模拟混凝土碱性环境下FRP筋的耐久性

Durability of FRP Rebars in Alkaline Environment of Concrete

通过碱溶液模拟混凝土内部孔隙水的碱性环境,研究了碱性环境对玻璃纤维增强塑料筋(GFRP筋)和玄武岩纤维增强塑料筋(BFRP筋)的拉伸强度、拉伸弹性模量以及剪切强度、破坏形态等的影响。结果表明:碱溶液作用降低了GFRP筋的拉伸强度和剪切强度,降低程度与时间有关;GFRP筋在碱溶液中发生了后固化反应,GFRP筋的力学性能变化是碱溶液作用和后期固化程度综合影响的结果。碱溶液作用降低了BFRP筋的拉伸强度、拉伸弹性模量和剪切强度,随着碱溶液作用时间的增加,拉伸强度与拉伸弹性模量降低程度有增加的趋势。玻璃纤维和玄武岩纤维中的Si-O键在水分子和碱溶液OH-作用下断裂,树脂基体中的酯键在碱溶液中水解以及纤维和树脂之间的粘结界面性能的退化是GFRP筋和BFRP筋力学性能退化的主要原因。BFRP筋的耐碱性比GFRP筋差,文章给出了机理分析并对提高FRP筋的耐碱性提出了相关建议。

The durability of glass fiber reinforced polymer （GFRP） rebar and basalt fiber reinforced polymer （BFRP） rebar in alkali solution is studied. The test results show that the tensile strength and shear strength of GFRP bars decrease in alkali solution, and the changing degree is related to the treated time. GFRP bars continue to cure when being suffered from alkaline solution. The mechanical performance change of GFRP bars is from the role of alkali solution and the degree of post-curing. Alkali solution reduces the tensile strength, tensile modulus of elasticity and shear strength of BFRP bars, and the changing degree of the tensile strength and elasticity modulus increase with the increase of the treated time. Si-O bonds in the glass fibers and basalt fibers rupture under the role of water molecules and OH - , the hydrolysis of ester bonds in resin matrix in alkaline solution and the performance degradation of the bonding interface between fiber and resin are main reasons for the performance degradation of GFRP bars and BFRP bars. The alkali resistance of GFRP bars is better than that of BFRP bars. The possible mechanisms are revealed and the relevant recommendations to improve the alkali resistance of FRP bars are presented in the paper.