Foamed Bitumen Stabilisation Project – Warwick, Qld
By Warren Smith, Stabilised Pavements of Australia

Introduction

The Department of Main Roads, Queensland, has for some time been looking at using bitumen in stabilisation works to overcome some of their problems. They have been using cements in their stabilisation to rehabilitate pavements successfully for many years and they have just recently successfully recommenced the use of lime in subgrades.

Due to the fact that many of their highways in Queensland have thin pavement depths over very plastic subgrades, the use of deep lift cementitious pavement rehabilitation has been more limited than in other States.

In the early nineties, the QDMR carried out a number of trial projects using combinations of bitumen emulsions and cement with only moderate results. However, with the reappearance of foamed bitumen stabilisation with a higher level of technology in both the understanding of the procedures and the machinery used, the QDMR has begun to undertake a number of foamed bitumen stabilisation projects.

Postscript (June 1999)

As a postscript, this job was successfully completed in late May, 1999. It was actually extended to be 18km or approximately 143,500m² of State Highway completely rehabilitated using foamed bitumen stabilisation in 37 working days under traffic.

The work methodology was refined slightly during the job to obtain the best results most efficiently. The total cost to the Department of Main Roads, including the bitumen seal wearing course, was between $16.50 and $18.00/m².

By enhancing the existing road pavement asset insitu using Foamed Bitumen Stabilisation, the Main Roads has been able to avoid the removal and dumping of up to 60,000 tonnes of “unsuitable” material and the quarrying and introduction of up to 60,000 tonnes of new pavement material.

Hence, in terms of engineering excellence, huge savings in costs, the speed and lack of disruption, and the environmental benefits of recycling the deteriorated asset, this project has been an unqualified success.

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