Research On The Performance And Mix Proportion Design Of Recycled Aggregate Permeable Concrete

In this paper,water cement ratio(0.28,0.30,0.32),particle size distribution(small particle size 4.75mm-9.5mm,large particle size 9.5mm-16.0mm)and target porosity(10%,12%,14%,16%)are used as variables to study the influence of the three factors on the mechanical properties and water permeability of recycled aggregate permeable concrete,and the three-factor importance ranking is achieved by using Minitab platform Analysis.At the same time,through the linear fitting of MATLAB analysis software,the improved method of mix proportion design of recycled aggregate permeable concrete is put forward.Finally,the paper analyzes the economic effects of recycled aggregate permeable concrete.The main research contents and results are as follows:(1)In this test,the effect of each single factor on the compressive strength of recycled permeable concrete from large to small is as follows:particle gradation>target porosity>water cement ratio.Particle gradation have the greatest effect on compressive strength,and the compressive strength of the continuous grading is significantly higher than that of the single grading,and when the ratio of small to large particle size is around 8:2,the maximum compressive strength is taken.(2)The pore distribution of recycled permeable concrete with continuous gradation is more uniform,and the specific surface area of cement paste bonding is larger,which leads to a higher flexural strength.With the expansion of target porosity,the internal porosity of recycled permeable concrete increases,which is not conducive to the development of flexural strength of concrete itself.As for the particle grading,there is a good linear fitting relationship between the compression ratio and the compressive strength of recycled pervious concrete.(3)The effect of each single factor on the permeability of recycled pervious concrete from large to small is as follows:target porosity>particle gradation>water cement ratio.That is to say,among the three factors,the target porosity is the main factor affecting the permeability of recycled aggregate permeable concrete.(4)Under different target porosity,the influence of water cement ratio on the permeability of recycled aggregate permeable concrete is different:under the smaller target porosity,the permeability of recycled aggregate permeable concrete is enhanced,which is because the fluidity of cement slurry is enhanced when the water cement ratio is increased,and it is easier to form connected pores.However,under the larger target porosity,when the water cement ratio increases,the cement slurry is easy to infiltrate and block,which affects the development of the water permeability of recycled permeable concrete.(5)Through linear fitting,taking the actual porosity as the intermediate variable,this paper gives the functional relationship between the actual porosity and compressive strength,the actual porosity and flexural strength.And the functional relationship between the actual porosity and the target porosity and particle grading also is given.At the same time,based on the volume method,this paper proposes a new mix design method based on the target porosity and particle grading.