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HVSIA meeting.20-22 June 2007 Gautrans HVS Programme. Elzbieta Sadzik

Gautrans HVS Programme

HVSIA 4th meeting20-22 June 2007

Gauteng Department of Public Transport, Roads and Works


Overall trends in South AfricaIntensified migration to urban areas coupled with sustained economic growth of between 5 and 6%: necessitates greater investment in infrastructure to support SA’s socio-economic developmentLarge capital projects in support of economy and FIFA 2010 Significant capital investment in infrastructure provision (>6% of GDP), particularly in roads, electricity, housing, rail and ports

… but, acute lack of skilled resources and insufficient funds available for preservation of existing infrastructure


SAICE Infrastructure report (Nov ’06)Road type Rating Comment

National roads C

Most in fair to very good condition, with recent strategic acquisitions in poorer shape. Increasing use of user-pays (tolling), but funding remains a challenge, especially given that key roads will soon require extensive refurbishing.

All other roads D-

Generally inadequate funding and management systems leading to neglect of maintenance, combined with overloading, means that maintenance backlogs are growing. Less condition monitoring than in the past. Shortages of skilled personnel. Decisions have been taken to stop maintaining some roads.


Road Network Condition - GautengTendency since 2003:

• Good to very good roads decrease by ± 100 km pa. • Poor to very poor roads increase by ± 50 km pa.

0%10%20%30%40%50%60%70%80%90%

100%

1985

1986

1987

1988

1989

1990

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

Year

Leng

th (%

)


Predicted road network condition by 2010By 2010 Soccer

21 26 3326 25 25

49 4153

0%10%20%30%40%50%60%70%80%90%

100%

Current budgetwith no grants for

10 years

Current budgetwith no grants for2007 and 2008

Current (withgrants)

% N

etw

ork

Leng

th

Good to very good Fair Poor to very poor


Gautrans HVS ProgrammeStrategic Plan 2006 - 2009

Focus Areas:Sustainable Development and the EnvironmentLabour-Intensive ConstructionAsphalt PerformanceProvision of Low Volume Roads (including upgrading of unpaved roads)Vehicle Pavement Interaction (including dynamic loads and contact stresses)Concrete pavementsStructural Pavement Design methods


Gautrans HVS ProgrammeHVS programme projects:

Ultra Thin CRCP (sponsors: SANRAL & GDPTRW) – Concrete PavementsGuidelines for bitumen stabilization with ETB & FB (sponsors: SABITA & GDPTRW) – Sustainable Development and the EnvironmentForensic testing of AC Part 1&2 (sponsor: GDPTRW) – Asphalt PerformanceValidation of HMA design protocols for permanent deformation (Sponsor: GDPTRW) – Asphalt PerformanceSIM testing HVS and MMLS (sponsor: GDPTRW) – Vehicle Pavement InteractionGuidelines for design and construction of LIC (Including documentation and training issues) – Labour Intensive Construction


Gautrans HVS programmeProject status:Ultra Thin CRCP

Phase I completed and reported during HVSIA 06Phase II consists of comparing the proprietary Dannish concrete mix (Contec-Aps) to modified South African mixes;CompletedPhase III evaluating structural performanceof construction joints.Completion: Sept 07


UTCRCP HVSUTCRCP HVS Sections –Phase 1

60 m

HVS426A5

HVS429A5

HVS427A5

HVS428A5

3.7

m

20 mm AC150 mm G7(CBR = 15 %)

40 mm UTCRCP

1.0mm (40 kN) Surface Deflection Before Overlay

HVS430A5

HVS431A5

3.7

m

40 mm UTCRCP20 mm AC

150 mm G7

150 mm C4

0.3mm (40 kN) 0.6mm (40 kN)


UTCRCP UTCRCP –– Sections at FailureSections at Failure


UTCRCP UTCRCP –– HVS RepetitionsHVS Repetitions

Tire Pressure = 800 kPa (Truck), 1400 kPa (Aircraft)Speed = 9.0 km/h, Load Application = Canalized bi-directionalAircraft Wheel Used for wheel loads above 100kNShaded Areas = Surface Water Added Continuously

426A5 427A5 428A5 429A5 430A5 431A530 2,00040 18,000 40,000 100,000 38,000 40,160 40,00060 20,500 40,000 40,500 40,000 40,080 40,08880 26,500 197,000 59,650 177,704 122,764 120,00080 130,50080 122,500 52,650 800,000 703,189

100 23,000 21,547120 20,528125 137,000140 135,100 1,360140 103,300

Total Reps 463,400 530,000 252,800 257,704 1,046,439 903,277

Total ESAL's (n=4.5) 92,190,469 10,470,348 2,892,170 4,306,993 25,761,052 18,915,197

Test Wheel Load (kN)

HVS Repetitions Per Test


UTCRCP UTCRCP –– Conclusions Phase 1Conclusions Phase 1Do not use “spacer bars” or asphalt paver for placement;Debonding between UTCRCP and asphalt support layer in presence of water – increase in stress; Presence of anchors did not have a major impact on curling;Steel fibre length and shape do impact performance –optimum 30 mm x 0.5mm hook end fibre; Amount of steel not that crucial according to FE model, but lab test indicate optimum to be - Ø 5.6mm @ 50x50mm – HVS tests to verify this.


