Experimental Study On Water Absorption And Chloride Diffusion Coefficient Of Recycled Concrete

With the continuous development and progress of China’s economy,recycled concrete is playing a more and more important role.Recycled concrete can effectively solve the problem of environmental pollution caused by construction waste,save natural resources and reduce construction cost effectively.Therefore,the research on the application of waste concrete aggregate to the construction project will not only help to turn waste into treasure,but also provide a theoretical basis for the promotion and application of recycled concrete.This paper studied the water cement ratio of 0.3,0.4,0.5,0% recycled coarse aggregate content,10%,20%,30%,20%,50%,60%,70%,80%,90%,80%,curing age 7 and 28 days of recycled concrete specimen,on the compressive strength,splitting tensile strength test and water absorption test and chloride ion diffusion coefficient test,conclusion is obtained by experimental study on the following:(1)The compressive strength and tensile strength of recycled concrete increase with the decrease of water-cement ratio and the extension of curing age.When the replacement rate of recycled aggregate is between 20% and 40%,the compressive strength of recycled concrete is good.When the replacement rate of recycled coarse aggregate is 30%,the maximum tensile strength of recycled concrete is obtained.When the value range of replacement rate of recycled coarse aggregate is between 50% and 100%,the compressive strength of recycled concrete is not good.The tensile strength of recycled concrete is7.2%～11.5% of the compressive strength.(2)The water absorption rate of recycled concrete increases with the increase of water-cement ratio.It decreases with the extension of curing age.As the replacement rate of recycled coarse aggregate increases,the water absorption rate of recycled concrete will first decrease and then increase.When the replacement rate of recycled coarse aggregate is 20%,the water absorption rate of recycled concrete with different water-cement ratio is small.(3)The chlorine diffusion coefficient of recycled concrete increases with the increase of water-cement ratio and the replacement rate of recycled coarse aggregate.The chlorine diffusion coefficient of all recycled concrete with water-cement ratio of 0.4 and 0.5(replacement rate of recycled coarse aggregate is100%)is about 1.8 times that of ordinary concrete.(4)The law of power function exists in the water absorption rate and tensile strength of recycled concrete.The compressive strength and tensile strength of recycled concrete decrease with the increase of water absorption.There is a quadratic function relationship between the compressive strength of recycled concrete with water-cement ratio of 0.3 and the chlorine ion diffusion coefficient.Water-binder ratio of 0.4and 0.5 of the compressive strength and splitting tensile strength of recycled concrete and recycled concrete chloride ion diffusion coefficient of linear relationship,with the increase of recycled concrete chloride ion diffusion coefficient,the compressive strength and splitting tensile strength are reduced.The water absorption rate of recycled concrete is linearly related to the chlorine ion diffusion coefficient.The higher the water absorption rate of recycled concrete is,the greater the chlorine ion diffusion coefficient is.