Environmental Suitability and Carbon Footprint Savings of Recycled Tyre Crumbs for Road Applications

Abstract

With the aim of encouraging more waste diversions from traditional waste stockpiling and to reduce use of virgin materials in different engineering constructions, this paper presents the environmental suitability of reusing crushed used tyre instead of using virgin aggregate materials for road sub-base. Shredded tyre samples collected from a local recycling company in Melbourne were tested to evaluate any potential contaminant leaching from such material to the surrounding environment. Leaching tests were conducted for 100 potential contaminants following Australian Standard Leaching Procedure (ASLP) using three standard types of leaching solutions: acidic, neutral, and alkaline. From the series of leaching test results, it is clear that concentrations of all the assessed contaminants in the tested samples are either below their individual detection limits or below the Environmental Protection Authority (EPA) Victoria defined limits to label a material as hazardous. As such, in regards to leaching pollutants in the surrounding environment, tested crushed tyre samples are not hazardous and can be used for different engineering applications. Finally, a carbon footprint analysis was conducted considering a sustainable approach of using such crushed tyre with recycled concrete and recycled rock. It is found that through using such recycled materials carbon footprint savings per ton of road sub-base material would be 9.3 kg CO2e and 8.1 kg CO2e for using 2 and 3% tyre crumb, respectively.