Experimental Study of the Effect of Polypropylene Fiber and Microsilica on the Mechanical Properties of Concrete

Todays, concrete is one of the common materials in construction industry. The dependence of concrete properties on various parameters such as constituent materials, production and generation process, execution method and concrete treating condition made it a complex material. However, it has more advantages in the construction industry. In this case, these materials of mechanical properties such as tensile and compressive strength is discussed by civil engineers and researchers identified many ways to improving these properties which one of the is using of additive materials such as micro silica and polypropylene fibers. Therefore, in this research tensile and compressive strength tests performed on 40 models with the aim of investigating the effect of using micro silica with 0.04, 0.06 and 0.08 percentages and the mixture of these two materials on mechanical properties. The results showed that in the compressive test of 7-day concrete micro silica models and some of models of micro silica and polypropylene fiber mixture had acceptable response, as well as in 28-days concrete mixture models showed acceptable response. In the tensile test of 7-day models, all of the models showed lower strength than the original model, while in 28-day concrete models with micro silica 3% and polypropylene 0.04% increased tensile strength.