For grouting applications, diluted silicate solutions are injected into the ground and reacted with materials (setting agents) that precipitate or gel the silicate. The gel time depends on the amount and type of silicate and setting agent.
There is a variety of inorganic and organic setting agents. Inorganic setting agents such as calcium chloride form strong bonds, but setting times are more difficult to control because of the very fast reaction time. This necessitates a two-part application process. Organic setting agents, such as dibasic esters or sodium aluminates have longer setting times with liquid silicates allowing more control. This means that the silicate and setting agent can be pre-mixed and pumped as one system. Sodium silicate with a weight ratio of 3.3 is most often used in this application.
Sodium silicates have a proven track record in both soft gel and hard gel grouts. Soft gels are used to redirect water inflow in construction area's with high groundwater levels while hard gels are applied for soil solidification.