Experimental Study of the Effect of Glass and Polypropylene Composite Fibers on Physical and Mechanical Properties of Concrete and Cement Mortar

Concrete is the most widely used material in mining and civil projects and its mix design must be based on application, type of material and environmental conditions. In this study the effect of combined glass and polypropylene fibers on physical and mechanical properties of concrete and cement mortar was investigated. Nowadays, artificial fibers are used to improve the mechanical properties of concrete. Particularly, glass, polypropylene, carbon and steel fibers used in concrete lead to good results in improving its several properties. To this purpose, the concrete and cement mortar samples were made without fiber, with individual glass fibers (0.2, 0.35 and 0.5 volume percent of concrete or cement mortar), with individual polypropylene fibers (0.2, 0.35 and 0.5 volume polypropylene fibers 0.17 volume percent and glass fibers 0.18 volume percent of concrete or cement mortarpercent of concrete or cement mortar), and with combined glass and polypropylene fibers (). The physical properties including effective porosity, longitudinal waves velocity and the mechanical properties including Brazilian tensile strength and uniaxial compressive strength of the samples were analyzed. The results indicated that the effective porosity of concrete and cement mortar with combined glass and polypropylene fibers was less compared to the concrete and the cement mortar without fiber, with individual glass fibers and with individual polypropylene fibers. The velocity of longitudinal waves, tensile strength and uniaxial compressive strength of the concrete and the cement mortar samples with combined glass and polypropylene fibers were higher than the other samples. Compared to the concrete and the cement mortar samples without fibers, the tensile strength of the concrete and the cement mortar with combined glass and polypropylene fibers were increased by 15.22% and 16.44%, respectively, and their uniaxial compressive strength showed the increase of 27.3% and 20.56%, respectively.