Behaviour of micro reinforced concrete with hooked end steel fibres subjected to impact loads

Abstract

Reinforced cement concrete is a common material used for building constructions. In this work a trial has been created to utilize steel fibres in RCC members to extend strength and conjointly to extend resistance to impact load. Hooked end steel fibres (HESF) are used here for the preparation of concrete specimens. Concrete grade of M30 is selected and mix design was carried out for target strength of 38.25 N/mm2. Varied volume fractions of HESF such as 0%, 1%, 2%, 3% and 4% were added to concrete. Cube, beam and cylindrical specimens were cast with good compaction and cured fully as per standards. Hardened concrete strength of all the specimens with different quantities of HEFS were tested. Simple drop weight test was conducted on the specimens reinforced with different percentages of steel fibres. The impact load is produced by means of dropping a weight of 5.5 kg from 400 mm height. Impact energy of the specimens is derived from number of blows required to produce initial crack (N1) and number of blows to cause complete failure (N2). Impact energy of the specimens with different quantities of fibres are compared. Results indicated that the concrete specimens with 3% volume fraction of fibre has shown best performance and it is also seen that the increase in volume of fibre beyond 3% has resulted in reduced impact energy.