Chemical grouting is used in soils of medium to coarse grading. Materials such as sodium silicate and calcium chloride are mixed together in liquid form and solidified into a gel. There are two main processes:
‘Two-shot’ process: Pipes are driven into the ground. One chemical is injected followed by another meaning that the reaction, and soil strengthening, is rapid.
‘One-shot’ process: This involves chemical mixing prior to injection, with the hardening being delayed by the composition. This allows for wider borehole spacing.
Chemical grouting has the advantages of allowing economical spacing of bore holes, greater penetration of the grout, and more flexibility in terms of the time of grouting.