CSIR-UCB CSIR-UCB research research programmeprogramme

Road Pavements ForumRoad Pavements Forum

14 November 200114 November 2001

Where did it start?Where did it start?

Officially started in 1994Officially started in 1994 Sale of two refurbished HVS Mk IIIsSale of two refurbished HVS Mk IIIs Technology transfer package in Technology transfer package in

addition to sale of HVSsaddition to sale of HVSs Initial stages: HVS operationInitial stages: HVS operation Later stages: Value addition projectsLater stages: Value addition projects

Organisational structureOrganisational structure

CALTRANSTom Hoover

PRC of ITSPI: Dr J Harvey

University ofCalifornia, Berkeley

Contractor:Dynatest IncDr N Coetzee

Subcontractor:Transportek, CSIR

Technology transferTechnology transferCALTRANSTom Hoover

PRC of ITSPI: Dr J Harvey

University ofCalifornia, Berkeley

Contractor:Dynatest IncDr N Coetzee

Subcontractor:Transportek, CSIR

Post-graduate training

HVS and other value addition projects

Post graduate studiesPost graduate studies Masters degreesMasters degrees

Louw du PlessisLouw du Plessis Leoni LouwLeoni Louw Jeremy LeaJeremy Lea

Ph DsPh Ds Fenella LongFenella Long

Non-linear visco-elastic modelling of asphaltNon-linear visco-elastic modelling of asphalt Jorge ProzziJorge Prozzi

Empirical models of pavement deterioration developed from Empirical models of pavement deterioration developed from multiple data sources (near completion)multiple data sources (near completion)

Andrew HeathAndrew Heath A constitutive model for unbound materials (in process)A constitutive model for unbound materials (in process)

HVS operationHVS operation

Field operationsField operations Rigid pavement Rigid pavement

testingtesting Rapid setting Rapid setting

concreteconcrete Dowel- and tie-Dowel- and tie-

barsbars Widened slabsWidened slabs Dowel-bar retrofitDowel-bar retrofit

HVS operationHVS operation

Field operationsField operations Palmdale – Palmdale –

Operator and Operator and assistant assistant operatorsoperators

Value addition projectsValue addition projects

Rigid pavementsRigid pavements 11stst level analysis of HVS data level analysis of HVS data

Flexible pavementsFlexible pavements Mechanistic-empirical design Mechanistic-empirical design Subgrade designSubgrade design Unbound materialsUnbound materials Pozzolanic stabilizationPozzolanic stabilization Deep in situ recyclingDeep in situ recycling

Value addition projects:Value addition projects:Rigid pavementsRigid pavements

Warping of slabsWarping of slabs In John Harvey’s words: “Tell me the In John Harvey’s words: “Tell me the

deflection you want and I’ll tell you the time deflection you want and I’ll tell you the time to go and measure”to go and measure”

Longitudinal cracking of slabs because of Longitudinal cracking of slabs because of cantilever effectscantilever effects

Preliminary conclusionsPreliminary conclusions Reduce stiffness of support layerReduce stiffness of support layer Narrow slabs with tie-bars better thanNarrow slabs with tie-bars better than widened slabs without tie-bars andwidened slabs without tie-bars and narrow slabs without tie-barsnarrow slabs without tie-bars

Value addition projects:Value addition projects:Flexible pavementsFlexible pavements

Mechanistic-empirical designMechanistic-empirical design Input at bi-annual workshopsInput at bi-annual workshops Probabilistic design (risk of failure)Probabilistic design (risk of failure) Material response characterizationMaterial response characterization

Elastic response – Resilient modulus Elastic response – Resilient modulus modelsmodels

Plastic response – Permanent Plastic response – Permanent deformation transfer functionsdeformation transfer functions

Utilization of PMS data for validation Utilization of PMS data for validation of M-E design methodof M-E design method

Value addition projects:Value addition projects:Flexible pavementsFlexible pavements

Subgrade designSubgrade design Analysis of all suitable HVS data from Analysis of all suitable HVS data from

Richmond Field Station and South Richmond Field Station and South AfricaAfrica

New insight into subgrade behaviourNew insight into subgrade behaviour New subgrade design critical New subgrade design critical

parameters and transfer functionsparameters and transfer functions

Subgrade design:Subgrade design:Elastic responseElastic response

Ferricrete (wet)

0

2

4

6

8

10

12

14

25 29 32 36 39 43 46 50 53 57 60

Mr (MPa)

Co

un

t

Subgrade design:Subgrade design:Elastic responseElastic response

Sandstone

0

1

2

3

4

56

7

8

9

10

68 96 123 151 178 205 233 260 288 315 342

Mr (MPa)

Co

un

t

Subgrade design:Subgrade design:Plastic responsePlastic response

S-N regression model7 mm subgrade deformation

1,E+03

1,E+04

1,E+05

1,E+06

1,E+07

1,E+08

1,E+09

0 200 400 600 800 1000 1200

Subgrade elastic deflection (micron)

Cyc

les

Model Data

R2 = 0,659SEE = 0,375

Value addition projects:Value addition projects:Flexible pavementsFlexible pavements

Unbound materialsUnbound materials Comparison with Californian aggregateComparison with Californian aggregate

Material specificationMaterial specification Construction quality (density specification)Construction quality (density specification)

Synthesis report on South African experienceSynthesis report on South African experience Advanced laboratory testing and material modellingAdvanced laboratory testing and material modelling HVS test resultsHVS test results

Pozzolanic stabilizationPozzolanic stabilization Synthesis report on South African practiceSynthesis report on South African practice

Material and quality specificationMaterial and quality specification Mechanical behaviourMechanical behaviour

Durability study (carbonation) of cement-treated Durability study (carbonation) of cement-treated material and lean concretematerial and lean concrete

Value addition projects:Value addition projects:Flexible pavementsFlexible pavements

Deep in situ recyclingDeep in situ recycling Synthesis report on selected South African Synthesis report on selected South African

experienceexperience Process promoted by AALP in CALTRANS Process promoted by AALP in CALTRANS

regionsregions Lots of interest from regions and CALTRANS Lots of interest from regions and CALTRANS

ResearchResearch Gautrans comprehensive RDI planGautrans comprehensive RDI plan

Meeting between E Sadzik, T Hoover, J Harvey and N Meeting between E Sadzik, T Hoover, J Harvey and N Coetzee following PMS conference in SeattleCoetzee following PMS conference in Seattle

Pledged support for Gautrans process by funding Pledged support for Gautrans process by funding HVS and laboratory testingHVS and laboratory testing

ConclusionsConclusions

International Technology Transfer International Technology Transfer in actionin action

Financial benefit not only to CSIR Financial benefit not only to CSIR but South Africabut South Africa

South African practical expertise South African practical expertise exchanged for top international exchanged for top international analytical skillsanalytical skills