Study On Mechanical Properties Of High Performance Concrete With Waste Ceramic After High Temperature

The rapid development of China’s ceramic industry has produced a large number of waste ceramic,which not only occupy land resources,but also cause serious ecological environmental pollution.Therefore,how to dispose of waste ceramic reasonably has become an urgent scientific problem related to the national economy and people’s livelihood.Waste ceramic is an ideal choice for concrete aggregate and admixtures due to its similar chemical composition to cement,high hardness and excellent high temperature resistance.Therefore,this paper applies waste ceramic as aggregate and admixtures to high performance concrete,and studies the mechanical properties of high performance concrete with waste ceramic after high temperature and its influencing mechanism.The main research contents and conclusions of this paper are as follows:(1)High performance concrete with different replacement rates of waste ceramic aggregate of 0wt.%,20 wt.%,40 wt.%,60 wt.%,80 wt.% and 100 wt.% was prepared.The mass loss,visual inspection,flexural strength,compressive strength,fracture toughness and compressive toughness were tested at room temperature,200℃,400℃,600℃ and 800℃,and the mechanism of improving the mechanical properties of high performance concrete after high temperature was analyzed and discussed by scanning electron microscopy and mercury intrusion porosimetry.The results show that the surface color of high performance concrete with waste ceramic aggregate exhibits a general trend of dark gray-gray-off white with the increase of temperature,and the number of crack increases with the increase of temperature,and decreases with the increase of the replacement rate of waste ceramic aggregate.The waste ceramic aggregate has little effect on the mass loss of high performance concrete after high temperature.The strength and toughness of high performance concrete with waste ceramic aggregate show a trend of increasing first and then decreasing with the increase of temperature,and the critical temperature is 200℃-400℃.The strength and toughness after different high temperatures show an overall increasing trend with the increase of the replacement rate of waste ceramic aggregate,and the replacement rate of waste ceramic aggregate is 100 wt.%,which is conducive to improving and maintaining the mechanical properties of high performance concrete after high temperature.The improvement rate and retention rate of mechanical properties are 131.4%～268.1% and 97.3%～185.9%,respectively.The width of interfacial transition zone and porosity decrease first and then increase with the increase of temperature,and the waste ceramic aggregate can reduce the width of interfacial transition zone and the proportion of harmful pores.(2)In order to study the influence of waste ceramic powder on the mechanical properties of optimized high performance concrete with waste ceramic aggregate after high temperature,the waste ceramic powder of 0wt.%,15 wt.%,25 wt.%,35 wt.%,45 wt.% and 55 wt.% were used to replace the cement in optimized high performance concrete with waste ceramic aggregate,and high performance concrete with waste ceramic powder was prepared.The color change,crack development,mass loss,compressive strength and toughness were observed and tested at room temperature,200℃,400℃,600℃ and 800℃,and the influence mechanism on mechanical properties after high temperature was discussed.The results show that the surface color of high performance concrete shows a trend of dark gray-off white-red with the increase of temperature.The addition of waste ceramic powder can effectively reduce the number of crack on the surface of high performance concrete after high temperature.The effect of waste ceramic powder on the mass loss of high performance concrete after high temperature is not obvious,but the mass loss gradually increases with the increase of temperature.The strength and toughness of the high performance concrete with waste ceramic powder show an overall trend of increasing first and then decreasing with the increase of temperature,and the critical temperature is 200℃-400℃.The strength and toughness at different temperatures show different changes with the increase of the replacement rate of waste ceramic powder.The waste ceramic powder with a replacement rate of 35 wt.% is beneficial to reduce the loss of mechanical properties of high performance concrete after high temperature,and the improvement of mechanical property retention rate after high temperature ranges from 8.7% to 52.3%.The high performance concrete can burst under high temperature when the replacement rate of waste ceramic powder is 45 wt.% and 55 wt.%.The width of interfacial transition zone and porosity decrease first and then increase with the increase of temperature,and the waste ceramic powder can improve the width of interfacial transition zone and the proportion of harmful pores.This paper shows that waste ceramic can improve the high temperature resistance of high performance concrete.The research in this paper can not only reduce the use of natural aggregate and cement,but also realize the resource utilization of waste ceramic,protect the ecological environment,and lay a theoretical foundation for the development of low carbon high temperature and high performance concrete.