Investigation of properties of the composite material based on the epoxy and silica sand polydisperse mixture

The paper studies physical and mechanical properties of an epoxy and the silica sand polydisperse mixture. As a dispersion medium we used the epoxy L with hardener EPH 161, and as a disperse material we used the silica sand mixtures of two varieties, here named fine and coarse ones (two characteristic particle sizes). The particles microphotographs are given. The particle size distribution histograms are constructed. Student's t-test was calculated to determine the difference between the mean values of two independent samples. The statistical difference between the two samples was shown to be statistically distinguishable. The mixture porosity and permeability depending on the fine sand proportion were measured. It is shown that each component’s porosity has almost the same values, and the porosity has its minimum if the fine sand content is 40 %. The dependence of permeability on the fine sand proportion is plotted. It is calculated how the effective pore radius affects the proportion of the fine particles. Mechanical tests of the polymerized samples were performed using the universal testing machine ZWIC Z-250. Non-monotonic dependence of ultimate tensile and compressive strength of the polymerized samples depending on the fine particle proportion was revealed. Pairwise linear correlation coefficients of mechanical characteristics with the medium porosity have been calculated. It is shown that there is an inverse relationship between tensile and compressive strains.