MENG Qingkun ¹, JIA Shuaide ¹, KANG Dawei ¹, NI Ya ², KANG Zhuangsu ², SUI Yanwei ¹, WEI Fuxiang ¹, XIAO Bin ¹, MIN Liang ², ZHANG Taike ³, QI Jiqiu ¹
(1. School of Materials Science and Physics, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China; 2. Jiangsu CUMT Dazheng Surface Engineering Technology Co., Ltd., Xuzhou 221000, Jiangsu, China, 3. Guangdong Bay Area Communications Construction and Investment Co., Ltd., Guangzhou 511462, Guangdong, China)

Abstract: In order to meet the fire protection requirements of bridge cables, SiO2 aerogel composites were prepared using basalt fiber, basalt-high silica fiber composite and high silica fiber as the matrix. The temperature response characteristics of the cable model under the protection of the composites in hydrocarbon fire were explored. Furthermore, the evolution of the microscopic morphology, phase composition, mechanical properties and thermal conductivity of the composites before and after the fire test was studied. The aerogel was evenly filled within the fiber skeleton in the as-prepared composites, and the fiber was well combined with the aerogel. Basalt fibers crystallized and softened in high-temperature flames, resulting in the collapse of the fiber skeleton and the fragmentation of aerogels, and the porous structure of the aerogel lacking fiber support collapsed and particles grew at high temperatures. As a result, the mechanical and thermal insulation properties of basalt fiber-reinforced composite deteriorated significantly after exposure to high-temperature flames. A synergistic thermal insulation effect was achieved between the fiber and aerogel in the high-silica fiber/aerogel composite. The aerogel can protect the fiber from crystallization, and the integrity of the fiber skeleton can reduce the thermal radiation of the SiO₂ aerogel, so that the pores and particle size of the aerogel can remain stable in the high-temperature flame. The tensile strength and thermal conductivity before and after combustion are 0.736 MPa and 0.0205 W·m⁻¹·K⁻¹, 0.560 MPa and 0.0229 W·m⁻¹·K⁻¹, respectively. The 10 mm thick high silica fiber/aerogel composite was used to protect the cable model, and after burning in a hydrocarbon fire at 1100 ℃ for 120 min, the surface of the cable model was only 259 ℃. The high-silica fiber/aerogel composite exhibits excellent fire resistance and thermal insulation properties, making it promising for application in the field of bridge fire protection.
Key words: bridge fire protection; aerogel composites; fiber; hydrocarbon fire; thermal insulation performance