and reused in the gravel base course.

parts of the project are situated within the landscape protection zone “Biosphere Reserve Schorfheide”. therefore an environmentally friendly construction method was required, while minimising the logistical impact and resources. specifically, this meant that the 60,000 m² of old concrete slab had to be recycled on site and used as an Rc-aggregate which was mixed into the gravel base layer. consequently the usually known hauling routes for the supply of new aggregates could be avoided. Hereby, a very environmentally friendly and in addition cost-effective solution had been found. the original cross-section of 9.5m width per traffic direction was widened to 11.5 m in order to have two traffic lanes and one emergency lane. various alternative design options had been evaluated, resulting in the choice for a 30 cm gravel base course.

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3.7.1. preparatory work and development

during the construction period, traffic was diverted to the opposite traffic lane. first the existing concrete surface was stress-relieved using a drop pile concrete breaker, as shown in figure 1 on the right. after an excavator with screening bucket has removed the slab, dumpers transported the crushed concrete to the crushing plant.

figuRe 1 - stRess-Relieving and Removal of tHe concRete suRface

3.7.2. crushing and sizing

the crushing was carried out with an impact mill crusher with a maximum capacity of 350 ton/hour which was equipped with an integrated steel separation system by means of a magnet and the automatic refeeding of oversize material into the crushing process.

in order to achieve the required grain size distribution of 0 to 45 mm (see figure 2, right, following page) the excess sand was separated (see figure 2, left) and reused in the earthwork. this type of crushing plant was selected, as it produces particularly advantageous cubic grain forms. large proportions of the old concrete volume could be valuably reused. only about 4% of excess sand was downcycled.

the crushing plant was positioned directly adjacent to the route in the middle of the building site. this resulted in a short transport distance between the construction site and the crushing location of only 0 to 1.5 km.

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figuRe 2 - impact mill cRusHeR and ReQuiRed gRain size distRiBution

3.7.3. gravel base course construction

figuRe 3 - douBle-layeRed constRuction of a gRavel Base couRse

after completion of the breaking and crushing of the old concrete surface, the double-layered gravel base course formation was constructed with the generated 25,000 tons and the additionally delivered 18,000 tons of technically equivalent Rc-aggregate. the installation of the bottom layer with a thickness of 20 cm was carried out by a bulldozer, (left in figure 3); the top layer with a thickness of 10 cm was carried out by a road paver (see figure 3, right). each layer was compacted with smooth rollers. finally, the 30 cm double-layered concrete slab was paved with a slipform paver.

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3.7.4. summary and outlook

in 2009, on the motorway BaB a11 between Berlin and stettin, within the framework of a complete reconstruction, 60,000 m² of damaged concrete surface dating from 1936 was recycled and reused in a gravel base course. the processing site was directly adjacent to the construction site. the transport costs for coarse aggregate were reduced to a transport distance of 1.5 km.

this resulted in a very environmentally friendly, cost-effective solution for this type of building measure.

the transportation of concrete rubble and Rc-aggregate over 1.5 km caused costs of approximately 2€/ton. thus, this alternative was significantly more cost-effective than the recycling in a usually adopted stationary plant with transport routes of 10 km and more.

further optimisation options:

• providing the crushing of the old concrete would take place on the spot itself, these costs could also be saved. However, in this case a slab width of approximately 15 m would be required, which was not the case in this project;

• the Rc-aggregate can be used with even more value, for example in a new concrete surface. in that case, higher demands would be placed on the Rc-aggregate.

3.8. fast tRack – Rehabilitation of concRete slabs on highWay and aiRpoRt pavements in one WoRking shift using fast setting concRete

Ralf Alte-Teigeler, Bietigheim, Stefan Höller, BergischGladbach, Germany

the increase of road and air traffic density demands trafficable surfaces with increased life spans and reduced maintenance requirements. particularly for areas with heavy traffic, concrete construction provides more advantages when compared with asphalt construction. However, where a concrete pavement sustains damage and requires the replacement of a single slab, this necessitates longer road closures, to allow sufficient time until the concrete has hardened. this is particularly

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problematic on high-volume traffic highways and at airports. However, in recent times a system has been developed which allows reconstruction of single slabs within 6 to 8 hours and opening to traffic immediately afterwards. with this capability, the major disadvantage associated with concrete construction can be eliminated.

Con

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Composition of high performance repairconcrete with Sika basic mixture CR

350 kg/m³Quarzsand 2/8 mm

if necessaryRetarder

if necessarySuperplasticizer

160 kg/m³Water

900 kg/m³Crushed aggregates 8/16 mm


390 kg/m³Special rapid hardening cement

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compressivestrengthtensile strength

split tensile strength

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Typical strength development of high performance repair concrete

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Testing method:CDF-Procedure

the system of single slab replacement within 6 to 8 hours was developed in a step-by-step process. the first step was made at leipzig airport in 1994. concrete pavements that had sustained edge damage were required to be repaired in a construction window of 2 to 3 hours (including hardening time), and the runway had to be re-opened immediately afterwards. after several attempts

a mixture for a repairing mortar on a portland cement base without any resin additives was developed. the mixture showed short hardening times and a similar expansion-coefficient to concrete. the result was successful and follow-up examinations showed that the repaired edges remained in a perfect condition after more than 10 years.

the second step involved renewing small slab parts in short work windows. the previously developed quick-setting repair mortar technique was applied and the first concrete mixture was developed. due to the success of these works, the third step of replacing entire concrete slabs followed, and is presently in implementation. with further development it became clear that the success of this procedure depends on an optimal combination of material, machines, devices and staff.

3.8.1. material requirements

in cooperation with sika, the special concrete mixture was developed. it consists of the components listed in figure 1, following page. one of the most important components is the specially-prepared portland cement. Resin additives are not used. this composition allows high final strength, after only a short period, sufficient freeze-thaw-resistance and as a result a successful long-term solution is achieved.

in addition to these requirements, reasonable material prices and careful processing are important. at a temperature of 20° to 25°c the processing time takes 40 minutes. at lower temperatures processing and setting times are extended.

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C

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160 kg/m³Water




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Strength in MPa

Age of concrete


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figuRe 1 - concRete composition, development of concRete stRengtH and fReeze-tHaw-Resistance

3.8.2. machinery – mobile mixers

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160 kg/m³Water




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Strength in MPa

Age of concrete


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figuRe 2 - moBile mixeR foR fast setting concRete

a special mobile mixer with a volume of 16 m³ was developed, as shown in figure 2. this allows the quantities of each component to be weighed, water to be added and the mixing procedure to take place directly at the construction site. the time required for delivery of ready-mixed fresh concrete is eliminated.

concrete construction can begin directly after the mixing procedure, hence a short work-time time of 40 minutes is optimal. specific transport concrete plants and vehicle mixers are only partly suitable for this application.

in addition, the volume of 16 m³ also permits replacement of larger areas (for example, 7.5 m x 7.5 m x 0.4 m) which are common on airport pavements, with only one mixing process required.

previous attempts with smaller mixers of 1 m³ capacity have produced suboptimal results, because subsequent mixing process were required, which necessitated joints and transitions with existing concrete areas, which become weak spots.

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Con

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160 kg/m³Water




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Age of concrete


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figuRe 3 - cutting tHe existing concRete field

after the installation of the required construction site safety measures, the existing damaged concrete pavement is carefully removed without damaging the existing base course. this requires the separation of the existing pavement, facilitated by a series of surface cuts in segments of approx. 0.8 x 0.8 m, as shown in figure 3. the cuts at the edges of the slab segments should be slightly inclined, to facilitate easy slab removal in subsequent stages of the process.

figuRe 4 - lifting out of concRete paRts

in the next stage, stud bolts with eyes are installed in the concrete and the parts are lifted out of place with suitable machinery. Figure 4 shows how a segment is lifted out by means of an excavator and chains. after the removal of the old concrete, dowels and anchors are installed according to the german ztv Beton (additional technical contract conditions and guidelines for the construction of concrete road pavements).

figuRe 5 - pRepaRed single field witH dowels and ancHoRs.

the surface of the base course is cleaned and according to the requirements a fleece material is laid out. the next step in the process involves the mixing of the fast setting concrete. the binding agent and grain gravels are already premixed when dry. at the construction site, only water and later plasticizing agents or retarders are added, and then mixed. the in-situ placement of concrete follows immediately afterwards.

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then, the concrete consolidated and an even surface obtained by means of a manual vibration board. in order to prevent the concrete from drying too rapidly and developing cracks, the surface is covered with wet mats after application of the finishing treatment. two or three hours after the construction process, the joints around the slab can be cut. sealing works can be done immediately or at a later stage.

the working steps described can be completed within a time period of 6 to 8 hours. preferably, these works are undertaken during times of reduced traffic volume.

figuRe 7 - time scHedule of single concRete slaB Replacement

in figure 7 the schedule of a night-shift slab replacement procedure undertaken from 10.00 p.m. to 04.00 a.m. is shown. when this schedule is properly implemented, the entire roadway can be reopened the next morning before the beginning of the peak traffic period.

to adhere to this strict schedule a number of conditions are required to be fulfilled. the machines and devices should be optimally coordinated. the concrete mixture has to be precisely prepared, and

the skill and knowledge of the involved staff is also of high importance. construction projects such as these are only successfully realised with the help of a motivated and experienced construction team.

perspective

in former times it was a common practice to renew damaged concrete pavements in the first instance, or permanently, with asphalt. the lifespan of these asphalt pavements was limited, and there was the further risk of subsequent damage in form of “blow ups“, as the even distribution of pressure over the entire road cross section could not be ensured. with the fast setting concrete system and specialised machinery introduced here, a solution was found which enabled single slabs in concrete construction to be replaced permanently without the risk of subsequent damage. during recent times this system has been successfully applied in germany, predominantly on the main lanes of highly trafficked highways and on airport runways.