UTCRCP Phase 2 UTCRCP Phase 2 -- APT TestsAPT TestsReconstructed APT Test Section 1

• Different Steel Mesh (max Ø 5.6mm @ 50x50mm), Steel Fibre and Concrete Mix Options

• Placed by Hand – Drum Mixer


UTCRCP Phase 2 UTCRCP Phase 2 -- APT TestsAPT TestsTest plan

• Loading: 0 – 40 000 reps @ 40kN40 – 80 000 reps @ 60kN80 000 + @ 80kN

• Water added from 200 000 reps 2 days wet, 5 days dry


UTCRCP Phase 2 UTCRCP Phase 2 –– APT ResultsAPT ResultsContec-Aps mix• Ø 5.6mm @ 50x50mm, Straight 12mm Fibre;• Repetitions = 1,356 million; • ESAL’s = 29,151 million


UTCRCP Phase 2 UTCRCP Phase 2 –– APT ResultsAPT ResultsRSA mix 1• Ø 4.0mm @ 50x50mm, Hooked Fibre 30mm;• Repetitions = 1,176 million;• ESAL’s = 25,099 million


UTCRCP Phase 2 UTCRCP Phase 2 –– APT ResultsAPT ResultsRSA Mix 2• Ø 5.6mm @ 100x100mm, Hooked Fibre 30mm;• Repetitions = 0,258 million; • ESAL’s = 4,336 million


UTCRCP UTCRCP –– Conclusions Phase 2Conclusions Phase 2Hand placed performs equal or better than asphalt paverlaid; The absence of asphalt inter layer had no noticeable impact;The absence of anchors had no noticeable impact;Hooked Fibres did prevent previous “explosive” failures noticed during phase 1; Major difference in performance between Steel Mesh with 50x50mm and 100x100mm spacing for same Ø –Wider shrinkage cracks the larger the spacing;Presence of crack with subsequent moisture increase is critical to performance;Construction Joints ???


Objectives: Phase IIIEvaluate the structural performance of construction joints:• Constructed 4 slabs, slab 1 and 3 during the first day

and slabs 2 and 4 the following day.• Each joint differently constructed

Measure slab shrinkage and slab curl prior to HVS loading


UTCRCP Phase 3 UTCRCP Phase 3 -- APT TestsAPT TestsSteel Mesh Ø 5.6mm @ 50x50mm, with 3 Construction Joint SolutionsPlaced by Hand – Pan Mixer

3,7m

WheelPaths

24 m

50 mm Concrete

Additional Ø5.6 mm x 500mm Dowel Bar @ 150mm

6m

0.5m0.5m

Ø5.6mm # 50x50mm RSA Binder

50 mm

Ø5.6mm steel mesh placed @ 50x50mm intervals at centre of slab continuing through day-joint

50 mm

Additional Ø5.6 mm x 1400mm Dowel Bar @ 150mm

Joint 1Joint 2

Joint 3

JDMD’s JDMD’s


UTCRCP Phase 3 UTCRCP Phase 3 -- ConstructionConstruction


UTCRCP FutureUTCRCP FutureConstruction • Construction Cost = $ 40 - 50/m2

• Construction time about 1/3 of current RSA practices

• High Quality Labour IntensiveStandard Specifications• Complete Standard Specifications• Complete QA Procedures

cncPAVE• UTCRCP Incorporated – August 2007

Postulated Alternative• Introduce as postulated alternative – 2007


Gautrans HVS programmeProject status:Guidelines for bitumen stabilization with ETB & FB

Inception report (Phase 1) finalized in January 2006Phase 2 structural and mix design to be completed by March 2008Phase 3, drafting of best practice guideline document for foamed-bitumen and bitumen-emulsion treated materials, to be initiated by mid-2008


Knowledge Based Approach

Gather all available field performance dataDistil best elements of mechanistic analysisValidate and refine for robustnessDevelop clear, strong linkage to field testing and specifications

