Effect of mesoporous silica nanoparticles on cement hydration and early-age performance

One of the most important advances in recent years has been the creation of mesoporous silica nanoparticles (MSNs) and their use in composites. MSNs have a high specific surface area, and due to their hydrophilicity, they can easily disperse in water. In this study, the effects of four well-known MSNs, including MCM-41, MCM-48, SBA-15, and SBA-16, on the cement hydration were investigated. Various amounts of MSNs, ranging from 0.2 % to 1.2 %, were substituted by cement, and isothermal calorimetry, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and ultrasonic pulse velocity (UPV) tests were conducted to study the hydration process and the performance of these materials. Mercury intrusion porosimetry (MIP) tests, along with compressive and flexural strength tests, were performed on cement mortar at various ages up to 28 days. The results show that MSNs improve the structure of the cement paste, increase strength, reduce pores, and create a denser structure in both the cement paste and mortar. An increase in compressive strength of up to 50 % at 1 day compared to the control sample was reported. Additionally, the performance of these materials confirms their pozzolanic and nucleation effects in cement paste. The findings indicate that these materials start showing beneficial effects at an early age and can significantly improve the properties of concrete at 1 day. Furthermore, this study includes a comparison between these nanomaterials, and the optimal consumption amount for each has been determined. It can be concluded that the optimal values for these materials lie between 0.2 % and 0.6 % substitution.