Combined effect of polypropylene fiber and silica fume on mechanical properties of concrete composite containing fly ash

A parametric experimental study has been conducted to investigate the combined effect of polypropylene fiber and silica fume on the mechanical properties (compressive strength, splitting tensile strength, and compressive modulus of elasticity) of concrete composite containing fly ash. Five different fiber volume fractions, four contents of fly ash, and four silica fume contents were used. The results indicate that the contribution of silica fume on the growth of compressive strength and splitting tensile strength is performed at the early curing period, and the contribution of fly ash on the growth of compressive strength and splitting tensile strength is performed at the later curing period, when the fly ash content is not beyond 20% and the silica fume content exceeding 3%. The addition of fly ash and silica fume greatly increases the compressive modulus of elasticity at 28 days curing. Though the addition of polypropylene fiber decreases the compressive strength of the concrete with fly ash and silica fume, the splitting tensile strength is improved and compressive modulus of elasticity is decreased effectively, which can decrease the rigidity and increase the ductility of the concrete composite containing fly ash and silica fume to protect the concrete from damages for large deformation.