IMPROVING THE IMPACT RESISTING CAPACITY OF CONCRETE USING TYRE RUBBER DUST

Abstract

Concrete is the most widely used construction materials in the world of which cement and aggregates are the major constituents. This has led to a continuous and increasing demand of natural materials used in their production. Also, the increasing utilization of these natural resources is emerging as growing concern for protecting the environment thereby; a need to preserve natural resources has arisen by using alternative materials such as recycled or waste materials. Concrete structures are subjected to static and dynamic loads. Due to its low tensile strength, low ductility and low energy dissipating characteristics, impact resistance of concrete is very poor. In this research, a study has been carried out on the use of waste rubber tyre dust as a partial replacement for fine aggregates in concrete construction for improving its impact resistance property. In the first part of this report, the background of the study and the extent of the problem were discussed. A review of relevant literatures was done to study previous works in the subject matter. The initial research was carried out by conducting tests on the raw materials to determine their properties and suitability for the experiment. Concrete mix designs are prepared using the IS guidelines (IS: 10262-2009) and a total of four concrete grades were prepared (M20, M25, M30, M35). The specimens were produced with 5, 10 and 15% replacements of the fine aggregate by rubber dust. Moreover, control mixes with no replacement of the aggregates were also produced to make a comparative analysis. The prepared samples were concrete cubes for compressive strength test and circular concrete discs for impact tests. The rubber surface was pretreated with sodium hydroxide (NaOH) of 1N solution for 20 minutes and then left to surface dry prior to mixing in concrete. This treatment modified the rubber surface allowing the rubber to better adhere to the cement paste. Various tests were carried out and results were compared between conventional concrete and concrete prepared with various percentages of fine aggregates replaced with rubber tyre dust. Results show that there is a reduction in compressive strength upto 42% as the percentage of rubber dust was increased to 15%; also the workability of fresh concrete diminishes drastically. iv However, with the increase in rubber dust percentage, impact strength of concrete improved. The overall results show that tyre rubber can be used in concrete if the percentage of replacement is restricted and the rubber surface is pretreated with chemicals to improve its bonding property in concrete. Its use should be restricted to particular cases where impact resistance or other improved property due to rubber is desirable.