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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
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Presentation FormatPresentation Format
• Heavy Vehicle Simulator (HVS)
• Mobile Load Simulator (MMLS 3 and MLS)
• Current focus areas
• Conclusions
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AcknowledgementsAcknowledgements
• Elzbieta Sadzik• Kim Jenkins• Fred Hugo• Benoit Verhaege• Hechter Thyse• Morris de Beer• Phil Paige-Green
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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)
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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
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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
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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
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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
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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
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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
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HVS for heavy duty applicationsHVS for heavy duty applications
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InstrumentationInstrumentation
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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)
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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
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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
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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
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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
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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
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Assessment of residual lifeAssessment of residual life
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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
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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
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Final conditionFinal condition
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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 +!!!!
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Model Mobile Load Simulator Model Mobile Load Simulator (MMLS 3)(MMLS 3)
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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
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Establishing MMLS 3 on site in Establishing MMLS 3 on site in MocambiqueMocambique
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MMLS3 Device DetailsMMLS3 Device Details
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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
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SUBBASE AND BASE SUBBASE AND BASE CONSTRUCTION IN LAB.CONSTRUCTION IN LAB.
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HMA CompactionHMA Compaction
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Seal Construction Seal Construction
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Graphical depictions of distressGraphical depictions of distress
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MMLS 3MMLS 3testing on corestesting on cores
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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)
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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
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MLS10 on test site in MozambiqueMLS10 on test site in Mozambique
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MLS: FullMLS: Full --scale wet trafficking scale wet trafficking
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Cracks Cracks afterafter HMA HMA debondingdebonding fromfromCTB baseCTB base
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Place of APT Place of APT * * Hugo et al, 1991 Hugo et al, 1991 –– TRR 1293 TRR 1293
Model APT
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APT Structure in South AfricaAPT Structure in South Africa
Steering Committee
Technical management
Needs Scope Prioritisation
Technicalpanel
Proposals Reports Guidelines
Review Pool
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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
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Current and Future APT Focus Current and Future APT Focus areasareasCold bituminous recycling (ETB and foam)
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Current and Future APT Focus Current and Future APT Focus areasareas
Vehicle-pavement interaction – SIM TM
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Current and Future APT Focus Current and Future APT Focus areasareas
AC mix design (HMA) – Permanent deformation
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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
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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
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MMLS has become a valuable MMLS has become a valuable associated APT tool which is associated APT tool which is expanding globallyexpanding globally
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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
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There is a choiceThere is a choiceGo alone Work togetherGo alone Work together