#FoundationFactFriday: What is polyurethane foam injection?
Foundation Fact: Polyurethane Foam weighs three and one half to five pounds pound per cubic foot and reaches 90 percent of full compression strength after 15 minutes.
Polyurethane foam injection is a slab jacking procedure that is uses much lighter material compared to traditional cement grout that weighs a whopping 140 pounds per cubic foot. The lighter material allows for a greater chance of long term success. In addition, there is a much shorter cure time with polyurethane foam injection compared to mudjacking with cement that can take up to 28 days to reach its final cure. Moreover, there is no worry for load bearing capacity with polyurethane foam because the material reaches 90% of its full compression strength after just 15 minutes. Load bearing traffic can happen near immediately due to the immense strength of the material with its ability to hold up to 14,000 pounds per square foot. Apart from the strength and cure time of the material, the polyurethane foam injection process leaves little to no mess by drilling holes only a 3/8” hole compared to mudjacking injection holes that range from one to two and a half inches.
Polyurethane foam injection is an application used for cracked, sinking and settling concrete slabs. The development and presence of cracks within concrete should be expected. Therefore, it is important to determine if the cracks found within concrete are simply shrinkage cracks that are to be expected or something that warrants repair. The magnitude or width of cracks and the presence of vertical displacement along the cracks are often two of the determining factors. Vertical displacement along the cracks is often present when settlement of the slab has occurred. A slab settling (or slab sinking) can be a result of many factors, but it is generally caused by movement within the soils that it rests upon. The movement within the underlying soils can be a result of factors, such as periods of drought conditions, periods of heavy rainfall, consolidation of backfilled soils that had been poorly compacted, decomposition or decay of materials within the soils, drainage issues, a lingering plumbing leak, erosion and/or simply the presence of poor native soils.