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the expense involved in the replacement of single concrete slabs using fast setting concrete are higher than replacement using conventional concrete. However, if the costs associated with blocking traffic during the construction process and while the concrete is setting are considered, the increased expense is compensated. furthermore, there is the economic advantage of avoiding traffic jams. due to the allowable timeframe in some instances (heavily trafficked roads, airport runways), single slab replacement with fast setting concrete is a requirement.

after many positive practical experiences and following the conclusion of a research project by order of the traffic ministry, this construction method was included in the german standard: ‘ZTV BeB’ (additional technical contract conditions and guidelines for the maintenance of traffic-use surfaces – concrete construction methods).

3.9. ReneWal of fatigued and WoRn concRete Roads using an ultRa-high-peRfoRmance concRete oveRlay - a field tRial using a heavy vehicle paRking lane

within the framework of a research project sponsored by the federal Highway Research institute (Bast), the university of kassel and Bast jointly developed a type of high-performance concrete (Hpc) (fck,cube,28d = 125 n/mm²) and an ultra-high-performance concrete (uHpc) (fck,cube,28d = 170 n/mm²) for the renewal of fatigued and worn concrete pavements. following comprehensive theoretical and laboratory tests, a field trial of the high-performance concrete was conducted using a heavy vehicle parking lane, approximately 250 meters in length.

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figuRe 1- installed ReinfoRcement (left) and view of tHe paRking lane (RigHt)

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an “ultra-thin white topping” surface made of continuously reinforced Hpc was applied to an 18 cm thick, jointed concrete base layer, as shown in figure 1, page 38. the carrying capacity of this pavement equals that of an old, fatigued concrete pavement. the jointless surface was continuously reinforced with steel meshes (rod diameter d = 8 mm, spacing a = 55/65 mm), as shown in figure 1. the concrete itself contained 1% (by volume) micro-wire steel fibres (d = 0.19 mm, l = 9 mm). to protect it against corrosion, the reinforcement content was dimensioned in such a way that the cracks expected as a result of temperature and shrinkage would not open up to a size of more than 0.1 mm.

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6/8 cm Hpc concrete wearing course 18 cm c 20/25 concrete base course 0/45 anti-frost layer 39 cm (ev2 120 mn/m2) 65 cm overall construction (ev2 45 mn/m2 at ground level)

figuRe 2 - poRta westfalica lane constRuction

to account for the bonding effect between the surface and the concrete base layer, (which is considerable if the two layers are thin), the 60 to 80 mm concrete surface layer was rigidly secured to the concrete base layer using steel anchors in one area of the test section, while in another area the use of a bitumen emulsion as a bonding agent was investigated. the construction of the test surface is shown in figure 2.

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figuRe 3 - compRessive stRengtH of Hpc (left) and uHpc (RigHt)

a high-performance and an ultra-high-performance concrete were developed for the purpose of this application, both of which had suitable characteristics as measured under laboratory conditions. the compressive strength progression curves are shown

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in figure 3. these results were initially used to carry out laboratory stress tests on a model construction with the same dimensions intended to be used for the test surface (see figure 4). after 1 million load repetition (pulsating stress profile) with 60 or 70 kn wheel load, no signs of fatigue were detected.

figuRe 4 - stRess tests caRRied out on tHe model constRuction

during the subsequent practical mixing tests, it was determined that the uHpc was not sufficiently robust, particularly regarding weather-related fluctuations in humidity levels. for these reasons, only the Hpc (with greater structural density) was installed as the test pavement.

the fine-grained concrete components (up to a grain size of 2 mm), for example: cement, quartz powder, microsilicon and quartz sand were supplied to the site as a ready-mixed dry compound. Basalt (2 to 8 mm), a fluxing agent and water were added during the mixing process. the Hpc is able to be laid and compacted using a mobile large-scale mixing system; its consistency was found to be in line with that required, and (as figures 5 and 6 show) the concrete can be laid and fully

compacted using a conventional slip form paver. the compressive strength reached the required target values of 100 to 115 n/mm², in accordance with din en 206

to ensure that the surface had adequate grip, a surface retarder was applied, with subsequent brushing creating an exposed aggregate concrete structure (figure 5, right).

figuRe 5 - distRiBution using an excavatoR and BRusHing of tHe suRface moRtaR

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the test course is now being monitored by the university of kassel and the federal Highway Research institute (Bast). a low noise construction method using uHpc is currently being developed for application in a further research project financed by the federal ministry for educational Research.

3.10. innovative and economical paving method foR compact asphalt pavements

Lars Keller, Matthäi Tecnologie GmbH & Co. KG, Verden, Germany

3.10.1. general

with compact asphalt, binder course and surface course are placed in one pass, which provides not only for a perfect bond of layers but also for strong interlocking between the layers - a crucial precondition for the longevity of roads. one possibility is to use a modular paver that simultaneously paves binder and surface layer. this system is an alternative particularly concept suited to building compact asphalt pavements “hot on hot”, although conventional road projects can also be carried out economically and to high standards of quality using the modular paving technology. the inline pave® process is based on the use of machines of series production, just slightly modified for “hot on hot” paving. this means for contractors that every single machine of the paving system train can also be used for conventional paving jobs at any time.

Figure 6 - Placement with sliP Form Paver

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modular paving means that the process of paving takes place by machinery working “in a line”, one immediately after the other. all machines feature a very compact design. dimensions and weights have been conceived so that transport from one site to another is a routine task.

an modular paving train comprises three machines: a feeder, a special paver for placing binder course and a standard paver for paving surface course. the paving process starts with the feeder. it receives binder and surface course mixes supplied by feed vehicles and transfers the mixes, by turns, either directly into the large material hopper of the paver for binder course or - via the modular pave transfer module - into the material hopper of the paver for surface course. a system of lights signals to the drivers of the material feed vehicles whether mix for binder course or surface course is needed.

the special paver’s task is to place binder course of high density and with high resistance to deformation. the machine comes with a special extending screed version for compaction at the highest level. the special extending screed has been developed for the special requirements of “hot on hot” paving. as a High compaction screed for the inline pave® process, it is capable of achieving an extremely high degree of pre-compaction, so that the paver for surface course weighing some 40 tonnes (including material and extra storage hopper) can travel on the binder course without adversely affecting it. the surface course is then laid directly onto the fresh, hot binder course. the special paver for placing binder course is equipped with a separate transfer module used for modular pave jobs.

the module transfers the mix received from the feeder – over the paver for binder course – into the material hopper of the paver for surface course. the transfer module mounts or demounts within a very short time. conversion can be completed in no more than 6 hours in the contractor’s workshop by just two persons.

the third player in the system train is a conventional paver. for this system application, the machines are equipped with wider track shoes (400 mm) and a water spraying system for the crawler tracks. an extra material hopper holding 25 tonnes, insulated against loss of heat, is placed into the paver’s regular material hopper and can receive a feed vehicle’s load.

pRoject: new constRuction of tHe B 178 (n) fedeRal HigHway neaR löBau, saxony, geRmany

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several bridge structures were located along the highway. on some of the bridges, hot mix needed to be placed, too, however only 4cm surface course on mastic asphalt.

that paving on the bridge decks was possible due to a unique advantage offered by the inline pave® concept. thanks to the paving train’s modular design, the feeder and the special paver for binder course could stop working and pass over the bridge, leaving the paver for surface course behind. this paver placed surface course in the required thickness of 4cm and in the conventional manner on the bridge deck. after the bridge, the entire modular pave train resumed work and continued paving “hot on hot”.

on other stretches of the B 178 (n) highway, the pavers were not allowed to access the bridges, as construction work had not yet been completed. in these places, too, the modular concept displayed its unique advantage. every single machine of the modular pave train was able to leave the highway by travelling down the embankment, without any prior conversion, and by-pass the bridge. as a modular pave team, they resumed work right after the bridge.

tests were also conducted to show how deep the paver for surface course sank into the binder course. the sinking depth was between 0.3 and 0.8 cm, resulting in an average of 0.65 cm. the imprints left by the paver had no adverse effects upon the asphalt pavement’s quality.

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3.10.2. laboratory tests

binder course surface course

density by volume in drill core 2,525g/cm³* 2,394g/cm³*density by volume according to marshallof mix sample 2,484g/cm³* 2,410g/cm³*volume weight 2,657g/cm³* 2,513g/cm³*voids content in drill core 5.0% by volume* 4.3% by volume*degree of density 101.6%* 100.0%*Bond of layers fulfilled 100% 100%* average of individual values.

3.11. ReconstRuction of the RunWays noRth and south at fRankfuRt aiRpoRt With WaRm mix asphalt

Dipl.-Ing. Bernd Nolle, TPA Gesellschaft für Qualitätssicherung und Innovation GmbH, Leinfelden-echterdingen, Germany

the runways are the liveliness of each airport. Regular checks, maintenance and repairs are required. the company f. kirchhoff straßenbau gmbH & co. kg, actually part of the stRaBag se, was awarded one of the most difficult and challenging projects, the reconstruction of the Runway north and south at frankfurt airport.

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3.11.1. the projects

the existing concrete runways, of which some sections were more than 30 years old, were damaged because of up to 200,000 aircraft movements per year. Hence complete renovation of the 60-m-wide / 45-m-wide and 4,000-m-long runways were required.

the reconstruction of these heavily used runways had to be carried out exclusively during the night time (between 10.30 p.m. till 6 a.m.) in small sections. the work was restricted to 7.5 hours. this ensures that the runway was remained open for unrestricted aircraft movements during the daytime.

Reconstruction work during the night time involved breaking up und removing the old runway in 15 m sections and replacing them with an asphalt layer of 600 mm thickness in total. these are so called “breaking-up” nights.

after 35 to 40 “breaking-up” nights the surface layer was milled of and replaced by a 40 to 50 mm thick stone mastic asphalt (sma) layer – the “Paving” nights.

a practicable solution was produced, however, this called for precise timing, the perfect coordination of all activities and total reliability from both the personal involved and the machinery. each detail and process was meticulously planned accurately within a 15 min time frame.

fraport ag invested euR 38 million in the reconstruction of the Runway north and euR 42 million in the reconstruction of the Runway south.

