An Investigation on the Effect of High Temperatures on the Mechanical Properties and Microstructure of Concrete Containing Multiwalled Carbon Nanotubes

Abstract

Abstract In this article, the effect of multiwalled carbon nanotubes on the properties of concrete was evaluated in the postheat-treated condition. For this, a number of cylindrical specimens (10 by 20 cm), including multiwalled carbon nanotubes in different percentages of 0.5, 1, and 1.5 % by weight of cement, were cast. Then, the concrete specimens were exposed to temperatures of 25°C, 100°C, 250°C, 500°C, and 700°C in an electric furnace, and after they cooled down, compressive and tensile strength tests were carried out on them. The results show that by increasing the number of multiwalled carbon nanotubes in concrete, the compressive and tensile strengths of concrete increase up to 138 and 88 %, respectively. In addition, the dissipation of energy and modulus of elasticity of the concrete specimens were up to two times greater than those of the control specimens. The scanning electron microscope test results indicated that a strong bond between concrete particles exists at room temperature and above.