Development of a Long-term Accelerated Pavement Testing Programme - - PowerPoint PPT Presentation

Development of a Long-term Accelerated Pavement Testing Programme and Structural Design Models

Paper I-1

S V Kekwick, H L Theyse and E G Kleyn (presented by Dr M de Beer)

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Introduction

• HVS development since late 1960s;
• Three production machines operational

from late 1970s to 1990s, plus prototype;

• Latest SA HVS commissioned 1999, with

dynamic load simulation capability;

• Underpins SA pavement engineering efforts

and developments

• a significant track record;

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

N14

N7

R12

N12

N10

N12

N1

N2

N9

N10

N14

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N10

N2

N1

N4

N1

N12

N14

N1

N5

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North

MACRO-CLIMATE: SOUTH AFRICA

Namibië

West Coast East Coast

Capetown Durban

DRY DRY DRY DRY DRY DRY DRY DRY WET WET WET WET MODERATE MODERATE MODERATE MODERATE

Botswana

DRY DRY

WET WET

& MAJOR ROAD SYSTEM

Surfacing Types of National Roads in South Africa (1997/8)

HMA (46,3%)

Chip & Spray Seals (45,6%) PCC (7,5%) CRCP (0,5%)

HMA

Base and Subbase Types

• f National Roads in

South Africa (1997/8)

29% 13% 7% 6% 6% 3% 27% 9%

G1/G2 Base on Stab Subbase (29%) G1/G2 Base on Nat gravel Subbase (27 %) HMA (13 %) PCC (9 %) C3/C4 Base on Nat gravel Subbase (7 %) C3/C4 Base on Stab gravel Subbase (6%) G3/G4/G5 Base on Nat Gravel Subbase (6%)

G3/ G4/ G5 o n Stab Subbase (3%)

This paper.....

• reviews factors that contributed to long-

term success of SA HVS programme

• describes strategic and operational

components of the programme

• discusses some specific examples of

development of design transfer functions

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Objectives of the SA HVS programme

• Long-term: development of structural

design models and transfer functions appropriate for local applications;

• Short-term: address specific pavement

needs and problems as identified;

• Ultimate goal
• to achieve optimal pavement design

and most cost-effective structures

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Before...... ......after Before...... ......after

HVS 1979 HVS 1979 1994 1994

Components of the SA HVS programme

• Steering Committee/Project Champions

will define:

– Goals – Specific tasks/purposes – Policies – Strategic plans – Work programme/activities – Operational statistics – Deliverables/end products

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Components of the SA HVS programme

• Technology Transfer/Implementation

– Test level: interaction of champions and Steering Committee – Test level: broader dissemination through presentations, workshops, site demonstrations – Longer-term: development of generic design parameters, higher degree work – Longer-term: inclusion in National guidelines

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Some significant SA APT- related developments

• Mechanistic - Empirical analysis
• Damaging effect exponent quantification
• Dynamic Cone Penetrometer (DCP)

design and analysis

• National guidelines/specifications
• Stress-In-Motion (SIM) technology
• Technology management
• Design transfer functions

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

315/80 R22.5 HVS TIRE ON VRSPTA

Vertical Contact Stress: Variable loads: 315/80 R22.5 Tire

Lateral Contact Stress: Variable loads: 315/80 R22.5 Tire

Longitudinal Contact Stress: Variable Loads: 315/80 R22.5 Tire

Basic organizational process of converting needs to a products

QUALITY CONTROL PRODUCING PLANNING FINANCING

Managerial guidelines, statistics, goals, purposes, policies, plans, programmes, deliverables

DESIGN THE SOLUTION UNDERSTANDING

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Process for partnered research and practice

PRODUCTS

UNDER- STANDING PROCESSES DEFINED ENHANCED UNDERSTANDING & CAPABILITY ENHANCED UNDERSTANDING & CAPABILITY

NEED NEED

RESEARCH PRACTICE

Examples of structural pavement design models

• Transfer functions for:

– effective fatigue and crushing of lightly cemented layers – permanent deformation of natural gravel base and subbase layers – permanent deformation of imported (selected) and in situ subgrade layers

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Fatigue Cracking and aging

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Number of load applications

1 2 3 4 5 6 1.00E+01 1.00E+02 1.00E+03 1.00E+04 1.00E+05 1.00E+06 1.00E+07 1.00E+08

Strain Ratio 

/

b

A (95%) B (90%) C (80%) D (50%)

Road Category (Expected Performance Reliability)

Fatigue

SURFACE DISINTEGRATION

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

0.2 0.4 0.6 0.8 1 1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04 1.00E+05 1.00E+06 1.00E+07 1.00E+08 1.00E+09

Stress Ratio Number of load applications



v /UCS

A (95%) B (90%) C (80%) D (50%)

Road Category (Expected Performance Reliability)

Crushing

RU RUTT TTING NG

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Permanent deformation

G89TF50

50 100 150 200 250 300

1 mm 2 mm 3 mm 5 mm 10 mm 20 mm

Permanent Deformation

1E+03 1E+04 1E+05 1E+06 1E+07 1E+08

NUMBER OF LOAD REPETITIONS VERTICAL STRESS (kPa)

Conclusions

• SA HVS programme has been the

dominant force in SA pavement engineering development for more than 20 years

• significant advances in SA pavement

engineering have arisen directly from the programme

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Conclusions

• Factors influencing the success of the

SA HVS programme include:

– identification of longer-term goals from the

• utset

– interactive relationship between funders and research team – mechanisms for technology transfer and information dissemination

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE

Conclusions (continued)

• Factors (continued):

– developed understanding of the role of APT in pavement engineering – formalisation of processes such as strategy development, progress monitoring, definition of deliverables – appreciation of the need for higher-level analysis to attain long-term benefits

• up to four HVSs operating at the

same time gave added impetus...

ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE