Effect of nano-SiO 2 modification on the seismic performance of recycled aggregate concrete shear walls

Nano-silicon dioxide (nano-SiO2) can strengthen recycled aggregates and interface transition zones (ITZs), thereby improving the properties of recycled concrete structures. This study adopted nano-SiO2 modifications to improve the seismic behavior of recycled concrete shear walls. Quasi-static tests of one natural aggregate concrete shear wall and four concrete shear walls with different replacement ratios (30%, 50%, 70%, and 100%) of nano-SiO2 modified recycled aggregate (NSMRA) were conducted. The ductility factor, energy dissipation, lateral displacement components, stiffness, and strength degradation of NSMRA concrete (NSMRAC) shear walls were evaluated. The replacement ratio effects of NSMRA on the seismic behavior of shear walls were analyzed. It was determined that the NSMRAC shear walls exhibited higher ductility factor compared to recycled aggregate concrete (RAC) shear walls with similar conditions. The seismic behavior of the shear walls degraded as the replacement ratio of NSMRA increased. Based on the comprehensive evaluation of failure patterns and seismic performance indexes, the replacement ratio of NSMRA is suggested to be taken as 50% in the concrete shear walls. Finally, based on the summary of experiments and studies on the seismic behavior of RAC shear walls with shear failure, the applicability of existing formulae was evaluated by calculating the shear capacity of RAC shear walls, and the effect of nano-SiO2 modifications on the shear capacity of recycled concrete shear walls was analyzed.