Experimental Study On Mechanical Properties And Pervious Performance Of Recycled Mixed Aggregate Pervious Concrete

With the interesting development of the basic construction in China,the construction industry has increased steadily,but it has caused huge construction waste and environmental problems at the same time.It can be used to make the recycled mixed aggregate pervious concrete with certain compressive strength and pervious performance.It is an effective solution to construction waste caused by urban construction and to improve the permeability of street roads,and it is an important part of building sponge city.The recycled mixed aggregate in this paper is made up of recycled concrete,recycled brick and recycled block,the proportion is 0.75:0.15:0.1.and The recycled mixed aggregate is used as coarse aggregate of the recycled mixed aggregate pervious concrete.By reading the domestic and foreign research results,the preparation process was determined and the physical properties of the recycled mixed aggregate,such as,stacking density,water absorption and water content have been research;the effects of mixed recycled aggregate replacement ratio,water cement ratio,aggregate size on the compressive strength and permeability was tested and disussed,The test results show that with the increase of water cement ratio,the strength of recycled aggregate concrete first increases and then decreases,and the permeability decreases gradually,and the size of aggregate affects the amount of contact point among the aggregate and the change of old mortar content in recycled concrete,then affects the compressive strength of regenerated mixed aggregate concrete,the Permeability coefficient increases gradually with the increase of aggregate size.The mechanical properties of recycled brick aggregate and recycled block aggregate are low.So with the increase of the amount of recycled aggregate,this kind of defect accumulates gradually and has a significant influence on the compressive strength.On this basis,by adding silica fume and sand,the effect of silica fume content and sand rate on modification of compressive strength and water permeability is studied.The test results show that when the target porosity is 25%,mixed recycled aggregate replacement rate is 03%,water cement ratio is 0.31 and the aggregate size is 9.5~16mm,sand ratio is 9%,silica fume quantity is 6%,the compressive strength of the recycled mixed aggregate pervious concrete can reach 10.5MPa,compared with the control group(W5),compressive strength increase 70%.The compressive strength is greatly improved,and the permeability coefficient is 2.43mm/s.