Mechanical properties of nano-SiO2 reinforced engineered cementitious composites after exposure to high temperatures

Abstract

In this work, the effects of nano-SiO2 (NS), heating temperatures, and cooling measures on the physical, mechanical, and microscopic properties of engineered cementitious composites (ECC) after exposure to high temperatures were evaluated through a series of tests. The mass loss rate, cube, prism compressive strength, and splitting tensile strength of NS reinforced cementitious composite (NSRECC) specimens were tested after exposure to elevated temperatures of 100, 200, 300, 400, 600, and 800 °C. Changes in the color, appearance, and microstructure of the specimens were observed and discussed. The results revealed that NS has a weak effect on the color change of the specimens, whereas the heating temperature has a significant effect. The mass loss of the NSRECC specimens augmented with the temperature from 100 to 800 °C. Thus, the addition of NS to ECC can effectively enhance their mechanical characteristics after exposed to elevated temperatures by minimizing the pores and microcracks in the matrix. Notably, after exposed to a temperature of 200 ℃, the cube, and prism compressive strength and splitting tensile strength of the NSRECC specimens (with a NS content of 1 %) increased by 10.7 %, 25.1 %, and 25.6 %, respectively, as compared with those of the ECC without NS. However, the mechanical performance of the NSRECC specimens decreased markedly when the temperature exceeded 400 °C. Furthermore, the cooling measure of the specimens exhibited a certain influence over the apparent phenomenon and strength of the NSRECC after exposure to high temperatures.