CJGeo’s Permeation Grouting Experience
We have treated thousands of cubic yards of soil with permeation grouting. These projects range from stabilization of uncontrolled fill under foundations to water intrusion repair in tunnels. We use chemical grouts from multiple manufacturers for permeation grouting, allowing us to choose the right material to suite the job.
How Permeation Grouting Works
In permeation grouting, chemical grout is injected into soils in place, and reacts with native or introduced water to cure into a solidified mass. A catalyst may be added to speed the reaction time. Depending on the chemical grout being used, it may expand as part of the reaction process. Non-cohesive soils are the best candidates for permeating grouting. Layers of uncontrolled sandy fills commonly found under slab floors and slab foundations that are raised above finished grade are generally excellent candidates for permeation grouting. Generally, permeation grouting is done on a grid pattern in conjunction with a shallow foundation repair method such as foam jacking. This is a low-disruption alternative to deep foundation installation below slab floors.
Advantages of Permeation Grouting
Permeation grouting is an excellent alternative to deep foundation repairs in the case of unconsolidated granular soils below concrete slabs and foundations. Chemical grouting soil stabilization is generally paired with a shallow foundation repair such as polyurethane grouting in the case of settlement. Compared to deep foundation repairs, chemical grout soil stabilization is:
Permeation grouting is performed with compact, electrically-powered equipment. Dustless drilling is easily accomplished for interior applications, and mechanical connections in all components of the injection equipment ensure no loose material.
Compared to underpinning, permeation grouting is phenomenally less disruptive. Typical deep foundation repairs require 8″ diameter holes drilled through floors, and large access pits dug next to foundations. Deep soil stabilization only requires 1 5/8″ access holes drilled through floors and 3/8″ diameter injection pipes driven into the soil to be treated.
Permeation grouting is generally faster than underpinning repairs or other deep grout injection processes due to its compact equipment and ease of installation. Because of its compact equipment, fast reaction times and minimal surface disruption, work can easily be scheduled and planned to accommodate an area’s or structure’s normal use.
Permeation Grouting Materials
The material used for permeation grouting is generally driven by the soil characteristics and desired repair. Viscosity, expansion factor and reaction profile generally distinguish different types of chemical grouts used for permeation grouting. For example, addressing water flows generally requires a faster reaction. Denser soils usually require lower viscosity chemical grouts for permeation grouting than looser soils. Desired compressive strengths of treated soils and density of the soil or presence of large voids drive choice of the expansion factor.