Grouting and freezing unconsolidated and water-bearing strata

The process of grouting has undergone many changes in recent years. A definition must, therefore, be inclusive. Grouting is the process of injecting, under pressure, into soil and rock through boreholes or other openings, any solution or suspension containing materials that harden, stiffen, or swell in void spaces to produce a solid or semi-solid impermeable mass. Various cements, chemicals, asphalts and clays are the materials used in the grouting process. The use of tailings is also considered a type of grouting, since some hardening or stiffening takes place. Cement grout relies on chemical reaction to bring about setting or hardening in place. Chemical grouting consists of injecting solutions of two or more soluble salts, and it depends on the chemical reaction between the solutions to produce an insoluble salt which is precipitated in the voids. Asphalts are solidified by cooling. Clays depend on swelling caused by absorption of water to produce an impermeable mass. The liquid in a grouting mixture serves as the transporting medium. The pressure exerted on the liquid forces grout into the voids. continued pressure holds the grout in place until it hardens or swells --Introduction, page 1