Cumulative effect of Recycled Tyre Steel Fibre and crumb rubber on impact resistance of concrete

Abstract

Structures such as Rigid pavement, water-retaining structures and industrial floors maybe subjected to various environmental and loading conditions. Concrete is very sensitive to strain rate loading; hence Concrete structures exhibit different response under static loadings and dynamic or repeated loadings. Due to brittle property and low tensile strength of concrete, induced tensile stresses in concrete when dynamic forces and concrete plastic shrinkage loads are applied, cracking patterns are created in concrete which ultimately affect the durability of concrete structures. Combining crumb rubber and recycled steel cord extracted from waste tyre as fibre reinforcement in concrete can enhance the ductility property and impact energy storing capacity of concrete and again limiting the crack initiation and propagation in concrete structures. Application of recycled waste tyre products in concrete production will solve the disposal problem of used tyres which are dumped in environment. The overall objective of this study, is to assess the combined effect of recycled tyre steel fibre and crumb rubber on impact energy resistance of concrete. Concrete Compressive and tensile strengths of rubber concrete with 5%, 10%,12.5%,15% and 20% rubber content were tested on 7 and 28 days. The resulted optimum crumb rubber which is 12.5% replacement of fine sand and different dosages of recycled tyre steel fibre (RTSF) of 0.3%,0.6%,0.9% and 1.2% by mass of concrete were mixed in concrete to investigate impact resistance of Recycled tyre steel fibre reinforced rubber concretes (RTSFRC). To determine effect of fibre aspect ratio , the steel cord were cut into three different lengths,20mm,40mm and 60mm. 32 concrete cylindrical discs of 150mm diameter and 64 ±0.5mm samples were casted and tested on 28 days using Drop-weight test method described in ASTM-D1557.The effect of the fibre volume fraction and its aspect ratio on impact resistance were evaluated. The results indicated that, the Combining crumb rubber and recycled steel fibres enhance significantly the impact resistance of concrete.