Experimental Research On The Bond Performance Between Reinforcing Bars And Ceramsite Concrete During Freeze-thaw Cycle And Chloride Corrosion

Compared with ordinary concrete,ceramsite concrete has excellent properties such as light weight,high strength,fire resistance and heat insulation,and anti-seepage and frost resistance.Therefore,it is mostly used in the project to partially replace ordinary concrete,and the main structure of some projects uses ceramsite concrete.According to engineering experience It can be seen that due to the influence of the external environment.the durability of the traditional concrete material will be seriously reduced.For example,the cold and coastal areas have a significant impact on the bond performance between the reinforcement and concrete due to the combined effect of freezing and thawing and chloride ion corrosion,and even lead to Structural failure.Therefore,it is of great engineering application value to discuss the influence of freeze-thaw and corrosion on the bond strength between ceramsite concrete and steel bars.In this paper,the experimental method is used to study the influence of the type of steel bar,the number of freeze-thaw cycles and the concentration of chloride salt solution on the bonding performance,and propose a fitting formula to provide a theoretical basis for subsequent research and engineering design,the specific contents are as follows.(1)Do a central pull test on a ceramsite concrete test block with a strength of LC30,and design a total of three test variables,which are the type of reinforcement(bfrp reinforcement,threaded reinforcement,epoxy-coated reinforcement),and the number of freeze-thaw cycles(0 Times,15 times,30 times)and the concentration of the chloride salt solution(3.5%,7%,10%).Divided into 27 groups according to different variables,each group of three test pieces,a total of 81 test blocks.(2)Observe the failure mode of the test piece and record the test data.Sort out the test results and draw the bond strength-slip curve.(3)According to the test results,at the same chloride salt solution concentration,as the number of freeze-thaw cycles increases,the bonding properties of three different types of steel bars and ceramsite concrete have decreased to varying degrees,of which freeze-thaw Cycling has the greatest influence on the bond strength of epoxy-coated steel bars,followed by bfrp bars,and the smallest thread bars;under the same number of freeze-thaw cycles,as the concentration of chloride salt solution increases,the bond strength of bfrp bars and thread bars increases.However,as the concentration of the epoxy-coated steel bar increases,the bonding performance decreases.(4)Summarize the changes of the bonding strength of three different types of steel bars after freezing and thawing cycles and chloride salt corrosion,and perform formula fitting and result verification to provide a basis for subsequent research and actual engineering.