International Journal of Advanced Science and Technology Vol. 29, No. 08, (2020), pp. 1980- 1985 1980 ISSN: 2005-4238 IJAST Copyright ⓒ 2019 SERSC Abstract: Flexural behavioural understanding of fiber reinforced concrete necessitate the detailed investigation of load-deflection curve. This study provides additional insight on the solo contribution of fibers on bending properties. This paper aims to understand the pre-peak performance of polypropylene fiber and steel fiber reinforced concrete beams under two-point loading. Polypropylene fiber was used at 0.05% dosage by volume and steel fiber at 0.75%. Reinforced concrete beam specimens of 200mm x 300mm x 2100mm dimension were prepared and tested in simply supported condition. Load-deflection curves plotted and studied for pre-peak energy absorption capacity, gradient angle, load and deflections at yield and peak stages. Experimental results indicated an improvement in energy absorption capacity of steel fiber reinforced concrete specimens by 63.44%. Gradient angle became steeper for polypropylene and steel fiber reinforced specimens. Substantial increase of 52.2kN and 50.1kN were observed for yield and ultimate load values due to steel fiber inclusion in controlled concrete. Keywords: Bending properties, Gradient angle, PFRC, SFRC, I. INTRODUCTION Since 1980 good amount of investigations are carrying out in the area of fiber reinforced concrete. Synthetic, metallic, natural and glass fibers were used in mortar and concrete to improve its properties. The main objective of fiber reinforcement is to reduce the amount of micro cracks, size of crack and control its growth effectively in order to improve the concrete tensile strength [1]. Polypropylene fiber addition distinctly reduces the surface bleeding and the settlement of aggregate in fresh concrete. It is also helpful to control the shrinkage of concrete.Steel fiber in different geometry and aspect ratio is the most used metallic fiber in concrete.It acts as secondary reinforcement used along with conventional rebars as primary reinforcement. The influence of steel fiber on concrete depends on cross section, strength, fiber content, bond strength, shape and length [2].The steel fiber inclusion in concrete proved to be highly beneficial in improving the mechanical properties of concrete. The addition of steel fiber consistently improved the deformation capacity and also change the failure mode from brittle to ductile mode [3] [4]. Volume and aspect ratio of steel fiber greatly influence crack spacings, number of cracks and crack widths in concrete. [5] Smaller crack spacings and greater number of cracks were noticed for SFRC specimens. Figure 1 indicate the typical load-deflection curve. Pre-peak zone ranges from beginning of loading to till the concrete specimen reaches the ultimate or peak load (P u ). Usually linear curve was observed up to first crack or yield load (P y ). Portion of the curve between first crack and ultimate load was termed as cracked section and good number of cracks appeared in the face of beam specimen. Any improvement due to fiber can be evidenced in cracked section in form of more number of cracks, reduced crack width and increase in the load. Fig 1 Typical load deflection curve Different testing conditions and methods were used to understand the influences of fiber on the flexural behaviour. Basically ASTM 1018 and JSCE SF-4 were followed to evaluate the flexural behaviour of fiber reinforced concrete. Flexural toughness in JSCE approach provided a [6] simple technique which exhibited good correlation with fiber reinforcing matrix. Four-point loading flexural test on prism specimens were conducted as per the guidelines of ASTM C1609 to assess the flexural toughness Shashi Kumara S R, B C Udayashankar, D L Venkatesh Babu Pre-peak Flexural Performance Evaluation of Fiber Reinforced Concrete Beams