Data Sets:• More than 20 field sites with construction,

maintenance & performance info

• 7 HVS Sites (22 test sections) with construction & performance


The Design Process

LAB

DCPVisuals

Test Pits

FWD

Design InputsCapacity

Assessment

CBR 7-15%

200 mm BSM 1

130 mm C4

> 200 mm G6

Specifications

Mix Design

Materials Classification


Materials Classification Report- Example

Test or Indicator Samples G4 G5 G6 G7

Test Limits for Material Class

G4 G5 G6 G7

Cumulative Certainty for Material Class

DCP Penetration 12 0.13 0.29 0.06 0.00

FWD Stiffness 67 0.26 0.32 0.11 0.00

Grading Analysis 3 0.37 0.34 0.11 0.00

% Passing 0.075 3 0.43 0.37 0.11 0.00

Plasticity Index 5 0.46 0.47 0.11 0.00

California Bearing Ratio 2 0.49 0.54 0.16 0.03

Relative Moisture Content 4 0.52 0.57 0.19 0.00

Outcome: Material is most likely a G5 design equivalent

Confidence: Confidence of the assessment is medium. For structural rehabilitation, it is recommended that the sample size and number of test indicators be increased.


Structural Design Method

Based on the Structural Number ConceptImproved by incorporating established design principles and local experienceCalibrated for long term field performance


Disadvantages of SN ApproachNon-uniqueness of the index• E.g. Switching base and subbase give same SN

Insensitivity to placement of weak layers

CBR 7-15%

150 mm G1

150 mm C4

40 mm AC Thick1 x A1 = SN1

Thick2 x A2 = SN2

Thick3 x A3 = SN3

SN = SN1 + SN2 + SN3

Both of these limitations can be overcome by incorporating design rules of thumb that make the SN more intelligent.


Rules of Thumb1. Structural capacity is determined by the

combined long term load spreading capacity of all pavement layers

2. Subgrade quality is the point of departure for design, as it effects all layers above it

3. The type and quality of the base layer is critical, and suitable base material depends on design situation

Where does this come from:• Established knowledge in guidelines and textbooks• Trends in design catalogues (TRH4)• Trends in LTPP and HVS section performance


Suitability of PN-Based Method

Method not applicable to:• Design traffic > 30 msa• Design traffic < 1 msa (catalogue required)• Presence of thin, weak lenses• Subgrade CBR < 3 %


Summary: Structural Design

Simplified method for determining structural capacityRobust, Easy to understandWell and explicitly validated with TRH4, LTPP and HVS datasetsValid for design traffic up to 20 mesa (majority of SA roads)Should not use independently for traffic > 30 mesaRequires Material Class as design inputs


Gautrans HVS programmeProject status:Forensic testing of HMA Part 1&2 (HMA research)

Forensic studies completed and reports finalizedWorkshops held in three centers in South AfricaAcknowledgement that issues relating to rutting and durability of HMA needed to be sorted out


Gautrans HVS programmeProject status:Validation of design protocols for HMA rutting

Laboratory studies completed on control mixAPT studies on effect of temperature on rutting completedAPT studies on effects of contact stresses and layer thickness on rutting ongoingDesign optimization of “rut-resistant” HMA mixes ongoing


Main objectives of HMA rutting study

Compare permanent deformation results from APT with a range of laboratory tests with the aim to:

• Identify appropriate tests for permanent deformation prediction

• Develop protocols & acceptance criteria for selected tests

Test should be able to reliably forecast permanent deformation taking cognizance of:

• Mix composition, Pavement structure• Climate, Traffic


Road R80

7-day average maximum temperature: 58 ºC Minimum surface temperature: -0.6 ºCTest conducted over 40 ºC to 60 ºC temperature range


APT site


200 m x 40 mm HMA (single lane)

100 m x 25 mm HMA(single lane)

100 m x 60 mm HMA(single lane)

N

50 m x 25 mm HMA

(both lanes)100 m x 40 mm HMA

(both lanes)

50 m x 60 mm HMA

(both lanes)

Fatigue & Durability StudyExisting carriageway (western direction)

Layout of HMA sectionsMethodology

Not to scale

Pretoria Mabopane

Unused carriageway (western direction)Permanent Deformation Study


Basic properties of standard mix: Marshall

Binder type: 60/70 pen grade (PG 64)Optimum binder content: 5%

Property Test Results Specifications% voids in mix 4.3% 3 to 6%% VMA 15% > 14%% VFB 72% 65 to 75%Filler-bitumen ratio 1.1 1.0 to 1.5Film thickness 8.2 µm > 7 µm

