Research On Performance Of Permeable Concrete Based On High Strength Cementing Agent

Permeable concrete is an important ecological paving material in the construction of "sponge city".The strength of pervious concrete is affected by the cementing agent.In this paper,the preparation of high-strength pervious concrete cementing agent,preparation and forming method of test block,basic mechanical properties,water permeability and sulfate resistance are studied.The specific research contents are as follows:(1)According to the destructive characteristics of permeable concrete,it is determined that the cementing agent is composed of three components: reinforcement component,tackifying component and water reducing component.According to the mechanism of action and price factors of the material,the material proportion of each component is optimized comprehensively.The 28-day compressive strength of permeable concrete based on the optimum cementing agent proportion is 20.1 MPa,and the permeability coefficient is 5 mm/s.Through the qualitative and quantitative economic analysis of the cementing agent,the market development prospect and economy of the cementing agent are evaluated.(2)To optimize the feeding sequence and forming method during the preparation of permeable concrete,and compare the secondary feeding method with the three feeding method.The preferred three feeding method increases the 28-day compressive strength of permeable concrete by 17.18% and the permeability coefficient by 41.24% compared with the secondary feeding method.The aggregate contact of the test block prepared by the optimized three-layer interpolation method is tighter.(3)This paper conducts a single factor optimization experiment on the four factors of water-cement ratio,cement content,design porosity,and aggregate particle size.Through analyzing the influence of each factor on compressive strength,bending strength and water permeability,the optimum selection value of each factor is determined.The optimum watercement ratio is 0.25,the optimum cement content is 4%,the optimum design porosity is 20%,and the permeable mixing under the optimum mixing ratio state is determined.The 28-day compressive strength,flexural strength and permeability coefficient of the condensate are 25.6MPa,3.1 MPa and 5.7 mm/s respectively.The test shows that the addition of high strength cementing agent improves the compressive strength and also ensures high water permeability.(4)Linear regression analysis is carried out on each index to get the linear regression equation between compressive strength,bending strength and water permeability coefficient.(5)15,30,45,60,75,90,105 dry-wet cyclic immersion tests and 60,120,180 and 240 days long-term immersion erosion tests are carried out on the permeable concrete with the optimum mix ratio in the sulphate solution of 5%,7% and 9% concentration respectively.The sulfate corrosion mechanism of the test block was analyzed from the changes of the apparent corrosion resistance coefficient of the test block,the corrosion resistance coefficient of the mass and the compressive strength.The test results show that the dry wet cycle corrosion is more serious,the maximum reduction of the mass of the test block is 1.87%,and the maximum reduction of the compressive strength of the test block is 29.20%.More attention should be paid to erosion protection in practical engineering.(6)Establish the compression model of permeable concrete,simulate the compression failure of permeable concrete by PFC particle flow procedure,obtain the stress-strain curve under uniaxial compression,and analyze the development and change of cracks in material under compression and the failure mechanism.