Mechanical and physical performances of concretes made from crushed sands of different geological nature subjected to high temperatures

Abstract

This article focuses on the performance of concretes made from crushed sands of different petrographic nature subjected to high temperatures. Three types of concrete formulations were studied: concrete made from alluvial sand from the River Sanaga (CAS), concrete made with crushed Basalt (CSB) and concrete made from crushed gneiss sand (CSG). For each concrete family, the W/C ratio is kept constant and equal to 0.47. All studied concretes were subjected to heating-cooling cycles up to 300 °C, 600 °C and 900 °C. After cooling down to ambient temperature, the following properties were evaluated and compared with reference values obtained at high temperature: compressive and splitting tensile strengths, loss mass, water absorption by immersion, porosity, density, variation of volume. After exposure to elevated temperature, the degradation of compressive and splitting strength of CSB was higher than that of CAS and CSG. The same results are obtained for the loss in mass, water absorption by immersion and porosity. The percentage of volume increases and varies between 0.67% and 2.16%. CSB concrete has more macro-cracks compared to CAS and CSG concretes. From room temperature to 300 °C, density variation is low for CAS and CSG concretes. There is a variation of 1.6% for CAS concrete and 1.97% for CSG concrete. On the contrary, a drastic variation of about 7.93% of the CSB concrete is obtained. The magnitude of the degradation of concrete’s residual mechanical properties was seen to depend on the type of sand. The residual compressive strength of all concrete is strongly correlated with the physical properties. Based on the experimental study undertaken the following conclusion is drawn: concretes (CAS) and (CSG) show the best performance at high temperatures. Keywords: Concrete, High temperature, Crushed sands, Loss mass