Prime Resins has been stabilizing soil for over 20 years with our Prime Flex polyurethane foams and gels. The techniques used are dependent on what you are trying to accomplish and what type of equipment you have available. There are basically two methods for stabilizing soil – Permeation Grouting and Compaction Grouting.
Permeation grouting is a method where liquid resin is injected into the ground so that the resin permeates the soil before reacting. Once reacted, the soil and resin form a strong, solid, impermeable mass in the ground that increases the load bearing capacity of the soil.
Prime Flex 910 is a rigid hydrophobic foam that can be used for this application. 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” driven into the weak or unstable soil to a specific depth. A small single component electric pump such as our Impact 540 is ideal for pumping the resin into the probes. The probes are raised at specific intervals as the resin is injected to form columns of stabilized soil.
Hydro Gel SX is a polyurethane gel that can be mixed with up to 15 parts water and injected using our M2 air operated pump. Hydro Gel SX forms a flexible gel that bonds sand and soil together to form an impermeable mass. Due to the high water to resin ratio Hydro Gel SX is very economical and can be used as a grout curtain for containment of hazardous below grade contaminates or for cutting off ground water movement.
Compaction grouting is a method where fast setting polyurethane foam is injected into loose soil. The foam expands rapidly forming balls or columns of dense structural foam. The expansion compacts the surrounding soils and increases the load bearing capacity.
Our Precision Lift foams can be injected into soil using specialized equipment that heats the resin and speeds up the reaction. The expansive forces of the foam combined with the injection pressure from the pump compact the soil and fill voids in the area immediately adjacent to the foam.
Prime Flex 920 with a full dose of catalyst can also be used to compact soil. In this case the reaction time is accelerated so that loose soil adjacent to the probe are forced outward as the resin expands.
Compaction and Permeation Grouting at the Same Time
Injecting any of our foams can actually both permeate and compact soil at the same time. Depending on the reaction time of the material (controlled by formulation, amount of catalyst, and temperature settings of equipment), the foam will permeate the soil as it is expanding. Once the outer layers of the foam begin to solidify, the permeation process ends and the compaction process begins. Injection pressures from the pump and expansive pressure from the continuously injected resin force the outer material tight against the surrounding soil causing it to compact. This all happens in minutes and allows treated areas to be returned to service immediately.