Study On Damage Performance Of High Performance Lightweight Aggregate Concrete Under Load And Erosion Medium

As a good building material,high performance lightweight aggregate concrete has the advantages of high specific strength,heat insulation and good seismic resistance,so it has been widely used in long-span bridges and high-rise buildings.However,there are a variety of corrosive ions,such as SO42-,Cl-and so on.The harmful ions penetrate into high performance lightweight aggregate concrete and react with the hydration products of cement,generate low solubility of precipitate.Thus cause the expansion and cracking of high performance lightweight aggregate concrete.In finally,It can reduce the mechanical and durability,increase the structural damage and shorten the service life.This paper is based on Youth Science Fund Project“conformation mechanism and the effect of arch shell structure for lightweight aggregate high strength concrete on mechanical properties and medium transfer performance”.The damage of high performance lightweight aggregate concrete is monitored by non-metallic ultrasonic testing,and the dynamic elastic modulus index is used to reflect the change of the mechanical properties of high performance lightweight aggregate concrete.By redefined the relative dynamic elastic modulus to measure high performance lightweight aggregate concrete of the injury tolerance,and studying the damage failure law of high performance lightweight aggregate concrete under sulfate,sulfate-chlorine salt and sulfate-chlorine salt and mechanical factors,and set up the damage evolution equation of high performance lightweight aggregate concrete under different service conditions.The main findings are as follows:1.The erosion of high performance lightweight aggregate concrete in sulfate,sulfate-chlorine salt and sulfate-chlorine salt and bending load is a long-term and slow process.The variation of dynamic elastic modulus(Ed)of high performance lightweight aggregate concrete under several soaking conditions is similar.The change of dynamic elastic modulus is usually increased slowly before soaking,then tends to gentle,to the second parabolic curve change process slowly declining later.2.Under the effect of single sulfate attack,the dynamic elastic modulus and the velocity of ultrasonic wave of high performance lightweight aggregate concrete are changed accordingly.Through the change value of dynamic elastic modulus and ultrasonic wave velocity of high performance lightweight aggregate concrete,the mechanical properties and internal structure characteristics of high performance lightweight aggregate concrete are reflected.Between ultrasonic wave in highperformance lightweight aggregate concrete and the dynamic elastic modulus of high performance lightweight aggregate concrete are interrelated,and set up the regression equation between them.3.Under the effect of sulfate-chloride salt attack,compared with single sulfate solution of high performance lightweight aggregate concrete,it was found that the addition of chloride delayed the damage process of dynamic elastic modulus of high performance lightweight aggregate concrete,which affected the corrosion effect of sulfate on high performance lightweight aggregate concrete.The dynamic elastic modulus damage of the gravel shape high performance lightweight aggregate concrete is lower than that of the spherical high performance lightweight aggregate concrete.4.Under the effect of sulfate,chloride salt and bending load,compared with sulfate and chloride salt compound erosion,it is found that the effect of external load speeds up the damage process of high performance lightweight aggregate concrete,and does not change the damage mechanism of high performance lightweight aggregate concrete.Building the damage evolution equation of high performance lightweight aggregate concrete of the damage degree and soaking time,the quadratic function can well fit the correlation of both.Monomial coefficient denotes the initial change rate of high performance lightweight aggregate concrete,quadratic term coefficient denotes the damage rate of high performance lightweight aggregate concrete,and determines the damage schedule of high performance lightweight aggregate concrete.Based on the study of the three main factors affecting the performance of high performance lightweight aggregate concrete,such as sulfate,chloride salt and bending load to study the deterioration of the performance of high performance lightweight aggregate concrete,it provides a theoretical basis for the evaluation of the damage of high performance lightweight aggregate concrete structure,and one of great significance to promote the application of high performance lightweight aggregate concrete in engineering.