Cement and chemical grouts are used in a wide variety of construction projects ranging from new construction to rehabilitation. For example, Portland and ultrafine cement grouts are predominantly used to stabilize soil and/or control water in civil projects including earthen dams, levees, mines, tunnels, subways, vertical shafts, below-ground structures or waste encapsulation. These types of large-scale projects will often require significant volumes of grout to be injected. Chemical grouts will often complement the cement type grouts and in some cases will be the predominant grout used for a particular situation.
On many civil projects where grouting is expected to occur, the engineer of record or grouting consultant will have prepared a grouting program defining which type of grout is planned. In some cases, however, the need for water control or soil stabilization is not anticipated and a grouting program is developed quickly. The type of grout material used for injection for an immediate need generally runs through a trial-and-error process. Because of the economic advantage, Portland cement grout will often be the first attempted. If geologic conditions won’t accept the Portland cement grout, then an ultrafine cement grout will be utilized. If Portland or ultrafine cements are successful, an acrylic resin like acrylamide will often not be employed.
Grouts are also used extensively in the rehabilitation of deteriorating sanitary sewer infrastructures, concrete dams or below-grade structures. Generally for these types of projects, acrylic gels and polyurethane foams are used. Both are used to seal leaking cracks and joints. However acrylamide gel is predominantly used in the pipeline system whereas the polyurethane foams are used in and around manholes and vaults. Where voids have occurred behind below grade structures, the highly expansive polyurethane hydrophobic foams are commonly used to fill the void. Some specially designed polyurethane foam is also used for the lifting of concrete slabs, which provides structural support by using a lightweight solution that won’t promote additional slab settlement. Cured structural foam weighs approximately 4 lbs pounds per cubic foot compared to much heavier mudjacking material.
When faced with the need to stop leaks, stabilize soil, or control water, it is recommended that a qualified grout consultant and grout injection contractor be engaged to provide installation recommendations and a knowledgeable grout supplier should be consulted to assist with proper grout selection.