Abstract：In order to investigate the microscopic and macroscopic mechanical properties of nano-SiO2 concrete under the dissolution condition, the 2M NH4Cl solution was used to accelerate the corrosion test, the evolution of pore characteristics, microscopic appearance and microstructure of nano-SiO2 concrete was analyzed by means of nuclear magnetic resonance(NMR)technique, field emission scanning electron microscopy and energy spectrum analysis. Meanwhile, the influence of pore structure parameters and pore radius distribution on the corrosion damage of the different dissolution ages and nano-SiO2 dosage was studied by using grey correlation entropy analysis. Based on this, the relationship model between concrete pore characteristics and corrosion resistance was established. In the test, the water to binder ratio was 0.29 and the replacement ratios of nano-SiO2 were 0, 1%, 3% and 6%, respectively. The results show that the incorporation of nano-SiO2 significantly improves the compressive strength of concrete, <100 nm pore size ratio has the greatest influence on concrete corrosion resis-tance, the grey entropy correlation degree is greater than 0.999. Compared with the reference group, the nano-SiO2 concrete is formed by the outwardly radiated fibrous C-S-H after dissolution, filling the cracks caused by the dissolution, which improves the corrosion resistance and delays the deterioration of the concrete. A grey model GM(1, 4)is established for the influence of pore radius of <100 nm, 100-1000 nm and porosity on the corrosion resistance of concrete. The average absolute errors between predicted values and experimental values of four concrete GM(1,4)models are 8.18%,7.03%,7.83% and 7.90%, respectively. This study provides a theoretical basis for practical engineering applications of nano-SiO2 concrete.
