Carbonation Resistance of Hybrid NanoSiO_(2) Modified Cementitious Surface Protection Materials

Hybrid nanoSiO_(2) (HNS) modified cement pastes were explored as a kind of surface protection material (SPM).The carbonation resistance and mechanical properties of SPMs coated samples were tested.Thermogravimetric analysis (TGA),X-ray diffraction (XRD),scanning electron microscope (SEM),and mercury intrusion porosimetry (MIP) were further employed to evaluate the chemical composition and microstructure characteristics of SPM.Besides,thermodynamic modeling was adopted to simulate the changes in the phase assemblages of SPM under the carbonation process.The results showed that SPM with 1 wt% HNS could effectively enhance the carbonation resistance.The incorporation of HNS could densify the microstructure and refine the pore structure.Moreover,the thaumasite can be stable at ambient temperature with the addition of HNS,which is beneficial to maintain alkalinity under the carbonation process.