RBR Conservation located in London, UK specialise in structural grouting, a technique used in reinforcing masonry by filling voids in masonry housing with non-shrink grout. It is used beneath metal bearing plates to ensure a consistent bearing surface between the plate and its substrate to stabilise the structure.
The requirement for this work is assessed through thermal image surveys. The procedure is carried out using a precise injection system which is set out through design locations on building elevations.
After the works are complete, the structural integrity of the wall is restored to its original strength and in addition, the majority of voids are filled, thereby excluding the presence of water being retained in the wall. During this procedure on a stone façade it is necessary to confirm that the original pointing is of lime-based material and is in good condition.
Masonry grouting is a process used to reintroduce structural integrity to solid single thickness walls comprising of natural stone facings such as limestone, granite or sandstone with a random rubble internal core or ashlar faced stone with out of bow internal edges. The original wall will generally have been constructed of a lime mortar to bind all of the elements together. Over period of time, particularly if a structure has moved and cracked water penetration can gradually leach fine particles from the lime mix reducing its bonding capacity and ability to support the wall or loads imposed upon it.
Grouts can be a slurry mixture of lime, sand and water or a more thixotropic design mixture specific to the characteristics of the structure under repair. These can be used alone or with Grout Ties to provide more tensile strength within the structure to withstand delamination of component parts of a wall.
Grouting requires a high degree of quality control to ensure that the objectives of void filling and consolidation are achieved without damaging the structure through excessive grout pressure. We can repair this type of wall utilizing a low pressure hand operated pump system with either lime or cement based grouts This method minimizes hydrostatic pressure within a wall and hence disruption to the building and its occupants whilst work is in progress.
Grouting must never be attempted when water is actually present in the structure.
Once a grouting regime has been successfully completed, it will prevent the barrelling effect voids have on a structure.