Research On Permeability And Environmental Performance Of Recycled Aggregate Permeable Pavement Of Construction And Demolition Waste

With the continuous development of China's urbanization process,construction and demolition projects are increasing year by year,and construction and demolition waste emissions are also increasing year by year.At the same time,the urbanization process has also led to serious urban waterlogging problems.Foreign countries began to study water-permeable pavements in the 1970 s,and the country has also begun to promote water-permeable pavements since the 21 st century.If the above two problems are combined,it can not only benefit sustainable development,but also alleviate the problem of waterlogging in modern cities.Therefore,the application of construction and demolition waste to permeable pavement base fillers has research value and broad application prospects.In this paper,through the experiment,the applicability of the construction and demolition waste as a substitute material for the permeable pavement base is studied.According to the analysis of the composition of construction and demolition waste,it can be seen that the quantity of bricks and concrete accounts for the vast majority,so these two common construction waste materials are mainly studied to evaluate whether they are suitable as permeable pavement base materials in different proportions and different gradations and different environments,geotextiles are used to filter pollutants in this study.Laboratory tests include basic physical properties of construction and demolition waste,such as water absorption,heavy compaction test,chemical composition analysis of XRF fluorescence spectrometer,homemade rain model test and column leaching test.1.The water absorption test shows that the water absorption rate of recycled aggregate is better than natural aggregate;2.Heavy compaction test results in maximum dry density and optimal moisture content of construction and demolition waste mixtures with different ratios and different gradation;3.In addition,self-made rainfall model test device,the construction waste mixture shows good water seepage performance and water storage performance,among them,the water permeability of 100% concrete performs best,the water storage capacity of 100% bricks when gradation 3 performs best;4.And compared with the geotextile reinforced and unreinforced after the infiltration of solid suspension total changes and permeability coefficient changes,It was found that geotextile can block a certain degree of solid suspended solids,The geotextile reinforcement has little effect on the permeability coefficient;5.The long-term permeable performance of geotextiles reinforced with 7-days cycles was studied,and the permeability coefficient of each working condition have a certain degree of decline;6.Exploring the causes of clogging,it is found that the construction and demolition waste mixtures of gradation 2 in the experiment has the best long-term performance,the impact of calcite precipitation on the clogging is negligible,the physical clogging caused by the accumulation of fines may be more obvious;7.Thecolumn leaching test explores the changes of six heavy metal contents(Cd,Cu,Cr,Pb,Zn,Ni)at different mixing ratios,different pH values and different liquid-solid ratios,and compare with soil background value and national groundwater standard.In general,construction and demolition waste used underground will not pollute the groundwater and can be applied to underground fillers.