Experimental Study On Aseismic Performance Of Enhanced Recycled Coarse Aggregate Concrete Columns

The recycling technology of concrete can realize the utilization of building waste resources,but the regenerated coarse aggregate has a lot of angle,small apparent density,high water absorption and large crushing index,which makes the performance of recycled concrete inferior to ordinary concrete.Strengthening the recycled coarse aggregate can significantly improve its physical properties,and further improve the performance of recycled concrete.It is significant for engineering application to study the seismic performance of recycled aggregate concrete members reinforced by coarse aggregate.The research work in this paper mainly includes wood property test and component aseismic performance test.(1)strengthen the recycled coarse aggregate by soaking the silica fume cement slurry,and test the apparent density,accumulation density,gradation curve,water absorption rate and crushing index of natural coarse aggregate,recycled coarse aggregate and reinforced recycled coarse aggregate respectively,so as to study the performance improvement effect of strengthening recycled coarse aggregate.(2)5 roughed recycled concrete frame columns and 3 common concrete frame columns were made,and their seismic performance was studied by low cycle repeated loading tests.The damage process and final failure mode of eachcomponent in the loading process are studied,and the influence of axial compression ratio and the volume ratio on the failure mode of the reinforced concrete frame column strengthened with coarse aggregate is analyzed.(3)on the basis of the low cycle test data of the frame column,the failure mode,hysteretic behavior,stiffness degradation,bearing capacity attenuation and ductility of the components are analyzed.The difference of seismic performance of concrete frame columns reinforced by recycled coarse aggregate and ordinary concrete frame columns and the contrast of two concrete frame columns with non coaxial pressure comparison are analyzed and compared.And the influence of volumetric stirrup ratio on RC Frame Columns Strengthened with coarse aggregate is also discussed.The results show that the intensification of silica powder soaking can improve the strength of recycled coarse aggregate and improve the performance of recycled concrete.With the increase of axial compression ratio,the deformation capacity,bearing capacity and energy dissipation factor of ERCA frame column will increase first and then decrease,while the deformation capacity,bearing capacity and consumption of NCA frame column can be reduced.The energy coefficient and other indexes continue to decrease,which indicates that the ERCA frame column has the best seismic performance when the axial compression ratio is moderate,and the ERCA frame column is badly damaged when the axial pressure is large,but the difference is small when the axial pressure ratio is low.With the increase of the volume matching ratio,the bearing capacity and deformability of the ERCA frame column increase and the stiffness degradation speed is increased.And the intensity attenuation degree decreased.Therefore,reasonable selection of axial compression ratio and volumetric stirrup ratio of ERCA column can improve its seismic performance in structural design.