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3.11.2. the Reconstruction

tHe system

the complete reconstruction of these projects was completed in over 600 nights. the Runway north was promptly reopened every morning at 6.00 a.m. for air traffic.

due to the weather conditions the construction work had to be executed in spring and autumn only. Hence, the construction process was divided into 5 stages for the Runway north and 4 stages for the Runway south.

3.11.3. the construction process

the logistic of the construction process and the practical knowledge of all partners involved contributed to the successful renovation of the runway.

the work was restricted to 7.5 hours during night time. each job, each step and each action was meticulously planned and calculated to the minute.

the concept and strategy of the construction process was established during the tendering process. this concept was used for optimal planning and preparation of the reconstruction process.

the number, the brand and the power of the construction equipment were chosen to meet the time frame requirements. the machine combination for the project was planned to bypass any machine breakdown.

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3.11.4. the personnel placement and the construction equipment

the task was to ensure one hundred percent availability of machinery with exceptionally high performance. two service trucks with spare tools and parts were on site each night to ensure operational readiness of the equipment.

to ensure quality during construction a plan was established by the company owned laboratory. during the construction process the bearing capacity of the subgrade, the density, the consistency of the asphalt mixes and the asphalt temperature were checked and recorded.

night peRsonnel and machineRy at place“Breaking-up” nights “Paving” nights

• 60 technicians• 7 excavators with Hydraulic Breakers 40 t• 2 Bucket excavators• 4 mobile excavators 15-22 t• 25 trucks• 2 Bulldozers cat d 5• 4 asphalt pavers, paving width 8.5 m• 4 asphalt Rollers• 2 asphalt cutters• 1 drilling apparatus• 2 wheel loaders lH 580• 2 Road sweepers• 1 pavement marking machine

• 55 technicians• 4 Heavy-duty cold milling machines, milling

width up to 2.20 m• 6 Road sweepers + 2 large scale Blowers• 1 distributor• 4 asphalt pavers, paving width 7.5 to 8 m• 6 asphalt Rollers• 25 loading trucks• 1 drilling apparatus• 3 pavement marking machines

3.11.5. the “breaking-up” nights

the runway was divided into 15-m-long and 60-m-wide sections. each night 900 m² of the existing concrete runway were replaced with 1,500 t of new asphalt mixture. Before the reopening of the runway in the early morning the runway lighting and the runway marking were restored after the pavement construction process was finished.altogether there were 269 “breaking-up” nights required of each runway.

at 10 p.m. all the construction equipment required were formed a convoy on the apron system. after closing the runway for aircraft traffic, a convoy consisting of trucks and automotive construction machines were began moving to the construction site at 10.30 p.m. just a few minutes after crossing the concourse, seven 40 t excavators were taking up position and starting breaking up the existing concrete runway using 3 t atlas-copco-hydraulic breakers. at the same time the loading excavators arrived from the construction equipment parking area, started to load the broken concrete and excavated to 800 mm below the original runway surface. following the excavation, the existing subgrade was be compacted to the ev2-value of 50 mn/m² surface.

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afterwards a 200 mm thick Recycled crushed concrete (Rcc) layer was applied. sporadic sand and humus areas were replaced by Rcc material. during the construction of the Rcc layer glass-fibre Reinforced plastic (gRp) pipes for runway lighting were installed. the required cable shafts were located on the side of the runway the night before. up to 400 m of gRp pipes were installed within one construction section.

the first asphalt base layer (240 mm thick) was applied using bucket excavators and two bulldozers and compacted using smooth steel roller. Because of the gRp pipes the use of an asphalt paver was not possible. However, for the construction of the second 240 mm thick asphalt base layer the paver was used. the second asphalt base layer was laid using two asphalt pavers with a paving width of 7.5 m and was compacted. following this a 120 mm thick asphalt binder layer was constructed.

a high performance warm mix asphalt was used. Because of the special asphalt mixes in combination with a chosen temperature regime, the asphalt had a good deformation performance after one hour of construction. at 6.00 a.m. the asphalt temperature was below 85 °c at the surface in order that take-offs and landings were occurred without risk to the aircraft. not only the project logistics were highly technical, but also the mix design.

after the construction of the asphalt binder layer, the new lighting was installed in addition to runway marking and cleaning. Because only one middle underfloor light was allowed to be turned off each night, the light under the construction section was removed, cleaned and installed in the construction section from the previous night, parallel to the breaking-up sections.

3.11.6. the “paving” nights

after the “breaking up” nights the reconstruction of the airport runway was not completed. if a sufficient amount of new runway was completed, the excavators had a break for five nights.

40 mm of asphalt binder layer was milled of 100 m lengths each night and was replaced by a 40 mm stone mastic asphalt surface layer. the installation of the runway lighting and marking followed this construction. asphalt paving was needed to be carried out within 7.5 hours. speed was the issue here and massive equipment was required.

four heavy-duty cold milling machines (milling width 2.20 m) are used and started milling off 40 mm of the asphalt binder layer (6,000 to 8,.500 m²) within 1.5 hours. four pavers with a paving width of 7.5 m followed them. the 4 pavers were started in the middle of the runways (approximately width 30 m). in a second work step the 4 pavers were completed the outer lines of the runway (approximately 2 x 15 m).

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the pavers replaced the 40 mm of milled asphalt binder layer with 40 mm of stone mastic asphalt at a paver speed of 3 m/min. finally six steel rollers were used to compact the asphalt surface layer.

Before the reopening of the runway the runway lighting and the runway marking were restored.

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3.12. hot on hot asphalt paving in geRmany

Rudi Bull-Wasser, Asphaltbauweisen Bundesanstalt für Strassenwesen (BASt), Germany

compact asphalt pavements are pavements consisting of surface and binder courses laid in one operation one after another and compacted together. the development of the compact asphalt (“hot on hot”) pavement technology started in germany back in 1996. Hot on hot paving results in better interlocking of the courses, a saving on the thickness of the wearing course, and a reduction of the paving time. the heat of binder course ensures better compactability of the thin surface course. in this case well-bonded package of two courses is produced, without using bituminous binders for a tack coat.

there are two variations of that paving method:

• one method is the simultaneously laying of both upper asphalt layers (surface and binder course or surface and base course) in a single pass, with both layers being laid hot on hot without driving the paver on the binder course. this can only be done with a special paver. this method is now part of the german standards;

• the second method is the laying with two pavers driving in line. Here the paver for the surface course drives on the highly pre-compacted binder course. again the rolling is completed in one pass together for both layers.

compaRison of aspHalt layeRs

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Benefit:

• rapid placement of multiple lifts of asphalt reduces construction time by 30%;• High bonding and interlock of the two courses of asphalt;• improves resistance to shear stresses and deformation;• Reduces thickness of surface course and saves high quality, expensive aggregates.

cost:

• reduction in overall cost by as much as 30 percent.

summary

compact asphalt is a method to place two lifts of asphalt concrete at the same time in one operation. this reduces the overall construction time and cost, improves bonding between two asphalt layers that are laid hot on hot. it also permits the upper asphalt layer to be thinner thereby saving on high quality, expensive aggregates which have a high polished stone value (psv).

References

contact: Rudi Bull-wasser, Bast federal Highway Research institute, e-mail: [email protected]

3.13. thin Whitetopping oveRlay oveR a defoRmed asphalt pavement of a highly tRafficked uRban inteRsection

Dr. László Gáspár – Katalin Karsai – Tibor Bors, Institute for Transport Sciences, Hungary

pHoto 1 - defoRmed aspHalt pavement suRface along tHe expeRimental section (octoBeR 2007)

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the construction of thin or ultra-thin whitetoppings is considered as an up-to-date rehabilitation technology for flexible pavement structures with repeatedly deformed pavement surface. the experiences on the first use of this technique in Hungary are presented briefly. a highly trafficked urban intersection with traffic signal was the site of the test section. the deteriorated asphalt layers were milled in 120 mm depth. a 85 m-long whitetopping in 120 mm thickness was placed using manual paving technique. 1.75 x 1.75 m slabs were cut in the thin cement concrete layer without joint filler and dowels.

3.13.1. selection of the site for tW trial section

in Hungary, a ministerial decision was made on making a trial with a thin concrete overlay for the rehabilitation of a repeatedly rutted asphalt concrete pavement. in county csongrád, ten possible sites were scrutinized so that the most suitable could be chosen as a trial section. they were ranked based on the actual deformation of asphalt layers, the quality parameters of cored asphalt layers, the pavement bearing capacity, the eventual public transportation (tram, trolleybus etc.) and the availability of pavement surface public utility fittings (e.g. manhole cover). the following site was selected for the trial: szeged, main road no. 5, km 165+145 – 165+230, in an intersection with traffic signal.

the 85 m-long section of 7 m width to be rehabilitated has a high lorry traffic (number of daily trucks: 2743; aadt: 13,785 vehicle/day). in spring 2007, 150 mm deep ruts were measured in the right traffic lane.

it was decided that cement concrete mixture composition variants developed using the laboratory test results of kti (institute for transport sciences) cement concrete laboratory should be produced in a mixing plant, and laid in a previous small-scale trial in order to select the optimum mix design, and the most appropriate laying technology.

3.13.2. preliminary laboratory test results

after various modifications, the cement concrete mix design met the quality parameters presented in table 1 (1% plastic fiber was applied).

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table 1 - main quality paRameteRs of the tW cement concRete mix design

quality parameter type parameter valueair content, % 4.9slump, mm 480

compressive strength, n/mm2

1 day 27.152 days 39.3228 days 73.05

split tensile strength at 28 days, n/mm2 4.97water penetration depth, mm 6

frost resistance test, 50 cyclesloss of mass, % 0.11loss of compressive strength, % 3.60

shrinkage at 75 days, ‰ 0.342

3.13.3. the construction of the trial section

as it was already mentioned, previous small-scale trials were performed in order to test the laying conditions, and to check the concrete quality parameters achieved. four previous trials were carried out since the laboratory test of cores taken from the laid concrete layer during the first trials resulted in too high porosity, too low strength and not suitable surface texture. Relatively late, on 11th october 2007 (at a temperature range of 6-10°c) started the trial work by the traffic diversion from the section, as well as the demolition of the pavement of failed right traffic lane. no fiber was added to the mixture to reach appropriate pavement surface texture.the old asphalt pavement was milled in 120 mm. (the thickness of remained asphalt layers amounted to 100-120 mm.) the milled asphalt pavement surface was cleaned by compressed air to enhance the future bonding. the whitetopping was placed in 120 mm on 15th and 16th october 2008 using manual laying technique. needle vibrator and vibration beam were used for the compaction. (photo 2).

pHoto 2 - concRete pavement compaction of tHe expeRimental section

1.75 x 1.75 m slabs were cut in the whitetopping without joint filler and dowels. in three days after the laying of this whitetopping, cores were taken for further laboratory tests.

