Use of waste rubber tyres as aggregate in concrete

Abstract

Recycling can be a viable option in the waste management of many materials. Noting the increasing volumes and difficulty in the disposal of wastes from rubber tyres, this paper discusses test results of use of recycled tyres in concrete for possible application in the construction industry. In 2008, around one billion end-of-life tyres (ELTs) were being produced globally each year. As a possible means of disposing the tyres, it is proposed to use rubber tyres as coarse and fine aggregate in concrete. Tyres cut into pieces with maximum size of 20 mm to use as coarse aggregate, and crumb rubber tyres used as fine aggregate. The replacement of the rubber tyres aggregates in concrete was done in three phases. In the first phase, fine rubber tyres aggregates were used to replace 50% of the normal sand. Secondly, coarse rubber aggregates tyres were used in the replacement of 50% of the normal gravel. Finally, both fine and coarse rubber tyres aggregates were used to replace the sand and gravel by 25, 50, 75 and 100%. Compressive strength, splitting tensile, and flexural strength tests were conducted according to the various BS codes. Although concrete made from tyres had lower strength than the normal concrete, it had elastic failure behaviour. It did not collapse completely when tested. The cohesiveness was an advantage for using it in places such as landscaping, sports field ground, architectural finishing, and other engineering applications. This paper also demonstrated the variation in the compressive strength of the non-conventional concrete when the BS and ACI methods are used in the design of the mix. Key words: Recycling, rubber tyres, compressive strength, tensile test, flexural strength.