Prime Resins Soil Conditioning

General Information

Fundamental to healthy concrete is a solid substrate. Well-compacted soils provide a foundation upon which concrete structures perform. Over time, forces of nature take their toll. Decomposing soils, erosion, freeze-thaw cycles and groundwater migration can break down this foundation. This is the root cause for the damage or failure of many structures, from buildings to highways.

Injecting polyurethane resins and gels into loose or less dense soils, voids, pores and fissures will strengthen the earthen substrate and provide watertight encapsulation. Prime Resins has been providing soil stabilization solutions for more than 20 years with their Prime Flex polyurethane foams and gels. The techniques and products used depend on what you are trying to accomplish, the type of substrate you are working with and what type of equipment you have available.

Soil stabilization solutions generally fall into three areas: permeation grouting, compaction grouting and void filling.

Permeation Grouting

Permeation grouting is typically defined as the flow of a low viscosity grout into the pores of the soil without displacing or changing the soil structure. The characteristics of the ground are modified with the activation of the grout into a foam or gel. This serves two purposes:
• to increase the strength and cohesion of granular soils, increasing its load-bearing capacity
• to decrease the permeability of the soil

Migration of water through poor or loose soil substrates (sandy soils, poorly compacted fill, decaying organic matter, etc.) results in erosion, movement and/or loss of soils causing failure in above- and below-grade structures such as slabs, foundations, roadways and bridges. Permeation grouting is usually the solution for these situations. A low dose of catalyst is used slowing down the reaction, which allows the material to permeate loosely compacted soil. The resin is normally injected through small diameter pipes or “probes.”

Compaction Grouting

Compaction grouting is a process by which rapidly expanding chemical grout (fully expanded in 30-60 seconds) is injected through probes into the ground. (One such process is currently under patent: US6634831 B2.) The foam fills voids in the immediate area, fractures the soil with lenses and veins of resins, and compacts the surrounding soil using expansive pressure. Where soil has eroded or settled underneath concrete, resulting in uneven or unstable slabs, is often a situation that calls for compaction grouting in advance of slab lifting.

Void Filling

Erosion, settling soils and decaying material can result in voids around or underneath structures, undermining their integrity and potentially leading to damaged structures. Voids can be quickly and cost-effectively filled with our Prime Flex 985 series of products. These structural foam resins are injected using a two-component pump. The Prime Flex 985 will flow into the voids and cavities and fill them by expanding up to 20 times (depending on formulation). The rigid foam re-establishes contact between the slab and the sub-grade and is strong enough for heavy traffic loads within 15 minutes.

In highway projects, roadways can often remain open to traffic.