Chloride absorption capacity of calcium silicate hydrate (C-S-H) and its effect on steel corrosion in simulated concrete pore solution

The effect of calcium silicate hydrate (C-S-H) on chloride (Cl-) binding and steel corrosion in simulated concrete pore solution (SCPS) was evaluated. The results showed that Cl- absorbed by C-S-H conformed to Freundlich isotherm for 0.1-1.0 M of Cl-. When C-S-H reached equilibrium in saturated Ca(OH)(2) solution, its degree of polymerization increased. The high pH is unfavorable for the absorption of Cl- by C-S-H, but favorable for the passivation of steel. The synthetic C-S-H powder contains NO3-, which prolongs the passivation time of steel, but the presence of silicate is favorable for the formation of a passivation film with good corrosion resistance. The addition of C-S-H promoted the chloride threshold value of steel corrosion and delayed the corrosion development process.