Experimental Study On Compressive Strength Of Desert Sand Concrete After High Temperature And Fire Evaluation

In recent years,excessive mining of mountain sand and river sand has caused serious environmental problems.Desert sand plays an active role in the economic construction of the western region.At this stage,the research on desert sand concrete is not deep enough,and there is no relevant standard for desert sand concrete.Building fires all over the world are prone to frequent occurrences,and the performance of buildings deteriorates after the fire.Research on concrete performance after fire is highly valued by researchers at home and abroad.In this paper,the mechanical properties and microstructure analysis of desert sand concrete after high temperature are carried out The main research contents are as follows:1)In this experiment,the compressive strength test of DSC after high temperature was carried out,and the effect of desert sand replacement ratio,fire temperature,temperature raising rate,standing time and cooling method on the mass loss rate,ultrasonic wave speed of DSC after high temperature was analyzed.The relationship between the compressive strength and the mass loss rate and ultrasonic wave speed of DSC after high temperature has been determined.An empirical regression formula for the mass loss rate and the ultrasonic method to estimate the temperature of DSC was established.2)Consider the impact of five factors on the compressive strength of desert sand concrete after high temperature,such as desert sand replacement ratio,fire temperature,temperature raising rate,standing time and cooling method,and then use python to realize BP neural network model to predict the compressive strength of DSC after high temperature.3)XRD was used to study the change law of desert sand concrete phase composition after high temperature.SEM was used to analyze the internal micro-morphology of desert sand concrete after high temperature with the changing law of fire temperature,standing time and cooling mode.Finally,a method for estimating the fire temperature based on the microstructure characteristics of DSC after high temperature is given.4)Using stereology principles,digital microscope and Image-Pro Plus software,the internal pores of desert sand concrete after high temperature were studied.The relationship between the pore size distribution of desert sand concrete after high temperature and desert sand replacement ratio,fire temperature,temperature raising rate,cooling method and standing time is analyzed.The relationship model between compressive strength and porosity of desert sand concrete after high temperature was established.