arra semi-annual meeting | minneapolis, mn | …...“ecopistas” (an ecorodovias concession since...

ARRA Semi-Annual Meeting | Minneapolis, MN | October 16-19, 2017

ARRA Semi-Annual Meeting | Minneapolis, MN | October 16-19, 2017

“North versus South! – A Recycling

Perspective from Down-Under“Is it relevant?

Kim Jenkins

:

Wechsel des Folienlayouts

My home: Stellenbosch, South Africa

:


Big 5

:


What aboutthese animals?

:


World Class: Long distance athletes

:


7

Cricket – a strange game

1874

1974

:


Outline - North versus South

8

1. Pavement Structure Differences

2. Implications on Pavement Rehabilitation Needs

3. Important Factors

4. Structural Design

5. Application: Case study

:


Pavement Design Philosophy: North versus South

Northern Hemisphere: thick asphalt Southern Hemisphere: thin asphalt

HMA

SIMILAR LOAD SPREADING

Increased stiffness spreads the load

wider

Improved resistance to water ingress

:


FDR versus CIR

Good news ! Milled material (RAP) is the best material that

can be recycled

RAP =Reclaimed Asphalt Pavement

:


General Comments from several States on FDR and CIR

Gravel factor of 1.4 x Class II granular base being used for design

Asphalt layers overlaying BSM are thick

Contribution of BSM only in structural system, not inter-layer

SN does not account for MrBSM directly reducing eHMA

Layer coefficients for SN design are variable

Integration of BSM into MEPDG? (explicitly)

California using triaxials for research of ME design function but not (yet) for application

Challenges with FDR and CIR in different silos (solved!)

Influence of high RAP% in BSM can be included

:


Cohesion C

0

100

200

300

400

500

A-75C

-0

B-75C

-0

C-75C

-0

A-75C

-1

B-75C

-1

C-75C

-1

A-75M

-0

B-75M

-0

C-75M

-0

Coh

esio

n [k

Pa]

E E E E E E FFF20

25

30

35

40

45

50

A-75C

-0

B-75C

-0

C-75C

-0

A-75C

-1

B-75C

-1

C-75C

-1

A-75M

-0

B-75M

-0

C-75M

-0

Fric

tion

angl

e [d

egre

es]

Friction Angle f

E E E E E E FFF

(Ebels, 2006 & Jenkins, 2000)

25% RAP 25% RAP75% RAP 75% RAP

Influence of Mix Composition (RAP %)

BSM– are shear parameters sensitive to material composition?

:


Durability of BSMs Improved Moisture Simulation

Moisture Induction Sensitivity Test MIST

(Twagira, 2008)

:


0

10

20

30

40

50

60

70

80

90

Q+ 0C

-F

Q+ 1C

-F

Q+ 1L -F

Q+ 1C-

E

Q+ 1L -E

H+ 0C

-E

H+ 1C

-E

H+ 1L -E

BSM 1

BSM 2

BSM 3

Resi

du

al

co

hesi

on

[%

]

Tested BSMs

Aggregate geology and active filler is importantWhat else?

Resistance to Moisture Damage: Retained Cohesion

:


Dal Ben, 2014

Influence of RAP on BSM performance ITS versus Temperature

:


Tests performed for all BSM-foam at 25°C

Dal Ben, 2014

Influence of RAP% on BSM Permeability

:


Factors influencing permeability of BSM-

foam mix and include:

• particle (aggregate) size distribution

(grading);

• particle shape;

• molecular composition of BSM;

• air voids (i.e. compaction);

• degree of saturation;

• type of flow, and

• temperature.

Dal Ben, 2014

Influence of RAP% on BSM Permeability2

:


MIST Conditioning: Moisture Induced Simulation Test

The pulsing and infiltration of moisture at 145 kPa

is linked to the dynamic loading of traffic

Influence of RAP% on Moisture Damage based on Triaxial Tests

:


➢ All beams compacted in a mould

➢ Testing temperature: 25°C

➢ LVDT on top of the beam to accurately measure displacement in

the middle of the beam.

LVDT

(Campher, 2012)

Flexibility of BSM: Strain-at-break from 4 Point Beam Loading

:


Specimen

specification

Material parameter

Average

Maximum Stress

(kPa)

Average Strain-

at-break

(µԐ)

Average

Dissipated

energy (Pa)

Average

stiffness

(MPa)

0.9% Emulsion; 1%

Cement 174.4 376.5 39.1 524.2

2.4% Emulsion; 1%

Cement 254.9 537.2 89.8 473.1

2.4% Emulsion; 2%

Cement 320.4 391.1 78.8 821.6

2.4% Foamed; 1%

Cement 211.6 480.8 68.7 447.4

2.4% Foamed; 2%

Cement 383.8 508.7 151.3 761.9

-40.00 -20.00 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00

Average Strain-at-break (µԐ)

Average Dissipated energy (Pa)

Average stiffness (MPa)

