A large aspect of achieving sustainability comes from the materials we use in road construction and maintenance. A key aim of using these materials in road construction is to support the circular economy in Western Australia, and where possible to support up-cycling, avoid down-cycling and keep materials circulating within the economy, reducing the need for more raw, virgin materials.
We have developed a Recycled Materials Reference Guide that outlines different recycled materials that have been or potentially may be used for road construction and maintenance, and opportunities where these materials may be incorporated into future Main Roads projects.
The guide outlines the use of materials including crushed recycled glass, Alcoa red sand, crushed recycled concrete, mining waste (overburden), reclaimed asphalt pavement, and crumb rubber. This Reference Guide details the corporate commitments, under the Waste Authorities ‘Waste Avoidance and Resource Recovery Strategy 2030’, Main Roads have made regarding the use of specific recycled materials. The key Main Roads specifications that outline the appropriate use of these products within Main Roads projects and maintenance programs are also included in the Guide.
Download the Recycled Materials Reference Guide
Two key recycled construction materials used across the Main Roads network is crushed recycled concrete and crumb rubber.
Crushed Recycled Concrete
Crushed recycled concrete was recently trialled on our Kwinana Freeway Northbound Widening and Murdoch Drive Connection projects under full-depth asphalt, with some of the recycled material coming from the Subiaco Oval demolition.
We collaborated with the Department of Water and Environmental Regulation, the Waste Management Authority and industry to develop specifications.
Through the Western Australia Waste Authority’s Roads to Reuse Initiative, we are committed to using recycled construction and demolition materials in our projects. We have currently used 117,000 tonnes of crushed recycled concrete across the state network, with this figure set to increase as a number of our upcoming projects have forecast the use of the material.
Crumb rubber is produced from recycled scrap rubber such as waste tyres, and when combined with bitumen produces a highly durable road construction material. In sprayed bituminous seals, crumb rubber modified bitumen reduces oxidation and improves stone retention and can mitigate against some types of cracking. In asphalt mixes, crumb rubber modified bitumen reduces reflective cracking and improves stripping resistance. Crumb rubber modified bitumen is used in high traffic volume environments, on bridge decks, over existing cracked road surfaces and where cracking of the road surfaces is expected.
The use of crumb rubber is high on our sustainability priorities, as it provides better performance and better durability as well as reduce scrap rubber from going to landfill.
In 2021/2022, over 1,900 tonnes of crumb rubber were used on the state road network. This is equivalent to 380,000 car tyres! Crumb rubber modified asphalt was used across the metropolitan area to resurface key routes including Kwinana Freeway, Leach Highway and Roe Highway.
Crumb rubber modified open-grade asphalt was also used on a 3 km section of the Mitchell Freeway Widening. BMD Constructions completed this work with Fulton Hogan undertaking the asphalting. This was the first use of Main Roads’ new crumb rubber asphalt specifications within a design & construct contract. The success of these works has seen us commit to further increasing the use of crumb rubber in future projects and works.