Dynamic creep modulus ~ 16.4 MPa 15-20 MPa

Marshall Stability ~11 kN 10 to 18 kNMarshall Flow ~3.0 mm 2 to 6 mmITS ~1 187 kPa > 800 kPaStatic creep ~242 MPa > 100 MPaGyratory voids (300N) ~2.4% >2.0%


Effect of temperatureHamburg Rut Test (Field mix with different Temperatures) @ 40mm

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

Wheel Passes

Rut

dep

th (m

m) A7c40-5 @40deg

A7c40-6 @40degA7c40-3 @50degA7c40-4 @50degA7c40-1 @60degA7c40-2 @60degA7c40-7 @55degA7c40-8 @55degA7c40-9 @45degA7c40-10 @45deg


Creep slope vs. temperatureRelation between temperature and rut rate for standard mix under Hamburg test

y = 2E-05e0.1152x

R2 = 0.9254

0

0.005

0.01

0.015

0.02

0.025

35 40 45 50 55 60 65

Temperature ºC

Stea

dy s

tate

rut r

ate

mm

/pas

s

Hamburg results (40mm field cores)


Permanent deformation under HVS (60ºC)


APT: effect of temperaturePermanent deformation HVS tests 441A (60ºC) and 442A (40ºC)

0

2

4

6

8

10

12

0 20 000 40 000 60 000 80 000 100 000 120 000 140 000 160 000 180 000 200 000

Wheel Passes

Perm

anen

t def

orm

atio

n [m

m]

Avg CS 60ºC

Avg TS 55ºC

Avg CS 40ºC

Avg TS 40ºC


MMLS field vs. MMLS lab (60ºC)


MMLSMMLS 7200 r/h, 750 kPa, 2.9 kN, 40mm

0.00

0.50

1.00

1.50

2.00

2.50

0 50000 100000 150000 200000 250000 300000 350000 400000

Wheel Passes

Perm

anen

t def

orm

atio

n [m

m]

test A 60 ºC

Test C 50 ºC

Test D 40 ºC


Preliminary observationsCurrent (Marshall) design methods may be inappropriate for demands at heavily trafficked sites and high temperature conditionsConsistent results from most lab test methods, with certain exceptions (dynamic creep)For tested mix, temperature is a key factor impacting on permanent deformationMMLS testing appears to overestimate resistance of mix to permanent deformation


Gautrans HVS programmeProject status:SIM testing on HVS and MMLS wheels

• Comparison between HVS and MMLS3 contact stresses on rough and smooth surfaces -completed


MMLS and HVS on SIM


Comparison between MVCS of MMLS and HVS

Maximum Vertical Contact Stress (MVCS) (12R22.5 of HVS MK IV+ compared with MMLS3)

ROUGH AND SMOOTH TEST SURFACES

0100200300400500600700800900

10001100120013001400150016001700180019002000

300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100Tyre Inflation Pressure (kPa)

Maxim

um V

ertic

al Co

ntac

t Stre

ss (M

VCS)

(kPa

)

HVS - 12R22.5 - SMOOTH SURFACE

- - - HVS - 12R22.5 - ROUGH SIM SURFACE

MMLS3 - DIAMOND -SMOOTH SURFACE

- - - - MMLS3 - DIAMOND -ROUGH SURFACE

1:1


HVS/SIM tire comparison outcomes

The average MVCS of the MMLS test tyre was roughly 30 percent lower than those found for the HVS tyres on both rough and smooth surfaces On average, the MVCS for the relatively smooth test surface was found to be approximately 23 percent higher than those found for the HVS tests tyres


Related research

PSPA evaluation• Separate feedback

LTPP sections• Ongoing evaluation of old HVS sections (4 Gauteng,

2 PAWC)• Separate feedback

Instrumentation• Completion of investigation into parameters for

instrumentation• Separate feedback


Gautrans HVS ProgrammeHVS future projects:

HMA performance• Testing of rut resistant mixes including Hi-Modulus

Asphalt (HiMA) mixes• Fatigue and durability evaluation of HMA• Updating of design guidelines

South African Pavement Design Method• Model development• Validation & calibration


SAPDMMajor upgrade / improvement of SAMEDMStructure based on AASHTO 200x22 Project briefs / focus areas – June 2007• Immediate (18 months) deliverables

o Incorporation of existing work• Short term (3 year ) deliverables

o New research/application – short duration• Medium term (5 year) deliverables

o More detailed new research and implementation


Technology transferMarketing brochureSATC – July 2007• SATC papers• SATC workshop

Technology development symposium – May 2007RPF feedbackReports / Executive Summaries Website


Gautrans HVS reports available onwww. gautrans-hvs.co.za


Thank you

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