玄武岩纤维混凝土抗冻性及损伤劣化模型研究

Research on frost resistance and damage degradation model of basalt fiber reinforced concrete

为了研究玄武岩纤维混凝土(BFRC)的抗冻性能,本文做了如下试验研究:制备了7组不同纤维长度、不同纤维体积掺量的BFRC,分别对其进行快速冻融试验,并以质量损失率、相对动弹性模量以及强度等性能指标为参数,分析探讨BFRC的抗冻损伤劣化规律。同时,通过压汞(MIP)试验,分析在不同冻融状态下BFRC孔隙结构的变化规律。试验结果表明,随着冻融次数的增加,BFRC的质量损失率先下降后上升,强度以及相对动弹性模量随冻融次数的增加而逐步下降;掺加BF能够减缓混凝土冻融破坏,提高抗冻性,其中,BF9-1.0抗冻性能最优;MIP测试结果显示,掺加BF对混凝土的孔隙分布有着明显的改善作用;以相对动弹性模量为损伤变量构建的指数函数和二次多项函数的损伤劣化模型相关系数R^(2)均在99%以上,可以准确预测BFRC冻融损伤的劣化程度。因此,掺加纤维长度为9mm、纤维体积掺量为1.0mg/m^(3)的BFRC抗冻性能最佳。

In order to study the frost resistance of Basalt Fiber Reinforced Concrete(BFRC),this paper conducted the following experimental research:seven groups of BFRC with different fiber lengths and fiber volume fractions were prepared.They were subjected to rapid freeze-thaw tests,and parameters such as mass loss rate,relative dynamic modulus of elasticity,and strength were used to analyze and explore the frost resistance degradation behavior of BFRC.Meanwhile,Mercury Intrusion Porosimetry(MIP)tests were carried out to analyze the changes in the pore structure of BFRC under different freeze-thaw conditions.The experimental results showed that with the increase of freeze-thaw cycles,the mass loss rate of BFRC first decreased and then increased,while the strength and relative dynamic modulus of elasticity gradually decreased.The addition of basalt fiber(BF)could slow down the freeze-thaw damage of concrete and improve its frost resistance.Among them,BF9-1.0 exhibited the best frost resistance performance.MIP test results revealed that the addition of BF significantly improved the pore distribution of concrete.Damage degradation models based on the exponential function and quadratic polynomial function with relative dynamic modulus of elasticity as the damage variable had correlation coefficients(R^(2))of over 99%,enabling accurate prediction of the extent of frost damage in BFRC.Therefore,BFRC with a fiber length of 9 mm and a fiber volume fraction of 1.0mg/m^(3) exhibited the best frost resistance performance.