Austroads has published two guides which explain how practitioners can use fit-for-purpose materials for sealed and unsealed construction and maintenance of roads with low to medium traffic volumes.
A fit‑for‑purpose material has properties and performance characteristics which suit a chosen design application. It can be marginal or non-standard and may have been improved through mechanical or chemical stabilisation, or used in an operating condition which is not detrimental to its ongoing performance.
Austroads Program Manager Assets, Ross Guppy, explained that stricter legislation and land access requirements are curbing the opening of new quarries and gravel pits.
“Gravel is also being transported over longer distances, increasing the costs of road construction and maintenance.
“There are many different traffic and environmental conditions in Australia. Investigating the operating conditions affecting material performance, then modifying the material or imposing design, construction or maintenance constraints to make it fit-for-purpose is a cost effective and sustainable solution.
“Austroads commissioned a technical project to understand what influences material performance, and to demonstrate how a material can be made fit-for-purpose within different design scenarios and operating conditions. The project also examines life cycle costing to demonstrate how a material can be supported through its in-service life to ensure it performs as initially expected.”
“We developed two reports, one containing an evaluation and user guide and one containing the technical basis providing the evidence for the evaluation,” Tyrone Toole, co-author, said.
“Both reports include case studies that demonstrate how to assess the best use of available marginal and non‑standard materials on roads in various geographical and climactic Australian conditions. The case studies include examples of material assessment and options assessments in addition to life‑cycle cost assessments for a range of different scenarios.
The evaluation and user guide report contains assessment guidance to help identify the most fit-for-purpose material based on considerations such as material properties, climatic conditions and traffic conditions as well as presenting design and construction considerations to reduce material risk, including stabilisation and modification. Economic issues such as haulage distance and stabilisation costs are discussed to ensure a holistic understanding of fit-for-purpose material use. The user guide also includes guidance on undertaking a life‑cycle cost assessment and the key components of this assessment which need to be considered.
“The technical basis covers the justification for the information presented in the evaluation and user guide report including an explanation of the effects of traffic volumes and climate on material performance, the development of a material risk assessment and criteria, and risk management techniques for increasing fit-for-purpose material options,” co-author, Zia Rice, said.
“Outcomes from this project can significantly reduce the cost of road construction and maintenance for road operators, particularly in rural and remote areas on low-volume traffic roads,” Mr Guppy said.