Mechanical properties of fiber-reinforced concrete containing waste porcelain aggregates under elevated temperatures

Abstract

Concrete has recently found increasing applications in structures exposed to high temperatures. It is, therefore, necessary from an engineering viewpoint to improve the mechanical properties of the concrete used in such structures. Concrete structures exposed to high temperatures are prone to serious damages due to the heat-induced physical and chemical changes in concrete that reduce its compressive, tensile, and flexural strengths as well as its modulus of elasticity. A remedy is to use refractory materials to increase the heat resistance of concrete. In this study, waste porcelain ceramic was used as aggregate material to achieve enhancements in concrete mechanical properties under high temperatures with the simultaneously additional advantage of abating environmental pollution. Additionally, polypropylene and steel fibers, as well as ordinary Portland and refractory cement, were used to cast 120 cylindrical specimens 100 mm × 200 mm in size to be exposed to temperatures of 400 and 800 °C in a laboratory furnace. The compressive and tensile strengths of the specimens were measured upon cooling, their weight losses were determined, and finally, crack assessment was performed using fractal dimension. All the specimens exhibited reduced compressive and tensile strengths with increasing temperature albeit at different rates depending on their ingredient materials such that higher strengths were recorded at 400 °C for specimens containing Portland cement and at 800 °C for those containing refractory cement. Application of steel fibers increased heat resistance and decreased strength drop by up to 20% and 30% at 400 and 800 °C, respectively. This is while the application of polypropylene (PP) fiber had no significant effects on such mechanical properties as compressive or tensile strength but it prevented concrete spalling.