Experimental Investigation on Effect of Aggregates and Steel Fibers on Modulus of Elasticity of Concrete

Plain, unreinforced concrete is a brittle material, with a low tensile strength, limited ductility and little resistance to cracking. In order to improve the inherent tensile strength of concrete there is a need of multidirectional and closely spaced reinforcement, which can be provided in the form of randomly distributed fibres. Steel fibre is one of the most commonly used fibres. Short, discrete steel fibres provide discontinuous three-dimensional reinforcement that picks up load and transfer stresses at micro-crack level. This reinforcement provides tensile capacity and crack control to the concrete section prior to the establishment of visible macro cracks, thereby promoting ductility or toughness. The modulus of elasticity of concrete is a very important parameter reflecting the ability of concrete to deform elastically. In addition, in order to make full use of the compressive strength potential, the structures using high strength concrete tend to be slimmer and require a higher elastic modulus so as to maintain its stiffness. Therefore, knowledge of the modulus of elasticity of high strength concrete is very important in avoiding excessive deformation, providing satisfactory serviceability, and avoiding the most cost-effective designs. The present experimental study considers the effect of aggregate size and steel fibres on the modulus of elasticity of concrete. Crimped steel fibres at volume fraction of 0%.0.5%, 1.0% and 1.5% were used. Study on effect of volume fraction of fibres and change of aggregate size on the modulus of elasticity of concrete was also deemed as an important part of present experimental investigation. This work aims in studying the mechanical behaviour of concrete in terms of modulus of elasticity with the change of aggregate size reinforced with steel fibres of different series for M30 and M50 grade concretes. The results obtained show that the addition of steel fibre improves the modulus of elasticity of concrete. It was also analyzed that by increasing the fibre volume fraction from 0%, to 1.5% there was a healthy effect on modulus of elasticity of Steel Fibre Reinforced concrete.