Effect Of Mixed Aggregate Grade With Brick On Strength And Deformation Of Recycled Concrete

Our country produces a large number of construction waste every year,but the utilization rate of resources is relatively low compared with European and American countries.Improving the utilization rate of construction waste resources can not only reduce the environmental pollution,but also save natural materials.Therefore,it is urgent to use construction waste in concrete engineering practice.In recent years,most of the scholars at home and abroad are devoted to the application research of waste concrete,but the research of crushed brick is relatively less.This paper measured the basic parameters of recycled coal gangue brick aggregate concrete,designed the mixed crushing test scheme of recycled coal gangue brick aggregate and natural limestone aggregate,studied the gradation crushing law of recycled mixed aggregate under different pressures,analyzed the components of recycled mixed aggregate crushing grading,and tested the aggregate density and porosity of total aggregate and coarse aggregate.Furthermore,concrete test blocks were used to measure the compressive strength and elastic modulus of recycled concrete test blocks,and the relationship between the aggregate content and gradation composition of recycled coal gangue bricks and the strength and elastic modulus of recycled concrete was analyzed.The following main research results were obtained:(1)The minimum porosity of regenerated mixed aggregate can be quickly determined by "interpolation approximation method",so that the regenerated mixed aggregate can reach the densest state.After mixing and crushing,the aggregate porosity presents a bell curve distribution with the increase of sand rate,increasing first and then decreasing.When the sand rate reaches about 40%,the porosity and packing density reach the maximum,and the fractal dimension D value is the minimum.At this time,the aggregate is the most dense.(2)The unconfined compressive strength,compressive elastic modulus and flexural tensile elastic modulus of the concrete test blocks with different recycled gangue brick content decrease with the increase of recycled gangue brick content;Increases with increasing curing age.(3)When the recycled mixed aggregate reaches the highest compactness,the configured recycled concrete has the highest compressive strength.