Modified cement-sodium silicate material and grouting technology for repairing underground concrete structure cracks

The concrete cracks in an underground structure which usually result in serious water leakage are generally treated by grouting repair. However, the widely used cement-sodium silicate (C-S) grouting material for treatment has drawbacks. One is that the gelation time is so short that the grouted slurry will be likely to plug the grouting pipe; the other is that the C-S material has low corrosion resistance against water so the strength of the C-S material will decrease sharply after interaction with the underground water. By considering the disadvantages of the traditional C-S material, this study improves the C-S material with ultrafine fly ash (UFA) and Na2HPO4 and obtains its proper proportion by testing. In addition, a new grouting technology for concrete crack treatment is proposed for underground concrete structure. The modified C-S material and the repair technology have been successfully applied in a typical underground project suffering from serious water leakage, and it shows excellent repair effect. This study can provide theoretical and empirical reference for similar underground engineering.