Improvement in fire resistance of glulam beams containing modified laminae by thermal treatment, inorganic impregnation and compression in the fire-side tension zone

• Published in: Construction & building materials 2024-02, Vol.416, p.135138, Article 135138
• Main Authors: Li, Xiang, Yue, Kong, Tang, Zhongqiu, Lv, Chenglong, Li, Quan, Wu, Peng, Zhang, Zhongfeng
• Format: Article
• Language: English
• Subjects: Chinese fir; Compression; Inorganic impregnation; Mechanical properties, Fire resistance; Thermal treatment
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2024.135138

Fast-growing wood species are unsuitable for direct use in load-bearing structures due to their loose fiber structure, low mechanical strength, and inadequate combustion performance. Traditional impregnation using low-molecular-weight resin may enhance certain characteristics but also poses environmental pollution risks. This study explores an alternative approach: subjecting Chinese fir lumbers to thermal treatment, impregnation with an inorganic solution, compression, and utilization as exposed side laminas for glulam beams. The fire performance of full-scale beams was evaluated under three-side fire exposure conditions. Results revealed that addressing the mechanical deficiencies of thermally treated wood could be achieved through 2.0 mol/L inorganic solution impregnation combined with a 20% compression ratio. The modifier weight percent gains in specimens after thermal treatment increased by 24.8% under identical conditions. Composite modification notably enhanced both mechanical and combustion properties, manifesting promising flame-retardant effects. Building upon these findings, fire-resistant laminas were created and applied to the tensile zone of the glulam beam to investigate residual bearing capacity post three-side fire exposure. After 60 min, the modified laminas-containing beam in the fire-exposed tension zone showed a 31.4% increase in residual bearing capacity over the untreated beam. This study underscores that the combined modification methods are not only cost-effective and environmentally friendly but also establish a vital theoretical foundation for safeguarding the structural safety of rapidly cultivated fast-growing wood in fire scenarios. •A modification method to improve wood's mechanical and combustion performance.•Containing modified laminas on fire-side of glulam beams reduces charring rate.•An exact formula for calculating glulam beams’ residual bearing capacity post-fire.