Compaction Grouting (Compaction Grout Columns)
Compaction grouting, also known as low mobility grouting, is a ground improvement technique that reinforces unsuitable soils in-place and is used to remediate sinking structures or to underpin existing foundations. Compaction grouting can be performed with only 6 feet of overhead space. The process of compaction grouting involves advancing small-diameter temporary steel casing to a predetermined design depth and then pumping a stiff (low mobility, low slump) grout in controlled lifts at high pressure as the casing is gradually withdrawn. This process displaces and compacts the surrounding soil and builds high-stiffness compaction grout columns. The stiff columns, combined with the improved surrounding soils, act together to support the structure. The grouting material is mixed on-site with a mobile mixer and is injected in a controlled manner to predetermined volume, pressure or movement criteria. In some instances, compaction grout columns can be used to jack up existing structures that have undergone settlement.
