Study On The Influence And Relevance Of Mix Ratio Parameters On The Permeable Concrete Performance

Due to its good water permeability and air permeability,permeable concrete is an important material for the construction of modern sponge cities.It can effectively alleviate the urban heat island effect and flood disasters and improve the urban surface soil ecological environment hence it has attracted much attention at present.However,there is no systematic theoretical support on the relationship between design parameters and performance of Permeable concrete mix ratio.Therefore,it is of great significance to study the influence of mix ratio parameters on the performance of permeable concrete and its correlation to promote the application and development of permeable concrete.In this paper,The effects of water-cement ratio of different target porosity,different grading volumetric sand ratio and bone cement ratio on the strength,permeability coefficient,effective porosity and pore structure of permeability concrete were first systematically studied,At the same time,the effects of aggregate size,admixture and fiber on the properties and pore structure of permeable concrete were discussed.Finally,the correlation between the pore structure and the performance of the permeable concrete was analyzed.The research results of the effect of mixing ratio parameter on the performance of permeable concrete show that the compressive strength of permeable concrete increases first and then decreases with the increase of water-cement ratio and volumetric sand ratio,but decreases with the increase of aggregate cement ratio.The water permeability coefficient decreases with the increase of the water-cement ratio,and increases with the increase of aggregate cement ratio and the volumetric sand ratio.The results of the study on permeable concrete with fibers and admixtures show that the content of fibers and admixtures has an effect on the performance of permeable concrete,and there is an optimum value.Where in the optimal volume content of the polypropylene fiber and the fine steel fiber is 0.2%,The optimum content of fly ash and mineral powder is 10% and 20% of cement mass.When fly ash and mineral powder are mixed to replace 20% of the total cement and when fly ash: mineral powder is 7: 3,the performance of permeable concrete is the best.When the total content of fly ash and mineral powder is 30%,the optimum proportion of the two is 1:1.Fitting the equation between water cement ratio,volume sand ratio and properties respectively,The optimum values of water cement ratio and volume sand ratio can be predicted by the optimal value of the equation: when the target porosity is 15%,20% and 25%,the corresponding optimum water cement ratio is 0.33,0.31 and 0.31.When the aggregate is 5-10 mm gravel,10-20 mm gravel and two kinds of particle size 5-10 mm: 10-20 mm = 3:7,the optimum volume sand ratio is 5%,10% and 15%.The larger the pore size in permeable concrete,the smaller the contour coefficient.With the increase of 10-20 mm aggregate content,the number of pore decreases,but the proportion of pore size above 3 mm increases.When the target porosity increases,the proportion of pore above 6 mm increases.When the volume sand ratio is the optimum value,the equivalent pore size distribution is closer to the normal distribution and the fractal dimension decreases.