Experimental Study On Seismic Behavior Of Interior Joints Of After-mixing Coarse Aggregate Concrete

The booming development of the construction industry has caused great damage to the ecological environment.Reducing energy consumption and pollutant emissions has become a new direction of the development of the industry.Concrete,as the largest building material,is widely used and has an important impact on the environment.The green development of concrete has become the industry trend,and then after-mixing coarse aggregate concrete as ecological green concrete has important research significance and promotion value.After-mixing coarse concrete refers to the commercial concrete,on the basis of the castin-place concrete plus a percentage of coarse aggregate on the working plane,after a mechanical device secondary stirring,and form a new type of concrete(Before the concrete is poured to the working face,the green concrete construction equipment is used to pump the concrete with appropriate proportion of high quality coarse aggregate into the concrete that has been mixed.The concrete is obtained after the second batch of material is mixed evenly and then poured and vibrated).After admixture of aggregate concrete can increase the content of coarse aggregate in concrete and reduce the use of cementitious materials such as cement.Besides saving the cost of building materials,it can also improve the strength of concrete,improve the durability of structure,crack resistance and other properties.In view of the lack of research on the seismic performance of after-mixing coarse aggregate concrete,the test designs 8 interior joint specimens of after-mixing coarse aggregate concrete and 3 interior joint specimens of common concrete,and studies the influence of aftermixing ratio,axial compression ratio and volume-stirrup ratio of core area on the seismic performance.Through low cycle loading test,the failure process and the failure pattern,hysteresis curves,skeleton curves,ductility,rigidity degeneration,steel bar strain,residual strength and residual displacement and plastic hinge rotation of interior joints with after-mixing coarse aggregate concrete are analyzed,the conclusions are as follows: the failure process and failure characteristics of after-mixing coarse aggregate concrete joints is similar to the common concrete joints;When the axial compression ratio was increased,the seismic performance of the joints showed a trend of increasing first and then decreasing,and reached the peak when the axial compression ratio was 0.2.The seismic performance of the joints is increased by increasing the volume-stirrup ratio of core area Under the same axial compression ratio,the seismic performance of the after-mixing coarse aggregate concrete is not significantly different from that of the common concrete,but the quantitative analysis shows that the seismic performance of the after-mixing coarse aggregate concrete is slightly worse than that of the common concrete.Through calculating the cost of after-mixing coarse aggregate concrete and the CO2 emissions in the production process,It is found that when the after-mixing ratio is 20%,unit cubic meter after-mixing coarse aggregate concrete can save 10% of material cost and reduce nearly 20% of carbon dioxide emissions.The use of after-mixing coarse aggregate concrete can generate huge economic and ecological benefits.