% Change in parameter value

Fle

xib

ilit

y r

ela

ted

p

ara

me

ters

Increase in bitumen emulsion (specimenscontaining 1% cement)Increase in cement (stabilised with bitumenemulsion)Increase in cement (stabilised with foamedemulsion)bitumen

Flexibility of BSM: Strain-at-break Results

Flexibility = 1/Cem%

:


b

AYRTON SENNA HIGHWAY

:


Originally constructed early 1970s

“EcoPistas” (an EcoRodovias concession since 2009)

Rehabilitation in July 2011Currently 15 000 heavies/direction/day

Lane Closure 22:00 – 05:00

:


Results of Pavement Investigations

HMA ± 100mm

SELECTED COARSE GRAVEL (CBR >25) ± 200mm

EMBANKMENT (RIVER LEEVEE) (CBR > 15)Semi-infinite

GRADED CRUSHED STONE ± 200mm

CEMENTED CRUSHED STONE ± 250mm

6% CEMENT

:


Rehabilitation Options?

350mm

BSM-a 200mm

BSM-b 130mm

20mmHMA

?

DeviatorStressRatio

100mm

50mm

:


SN DESIGN EXAMPLEPavement Design

SN DESIGN TRAFFIC= 8.5 x 106 STANDARD AXLES (80kN)

h1.K1

h2.K2

h3.K3

h4.K4

Asphalt

BSM

Granular

Subgrade

Wirtgen: KBSM = 0.30 to 0.35 VDOT on I81 has KBSM = 0.37 to 0.44 …be careful!

:


Lab Triaxial Analysis

Permanent deformation (rutting) design for granular material

Design Life for 10mm rut

Deviator Stress Ratio

:


Design Function for BSM

𝑁 = 𝑓 (𝑅𝐷, 𝑅𝑒𝑡𝐶, 𝑃𝑆, 𝑆𝑅𝑥)

Relative Density Plastic Strain (a/b)

Retained Cohesion Stress Ratio

a b

Case Study

:


Modelling (Rubicon LET)

50

200

∞

BSM

GCS

HMA

S/G

100

100

100

“BALANCED PAVEMENT”

85 / 15 RAP / Dust blend

100% RAP

100% RAP

Modular Ratio Rule

2

3

2.3

1.2

MaterialModular

Ratio

Maximum stiffness

(MPa)

Crushed stone 1.8 – 2.0 300 - 500

Gravel 1.5 – 1.8 150 - 300

Soil 1.2 – 1.6 50 - 150

MaterialModular

RatioMaximum

stiffness (MPa)

HMA 5 1000 - 2500

BSM 2 - 3 500 - 1200

CTB 2 - 3 300 - 500

Crushed stone 1.8 – 2.0 300 - 500

:

Wechsel des Folienlayouts BSM Class Cemented

Subbase Granular Subbase

BSM (RAP + GCS)

900 – 1750 700 – 1200

BSM (GCS Grade Crushed Stone)

800 – 1200 600 – 900

ELT Mr = f (aggregate type and quality, RAP %, bitumen %, support, traffic, climate)

Supporting Layer

Effective Long Term Stiffness of BSM for Design

Actual 600/1000/1200

:


BSM Modulus Values : Triaxial testing

33

Pavement Design – Case Study

Dry cure Humid Cure3 7 14 28 60 1 7 28 days

:


BSM Modulus Values : FWD back-calcs

34

Pavement Design – Case Study

Mr (MPa)

:


FWD Analysis: From km 15+650 to km 16+250

SLOW LANE Applied Load: 8 ton axle load, 541 to 607 kPa applied pressure

Pavement LayersThickness (mm)

Poisson’s ratio

Derived resilient modulus (MR) (MPa)

Average 80th %ile (high) 80th %ile (low)

Asphalt surfacing 50 0.4 3000 3000 3000

BSM base 100 0.35 1633 1954 1312

BSM upper subbase 200 0.35 1192 1527 857

Natural lower subbase

250 0.35 346 459 253

Subgrade support Inf 0.35 275 309 204

Analysis of FWD survey – October 2014

:


To local stockpile

REMOVE 100mm HMA

:


Impact crusher (20mm gap setting)

DAYTIME OPERATIONS

Processing the RA

:


KMA 220 mixing plant

Mix 1: 100% RA + 2% Foamed Bitumen + 1% lime

Mix 2: 85% RA / 15% dust + 2.1% Foamed Bitumen + 1% lime

:


250mm

100mm

REMOVE 250mm CTB LAYER

:


18th November 2011

:


…years later

:


Conclusions

Investigation for rehab (new)

Mix design system in place

Equipment available (vib hammer & triaxial)

Testing protocols

System accounts for N Hemisphere - RAP%

Pavement design (N Hem – Climate & Cure)

New ME design function (N Hem – sd/sdf)

Application - in plant vs in place (N Hem too)

:


Thank you

Questions??

arra semi-annual meeting | minneapolis, mn | …...“ecopistas” (an ecorodovias concession since...

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