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3.13.4. quality control

the final cement concrete mix design actually used for the trial work slightly differed from the one developed in the kti-laboratory, and presented in table 2.

table 2 - concRete mix design actually applied in the Whitetopping tRial

material quantity (kg/m3)cem i 42.5 n 420sand type oH 0/1 168sand type oH 0/4 503chippings kz 2/4 445crushed stone 4/11 582(tap) water 180plastificator type sky 581 1.0% 4.2air-training agent type micro air 107-5 0.29

as quality requirements, 390-450mm slump (msz en 1235-5) and 5.0-6.5 vol% air bubble content (msz 12350-7) of the fresh concrete were identified. the following parameters were tested: density, temperature, optimum time for curing plastic covers, strength values. the test results obtained are summarized in table 3. Photo 3 presents the surface of whitetopping with joints.

table 3 - stRength test Results at the age of 28 dayscube (150x150x150 mm) Beam (150x150x600 mm) cylinder (150x300 mm)

the mean value of

compressive strength (n/mm2) flexural strength (n/mm2) splitting tensile strength (n/mm2)

60.6 6.6 3.38

pHoto 3 - wHitetopping suRface witH joints (apRil 2008).

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3.13.5. conclusions

Based on the experience and test results of the thin whitetopping trials, the following conclusions can be drawn:

• preliminary laboratory tests proved the use of fiber, plasticizer and air-training agent help in meeting the predetermined requirements of the mixture,

• the high (420 kg/m2) share of cement in the mixture, and the low (0.395) water-cement factor could successfully increase the early strength of the mixture allowing to reopen the trial section to traffic relatively soon,

• the early compressive strength values of concrete cubes proved that the trial tw section could have been opened to traffic already on the third day after the laying of the course,

• the mean value of the flexural strength of the samples reached 6.6 n/mm2, some 10% above the planned 6 n/mm2,

• the texture depth values of the completed tw surface exceeded the specified 0.5 mm value, the too high standard deviation came from the manual methods used for surface roughening.

3.13. loW-cost cement concRete pavement that alloWs eaRly opening to tRaffic

Junichi Noda, Concrete Research Group, Japan Cement Association,[email protected], Japan

3.13.1. What

japan cement association (jca) conducted research and study on cement concrete pavement that enables faster opening to traffic in 2009. the finding is that use of high early strength portland cement with lower cement water ratio allows opening to traffic after 24 hours of curing. since this cement is widely available in market and does not need a special admixture, this concrete method can be regarded as a low cost one.

3.13.2. Why

it is well known that cement concrete pavement, in spite of higher durability needs longer curing time before opening to traffic compared with asphalt pavement. this is a crucial condition of road construction in areas where longer road closure is not permitted in order to avoid traffic congestion. this condition is generally true all over in japan. in heavily trafficked or urbanized areas road construction is usually to be conducted at night, while even in rural areas road closure for longer days is usually difficult. therefore it is unrealistic to use ordinary portland cement again

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and close 14 days only for curing at the time of rehabilitation. this is why existing concrete pavement is going to be overlaid with asphalt materials, which has been a major repair procedure for concrete pavement in japan.

3.13.3. how

for the purpose of finding a mix that can shorten as fast as 24 hours for curing time for joint cement concrete pavement, japan cement association conducted extensive laboratory tests in combinations of type of cement, curing time and mix conditions. consequently jca found that a mix combination of high early strength portland cement and lower cement water ratio achieves the objective.

a trial construction using the mix was conducted in a concrete plant yard. it revealed that shipping the materials for 40 minutes from another plant was possible and that workability during construction was sufficiently obtained. after 21 hours for curing the materials, it was proved possible to open to traffic as scheduled. the rehabilitated road has been in a generally good condition so far for a year.

3.13.4. plan, progress and success

the road surface is being monitored in order to further improve this method.

3.14.5. lessons learned

it is possible to find an inexpensive concrete mix that can control curing time by choosing type of cement and cement water ratio without relying on a special admixture.

(Unit: cm)

64m

4m Pacific Ocean Cement Company, Kumagaya Factory, 500 vehicles / day

40

400

Subgrade (K value: 30)

20

20

Early opening concrete

Granular base

Joint interval: 6m pHoto 1 - tRial constRuction site (BefoRe)

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(Unit: cm)

64m

4m Pacific Ocean Cement Company, Kumagaya Factory, 500 vehicles / day

40

400

Subgrade (K value: 30)

20

20

Early opening concrete

Granular base

Joint interval: 6m

figuRe 1 - design stRuctuRe foR eaRly opening concRete

table 1: mix foR eaRly opening concRetemaximum size of aggregate (mm) 20

type of cement High early strength portland cement

target slump flow (cm) 40 ± 2.5target air content (%) 4.5 ± 0.5water cement ratio (%) 35fine aggregate ratio (%) 42

unit weight (kg/m3)

water 165cement 471fine aggregate 705coarse aggregate 991

admixturesuper plasticizer (%) 2.0air entrained (%) 0.01

target bending strength after 24 hrs 3.5n/mm2

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10:00 May 14, 2009 15:00 May 14, 2009 9:00 May 15, 2009 12:00 May 15, 2009

Manual finishing of early opening materials

Curing by mat

Joint setting

18 hrs

Opening to traffic

figuRe 2 - constRuction flow foR eaRly opening concRete

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3.15. WaRm mix asphalt in Japan

Kazuyuki Kubo, Public Works Research Institute, Tsukuba, Japan

in japan, the annual amount of asphalt mixture in 2008 is over 50 million tons. if these mixtures were warm mix asphalt (wam), the emitted co2 amount could be reduced in 150 thousand tons, while the shear of wam among the whole asphalt mixture was actually less than 1%.

cumulative constructed area using wam is close to 3 million square meters, and the most popular objective is to improve the workability of asphalt mixture in cold areas.

Here, the simulation result of the effect of wam is introduced, and possible other benefit of wam in japan is explained.

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100 120 140 160

・ｷ・x・・

経過時間分

標準混合物

中温化混合物

気温

出荷時

出荷時

現着時

現着時

交通開放温度50℃

標準混合物製造目標温度165℃±14℃

標準混合物敷均し目標温度150℃±10℃

中温化混合物製造目標温度135℃±14℃

中温化混合物敷均し目標温度120℃±10℃

Open to traffic: 50 degree C

Tem

pera

ture

Time (minutes)

Standard Asphalt Mixture

Warm Mix Asphalt

Air Temperature

Asphalt Plant

Asphalt Plant

Construction Site

Construction Site

Target temperature range for mixing

Target temperature range for construction



figuRe 1 - compaRison of mixtuRe tempeRatuRes

3.15.1. simulation of the Wam’s benefit

Figure 1 shows the comparison of mixture temperature between usual asphalt mixture (dense-graded) and wam.

in this figure, wam can shorten the traffic closure time during construction time by more than 40 minutes. according to the simulation of japan Road contractors association, if the whole road construction work in japan had been done using wam in 2009, the estimated benefit and cost are as follows:

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benefitReduction of co2 emission 85 million yenReduction of fuel cost at asphalt plant 1,275 million yenReduction of traffic jam caused by construction work 16,382 million yen

costincrease of asphalt mixture price 12,140 million yen

3.15.2. other benefits of Wam

Figure 2 shows the location of asphalt plants in japan. the total number is 1,223 in 2006. each circle shows the 20-km area for each plant, which is regarded the maximum distance to provide asphalt mixtures in proper temperature. while the scale projects is typically small in japan, the use of mobile asphalt plants is very rare. therefore, wam is expected to expand the covered area by each asphalt plant. adding to say, in urban areas, it is also expected to reduce the number of asphalt plants and improve the cost efficiency of each plant, which will be finally reflected to the asphalt mixture price.

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100 120 140 160

・ｷ・x・・

経過時間分

標準混合物

中温化混合物

気温

出荷時

出荷時

現着時

現着時

交通開放温度50℃

標準混合物製造目標温度165℃±14℃

標準混合物敷均し目標温度150℃±10℃

中温化混合物製造目標温度135℃±14℃

中温化混合物敷均し目標温度120℃±10℃

Open to traffic: 50 degree C

Tem

pera

ture

Time (minutes)

Standard Asphalt Mixture

Warm Mix Asphalt

Air Temperature

Asphalt Plant

Asphalt Plant

Construction Site

Construction Site





figuRe 2 - location of aspHalt plants and tHeiR coveRing aRea

3.15.3. summary

wam is expected to realize many benefits, such as co2 emission reduction, mitigation of severe traffic congestion in urban areas etc. in japan, law concerning the promotion of procurement of eco-friendly goods and services by the state and

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other entities (law on promoting green purchasing) has been enacted since 2000, and wam has been added as a “eco-friendly good” in this law since 2010.

3.15.4. References

Japan Road Contractors Association, Warm mix asphalt for CO2 Reduction in Japanese, 2010.

