玄武岩纤维改善再生混凝土抗氯离子渗透性能研究

为研究玄武岩纤维对再生混凝土抗氯离子渗透性能的影响,本文对4种玄武岩纤维体积掺量(0%、0.2%、0.4%、0.6%)下5个粗骨料质量替代率(20%、40%、50%、60%、80%)的再生混凝土及1组普通混凝土进行了电通量试验,并利用傅里叶变换红外光谱(FTIR)和压汞法(MIP)从水泥水化和孔结构的角度探究了玄武岩纤维对再生混凝土抗氯离子渗透性能影响的微观机理。结果表明,玄武岩纤维显著提高了再生混凝土抗氯离子渗透性能,其中玄武岩纤维掺量为0.2%,粗骨料质量替代率为50%时改善效果最好且优于普通混凝土。基于FTIR发现玄武岩纤维是通过改变再生混凝土水化产物C-S-H的聚合度和CaCO₃的生成而改善其抗氯离子渗透性能。通过MIP得出最优组合掺量下,再生混凝土的孔径分布得到优化,孔隙率最小,进而提高了其抗氯离子渗透性能。

Improving Chloride Ion Penetration Resistance of Recycled Concrete by Basalt Fiber

In order to study the effect of basalt fiber on the chloride ion penetration resistance of recycled concrete, the electric flux test of recycled concrete with five coarse aggregate mass replacement rates (20%, 40%, 50%, 60%, 80%) under the volume content of four kinds of basalt fibers (0%, 0.2%, 0.4%, 0.6%), and ordinary concrete were carried out. The microscopic mechanism of the effect of basalt fiber on the chloride ion penetration resistance of recycled concrete was studied from the perspective of cement hydration and pore structure by fourier transform infrared spectroscopy (FTIR) and mercury injection method (MIP). The results show that the addition of basalt fiber greatly increases the chloride ion penetration resistance recycled concrete. The combination of basalt fiber content of 0.2% and coarse aggregate replacement rate of 50% achieve the best chloride ion penetration resistance, even better than ordinary concrete. Based on FTIR, it is found that basalt fiber improves its chloride ion penetration resistance by changing the polymerization degree of hydration product C-S-H and the formation of CaCO₃ of recycled concrete. Based on MIP, it is found that under the best combined dosage, the pore size distribution of recycled concrete is optimized, the porosity is the smallest, and its chloride ion penetration resistance is improved.