Jet grouting is a procedure for mixing in situ soil with injected cement grout in order to create a cement stabilized soil. With the proper quality control, the stabilized soil exhibits increased strength and decreased permeability. These modified properties allow that soil to be used as an engineered product for foundation support and groundwater control. Underpinning of existing structures and cutoff walls for excavation support are two typical applications. Jet grouting is particularly effective when the subsurface to be treated contains existing utilities or other buried obstructions.
The process involves the drilling or jetting of small diameter pipe (4”) to the desired depth of treatment. Once that depth is reached, a neat cement grout is injected under high pressure (6,000 psi) through ports at the bottom end of the drill pipe. The drill pipe is withdrawn at a controlled rate creating a circular column of treated soil. These columns are located as required for vertical support or overlapped to create a wall or barrier to the horizontal movement of weak soil and groundwater.
