Comparison of Mechanical Properties of Gypsum with and without Polypropylene Fibers

Abstract

Gypsum is a mineral belonging to the group of sulfates, i.e., sulfuric acid, which is often found in Earth's crust. In this paper, two main types of gypsum, gypsum α and gypsum β, with different water content were prepared. Samples with and without polypropylene fibers, with different fiber content and different fiber lengths during preparation, produced in a gypsum factory located in the Debar region, North Macedonia, were studied. Physical properties such as density, porosity, water absorption capability and their kinetics, packing factor, hardening and others were examined using different methods. The main goal of this paper was the determination of mechanical properties of gypsum such as the compressive and flexure strength and the module of elasticity of the gypsum prisms. For the determination of elastic properties, the nondestructive method of ultrasound testing was used. In this test, the strength and quality of a prism is assessed by measuring the velocity of an ultrasonic pulse passing through a gypsum structure. This test is conducted by passing a pulse of ultrasonic wave through a prism and by measuring the time taken by the pulse to get through the structure. Higher velocities indicate good quality and continuity of the material, while slower velocities may indicate gypsum with many cracks or voids. The comparison of the obtained results from these two types of gypsum shows different mechanical and other physical properties.