Study On Permeability Performance Of Pervious Concrete Under Specific Strength

Pervious concrete has various benefits such as improving urban water-capacity,alleviating urban water-logging and urban “heat island effect”,however,the problem of weak permeability of high-strength concrete has not been solved.Therefore,the paper determines the conservative mixing ratio of the pervious concrete that attain the standards of C20 by using Orthogonal test method,then,the main results are obtained that studied the effective porosity,aggregate specific surface area and the properties of concrete under different film thickness conditions,the main results are as follows:(1)It is found that the method of standard curing box drying is more accurate than the method of natural air drying by optimizing the method of determining the effective porosity of pervious concrete.(2)It is concluded that the specific surface area of the aggregate of theoretically calculated is better according to the shape of the sphere and the equivalent particle size of the particle size range of 2/3,in which contrasted theoretical calculation and experimental analysis of the specific surface area of the aggregate.(3)The conservative compounding ratio of C20 pervious concrete was determined by using orthogonal test design and the concrete composed of basic materials.It is as follows: the water-cement ratio is 0.3,the mixing ratio of 5~10mm and 10~13.2mm grade aggregates is70%: 30%,the target porosity keeps 14%,and the proportion of water reducing agent is 1.2%.(4)It is found that as the thickness of the outer surface of the coarse aggregate increases to the later stage,the effective porosity and permeability performance of the sample are slower than the thickness of the film of increasing the trend in the early stage;the compressive strength is not increased significantly in the early stage of thickening of the film thickness,the increases of compressive strength keeps more higher rate in the middle of thickening of the film thickness,the rate of increasing the compressive strength begins to decrease in the later stage of thickening of the film thickness,in which study the performance of the pervious concrete under different film thickness.At the same time,it is concluded that the film thickness of the permeable concrete is 450 um in which ensure certain strength andcontaining better permeability performance.the amount of material per cubic material is: The coarse aggregates of 5~10mm and 10~13.2mm are mixed with 1180.6kg and 501.27 kg respectively,Portland cement with strength 42.5 of 462 kg,polycarboxylate superplasticizer of5.55 kg,mixing water of 138.67 kg.(5)It is introduced that the composition about the pervious concrete in application,and are summarized that the advantages and disadvantages of pervious and ordinary concrete in engineering applications.Stratified,embedded and line applications of pervious concrete are proposed,then,it were pointed the advantages and disadvantages of pervious concrete in engineering applications,which provide reference for future engineering applications.