Research on the Damage of Nano-SiO2 Steel Fiber-Reinforced Concrete after High Temperature Based on Acoustic Emission Technology

The four-point bending load performance of nano-SiO2 steel fiber concrete (NSFC) under different temperatures was studied, and compared with ordinary concrete (NC), steel fiber concrete (SFRC) and concrete mixed with nano-SiO2 (NNC), using acoustic emission technology Real-time monitoring of the whole process, the distribution law of acoustic emission signal, the change of acoustic emission parameters with the increase of load, and the corresponding relationship between it and the flexural strength of concrete are obtained. The results show that there is a relatively monotonically increasing relationship between the intensity and duration of concrete acoustic emission signals and the strength of concrete at different temperatures. The intensity and duration of acoustic emission signals of NSFC are wider and longer than those of the other three types of concrete. The incorporation of nano-SiO2 can effectively improve the mechanical properties of concrete after high temperature.