Study On The Influence Of Emery And Steel Fiber On The Performance Of Recycled Concrete After Temperature Cycle

The use of recycled concrete can reduce the exploitation of natural aggregate and realize the reuse of construction waste,so as to protect the environment and save economic cost.At the same time,the mechanical properties of recycled concrete are lower than that of ordinary concrete due to the problems of large porosity.After adding steel fiber and emery,the mechanical properties of recycled concrete are improved.At present,the improved recycled concrete has been used in practical projects.However,the environmental temperature is one of the causes of concrete damage.Previous studies mainly focused on the measurement of the residual stress of concrete after one high temperature test,while the study of multiple temperature cycles simulating the environmental temperature was less.In this paper,the influence of steel fiber and carborundum on the mechanical properties of recycled concrete under different times of temperature cycling is studied.1.The test mix proportion is based on C30 concrete(C),recycled coarse aggregate is made of 20% substitute instead of natural coarse aggregate to make recycled concrete(RC);steel fiber recycled concrete(SFRC)is made of steel fiber with volume ratio of 1% on the basis of recycled concrete;on the basis of recycled concrete,emery recycled concrete is made of equal quality emery with 10% substitute for fine aggregate Concrete(SICRC).2.After 0,50,100 and 150 cycles of 0-80 ? temperature for four kinds of concrete test blocks,the cube compression test,split tensile test,four point bending test and compression fatigue test are carried out.3.In order to better analyze the fatigue life,the data from the anti pressure fatigue test are analyzed based on the theory of Weibull distribution.The basic mechanical properties of the four kinds of test blocks decreased with the increase of temperature cycles.The compressive strength,splitting tensile strength and flexural strength of RC increased most obviously after 150 temperature cycles with the addition of steel fiber and carborundum,which was close to or even reached the strength of C under the same conditions.Although the addition of steel fiber and emery also improved the compressive fatigue performance of RC under the same conditions,the number of temperature cycles had no significant effect on the increase of fatigue life of RC.According to the Weibull distribution theory analysis of the anti pressure fatigue test results,the test blocks all well meet the steady probability of two parameters,and the fatigue equations under different failure probability are obtained.Through the comparison of the fatigue strength calculated by substitution,it can be concluded that the fatigue performance of RC after the addition of corundum or steel fiber has no obvious change under the temperature cycling condition.The research results can provide reference for the influence of corundum and steel fiber on RC under the influence of daily ambient temperature change,and provide theoretical basis for practical engineering application...