Experimental Study On Pervious Concrete Made From Recycled Aggregate

Because of its porous properties,pervious concrete with a variety of excellent performance breathable,permeable,sound absorption,etc.It can be used to a variety of water conservancy project and rail or highway engineering,slope surface treatment,maintain the ecological balance.In addition,its application complies with sponge city concept,that is to meet absorbent,water storage,water seepage,water purification,drainage features,and it can enhance the function of urban ecosystem and reducing the incidence of urban flood.Incorporation of recycled aggregate in pervious concrete,it has reached the green environmental protection,resource-recycling benefits.Therefore,the study of recycled aggregate pervious concrete has very important significance.In this paper,do a systematic research and analysis in the method for producing recycled aggregate pervious concrete,mechanical properties,water permeability and durability by side comparison tests,mineral admixtures modified test and endurance test,successfully prepared a recycled aggregates pervious concrete,its compressive strength greater than 20MPa,permeability coefficient greater than 0.30cm/s and with the good durability.The main research contents and results are as follows:(1)Mix proportion design for recycled aggregates pervious concrete using volume method,experiments show that the measured porosity and the target porosity to get relatively close in this way,it is feasible.(2)Under the premise to meet the water permeability,it is recommended not mixed with fine aggregate.In order to obtain high strength recycled aggregate pervious concrete,it should be used 5mm-10mm single grain of coarse aggregate、control water-cement ratio of about 0.3 and target porosity of 15%.(3)The silica fume and fly ash in appropriate dosage can be greatly improved strength of recycled aggregate pervious concrete,especially in the case of two complex mixed,it will get higher strength.Moreover,although the incorporation of silica fume and fly ash will reduce permeability coefficient of porous concrete,but the lowest also reached 0.33cm/s,it is permeable to meet the general engineering requirements.(4)It can be found that silica fume and fly ash can help improve the sulfate resistance of recycled aggregate pervious concrete pervious by sulfate resistance tests and freeze-thaw cycle test.A group specimen of single doped silica fume show a good freeze-thaw resistance in the freeze-thaw cycle test,but the fly ash is less than silica fume in that.In addition,salt solution freeze-thaw cycles of pervious concrete have a serious harm,it can not be ignored.