Research of the optimal concentration of polypropylene fibers in coarse-grained crushed stone-sand mixtures reinforced with cement

Abstract

Recently crushed stone-sand mixtures are one of the most widely used road construction materials for the arrangement of base layers of road pavements in Ukraine. More and more often both mineral and combined binders are used to strengthen roads during construction, repairs and reconstruction. One of the ways to improve the properties of building materials is to reinforce them with various fibers. Analysis of literature sources has shown that the addition of fibers into the composition of cement-reinforced soils and cement concretes significantly improves the physical and mechanical properties and durability of these road-building materials.

The article presents the results of an experimental study on the establishment of the optimal content of polypropylene fibers on the physical and mechanical properties of coarse-grained crushed stone-sand mixtures reinforced with mineral binder (cement). The studies were carried out on a coarse-grained crushed stone-sand mixture reinforced with cement in an amount of 2%.

The results of the study showed that for these mixtures, according to the studied indicators, namely compressive strength and indirect tensile strength, the optimal content of polypropylene fiber with a length of 18 mm is 0.03% of the mass of the mineral part of the mixture. At these concentrations, the compressive strength limit increases by 3.4%, and the indirect tensile strength increases by 35%. It was found that a further increase in the concentration of polypropylene fibers from the optimal one leads to a negative impact on the indicators studied and levels their work in the material, as the mixture is oversaturated with fibers and a large number of them are knocked into bundles, which are unevenly distributed in the mixture and ultimately worsen the physical and mechanical indicators.