3.16. pavement ReconstRuction of the mexico–queRetaRo highWay (tepalcapa – palmillas)

the Road system is the main transportation mode used to move passengers (98.5%) and freight (85%) in mexico, integrating the country both economically and socially. it is the fundamental element of the chain of production and distribution of goods for the internal and external market. the road network in mexico is 366,000 km long, 36% is paved.

an important part of the national Road agency (secretariat of communications and transportation, sct) program is aimed to improve the conditions and capacity of the road network. the mexico – Querétaro Highway is one of the principal routes of the country carrying an annual average daily traffic of nearly 50,000 vehicles (both directions). it is a toll road going from mexico city to the north, heading to nuevo laredo at the border with the united states of america. for a number of years it has been under continuous maintenance, improvements and reconstruction. in recent years it was decided to start a reconstruction strategy applying solutions using semi-rigid pavement structures and concrete pavements to reduce the number and scope of maintenance actions along a period of at least 30 years.

in late 2009 began the reconstruction of 16.5 km of the section between tepalcapa and palmillas, by removing partially the old flexible pavement and constructing a rigid pavement on top (inlay).

the scope of the work consists in the improvement of the horizontal and vertical alignment, the drainage structures and bridges, as well as the widening of the transversal section (eastbound) and the construction of a 14.5 m width concrete slab that allows three lanes and the shoulders (each direction).

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Westbound

Mexico Median Queretaro

Eastbound

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound

Work zoneFinished concrete pavementExisting asphalt pavement

Phase 1

Phase 2

Phase 3

Phase 4

3.16.1. organization of the worksite

due to the high traffic conditions it was decided to keep four lanes always open for both directions, so the first stage of the project consisted in finishing the widening and alignment improvements. once this was done, sections of 8 km are closed to traffic and the slab is placed in just one operation in the whole with of 14.5 m. this was decided trying to find a fair balance among user disturbance and time of construction.

the work is been doing between 8:00 h and 16:00 from monday to friday, on saturday the activity finishes at 13:00 h. the management of traffic is done crossing the vehicles from bound to bound over a provisional pavement on the median.

3.16.2. stabilized base

to improve the quality and homogeneity of the support, prior the placement of the concrete slab a stabilized (96 kg of cement per m3) base layer (30 cm) was constructed is some areas, using high capacity equipment (stabilizer and a cement/water mixing machines). the daily production of stabilized base was 570 m3.

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound


Phase 1

Phase 2

Phase 3

Phase 4

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound


Phase 1

Phase 2

Phase 3

Phase 4

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3.16.3. concrete slab construction

in order to guarantee the quality of the work and the accomplishment of the schedule, the contractor decided to hire the most experienced company in mexico for producing and placing the concrete. the pavement consists of a 35 cm thick slab of a doweled jointed portland concrete pavement (jpcp) with a high quality mix (flexural strength of 4.7 mpa, 28 days). the placement of the concrete is being done in one single operation for the whole with of 14.5 m, using a slipform paver equipped with a dowel bar inserter (dBi) and a stringless leveling control system, with this equipment configuration 1,850 m3 of concrete can be placed every day. the texture is created using a burlap drag and transversal tining. for ensuring a good curing, the surface is covered with an impermeable sheet in addition to the special compound applied right after texturing.

two plants are being used, with a combined production capacity of 400 m3 per hour of “dry” concrete (4-6 cm slump). the concrete is being hauled in dump trucks and flowboys that carry up to 16 m3.

the concrete layer is being constructed in four main phases as shown below:

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound


Phase 1

Phase 2

Phase 3

Phase 4

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound


Phase 1

Phase 2

Phase 3

Phase 4

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound

Westbound


Eastbound


Phase 1

Phase 2

Phase 3

Phase 4

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3.16.4. technical highlights

in order to reduce time and cost without affecting quality, some technical decisions were made:

• inlay solution to use the existing structure, reducing the use of new materials;• hiring an specialized and experienced company to produce and place the concrete;• use of high capacity and/or state-of-the-art equipment:

• stabilizer, water/cement mixer,• slipform paver for placing the concrete in the whole width in one single

operation,• dowel bar inserter (dBi),• stringless leveling control system;

• traffic management.

3.17. mechanical placement of doWels and ReinfoRcing baRs in concRete pavements

Carlos Jofré, IeCA, Spain

3.17.1. introduction

when constructing a concrete pavement with a slipform paver, concrete can be either dumped on grade in front of the paver or onto belt placers, side loading spreaders or other equipment placed on a hauling lane adjacent to the pavement.

acceptable concrete placement practices include:

• concrete needs to be deposited close to and uniformly in front of the paver or front spreader, taking care to minimize disturbance to the base, embedded steel, dowel bars, and side forms;

• concrete must to be placed such that one side of the paving lane is not overloaded with concrete.

one main advantage of dumping directly in front of pavers or spreaders is that concrete head in front of the machine auger can be easily maintained.

in addition, sometimes space for side hauling is scarce and even non-existent, as it is the case for tunnels except if the pavement is built by half-widths.

these considerations usually far outweigh all other drawbacks in comparison with side feeding, e.g. stringlines may have to be broken on at least one side of the paver to allow trucks to back in and pull forward away from the paver. possible disturbance

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to granular bases is not a big concern in motorways and main highways, where cement- or asphalt-treated bases are customarily specified.

in doweled jointed pavements, an open paving lane for hauling and dumping concrete in front of the paver requires dowel baskets to be placed just ahead of it. this may not allow time to check dowel bar alignment or verify that baskets are securely fastened to the base. in addition, safety of laborers fastening baskets in areas between the forward moving paver and backward moving dump trucks needs to be considered (figure 1).

figuRe 1 - wHen dumping concRete in fRont of tHe paveR, placement of dowel Baskets just aHead of it Becomes an “AGAINST THe CLOCK” task

in continuously reinforced concrete pavements front feeding is not possible if steel bars are attached to support assemblies laid on the base prior to concrete placement.

to overcome these difficulties, two methods have been developed:

• insertion of dowels into fresh concrete;• mechanical placement (tube-feeding) of reinforcing bars.

3.17.2. mechanical insertion of dowels

mechanical insertion of dowels into the plastic concrete is not a recent development. several types of placing equipment were already available in the 1960’s, when paving with fixed-form trains was common practice, each machine performing a specific task [1].

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when slip-form pavers were introduced, it was necessary to integrate dowel bar insertors (dBis) into the equipment frame (figure 2). the question of placing dowels without stopping the machine was solved satisfactorily. dBis are now in common usage with a number of models being utilized [2] [3] [4].the dowel bars to be inserted are stacked in a spreader car waiting at the side of the slip-form paver (figure 3). it is moved back and forth over a collecting rail which is grooved at the specified insertion points. as the car passes, the dowel bars drop into these grooves. when they are to be inserted, each dowel bar is immediately grasped by two vibrating insertion forks and pushed until it reaches the required depth (figure 4). level of vibration is carefully monitored to ensure full compaction of the concrete around the bars without being so severe as to displace them.

figuRe 2 - diagRam of a slip-foRm paveR witH integRated dowel BaR inseRtoR [2]

figuRe 3 - dowel BaR inseRtoR (dBi)

figuRe 4 - inseRtion of a dowel into plastic concRete

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during the insertion process, the dBi remains over the insertion position while the paver continues to advance (figure 5). this ensures that the dowel bars are inserted in the concrete without being dragged. the entire dowel bar insertion process is electronically controlled.

figuRe 5- diagRam of inseRtion pRocess of dowels [3]

figuRe 6 - inseRtion maRks of dowels in tHe loweR layeR of a two-lift pavement

figuRe 7 - oscillating tRansveRse scReed wiping out inseRtion maRks

to repair the scarring in the slab due to the insertion, if dowel bars are inserted from the surface of a concrete pavement laid in a single course, the dBi must be followed by a transversal finishing beam creating a concrete roll with sufficient material (figure 7). this device is not necessary in two-lift construction, where dowels are placed in the bottom layer.

inserted dowel bar accuracy can be checked by exposing bars in plastic concrete, by coring over ends of rebar, or by utilizing non destructive testing equipment as a magnetic rebar cover meter, a ground penetrating radar or a magnetic tomography scanner. Results show that dowels can be placed with dBis as accurately or better than when using baskets [4].

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3.17.3. mechanical steel placement (tube-feeding) in continuously reinforced concrete pavements

when tube feeding steel, the proper number of longitudinal bars is pre-spliced out ahead on the base and threaded through a battery of plan-spaced tubes mounted on the paver, where they are held at the specified vertical and horizontal positions as the concrete is placed between the tubes (figure 8).

figuRe 8 - tuBes assemBled to tHe slip-foRm paveR foR positioning ReinfoRcing BaRs

to allow concrete delivery trucks to run on the base, reinforcing bars are grouped either on its central part (figures 9 and 10) and/or at its edges (figures 11 and 12), in order to provide sufficient clearance. concrete is dumped in a feeding equipment with one or to receiving hoppers, where it is directed towards one or two conveyor belts. the flow of concrete is then discharged into the slipform paver. length and elevation of the conveyors are chosen to pass over the transition area where reinforcing bars shift from their initial position towards the tubes.

