Effect of steel and polypropylene fibres on strength characteristics of fly ash reinforced concrete

Abstract

With the ever-increasing population of the world, in general, and the developing countries, in particular, there is tremendous pressure on Civil Engineers to develop cost-effective and ecofriendly structures to fulfill the needs of the mankind. Within current practices of utilization, cement and concrete construction industries throughout the world has been the largest user of flyash, an industrial by-product, whose use and production have increased many fold during last three decades and have exploited it to the best advantage. Flyash nowadays is a fourfold issue: reduction in air/water pollution, beneficial conversion of waste into wealth, reduction in expenditure on disposal and augmenting the demand of much needed construction materials which is economical and sound. Fibres on other hand have provided to improve strength, stiffness and ductility of reinforced concrete members with their addition. They act as crack arrestors, change all modes of failure, and increase ultimate strain of the composite. Experimental investigation has been carried out to study the effect of the fly ash content with steel and polypropylene fibres on the properties of concrete. Cement has been replaced by mass with 15,20 and 25 per cent fly ash content. Two percentages of steel fibres (0.5 and 1.0 per cent) of aspect ratio 50 and same percentage of polypropylene fibres (0.5 and 1.0 percent), have been used in the investigation. Tests have been performed for Compressive strength, split tensile strength and flexural strength of different specimens. Test results indicate with the increase in percentage of fly ash content, the compressive strength, split tensile strength and flexural strength of concrete decreases but this decrease is compensated by the use of fibres in concrete. Steel fibres give better results than polypropylene fibres. Also with the percentage increase in fibre content, the strength increases.