Effect of high temperature on the mechanical properties of basalt fibre self-compacting concrete as an overlay material

Abstract

Basalt fibres are modern inorganic concrete fibres, fabricated by melting the basalt rock. These fibres exhibited remarkable resistance to elevated temperatures in comparison with other manufactured fibres. Thus, when the impact of fire is the main consideration, basalt fibres are favoured in the construction of concrete buildings. In this study, the effects of basalt fibres on the workability of fresh self-compacting concrete (SCC) were measured using slump flow, J-ring flow, V-funnel flow and L-box height ratio. The properties of hardened concrete such as compressive strength, splitting strength, modulus of elasticity, flexural strength, and Poisson’s ratio were examined at temperatures between 25 °C and 500 °C. Also, the bond strength between the basalt fibre SCC as an overlay material and a normal concrete substrate was analysed at elevated temperatures. The interfacial surface between the concrete parts of the hybrid samples was roughened in different ways to determine the best roughening mode, which induced high slant shear strength of concrete under fire. The experimental results revealed that increasing the temperature up to 500 °C reduced the tensile and compressive strengths of SCC by over 20%. The optimum slant shear strength of hybrid concrete under fire was achieved by roughening the interfacial surface through the sandblasting method.