For grouting application, silicate solutions (usually diluted) are injected into the ground and reacted with materials (setting agents) that precipitate or gel the silicate (such as through pH modification). Liquid silicates function as rapid-setting additives for cement and cement-clay grouts when they are added in small quantities. The gel time depends on the amount and type of silicate - the more silicate added, the faster the set.
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 of silicates with divalent or multivalent ions. This necessitates a two-part application process. Organic setting agents, such as dibasic esters 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.
N® sodium silicate is most often used, but potassium silicate can be used in areas where sodium addition may be an issue.
Because of their unique chemistry, silicates can be applied in both high and low temperature conditions such as geothermal wells or near-freezing. Using these reactions in the oilfield, liquid silicates are also used to block or re-direct water inflow, again at high or low temperatures.