Experimental Study On Physical And Mechanical Properties Of Recycled Construction Waste Aggregate

With the rapid development of urbanization,urban ecological environmental proble ms(such as urban waterlogging and heat island effects)have become increasingly pro minent,and the construction of sponge cities has emerged.At the same time,a large number of urban construction waste recycled materials have been successfully used in roadbed filling and ground treatment,green concrete aggregates,and ecological brick p roducts.However,there are relatively few theoretical research materials on the "spongebody" using recycled aggregates from construction waste in water storage structures,and there is no existing experience to follow.Based on this,the thesis relied on the Northwest Research and Development Project "Research on the System Structure and Technical Application of Construction Waste as a Water Storage Sponge",through the crushing and screening test,density determination,and density determination of waste concrete and waste bricks in construction waste.Water absorption test,crush value tes t,permeability test,as well as large-scale indoor compression and direct shear tests,di scussed the physical and mechanical properties of construction waste recycled aggregat es,and used construction waste recycled aggregates for urban sponge storage and drai nage structures.Filling provides test basis.The paper has achieved the following mainresults:(1)The physical performance test results of construction waste recycled aggregate show that: the water absorption rate of construction waste recycled aggregate increases with time,but with the increase of particle size,the water absorption rate decreases,a nd waste The water absorption rate of recycled brick aggregate is greater than the wat er absorption rate of recycled aggregate waste concrete;the water absorption rate of t he two types of recycled aggregates has a good negative exponential power function r elationship with particle size;the crushing value of construction waste recycled aggreg ate and natural gravel is similar The crush value is as follows: waste brick aggregate>waste concrete aggregate> natural crushed stone;the crush value of recycled aggregat e increases by 2.2% and 1.5% in the dry state after water absorption and saturation;buildings with different proportions In the case of the same gradation of waste recycle d aggregate,the relationship between the ratio and the permeability coefficient is roug hly linear.(2)The results of the large-scale compression test show that with the increase of the normal stress,the vertical strain also increases,and under the same test conditions,the strain of the waste brick aggregate is greater than that of the waste concrete agg regate,and the particles are also more broken.Large;with the increase of the water a bsorption rate of the aggregate,the strain amount shows a trend of first increasing an d then decreasing,and the particle breakage rate presents the same law.(3)The large-scale direct shear test results show that the Mohr-Coulomb strength theory can describe the shear strength of recycled coarse aggregates of construction w aste,but the nonlinear strength criterion can better represent the non-linear stress-strainrelationship of recycled coarse aggregates;For the construction waste recycled coarse aggregate,its shear strength is mainly determined by the normal stress,particle contactangle,and friction factor;the shear rate has varying degrees of influence on the recy cled aggregate shear strength;the larger the particle size of the recycled coarse aggreg ate Larger,the more obvious the stress-strain nonlinear relationship.The research results provide an important theoretical basis for the use of construc tion waste recycled aggregates in the construction of urban sponge cities.At the same time,it also has reference significance for the use of construction waste recycled aggr egates for highway and railway roadbed filling,green concrete aggregates,etc.