Concrete hoppers

Slip-form paver

Conveyors for concrete transferConcrete delivery truck

(bottom layer)

Bar welding

8.00

m

Concrete deliverytruck (top layer)

Tubes for barposiotioning

49 bars Ø 16spread on base

Bars (final position)

Concrete hoppers

Slip-form paver


(bottom layer)Concrete delivery truck

(bottom layer)

Bar welding

8.00

m






figuRe 9 - diagRam of mecHanical steel placement (two-lift constRuction, BaRs concentRated on centeR of tHe Base) in a continuously ReinfoRced concRete pavement [5]

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Concrete hoppers

Slip-form paver


(bottom layer)

Bar welding

8.00

m





Concrete hoppers

Slip-form paver



(bottom layer)

Bar welding

8.00

m






Concrete hoppers

Slip-form paver


(bottom layer)

Bar welding

8.00

m





Concrete hoppers

Slip-form paver



(bottom layer)

Bar welding

8.00

m






figuRe 10 - mecHanical steel placement: ReinfoRcing BaRs initially laid at tHe centeR of tHe Base

figuRe 11 - mecHanical steel placement: ReinfoRcing BaRs initially laid at tHe

edges of tHe Base

figuRe 12 - mecHanical steel placement: feeding eQuipment and slip-foRm paveR

Concrete hoppers

Slip-form paver


(bottom layer)

Bar welding

8.00

m





Concrete hoppers

Slip-form paver



(bottom layer)

Bar welding

8.00

m






if bars are connected by contact lap splices, tubes must have a diameter allowing the occasional passage of two bars at the same time (figure 13).

figuRe 13 - wHen using lap-spliced ReinfoRcement, tuBes must allow tHe simultaneous passage of two BaRs

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narrower tubes can be used if steel bars are flash butt welded (figure 14) rather than spliced. in addition to savings on the total amount of reinforcing steel, tubes can be matched to the diameter of the reinforcement (figure 15) with a clearance of just a few millimeters [6]. this helps to prevent intrusion of medium and coarse aggregates into the tubes that eventually could jam them.

figuRe 14 - flasH Butt welding of ReinfoRcing BaRs

figuRe 15 - flasH Butt welding allows to use naRRoweR tuBes

in addition to front delivery, mechanical steel placement exhibits a number of advantages compared with steel placed on chairs:

• no transverse bars are needed, excepting tie bars at longitudinal joints;• chairs or other types of supports are eliminated, as well as the labor required for

placing the steel on them. assembly operations are reduced to bar splicing;• the base of surface is free from obstacles and not occupied by reinforcements. this

facilitates the organization of the jobsite.

on the other hand, mechanical insertion is more critical with regard to placement accuracy than when reinforcement is placed on chairs. the location and depth of the steel should be verified on a routine basis.

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if placement is not adequately conducted, displacement of steel may occur, resulting in both high and low deviations relative to the slab surface [7]. steel too high in the pavement has resulted in longitudinal cracks [8], corrosion of the reinforcement and spalling of surrounding concrete, and even exposed steel in some instances. steel too low in the pavement can result in undesirably wide crack widths.

checks of bar depth and alignment should therefore be made by means of probing. with this aim, a probe, or ruler, can be inserted to determine the depth to steel from the surface of the slab at several locations across the paving width.

in spite of these potential problems, field studies have shown no significant difference in the performance of cRcp with steel placed on chairs and cRcp with steel placed using tube feeders as long as both are done properly [9]. inspections conducted at some works have shown that bars can be positioned in elevation to the nearest centimeter [6] [10].

3.17.4. RefeRences

• walker, B.j. and Beadle, d.: “Mechanized construction of concrete roads”. cement and concrete association, uk, 1975

• “IDBI In-The-Pan Dowel Bar Inserter”. gomaco international ltd., usa, 2003• “Slipform paver SP 500”. wirtgen gmbH, germany• “CDBI Compact Dowel Bar Inserter”. guntert & zimmerman const. div., inc.,

u.s.a., 2007• Bologna, g. and domenichini, l.: “Riqualifica di pavimentazioni bituminosi

ammalorate mediante copertura con lastra continua in calcestruzzo (Rehabilitation of deteriorated asphalt pavements by means of overlaying with a continuously reinforced concrete pavement”. l’industria italiana del cemento, nº 642, march 1990 (in italian)

• charonnat, y. et al: “A new process for the laying of monolihic composite CRC pavements”. Bulletin de liaison des laboratoires des ponts et chaussées, spécial xvi “Chaussées en béton – Concrete pavements”, paris, september 1990

• Rasmussen, R.o. et al: “Continuously Reinforced Concrete Pavement Design & Construction Guidelines” (draft may 2009). fHwa – cRsi, usa, 2009

• Roesler, j.R. et al: “Longitudinal Cracking Distress on Continuously Reinforced Concrete Pavements in Illinois”. j. perf. constr. fac.,volume 19, issue 4, november 2005, asce, usa

• gharaibeh, n.g. et al: “Field Performance of Continuously Reinforced Concrete Pavement in Illinois” in transportation Research Record 1684, tRB, usa, 1999

• garcía-arango, i.: “Los tramos con pavimento de hormigón armado continuo de la autopista del Cantábrico, entre Oviedo y Pola de Siero (The stretches with continuously reinforced concrete pavement at the Cantabrico motorway, between Oviedo and Pola de Siero)”. iv jornadas sobre pavimentos de Hormigón, oviedo,

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29 – 30 september and 1 october 1993. published by the asociación técnica de carreteras, spain (in spanish)

3.18. RepaiRs of a continuously ReinfoRced concRete pavement in south afRica

Nick Kong Kam Wa, BKS Consulting engineers, Pretoria, South Africa andBryan Perrie, Cement & Concrete Institute, Midrand, South Africa

with the ever increasing traffic facing road authorities across the world, pavement rehabilitation of urban freeways is becoming increasing challenging. this is especially true when no capacity upgrade has been undertaken for a number of years and traffic congestion is already an issue even before the start of any construction activities. this case study highlights the successful repair methods used in 2006 on a section of the national Route n1-20/21 between johannesburg and pretoria for the repairs of the existing continuously Reinforced concrete pavement (cRcp). this portion of the national Route is popularly known as the Ben schoeman freeway and is amongst one of the most heavily trafficked freeways in southern africa.

3.18.1. introduction

in 1987/88 the Ben schoeman freeway was the first freeway in south africa where a continuously Reinforced concrete pavement (cRcp) overlay was applied over the full width of the carriageway as part of the rehabilitation of the flexible pavement. the cRcp performed very well during the first 15 years. However, during the last few years prior to this repair contract, the number of “punch out” failures occurring on the pavement has been on the increase mainly due to water ingress through poorly maintained joints. with the average annual daily traffic (2005 figures) bordering on 150000, any repair activities on the freeway, even during week-ends, impacted severely on the traffic. this necessitated the use of innovative technologies for the concrete repairs so as to minimize the road user cost and at the same time reduces the risk of accidents which could be fairly high during construction.

3.18.2. background

prior to 2005, pavement maintenance on the Ben schoeman freeway was done by a routine maintenance team. asphalt cold mix were used for emergency repairs and for longer term repairs, a rapid hardening concrete was used which necessitated lanes to be closed from friday night to monday morning. the freeway, with its two system interchanges and five access interchanges operates at a level of service f most of the times and is very sensitive to incidents. thus, maintenance actions like these caused significant disruption to traffic even when done over week-ends. By 2005, the occurrences of these maintenance actions were becoming too frequent that

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the south african national Road agency limited (sanRal) appointed Bks consulting engineer to undertake the design and supervision of periodic maintenance contract which entailed the repairs of failed or about to fail concrete, stitching of wide joints and the sealing all longitudinal joints, amongst others.

due to the high volume of traffic and the strategic importance of this freeway, the brief from sanRal was to undertake all repair works at night from 21:00 to 5:00 in the morning. while the amount (or extent) of the works could be adapted to fit one night shift before re-opening the freeway to traffic in the morning, a major challenge remained in designing a concrete mix that would gain sufficient early strength by the end of the night shift. previous experience, albeit limited, on this freeway with a particular branded product was not too successful. the patch repairs although satisfying the initial strength criteria failed prematurely under cracking within the first six month of repair.

it should be realized that many proprietary products (e.g. polymeric concretes) that can reach strength in the limited time dictated by the authorities were traditionally aimed at small and localized repairs and not really for large-scale production. as a result, the costs of these proprietary products are often very expensive. However, during the past decade there has been an increase in new generations of high early strength concrete which enables large scale concrete repairs to be done in shorter time and in harsher conditions and at more reasonable rates. unfortunately, many of these new generation products are not readily available in south africa. furthermore, the estimated amount of repairs for the contract was too low for large scale production but high enough to warrant looking at alternatives local products even if these were limited.

3.18.3. concrete mix design

during design stage a limited laboratory study was done to investigate the capabilities of locally available products. major role players in the concrete industry were approached and were given an overview of the project with all the constraints. seven proprietary mixes from three suppliers were tested at an independent commercial laboratory in johannesburg. the brief was to come up with a durable and workable concrete mix which can gain enough strength within four hours for opening to traffic even in very cold climatic conditions as the contract was expected to run through at least one winter season. the two engineering properties evaluated during this preliminary investigation were development of flexural and compressive strength with time at a temperature of 0ºc and 25ºc and shrinkage cracking.

one should realize that in most specifications, concrete repairs are generally not allowed at temperature of 4ºc and falling. it is a known fact that even with the use of modern admixtures, thermal blankets, warm water, temporary shelters and so on, there are still a number of uncertainties of the behaviour of the mix in its plastic and

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hardened state. problems during the plastic state can cause severe delays and traffic backup but can generally be remedied on site with experimentation. on the other hand, the prediction of performance and durability of the hardened concrete in the long term is very difficult especially when high early strength materials are involved. it is a known fact that these types of concrete are more heterogeneous and more prone to microcracking. the pre-construction investigation provided great insight to the consulting engineer – in particular it revealed the following:

• the target third-point loading flexural strength and compressive strength after four hours of 2.3 mpa and 20 mpa respectively, could be achieved with a number of locally available products at a temperature of 25ºc but not at 0ºc. the target strengths were based on the opening strength criterion used by american concrete pavement association (acpa, 1989&1994);

• due to high amount of superplasticizers and other admixtures in the mixes, the flexural strength results tended to be erratic resulting in a generally poor relationship between flexural strength and compressive strengths;

• the drying shrinkage criterion of a maximum of 0.04 % as specified in the south african standard specifications for road and bridge works can be achieved by some local mixes but the coefficients of variation of the results are high and outside the test limit. these variations however were attributed to sample preparation in the laboratory rather than an inherent variability of the mix.

Based on these results the tender documents were amended so as to ensure that the concrete mix that would eventually be used would be fit for purpose. provisions were made to do various additional tests and trials at the start of construction so as to allow the contractor and the engineer to refine the mix performance as well as to check the practical applications such as workability and placement. in addition, due to the many risks and unknowns in this contract the durability tests (sorptivity and oxygen permeability) that are generally specified for structural concrete in south africa (alexander et al, 1999), were also specified in this contract. the tests are used to assess the effectiveness of initial curing and the compaction of the concrete respectively. the oxygen permeability is used to quantify the microstructure of the concrete and is sensitive to macro-defects such as voids and cracking.

the mix proportion in the approved mix design during construction is summarized in table 1. critical criteria of the final approved mix satisfied the specified requirements of durability, shrinkage, workability and strength. the dolomite aggregates was specifically selected in this contract so as to further minimize the effect of concrete shrinkage as dolomite has a low water demand as compared to other aggregates.

