Improving the Tensile Energy Absorption of High Strength Natural Fiber Reinforced Concrete with Fly-Ash for Bridge Girders

Abstract

Nowadays high strength concrete is used in bridge girders due to its improved mechanical properties. However, its behavior is relatively more brittle compared to that of normal strength concrete. Due to the highest toughness among natural fibers, coconut fibers are chosen. In this work, the impact of different fly-ash contents on tensile absorbed energy of high strength coconut fiber reinforced concrete (CFRC-SF) will be investigated for structural application. The mix design ratio of CFRC-SF is 1:2:2 (cement: sand: aggregate) with a water-cement ratio of 0.50 and silica-fume content of 15%. The coconut fibers of 5 cm length and content of 2%, by cement mass, are added. To prepare CFRC-SF5, CFRC-SF10 and CFRC-SF15, different fly-ash contents of 5%, 10% and 15%, respectively, (by cement mass) are added. For determination of splitting-tensile strength, pre-crack/ absorbed energy after crack and toughness indices, cylinders of size 100 mm diameter and 200 mm height are cast and are tested under splitting-tensile load as per ASTM standard. The tensile absorbed energy of CFRC-SF is increased up to 10% fly-ash content. Further study on durability of CFRC-SF is suggested due to the biological nature of coconut fibers.