Tannic acid treatment of fine recycled concrete aggregates (RCAs) for better impact resistance performance of cementitious materials
摘要
Fine recycled concrete aggregate (RCA) exhibits inferior bonding properties with cement due to its high water absorption and porosity. Incorporating fine RCAs in cementitious materials leads to the significant reduction in dynamic mechanical performance. To address this issue, a compound inspired by tea stains, tannic acid (TA), is used to treat the fine RCAs. The results suggest that the width of the interface transition zone (ITZ) between fine RCA and the new matrix is significantly reduced after this treatment, indicating the improvement in bonding properties. Dynamic compression tests are conducted to examine the impact resistance performance of cement mortar containing fine RCAs through employing the Split Hopkinson Pressure Bar (SHPB) apparatus. When subjected to impact loads, mortars with treated fine RCAs indicate higher dynamic compressive strength and enhanced completeness. The dynamic compressive strength and total energy absorption exhibit the exponential positive correlation with the strain rate. The strain rate effect is more pronounced when the strain rate is below 100 s−1. Importantly, mortars with treated fine RCAs manifest superior total energy absorption, enabling them to absorb and dissipate more impact energy. The mortar containing fine RCAs treated with 0.5%TA reveals excellent impact resistance performance, surpassing even that of the cement mortar with natural fine aggregates. Moreover, 0.5%TA group shows better economic benefits than the plain mortar, indicating that the TA treatment method has good application prospects.