Mechanical Properties of self Compacting Concrete using Crushed Sand and Hybrid Fibres

Abstract

Self Compacting Concrete (SCC) is one of the most outstanding developments in concrete technology. Due to its ability to compact by itself by means of its own weight, without the requirement of vibration, it contributes to a significant improvement in the quality of concrete. Furthermore, it significantly reduce the manpower required for construction. The elimination of compaction results in reduced costs of placement, a shortening of the construction time and improved productivity. Therefore, the use of SCC is increasing day by day with increasing areas of applications. Hence, an attempt was made to investigate the mechanical properties of SCC of M40 grade, using crushed sand as a partial replacement for river sand and hybrid fibre as additional reinforcement. Mechanical properties studied include compressive strength, split tensile strength and modulus of elasticity of concrete. Ultimate load and displacement of solid and hollow compression member were also studied. newline newlineIn this research work, cement was partially replaced with silica fume at 15% by weight cement. Variation in the compressive strength, split tensile strength and modulus of elasticity of concrete were studied when replacing river sand by crushed sand from 0% to 70%, in steps of 10%. The results show an increase in the mechanical properties up to 60% replacement and hence this optimum percentage was selected for further studies. newline newlineSisal fibre is dispersed randomly, with a cut length of 30 mm and aspect ratio of 100. SCC with sisal fibre content of 0% to 0.5%, in increments of 0.1%, were studied. The properties of concrete improved slightly at small dosages and degraded for higher dosages. Hybrid fibre, with 0.3% of sisal fibre and 0.6% of steel fibre, was then tried out to enhance the properties. newline newlineThe findings reflected that crushed sand can be used as a viable replacement material to river sand for producing SCC. Sisal fibre as reinforcement does not give the promising result in compressive strength. Hybrid fibres performed well and gave better resul