Multi-scale analysis of mechanical properties of RCA based on synergistic modification of carboxylic butadiene-styrene latex and PVA fiber

With the rapid development of the construction industry, construction waste is also increasing day by day. Considering the utilization rate of recycled coarse aggregate (RCA) concrete and the mechanical strength of RCA itself, this study carried out collaborative modification of RCA through new modifiers carboxylic butadiene-styrene latex (CSBL) and PVA fiber, aiming at improving the mechanical properties of RCA. In this study, compressive test and shear test were used to test the mechanical strength of the test block. Scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR) were used to reveal the microscopic morphology and chemical composition, respectively. Molecular dynamics simulation was used to evaluate the type and stability of the force at the weak interface. The results showed that the modified compressive strength and shear strength of RCA with replacement rate of 20% increased by 12.8% and 26.7%, and the optimal content of CSBL and PVA fiber was 15% and 1.5%, respectively. CSBL further hydrates the unhydrated cement, thereby optimizing the weak interface. PVA plays a role in limiting the development of cracks in RCA. The results of weak interface molecular simulation show that CSBL acts as a bridge at the weak interface, and CSBL mainly enhances the adhesion between the weak interfaces in RCA through a large number of hydrogen bonds and stable ionic bonds. Therefore, CSBL improves the application effect of PVA fiber in RCA, and this study provides useful insights for improving the performance of RCA materials.