Polyurethane grouting is a grouting technique that involves the injection of expanding polyurethane to cutoff water flow through concrete joints or cracks or to fill voids beneath slabs or behind subsurface concrete walls or to relevel slabs. The grout is injected under low pressure through a predrilled hole. The grout then expands to fill the crack or void. Many polyurethane grout products are available with variations in viscosity, reaction time, reaction with water, expansion characteristic and flexibility of the reacted grout. Polyurethane grouts can be single or multi-component grouts and can react when coming in contact with water or require a reactant. It is important to select the proper grout for the specific application. The process fills voids either for water cutoff or structural support. The technique has been used to fill voids beneath slabs, relevel slabs, fill voids behind subsurface walls and seal leaking cracks and joints in subsurface structures such as manholes or tunnels.
HB PolyLift® Polyurethane Injection is a releveling technique that raises concrete slabs and fills voids, using the regulated injection of lightweight, non-hazardous expanding polyurethane grout. When ground improvement is needed along with releveling, compaction grouting is performed for ground improvement and then polyurethane grout is injected to fill remaining voids and complete the lifting to final grade. Deeper loose zones are first densified with compaction grouting. Holes are then drilled through the concrete slab through which polyurethane foam is injected while monitoring the slab level from the surface. After re-leveling, the drill holes are cleaned and filled with cement grout. The treatment results in a densified subgrade, filled voids and a re-leveled and stabilized concrete slab.
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