Shape and Size Effects on Concrete Properties under an Elevated Temperature

Abstract

Concrete is a versatile material with tremendous applications in civil engineering construction. The size and shape of control specimens change according to different codes. Experimental, analytical and theoretical analyses were performed to suggest an equation to determine the suitable exposure time of an elevated temperature for small-scale specimens. First, the effect of the elevated temperature on the main properties of concrete was assessed. Cylinders and cubes with lengths of 10 and 15 cm were chosen as the test specimens. The specimens were exposed to temperatures of 200 °C, 400 °C and 600 °C and exposure times of 30, 45 and 60 minutes. Analytical calculations were performed to estimate the required time to reach a uniform temperature for different shapes and sizes. Thermal finite element analyses were conducted to study the thermal distribution on concrete specimens and to verify the proposed theoretical formulation. An equation for adjusting the elevated temperature’s exposure time was suggested.

Keywords: Sample size, elevated temperature, endurance, Mechanical properties of concrete.