Effect of organosilicon modified epoxy resin on slurry viscosity and mechanical properties of polyurethane grouting materials

Polyurethane (PU) grouting reinforcement materials are widely used in the construction and maintenance of civil engineering works such as coal mine, high-speed railways, subways and tunnels. The initial viscosity, allowable operation time and the mechanical strength of the grouting material are important factors affecting its application and how to strike a balance between these three factors is a key challenge in this field. In this study, a new strategy was proposed to overcome these problems. The use of alkoxy silane groups attached to the main chain of epoxy resin can reduce the entanglement between molecular chains and thus increase the flexibility of polyurethane molecular chain. A series of organosilicon modified epoxy (ME) resins were synthesized by modifying bisphenol A epoxy resin E51 with silane coupling agent KH550. The viscosity, mechanical properties and thermal stability organosilicon epoxy modified polyurethane (MEPU) were studied by adjusting the amount of ME. The apparent viscosity and shear strain viscosity of organosilicon epoxy modified polyurethane (MEPU) were investigated by means of a rotational viscometer and a rotational rheometer. The effect of ME on the mechanical properties of MEPU was systematically studied through the mechanical properties test (compression test, tensile test and impact test). The surface properties and microstructure of MEPU were investigated by water contact angle testing and scanning electron microscopy. The resulting MEPU exhibits low slurry viscosity and high compressive strength. Slurry viscosity tends to decrease as the proportion of ME increases. Compared to the unmodified polyurethane grouting slurry, MEPU-15 shows a significant reduction in slurry viscosity and maximum curing temperature for 48.7% and 8 ℃ respectively, and the consolidation fracture toughness increases 28.7%. At the same time, the addition of ME changes the polyurethane grouting material from hydrophilic to hydrophobic. In this work, polyurethane grouting materials with low slurry viscosity, high mechanical strength and low exothermic reaction have been successfully synthesized. It is possible for polyurethane grouting material to be applied more widely.