In this study, waste tire rubber powder (R) was subjected to modification using tannic acid (TA) and ZnO to produce R-TA-ZnO composites, aiming to enhance the immobilization of heavy metal ions and improve the photocatalytic properties of rubberized cement-based materials. The characterization of R-TA-ZnO was conducted using a comprehensive range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible-diffuse reflectance spectroscopy (UV-Vis-DRS), and other relevant methods. The findings of the study revealed that R-TA-ZnO exhibited notable hydrophilicity, surface activity, and photocatalytic properties, resulting in effective containment of the leaching of heavy metal ions. FTIR and XRD analyses confirmed the retardation of R and R-TAZnO. Nevertheless, the strength of the rubberized cement mortar with 5% R-TA-ZnO exceeds that of the rubberized cement mortar with 5% R (28 days) due to the interfacial bonding. The SEM and X-ray Computed Tomography (XCT) results of the rubberized cement mortar indicated that R-TAZnO exhibited strong binding to the cement paste, reducing both the number and size of pores. However, a high concentration of R-TA-ZnO led to the formation of larger pores, which did not contribute to the reduction of porosity. Furthermore, the rubberized mortar incorporating R-TAZnO displayed remarkable photocatalytic capabilities. The results of the 5-cycle degradation experiments and microscopic characterization confirmed its exceptional structural stability and reusability.
