Accelerated Pavement Testing and Modelling in South Africa

TRB WORKSHOP 153SOUTH AFRICAN HIGHWAY TECHNOLOGY AND PRACTICE

Mr Dennis RossmannMaterials and pavement specialist

South African National Roads Agency Ltd SANRAL

Presentation FormatPresentation Format

• Heavy Vehicle Simulator (HVS)

• Mobile Load Simulator (MMLS 3 and MLS)

• Current focus areas

• Conclusions

AcknowledgementsAcknowledgements

• Elzbieta Sadzik• Kim Jenkins• Fred Hugo• Benoit Verhaege• Hechter Thyse• Morris de Beer• Phil Paige-Green

History of HVS program in SA

MKI

Static linear tracking

loading device

Fixed facility

MKII

Mobile pavement tester

Single wheel loading

MKIII

Dual truck and

aircraft wheel

loads

Uni/bi directional

loading

5-6 km/hr (18 000

rep/day)

MKIV

Ltd dynamic

loading simulation

9 – 10 km/hr

(32 000 reps/day)

History of HVS program in SA

• During 1970’s and 1980’s fleet of 4 HVS’soperational in SA

• To date over 400 projects completed

• Currently 2 HVS’s operational

• APT program originally focused on heavy duty applications

• Since mid 1990’s focus broadened to include: • Low volume roads• Labour intensive construction quality

Example of HVS for Low Volume Example of HVS for Low Volume Applications: Applications: Structural CapacityStructural Capacity

Grit seal

160 mm G6 Natural gravel

base

90 mm “subbase”

In situ sand subgrade

20 mm sand

100 mm red sand

40 kN surface deflection40 kN surface deflection

RSD DEFLECTION AT 40kN ON SECTIONS 419A5 AND 420A5

0

100

200

300

400

500

600

0 200000 400000 600000 800000 1000000 1200000

Repetitions

Pea

k R

SD

Def

lect

ion

(mic

ron)

419A5 420A5

419A5 traffic at 80kN

419A5 traffic at 40kN

420A5 traffic at 40kN 420A5 traffic at 80kN

420 A5 water added

Straightedge rutStraightedge rut

Straightedge rut for sections 419A5 and 420A5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 200000 400000 600000 800000 1000000 1200000

Repetitions

Rut

(m

m)

419A5 420A5

419A5 traffic at 80kN

419A5 traffic at 40kN

420A5 traffic at 40kN 420A5 traffic at 80kN

420 A5 water added

OUTCOME OUTCOME

• Plastic strain bearing capacity estimate significantly higher for HVS testing than that determined from laboratory testing: Linear-elastic, multi-layer solution problem

• The structural bearing capacity of this typical pavement structure is adequate for application as a LVR, and similar structures may thus be used with confidence in other locations

HVS for heavy duty applicationsHVS for heavy duty applications

• Investigate the influence of the environment and accelerated loading on joint deterioration on• Plain aggregate interlock joints• Doweled joints• On 2 types of concrete aggregate

• Determine the remaining life of PCC inlay sections on a heavy truck traffic route

HVS for heavy duty applicationsHVS for heavy duty applications

InstrumentationInstrumentation

Instrumentation measures 4 main Instrumentation measures 4 main effects:effects:

• Slab movements due to environmental changes (mainly temperature)

• Elastic movements (deflections) due to HVS loading

• Relative movement across joints(Load Transfer Efficiency)

• Slab deformation (joint faulting)

Relationship between deflections and Relationship between deflections and temperaturetemperature

0

50

100

150

200

250

300

50000 100000 150000 200000 250000

REPETITIONS

DE

FLE

CT

ION

S (

mic

rons

) 40

kN @

620k

Pa

-10.0

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Tem

pera

ture

(°C

)

JDMD 1 JDMD 2 JDMD 4 JDMD 5 dT1 dT4 Surface temp

Zones of high rel movement

And low surface temperatures

Effects of Pumping

0

100

200

300

400

500

600

700

800

900

150000 200000 250000 300000 350000 400000 450000 500000REPETITIONS

DE

FLE

CTI

ON

S (

mic

rons

)

-5.0

0.0

5.0

10.0

15.0

20.0

25.0

JDMD 4 JDMD 5 dT(sun)

M d d 4 2 1 - 0 2 t r a f f i c 0 4 H 0 0 a n d

1 4 h 0 0 . x l s

Loss in slab support due to pumping causes increase d deflections

3 Nov

Rainfall = 94mm during the month

Deflection comparison: PlainDeflection comparison: Plain

JDMD DEFLECTIONS AT 40kN ON SECTION 421A5 (Data at 04H00 & 14H00)

0

100

200

300

400

500

600

700

800

900

0 100000 200000 300000 400000 500000 600000REPETITIONS

DE

FLE

CT

ION

S (

mic

rons

)

JDMD 1 JDMD 2 JDMD 3 JDMD 4 JDMD 5

M dd421-02 traffic 04H 00 and 14h00.xls

Data up to the 23/12/2003

Deflection comparison: DoweledDeflection comparison: Doweled

JDMD Traffic side DEFLECTION AT 40kN ON SECTION 422 A5

0

100

200

300

400

500

600

700

800

900

0 100000 200000 300000 400000 500000 600000 700000REPETITIONS

DE

FLE

CTI

ON

S (

mic

rons

) 40

kN

JDMD 1 TS JDMD 2 TS JDMD 3 TS

JDMD 4 TS JDMD 5 TS Horizontal TS (JD7)J D M D T r a f f i c s i d e s e c t i o n 4 2 2 A 5 T r a f f i c P E A K S . x l s

