Influence of raw material temperature on the properties of silicate-modified polyurethane grouting materials

Silicate-modified polyurethane (PU/WG) is an effective organic–inorganic hybrid-grouting material that blocks water and reinforces weak formations. In deep high-temperature formations, owing to environmental impacts, PU/WG raw materials are heated before grouting. To elucidate the basic characteristics of PU/WG grouting materials in deep, high-temperature environments, we investigated the effects of raw material temperature on the curing time and strength of PU/WG by considering different mass ratios during the curing time test. Furthermore, the influence of raw material temperature on the micro-structure of PU/WG was analysed from a microscopic perspective using scanning electron microscopy. Energy-dispersive X-ray spectroscopy revealed the composition and curing mechanism of PU/WG. The results indicated that as the raw material temperature increased from 24 to 60°C, the peak strength decreased from 41.65 to 14.51 MPa, and the peak strain decreased from 27.03 % to 8.83 %. Based on the experimental results of the curing time testing and strength test, we established a PU/WG curing time-variation model considering the coupling of raw material temperature and mass ratio and provided an optimisation scheme for the PU/WG strength, which provides effective guidance for grouting time design in high-temperature environments.