What is void grouting in concrete?

Void grouting is the process of injecting cementitious grout, resin, or polyurethane foam into voids beneath or within concrete structures. Voids can form from washout, settlement, poor compaction during original construction, or erosion over time. Left untreated, they cause uneven loading, cracking, and eventual structural failure. We typically use low-viscosity cementitious grout for large voids and expanding polyurethane foam for smaller, irregular cavities. The grout is injected through drilled ports at controlled pressure to fill the void without displacing the structure above. Void grouting is common beneath floor slabs, behind retaining walls, around piles, and under bridge abutments.