Reuse of rubber tire waste in concrete and asphalt

Abstract

For some years, disposal of used tires is a major environmental issue worldwide. This project was carried out to identify and study the feasibility on the possible reuse of rubber tire wastes. Two modes of encapsulation were identified. These were encapsulating waste rubber crumbs into Portland cement concrete and Asphalt concrete. Initially, work on encapsulation rubber tire waste into Portland cement concrete was directed toward achieving a suitable mix for low structural load application. The study found that up to 30% of 1-4mm sized rubber crumbs can be incorporated into concrete, replacing either coarse or fine aggregates. The resulting rubberized concrete could achieve an average compressive strength of 33 N/mm2. Such concrete can be used for foot paths, kerbs, sewer pipes, drains, culverts, and as foundations for equipments. For the second part of the project, the development of a rubberized asphalt concrete mix for low volume road was explored. This study found that a W3B asphalt mix using 1-4 mm rubber crumbs replacing 10% of aggregates at 5% binder content could achieve the material requirements of the South Carolina Department of Transportation (SCDOT) for low volume roads. However, it failed the stringent requirements on air content imposed by the Singapore Land Transport Authority (LTA) for wearing course. Finally, the leaching characteristics of both concrete and asphalt concrete made with rubber waste were investigated using the toxicity characteristics leaching procedure (TCLP). Heavy metals in the leachate were below regulatory limits as specified by the United States, Environmental Protection Agency (EPA). Both modes of encapsulating rubber tires waste were successful in providing new and non hazardous materials for civil applications.