Mechanical behavior of silicate-modified polyurethane/waterglass grout in fractured rock interface reinforcement at elevated temperatures

• Published in: Tunnelling and underground space technology Vol. 165; p. 106879
• Main Authors: Chao, Yuan, Qinhao, Huang, Junfeng, Liu, Shuchen, Li
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2025
• Subjects: High temperature resistant; Mechanical Performance Testing; New type of grouting material; Rock reinforcement; High temperature resistant; Mechanical Performance Testing; Rock reinforcement; New type of grouting material
• DOI: 10.1016/j.tust.2025.106879
• ISSN: 0886-7798

Grouting is an effective method for filling fractures and reinforcing rock masses. In deep underground engineering, grouting materials are subject to the adverse effects of high temperatures and large deformations during the curing stage, which can easily lead to the deterioration or even failure of the grouting material. Silicate-modified polyurethane/waterglass (PU/WG) is an organic-inorganic grouting material, in order to clarify the reinforcement effect of PU/WG grouting material on rock fractures in high-temperature conditions, we conducted a series of laboratory experiments on PU/WG materials and rock-grout interface samples cured at 20–80 °C for 7 days, including uniaxial compression tests, shear strength tests, and flexural strength tests. The results show that: (1) Although the mechanical properties of PU/WG materials remain stable within 20–80 °C, high-temperature curing accelerates the reaction and concentrates gas release, resulting in porous grout structures that reduce mechanical interlocking between the grout and rough rock surfaces, leading to adhesive failure; (2) Under normal temperature conditions, the peak strain of PU/WG materials exceeds 25 %, classifying them as a ductile material, and the peak strain can still reach 10 % under curing conditions at 80 °C; (3) The shear failure at the rock-grout interface manifests as a shear plane, followed by frictional sliding, and the PU/WG grouting body does not crumble, still maintains the transmission of normal stress. In summary, the stability of PU/WG materials in high-temperature environments and their adaptability to large deformations of rock masses give PU/WG grouting materials a significant advantage in the grouting reinforcement of fractures in deep underground rock masses.