Exposure of cement-based structures to sulfuric acid environments can cause significant degradation. Therefore, this study focuses on the effect of nano-SiO 2 on the sulfuric acid resistance of ordinary Portland cement (OPC)-sulfoaluminate cement (SAC) composites (as repair material). Samples were exposed to three concentrations of acid solution. The degradation kinetics, chemistry, and microstructures of the composites were analyzed. The results of degradation kinetics (dimensional change, mass and strength loss) showed that the nano-SiO 2 modified composites had a lower degradation rate compared to the composites without nano-SiO 2 . XRD, TG, MIP and SEM analyses demonstrate that nano-SiO 2 promoted hydration and improved structural compactness, which can not only enhance the diffusion resistance of composites to H + and SO 4 2- , but also form a protective barrier in acid environments. However, diffusion–dissolution-precipitation is still the main mode of degradation in composites subjected to sulfuric acid attack, regardless of nano-SiO 2 content mixed into the composite system.
Xing Cao,Weichen Yang,Shiwei Liu,Lin Fang,Runjie Liu,Rui Ma
To evaluate the feasibility and safety of municipal solid waste incineration fly ash (MSWIFA)-based geopolymer, its durability against water, 3% Na 2 SO 4 , 1% H 2 SO 4 and 3% H 2 SO 4 for 112 days was investigated. Results showed that H 2 SO 4 resistance of MSWIFA-based geopolymers was weaker than that of Na 2 SO 4 and deteriorated with increasing MSWIFA incorporation and H 2 SO 4 concentration. Under H 2 SO 4 erosion, CaCO 3 or C-A-S-H gels formed CaSO 4 ·2H 2 O, and this decalcification process caused cracks formation. Dealumination disrupted the electrostatic interaction of [AlO 4 ] - and Al-O coordination, reducing the solidification efficiency of Zn and Pb significantly. Conversely, Cu and Cr with Si-O coordination exhibited greater than 70% solidification efficiency.
危险品化学品经营许可证（带存储）