Synthesis and characterization of SiO_2-TiO_2 nanoparticles and their effect on the strength of self-cleaning cement composites

摘要

SiO2-TiO2 mixed oxides have been used in this research to improve compressive strength and selfcleaning characteristics of cement. SiO2-TiO2 samples have been synthetized by the heterocoagulation method and characterized by a series of techniques, such as infrared spectra with Fourier transform, X-ray diffraction and thermogravimetric/derivative thermo-gravimetric analyses. Photocatalytic characteristics of the prepared specimens have been evaluated in methylene blue aqueous solution under ultraviolet ray irradiation. It has been found that the structural-adsorption, surface properties, and the photocatalytic activity of the SiO2-TiO2 depend on the final stage calcination temperature. The experimental results have shown that the material which was heated to 800 degrees C exhibited a high-specific surface area (307.1 m(2).g(-1)) and highest photocatalytic activity. The physico-mechanical characteristics of the specimens were tested using a compressive strength study, thermogravimetric/differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM) to investigate characteristics of cement pastes containing SiO2-TiO2 and without them. It has been determined that the use of SiO2-TiO2 having a specific surface area of more than 300 m(2).g(-1) allows reducing the amount of additive in the production of cement paste with improved technical characteristics. Results achieved have shown the optimum amount of SiO2-TiO2 in the cement paste composition to be 0.1-0.5%. Besides, the discoloration test has been used to estimate the photocatalytic activity on the treated cement surface. (C) 2021 Elsevier Ltd. All rights reserved.