Experimental Study On Mixture Ratio Of Recycled Concrete On Road Surface

With the acceleration of urbanization in China,many old buildings have been demolished,resulting in a large amount of construction waste.It is common to pile them up or bury them in landfill,which will not only pollute the environment,but also waste a lot of resources,but the construction waste after processing into recycled concrete can be used again in the road surface layer.Recycled concrete is made of recycled aggregate made from construction waste through a certain process and added to natural concrete.On the premise that the concrete strength reaches the standard,the utilization rate of construction waste can be improved and the amount of natural aggregate can be reduced.In this test,recycled concrete is divided into two groups with natural gravel and natural gravel as coarse aggregate.The replacement rate of recycled aggregate,watercement ratio and sand ratio are the influencing factors.According to three factors and three levels,orthogonal method is used to carry out the test.Through the design and study of the mix ratio with the flexural strength as the index,the application scope of recycled concrete is expanded,which is of certain significance to the application of recycled concrete in road engineering.Based on plastic damage model,numerical simulation is carried out in finite element software.Through reasonable parameter setting and constitutive relation selection,the strength values of the three tests were calculated,and the numerical simulation and the actual test results were compared to calculate the error.The stress and strain distribution characteristics of the test specimens under different replacement rates of recycled aggregate were compared,and the reasons for the difference between the numerical simulation results and the actual test results were analyzed.Through the above experiments,the conclusions are as follows:(1)When the flexural strength is taken as the design index,the flexural and compressive properties of recycled concrete can meet the performance requirements of grade III and GRADE III road surface when A1B2C1 factors are combined,that is,the replacement rate of recycled aggregate is 30%,the water-cement ratio is 0.37,and the sand ratio is 36%.(2)The replacement rate of reclaimed aggregate has the greatest influence on the flexural strength of reclaimed concrete in gravel group and gravel group.In the compressive test,the replacement rate of reclaimed aggregate has the greatest influence on gravel group,and the water-cement ratio has the greatest influence on gravel group.(3)The sand ratio has the least influence on the compressive strength and flexural strength of the two kinds of recycled concrete.The effect of sand ratio on splitting tensile strength of gravel group has no obvious regularity.The change of sand ratio has more influence on the splitting tensile strength of gravel group.(4)In the numerical simulation,when the substitution rate is low,the three mechanical properties of the two kinds of recycled concrete can be accurately predicted,and the errors are less than 6%.However,the error increases with the increase of substitution rate,and the error of numerical simulation of splitting tensile strength is the largest.(5)Under the same replacement rate,the errors of different types of recycled concrete are different,and with the increase of replacement rate,the errors of different types of recycled concrete are quite different.