Effects of Pre-Treated Waste Tire Rubber on Properties of Concrete

Abstract

In present day scenario with increase in environmental protection awareness there is need to induce 3R (recycle, reuse, reduce) principle into the construction field. One such example can be use of discarded materials such as used tire rubber into building industry. The application of discarded rubber by incorporating it in concrete mixtures helps in creating landfill prevention and minimize the use of virgin raw materials. According to an estimate almost 1000 million tires are discarded after their service life every year which maybe effectively used in building industry as a partial replacement of aggregates. Tire burning, which extends as the simplest and cost effective method of used tire disposal, poses grave fire risks. Waste rubber has been tested for lending its use as a part of fine aggregate, coarse aggregate or both in manufacturing of concrete. This paper tries to build up on foregoing and earlier work researches carried out on the use of waste rubber as partially natural sand replacement with pre-treatment in conventional concrete mixtures. Pre-treatment with KMnO4 and NaOH were adopted to increase the hydrophilic nature of rubber (due to presence of silica) and hence be able to perform better bonding with cement at the interface. Various tests such as slump test, hardened density, compressive strength test, split tensile strength and RCPT (Rapid chloride penetration test) were performed on concrete incorporating pre-treated rubber as fine aggregate. The rubber particles were used as a partial replacement material for sand by weight and replacement level were kept at 5, 10,15 and 20 percent (by weight). The size of crumb rubber used was combination of 30mesh and 60mesh. The experiment results showed that workability as well as strength properties of concrete decrease with addition of rubber. However, part of compressive strength lost can be regained by treating rubber with NaOH before its use in concrete. The hardened density also decreased reason being the lower specific gravity of rubber particles as opposed to sand. Based on the observation of the experiments it can be recommended that tire rubber cannot be used in structural concrete but rather find its usage in non-structural applications mainly such as light weight concrete blocks, floor ribs, road side walks, partitions