UPDATED to 14H00 30 March 2004

Project OutcomesProject Outcomes

• Study illustrated the influence which the environment has on pavement performance evaluation parameters• Temperature changes have a profound influence on

measured: Deflections / LTE / Permanent deformations

• Doweled pavement joints outperform plain aggregate interlock joints in terms of• restricting relative movements• edge deflections• general slab deterioration such as joint faulting

Assessment of residual lifeAssessment of residual life

Section 424A5 PietermaritzburgN3Section 424A5 PietermaritzburgN3 --3 km 16.5 (PCC)3 km 16.5 (PCC)

28-05-2004 to 01-06-2004

MDD 3 & 2MDD 4

Crack 2Crack 3Crack 4

6 58 7TC 2

Deflections 60 & 80kNDeflections 60 & 80kN

0

100

200

300

400

500

600

700

800

900

0 100000 200000 300000 400000 500000 600000

Repetitions

Def

lect

ion

(mic

rons

)

-10

-5

0

5

10

15

20

25

Diff

eren

ce B

etw

een

top

and

bott

om T

empe

ratu

re

(°C)

JDMD 1 JDMD 2 JDMD 3 JDMD 4 JDMD 5 JDMD 6 JDMD 7

JDMD 8 JDMD 9 JDMD 10 Horizontal dT 1

Traffic- and test load = 60kN

Traffic- and test load = 80kN

Final conditionFinal condition

Outcomes: Inlay testingOutcomes: Inlay testing

• Pavement was subjected to 6.5mil in-service ESAL’s. Using the 4.2 power law pavement was subjected to another 5.9 mil ESAL’s = total of 12.4 mil

• Pavement was not considered failed after testing has stopped even with the significant amount of transverse cracking

• Comparing this to the Hilton testing benefits of CRCP are clearly visible

• Rehabilitation could be postponed for 3 years +!!!!

Model Mobile Load Simulator Model Mobile Load Simulator (MMLS 3)(MMLS 3)

Applications of the MMLS3: Applications of the MMLS3:

• Field testing on in-service pavements

• Lab testing on slabs/laboratory compacted pills/briquettes

• Lab testing on cores

Establishing MMLS 3 on site in Establishing MMLS 3 on site in MocambiqueMocambique

MMLS3 Device DetailsMMLS3 Device Details

Comparison between some MMLS3 Results on different paved mixesComparison between some MMLS3 Results on different paved mixes

0

0.5

1

1.5

2

2.5

3

3.5

4

0 100 200 300 400 500 600 700 800 900 1000

Axles (x1000)

Rut

ting

(mm

)

NCAT S9

Frankfort

Winburg

Winburg (km54)

Winburg slow

Power (NCAT S9)

Power (Frankfort)

Power (Winburg)

Power (Winburg (km54))

Power (Winburg slow)

Axles x1000

Rutting mm

1m

4mm

SUBBASE AND BASE SUBBASE AND BASE CONSTRUCTION IN LAB.CONSTRUCTION IN LAB.

HMA CompactionHMA Compaction

Seal Construction Seal Construction

Graphical depictions of distressGraphical depictions of distress

MMLS 3MMLS 3testing on corestesting on cores

Comparison of specimens with & without adhesion agent after completion of

trafficking

MMLS 3MMLS 3Testing of coresTesting of cores

Simulation of critical field conditions (temp/moist ure)Simulation of critical field conditions (temp/moist ure)

05

10152025

0 5 10 15

MMLS Ruts (mm)

Fie

ld R

uts

(mm

)

Field ruts at busy city intersection Field ruts at busy city intersection versus rutting measured under MMLS versus rutting measured under MMLS

MLS10 on test site in MozambiqueMLS10 on test site in Mozambique

MLS: FullMLS: Full --scale wet trafficking scale wet trafficking

Cracks Cracks afterafter HMA HMA debondingdebonding fromfromCTB baseCTB base

Place of APT Place of APT * * Hugo et al, 1991 Hugo et al, 1991 –– TRR 1293 TRR 1293

Model APT

APT Structure in South AfricaAPT Structure in South Africa

Steering Committee

Technical management

Needs Scope Prioritisation

Technicalpanel

Proposals Reports Guidelines

Review Pool

Benefit cost ratio of APTBenefit cost ratio of APT

3.52.9

2.4

6.1

5.1

4.2

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

4% 8% 12%

Discount Rate

Ben

efit

Cos

t Rat

ioGautrans & SANRAL Combined

Current and Future APT Focus Current and Future APT Focus areasareasCold bituminous recycling (ETB and foam)

Current and Future APT Focus Current and Future APT Focus areasareas

Vehicle-pavement interaction – SIM TM

Current and Future APT Focus Current and Future APT Focus areasareas

AC mix design (HMA) – Permanent deformation

Current and Future APT Focus Current and Future APT Focus areasareas

• Input into an improved M-E pavement design methodology i.e imposed stresses and field variables such as: • Temperature in layers • Degree of densification• Degree of saturation• Inherent variables in material properties

ConclusionsConclusions

• HVS & APT has had a major impact in the categorisation of local materials and pavement system response

• HVS owners: • South Africa• USA• Sweden/Finland• Possibly Sub continent & Far East?

• HVS International Alliance

MMLS has become a valuable MMLS has become a valuable associated APT tool which is associated APT tool which is expanding globallyexpanding globally

South African technology and South African technology and expertise has been, and will hopefully expertise has been, and will hopefully

remain, a significant contributor to remain, a significant contributor to APT internationally.APT internationally.

THANK YOU

There is a choiceThere is a choiceGo alone Work togetherGo alone Work together