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table 1- detail of appRoved concRete mixmix proportions

component type source proportion

cement ppc cem1 42.5R ppc 507 kg/m3

admixture contec Qsf worldcon (pty) ltd 35 kg per 100 kg of cement

coarse aggregate 19 mm nominal; dolomite oliefantsfontein 1263 kg/m3

fine aggregate silica sand delmas 630 kg/m3

3.18.4. construction aspects

due to the time limited time available in a shift, particular attentions were given to the construction method and equipment used. like any fast-track construction, well planned construction sequencing was also imperative. these are summarized below:

1. the boundaries of identified repair areas which were of minimum size of 1.5 x 1.5 m are determined based on the distress area, the surrounding cracks (transverse and longitudinal), joints and locations of existing reinforcements. these areas were sawn cut full depth into roughly 1.5 x 1.2 m panels and fitted with anchor bolts for the lifting hooks on the previous shift;

2. on the night of the repair, hooks are fixed to the anchors on the panels and lifted out with a 12 ton meter truck mounted crane;

3. 2,000 watt rotary hammer drills mounted horizontally on rails with adjustable depth settings were used to drill holes for longitudinal and transverse tie bars. the tie bars were placed using a 1,250 watt rotary drill to ‘spin’ the bar mixing a two part epoxy on embedment. a special epoxy that set in 60 seconds was used for that purpose. at the same time another team scabbled all vertical faces and applied a concentrate of contec Qsf binder so as to improve load transfer and bond;

4. all longitudinal and transverse distribution steel are then re-instated;.

mix properties

parameter approved mix specified

water: cement ratio 0.25 max 0.4shrinkage (%) 0.02 max 0.04compressive strength (mpa) 20.5 (4 hrs) min 20 (4hrs)*flexural strength(mpa) 2.2 (4 hrs) min 2.3 (4hrs)*sorptivity (mm//h) 3.8 max 7 oxygen permeability (log scale) 10.38 min 9.75

*the 28-day design strength is as per the standard specification in colto as per conventional concrete pavement.

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5. pre-weighed and pre-bagged materials (aggregates sand and binders) are loaded and mixed with a controlled amount of water in a pan mixer. the mix is then placed in the repair area and compacted using high frequency poker vibrators and high frequency heavy duty screed beam. the high frequency is essential to achieve good compaction of the mix;

6. the concrete is then finished with hand floats, bull floats (for widths greater than 2.5 m) and leveling beam;

7. soft broom (micro texture) and spring steel tine (macro texture) were used to provide surface texture required and thereafter the patch was cured with a resin based curing compound;

8. in very cold weather a thermal blanket is placed over the new concrete to retain heat.

some of the construction activities are illustrated in figure 1, following page. the average duration of the activities was as follows:

• lifting of panels: 0.5 hrs;• drilling tie bars, scabbling, cleaning out and placing steel: 1.5 hrs;• pouring concrete at a rate of 1.75 m3/hour: 2 hrs;• curing to achieve minimum strength at opening: 4 hrs.

due to good quality control in the mixing and placing of the concrete, test results were generally good and consistent. average results achieved from production are shown in figure 2. it was found that workability of the mix was very sensitive to temperatures and that it is very good at temperatures less than 18ºc. aggregates were thus stored in a cold room at temperature below 18ºc in order to slow down the hydration process and allow enough time to finish off the concrete. at this temperature working time was a maximum of about 15 minutes.

to date all the patches are performing very well. none one of the patches were damaged from lack of strength at time of opening to traffic (no tyre imprint/shoving or induced cracks) nor has any of them shown any long term durability problems.

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figuRe 1 - typical constRuction activities

figuRe 2 - aveRage concRete stRengtH oBtained

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3.18.5. conclusion

this case study summarises the experience gained on concrete repairs on one of the busiest freeways in southern africa. it showed that very early concrete strength can be achieved with the right technology. on average, flexural strength of at least 3.7 mpa was obtained within four hours of placement. more importantly, all patches to date are performing well without any secondary effects from shrinkage and microcracking.

3.18.6. References

acpa, 1989. technical Bulletin: Fast Track concrete Pavements. american concrete pavement association, skokie, illinois.acpa, 1994. concrete paving: Fast Track concrete Pavements. american concrete pavement association, skokie, illinois.kong kam wa ny; nganjo p, pickard k, dercksen jw and kotze H, 2007: The use of innovative technologies to facilitate rapid repair of concrete pavements: A case study for South Africa. proceedings of the 26th annual south african transport conference (satc 2007). csiR conference centre, pretoria.

3.19. Rapid inteRsection ReconstRuction in Washington state

Kurt Smith, Applied Pavement Technology, Inc., Urbana, Illinois, USASuneel Vanikar, Federal Highway Administration, Washington, DC, USA

in 2000, the washington state department of transportation (wsdot) reconstructed an urban intersection on state Route 395 using accelerated concrete paving techniques. the goal of the project was to document the rapid reconstruction of the intersection and develop a body of knowledge that could be applied to future work. the reconstruction of the intersection proper—including a portion of the approach and leave legs of the intersection—was conducted using a complete closure over a 3-day extended

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weekend (7 p.m. thursday to 6 a.m. the following monday). to effectively achieve this, a number of strategies were employed, including the use of a rapid-setting pcc mix, improved planning and coordination, and efficient construction sequencing. in addition, a comprehensive public outreach program was conducted.

3.19.1 urban intersection Reconstruction: state Route 395/kennewick avenue

the washington state department of transportation (wsdot) initiated a program in 1994 to replace selected hot-mix asphalt (Hma) pavement intersections with portland cement concrete (pcc) pavement. this decision was made primarily due to the recurrent rutting that developed on many of these Hma pavements, their relatively short performance life (often 8 years or less), and the high cost of maintaining these pavements in an urban environment (uhlmeyer and pierce 2001). in contrast, pcc pavements offer long performance lives with low maintenance requirements and fewer user disruptions; moreover, previous experience had indicated that, in certain circumstances, pcc pavements are more cost effective than Hma pavements even though their initial construction cost may be higher (uhlmeyer 2003).

stage 1: construction of the left hand turn lane

stage 3: construction of the southern approach with traffic pushed to the north

stage 2: construction of the northern approach with traffic pushed to the south

stage 4: construction of the intersection square (radius return to radius return)

figuRe 1 - constRuction pHasing foR inteRsection (nemati et al. 2001)

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Historically, pcc pavement reconstruction projects have often required extended closures and sometimes complex traffic management provisions (nemati et al. 2001). However, through the application of accelerated paving techniques—including the use of high-early strength concrete materials and the effective planning and coordination of critical path construction elements—localized reconstruction projects can be performed over a 2- to 3-day construction window, thereby minimizing prolonged disruptions to the traveling public. wsdot demonstrated the feasibility of accelerated paving techniques for three urban intersection reconstruction projects on sR 395 in kennewick, washington, located in the eastern part of the state. Highlights from one of the urban reconstruction projects (the intersection of sR 395 and kennewick avenue) are described below.

3.19.2. pavement design

sR 395 near the intersection of kennewick avenue carries about 20,000 vehicles per day, including 20 percent heavy trucks. to accommodate this traffic, a 12-in (305-mm) pcc slab was designed, placed on the existing crushed stone base course. nominal joint spacings range from about 12 to 16.4 ft (3.6 to 5.0 m), depending on the prevailing geometrics, adjacent structures, and presence of utilities. transverse joints on sR 395 contained 1.5-in (38-mm) diameter dowels, as did the transverse joints on the approach legs of kennewick avenue (nemati et al. 2001). tie bars (0.625-in [15.8-mm] diameter) were placed on 36-in (914-mm) centers along the longitudinal joints, including those on sR 395 in the intersection proper.

3.19.3. mix proportioning

the concrete mix played a critical role in the construction of the intersection, as the contractor’s work schedule required a material that could be achieve a compressive strength of 2,500 lbf/in2 (17.2 mpa) within 24 hours (nemati et al. 2001). furthermore, it was desired that a dense, durable material be produced that could resist freeze-thaw deterioration. after testing a number of different trial mixes, the resultant mix design provided in table 1, following page was selected.

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table 1 - pcc mix chaRacteRistics (nemati et al. 2001)characteristics quantity

cement (type iii) 705 lb/yd3

aggregate1.5 in0.75 in0.375 in pea gravel

940 lb/yd3

799 lb/yd3

140 lb/yd3

sandcoarsefine

590 lb/yd3

481 lb/yd3

water 254 lb/yd3

slump 3.25 inw/c 0.36air content 6.3%1 in = 25.4 mm1 ib/yd³ = 0.59 kg/m3

3.14.4. staging

figuRe 2 - concRete placement in inteRsection (nemati et al. 2001)

a staged construction process was employed to limit disruptions to the traveling public and to provide higher levels of productivity to the contractor. the first stages of the process included the construction of the approach legs of the intersection, which was performed about a week prior to the reconstruction of the central portions of the intersection (see figure 1, stages 1 through 3). those activities were constructed under traffic, and required periodic shifting of traffic in order to maintain one lane in each direction through the work zone area.

it was during the fourth stage of the project that the entire intersection was closed for the extended 3-day weekend period. this provided the contractor unencumbered access to reconstruct the central portions of the intersection. prior to the stage 4 reconstruction, the wsdot employed an effective public relations campaign to notify the public of the intersection closure to minimize disruptions and user inconvenience. numerous public meetings were held, business were notified in advance of the upcoming closures, flyers were distributed, alternative routes were identified, and local television and radio stations and newspapers were constantly updated on the impending construction.

