The effect of trio-fiber reinforcement on the properties of self-compacting fly ash concrete

Abstract

Present study is aimed to investigate the mechanical and durability properties of trio-fiber self-compacting concrete (TFSCC) containing fly ash. Self-compacting concrete was produced in all experiments with a water binder ratio of 0.38%, steel fiber and brass-coated steel fiber rate of 2% and polypropylene fiber added in the rates of 0%, 0.05% and 0.1%. In the scope of the study, fresh concrete experiments were performed such as flow diameter and flow time to 50 cm diameter (t50), V-funnel flow time, L-box and J-ring. Hardened concrete tests were performed for mechanical properties such as compressive strength, tensile splitting strength, flexural strength, ultrasonic pulse velocity. Additional tests were conducted in terms of durability e.g. to determine the impact of high temperature (ultrasonic pulse velocity and compressive strength at 200, 400 and 600 °C), freeze–thaw test (weight loss, ultrasonic pulse velocity and compressive strength in 50, 100 and 300 cycles) and high–pressure capillarity tests. Microstructures of the concrete samples were examined by taking their SEM images. It was observed that as the rates of steel and polypropylene fibers increased in the mixes, the flow diameter decreased while it increased with the increasing rates of fly ash and brass coated steel fiber. It was also seen that as the rate of polypropylene fiber in the mixes increased, losses in resistance to freeze–thaw impact decreased. It was determined when considered micrographs taken using SEM that fly ash provides favorable effects on concrete like forming full compactness at micro level and CSHs by binding calcium hydroxide and resulting in adherence on interfaces.