Evaluation of Issues Affecting Stabilised Granular Pavements

Perkins, Shaun (2022) Evaluation of Issues Affecting Stabilised Granular Pavements. [USQ Project]

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Transport for NSW and other road authorities manage roads within their allocated maintenance budgets. Significant funding is provided each year to rehabilitate pavements that have reached the end of their service life. Transport for NSW is obligated as the state road authority in NSW to complete pavement rehabilitations using the most efficient and sustainable techniques available. Insitu stabilisation of existing pavements is a sustainable method of recycling an existing pavement with minimal addition of new materials to achieve a design life comparable with other rehabilitation techniques. There are however, a number of factors that significantly impact the achievable life of stabilised pavements. To ensure that stabilisation remains a viable rehabilitation method, it is essential that the influence of these detrimental factors on the life and cost of the pavement are understood.

This report has completed a review of the available literature providing a background to stabilisation, different binders available, their effects and factors that cause this type of pavement to exhibit signs of distress and fail. The thickness and the density of the stabilised layer have been identified through the review of the literature as factors that can significantly impact the properties of a stabilised pavement, however the effect on the life and cost of the pavement has not been examined.

This report has examined two case study projects and three theoretical pavements typical of the existing pavements found in northern NSW on rural State Highways. The impacts of thickness and relative compaction nonconformances have been examined and discussed through theoretical sensitivity analysis. The analysis has presented that construction of a stabilised pavement with thickness of 10 mm less than required to achieve the expected design life, can result in a reduction of the pavement life of 45 %. The relative compaction has also been demonstrated to reduce the life of stabilised pavements of up to 28 %, even when within the tolerances allowed for in current specifications. Additionally, a density gradient resulting in lower density in the lower half of a layer has been shown to reduce the life of up to 37 % which is currently permitted under TfNSW specifications.

Whole of life cost analysis has been completed for stabilised pavements with nonconforming thickness and relative compaction to determine the financial impact to TfNSW of accepting a nonconforming pavement and whether payment deductions could be applied to recover the cost of increased maintenance required to extend the life of these pavements out to the 20-year design period. It was determined that a payment deduction of 30 % could be applied for thickness nonconformances up to 10 mm below the design thickness and confirmed that the deductions applied by TfNSW for relative compaction are suitable. The impacts beyond the financial cost are also raised, such as the reputational damage a road authority may suffer as a result of major maintenance required on a recently completed stabilisation project.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Current – Faculty of Health, Engineering and Sciences - School of Engineering (1 Jan 2022 -)
Supervisors: Nataatmadja, Andreas
Qualification: Bachelor of Engineering (Honours) (Civil)
Date Deposited: 20 Jun 2023 05:40
Last Modified: 20 Jun 2023 05:40
Uncontrolled Keywords: road maintenance; pavement rehabilitation; stabilised pavements
URI: https://sear.unisq.edu.au/id/eprint/51905

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