Surface modification of recycled tire rubber powders with Tannic acid and Nano-TiO2 for enhanced performance and photocatalytic properties of Rubberized Cement-Based materials

Abstract

The utilization of recycled rubber powder in civil engineering is currently insufficient, leading a significant hurdle to the environmentally friendly disposal of waste tires. To mitigate the adverse effects of rubber powder (R) in cement-based materials and enhance their application in road materials, this study aims to explore a novel modification approach. Tannic acid (TA) and TiO2 (<100 nm, SBET = 43.22 m2/g) were used to modify the surface of R through a simple adhesion self-assembly reaction, resulting in the formation of R-TA-TiO2 composites. A series of characterization tests, such as WCA, AI, FTIR, XRD, SEM, EDS, BET, XPS and UV–Vis-DRS, indicated that the hydrophilicity and chemical activity of the modified R-TA-TiO2 were significantly improved, and its surface possessed numerous cross-linking and stable sites for photocatalytic activity. Leaching and photocatalytic experiments confirmed the excellent heavy metal ion immobilization ability and photocatalytic performance of R-TA-TiO2. The results of basic mechanical tests and microscopic characterization of cement mortar revealed that the modified rubber enhanced the bonding ability between modified rubber and cement mortar, mitigated the negative effects in cement mortar, and exhibited pro-cement hydration ability. The flexural and compressive strengths of the modified rubber-cement mortar were considerably increased compared to those of the untreated rubber-cement mortar. Moreover, the modified rubber-cement mortar demonstrated excellent photocatalytic properties, and cyclic adsorption experiments verified its photodegradation stability and repeated properties. Microscopic characterization further showed that the modified rubber-cement mortar maintained its internal stable structure during photodegradation, indicating its potential for use in green road materials.