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3.19.5. construction

as previously described, the entire reconstruction of the intersection, including demolition of the existing Hma pavement and its replacement with concrete, took place over a 3-day extended weekend period, starting on thursday evening. the contractor began by first removing the existing Hma pavement and base to a depth of 12 in (305 mm), and then preparing the grade and setting the forms. the new concrete was placed in two major pours (one on friday and one on saturday), and placement locations were alternated within each pour. in this way, the concrete on the second pour could be cast against the previous day’s pour, thereby increasing productivity (no time needed to set up or dismantle forms).

Figure 2 illustrates the alternate placement of the concrete for each day’s pour. sections 1, 2, 3, and 4 were placed on friday and sections 5, 6, 7, and 8 were placed on saturday. overall, a total of 539 yd³ (412 m3) of concrete was placed.

the concrete was cured using a white-pigmented curing compound conforming to astm c309. the material was applied at a rate of 150 ft² per gallon (3.7 m2 per liter).

joint sawing on the project commenced about 6 hours after concrete placement. a detailed jointing plan had previously been developed and was followed during the sawcutting operations. sealing of the transverse and longitudinal joints followed soon afterward.

3.19.6. opening to traffic

the project used maturity meters to monitor strength development and to determine the time at which the pavement could be opened. the maturity meters were connected to temperature probes that had been embedded in the fresh concrete. laboratory maturity testing indicated that the concrete achieved the minimum compressive strength of 2,500 lbf/in2 (17.2 mpa) in about 8 hours. the intersection was ultimately opened to traffic between 4 and 6 p.m. on sunday afternoon, a full 12 hours before the required 6 a.m. opening time on monday morning.

3.19.7. summary

wsdot now routinely uses the above-described rapid rehabilitation technique in its program of pcc pavement urban intersection reconstruction. successful projects require the judicious selection of materials, careful planning, and better coordination of all activities, as well as cooperation between the owner agency, the contractor, and local officials. although initial construction costs for pcc pavements are higher than for Hma pavements, 40-year annualized costs (including user costs) are typically lower for the pcc alternative.

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3.19.8. References

• nemati, k. m., j. s. uhlmeyer, l. m. pierce, and j. R. powell. 2001. Accelerated Construction of Urban Intersections with Portland Cement Concrete Pavement. final Report. federal Highway administration, washington, dc.

• uhlmeyer, j. s. and l. m. pierce. 2001. “Reconstruction of Urban Intersections Using Portland Cement Concrete Pavement.” proceedings, seventh international conference on concrete pavements, orlando, fl.

• uhlmeyer, j. s. 2003. PCCP Intersections—Design and Construction in Washington State. Report wa-Rd 503.2. washington state department of transportation, olympia, wa. (available at http://www.wsdot.wa.gov/research/reports/fullreports/503.1.pdf).

3.20. inteRmittent RepaiRs of Jointed concRete pavements using pRecast concRete panels

Shiraz Tayabji, Fugro Consultants, Inc., Columbia, Maryland, USA and Suneel Vanikar, US Federal Highway Administration, Washington, DC, USA

precast pavement technology is a recently improved construction method that is being used in the united states to meet the need for rapid concrete pavement repair and pavement rehabilitation in high-volume-traffic roadways. precast pavement systems are fabricated or assembled off-site, transported to the project site, and installed on the prepared existing pavement foundation. the system compo nents require minimal field curing time to achieve strength before opening to traffic. the precast technology can be used for intermittent repairs or full-scale, continuous rehabilitation. in the intermittent repair of concrete pavements, isolated full-depth repairs at joints and cracks or full-panel replacements are made using precast concrete panels. these repairs are typically full-lane width. in the continuous applications, rehabilitation (resurfacing) or reconstruction of asphalt and concrete pavements is performed using pre cast concrete panels. this case study discusses the application of the technique for intermittent repairs along a section of highway i-295 in the state of new jersey.

3.20.1 introduction

pavement rehabilitation and reconstruction are major activities for all us highway agencies, and have significant impact on agency resources and traffic disruptions because of extensive and extended lane closures. the traffic volumes on the primary highway system, especially in urban areas, have seen tremendous increases over the last 20 years, leading in many instances to an earlier-than-expected need to rehabilitate and reconstruct highway pavements. pavement rehabilitation in urban areas is resulting in serious challenges for highway agencies because of construction-

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related traffic congestion and safety issues. in recent years, many agencies have started investigating alternative strategies for pavement rehabilitation and reconstruction that allow for faster and durable rehabilitation and reconstruction of pavements. a promising alternative strategy is the effective use of precast concrete pavement technologies that provide for accelerated repair and rehabilitation of pavements and also result in durable, longer-lasting pavements. accelerated construction techniques can significantly minimize the impact on the driving public as lane closures and traffic congestion are kept to a minimum. the safety of both highway users and construction workers is improved by reducing the frequency and duration of work zones.

3.20.2. the technique

the primary use of precast concrete pavement technologies is to achieve construction time savings in high traffic volume highway applications and for rapid repair/rehabilitation applications at airfield pavements. the following factors need to be considered when assessing the use of precast concrete pavement as a viable candidate for rapid repair of concrete pavements:

1. fabricating the precast concrete panels at a nearby plant. plant location is critical for economical production repairs, to reduce cost and to reduce traffic disruptions;

2. transporting precast concrete panels to the site (traffic issues, especially for night-time operations);

3. site access for heavy cranes;4. Rapid removal of old pavement;5. Rapid preparation of the base/subbase;6. installing precast concrete panel on finished base/foundation;7. matching adjacent pavement surface grade as closely as possible;8. interconnecting precast concrete panels and existing pavement using a mechanical

load transfer system, typically a version of the dowel bar retrofit technique;9. grouting the dowel/tie-bar slots, as applicable;10. injecting bedding grout to firmly seat panels, as applicable.

in the us, the intermittent repairs, such as full-depth repairs and slab panel replacement, are typically performed at night with a work window from about 8:00 pm until about 5:00 am the next morning. typically, 10 to 15 panel placements are targeted during each work window. the tight work windows and the need to open the facility to traffic by about 6:00 am in the morning make it necessary that the contractors have sufficient equipment and manpower to complete the planned work each night.

since about 2000, many highway agencies in north america have expressed interest in use of precast concrete for intermittent repair or continuous applications in heavily

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trafficked urban areas where extended lanes closures are difficult. the us and canadian highway agencies that have accepted the use of precast pavement for production repair work include:

1. caltrans,2. illinois tollway authority,3. iowa dot,4. ministry of transportation, ontario,5. ministry of transportation, Quebec,6. new jersey dot,7. new jersey turnpike,8. new york state dot,9. new york state thruway authority.

3.20.3. the new Jersey repair project

drilling holes for dowel bars.

precast panels arrive at the site. precast panel installed. this panel system has slots at the panel bottom for dowel bars. the slots are grouted and the panels undersealed the next night.

finishing the base grade.

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during 2007/2008, new jersey dot (njdot) used precast pavement for repairs along a section of i-295 in Burlington county. this project was originally bid as a cast-in-place full-depth patching project. it was converted to a precast panel replacement project because of concerns with construction traffic management. a total of 5,760 m2 (62,000 sf) of precast panels were installed using a proprietary precast pavement repair system known as the fort miller super slab system. the bid price for the slab repair portion was us$2.4 million. the project details are summarized below:

1. three lanes in each direction;2. aadt – 100,000 vehicles per day;3. existing pavement:

a. 35+ years long jointed reinforced concrete pavement with 25.8 m (78 ft 2 in.) long panels and 19 mm (0.75 in.) expansion joints (by design) and multiple cracks per slab panel.

b. slab thickness – 229 mm (9 in.) over 305 mm (12 in.) granular base;c. many expansion joints and cracks severely deteriorated, requiring repair/

replacement of a large no. of panels;d. repair areas were located in all three lanes in each direction.

4. Repair panels were 2.4, 3.1, 3.6, or 4.2 m (8, 10, 12, or 14 ft) long, full lane width, and with a thickness of 229 mm (9 in.);

5. load transfer at joints – four dowels per wheel path (8 dowels per joint);6. night-time placement – 8:00 pm to 6:00 am; work window about 8 hours;7. Rate of placement: 8 to 16 panels replaced per night.

the precast panel installation process is summarized below:

1. sawcut repair boundaries in advance;2. night of repair – remove damaged panel; prepare base; drill dowel bar holes in

existing adjacent panels; insert dowel bars; install precast panel;3. next night – patch dowel slots; underseal panel;4. perform grinding along the repaired areas;5. deflection testing conducted to determine joint deflection and load transfer

effectiveness at joints.

the precast panel installation steps are shown in the box. the repair project was completed in time and to the satisfaction of the new jersey department of transportation. there was minimal disruption to regular daytime traffic. the njdot has since awarded several additional rehabilitation projects requiring use of precast panels.

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tRaffic next day on completed RepaiR.

precast concrete pavement technology has seen significant improvements in the last decade. several precast concrete pavement systems have been developed and are being implemented on production projects. while current precast pavement projects have been in service for only a few years, the field performance of the installed panels, though short in terms of time, indicates that precast pavement systems have the potential for providing rapid repairs that will be durable. in addition, limited accelerated load testing to-date indicates that the precast systems are viable alternatives for rapid repair/rehabilitation of existing pavements.

the installation of precast pavements may have a higher first cost compared to traditional cast-in place full-depth/full slab repair methods. However, the rapid application that minimizes lane closures and the long-term durability may easily offset the higher initial costs. the cost of installing precast pavement repairs is expected to be competitive with cast-in-place concrete repairs as more precasters and contractors become proficient in this technology and the application becomes a routine treatment.

3.20.4. References

• tayabji, s., and Hall, k. (2008). Precast Concrete Panels for Repair and Rehabilitation of Jointed Concrete Pavements, Report no., fHwa-if-09-003, federal Highway administration, washington, dc.

• tayabji, s., Buch, n., and kohler, e. (2009). Precast Concrete Pavement for Intermittent Concrete Pavement Repair Applications, proceedings of the national conference on preservation, Repair, and Rehabilitation of concrete pavements, held in st. louis, missouri, organized by the federal Highway administration, washington, dc.

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