Chemical grouting is used to achieve results that cement-based grouts cannot provide. Polymethylene and polyurethane grouts can be used when excavations of the soils are to be performed. The soil's tensile, flexural, shear, bonding, and compressive strengths will have been increased, so excavation can be performed with minimal movement. This can be obtained by chemical grouting in soils that can not be penetrated with cement-based grouts due to the high density of the soils or the type of soils encountered. Polyurethane grouts are also used to stop water infiltration.