The present invention provides processes for infrastructure repairs and geo-stabilization with a low-exotherm polyurethane foam, grout or elastomer. The inventive process involves at least partially filling a cavity in the infrastructure or earth with a low-exotherm polyurethane foam, grout or elastomer made from at least one polyisocyanate, at least one isocyanate-reactive compound and an organic particulate material capable of absorbing heat, optionally in the presence of one or more chosen from water, surfactants, pigments, catalysts, alkali silicates and fillers and curing the polyurethane foam, grout or elastomer. The inventive processes may improve the repair of buildings, foundations, roads, bridges, highways, sidewalks, tunnels, manholes, sewers, sewage treatment systems, water treatment systems, reservoirs, canals, irrigation ditches, etc.; and in the geo-stabilization of mines, caves, wells, bore-holes, ditches, trenches, pits, cracks, fissures, craters, postholes, potholes, sinkholes, wallows, waterholes and the like. The inventive solid polyurethane compositions are made from at least one polyisocyanate, at least one isocyanate-reactive compound, and an organic particulate material capable of absorbing heat, optionally one or more chosen from water, surfactants, pigments, catalysts and fillers. Such solid polyurethane compositions may improve reaction injection molding (RIM), spray elastomer and cast molding processes.