Contribution of TiO2 and ZnO nanoparticles to the hydration of Portland cement and photocatalytic properties of High Performance Concrete

This paper aims to study the hydraulic and photocatalytic behavior of mixtures based on TiO2 and ZnO nanoparticles in cement pastes and High Performance Concretes (HPCs) for the self-cleaning application of building materials. The two nanoparticles were used to partially replace the cement of varying values from 0% to 3% by weight. Cement pastes were characterized by X-ray diffraction, X-Ray Fluorescence, Differential Scanning Calorimetry and Thermogravimetric analyzes to study their compatibility in the cement matrix. The addition of TiO2 in Portland cement resulted in better reactivity by the large presence of hydration products and the appearance of unreacted anatase titanium oxide which is responsible for the photocatalysis process. The cement pastes containing ZnO had clearly indicated the retarding effect of zinc in the hydration of Portland cement. The photocatalytic properties are determined by studying the efficiency of the degradation of nitrogen oxides (NOx) and by monitoring the discoloration of Rhodamine B under UV irradiation of HPC samples. The results showed that the introduction of titanium oxides in the HPCs exhibited a significant degradation efficiency compared to zinc oxide and the samples containing the later underwent greater discoloration of the red color coordinate (Rt).