Mechanical Properties of Recycled Concrete Reinforced by Basalt Fiber and Nano-silica

In this study, basalt fiber (BF) and nanosilica (NS) were used to improve the mechanical properties of recycled concrete (RC), thereby promoting its utilization. The effect of BF and NS on the impact performance of RC was studied using the split Hopkinson pressure bar (SHPB) test. The internal microstructure of RC was analyzed by scanning electron microscopy, mercury intrusion porosimetry and nuclear magnetic resonance test. The results showed that, as the strain rate increased, the destruction mode transitioned from fracturing to crushing. Moreover, the impact compressive strength, dynamic increase factor, and total impact toughness increased. The replacement rate has little to no influence on the failure state, impact compressive strength and specific energy absorption. BF is conducive to enhancing the integrity and improving the impact compressive strength, peak strain and impact toughness. NS can reduce the pore content of mortar and the corrosion effect of the fiber surface, enhancing the compactness of the mortar and the bridging effect of the fiber. With an increase in NS content, the impact compressive strength, peak strain, and impact toughness increase, leading to greater destruction integrity. The results show that BF and NS can more effectively enhance the mechanical properties of RC.