寒冷地区硅粉增强玄武岩纤维路面混凝土抗冻性能研究

为探究硅粉对玄武岩纤维路面混凝土抗冻性能的增强效果及改性机理,采用快冻法研究了不同硅粉掺量下玄武岩纤维混凝土质量损失、相对动弹模量、抗弯拉强度随冻融次数的衰减规律;借助压汞法(MIP)以及扫描电子显微镜(SEM),分析冻融前后孔结构及界面结构的演化,从细微观层面揭示硅粉增强机理。研究结果表明:9%(质量分数)硅粉掺量的玄武岩纤维路面混凝土抗冻性能增强效果最佳,相比基准混凝土,冻融320次后质量损失率降低了62.35%,相对动弹性模量提高了14.68%,抗弯拉强度提高了43.89%;MIP测试表明,掺入硅粉能够细化混凝土内部孔结构,减少孔隙数量,优化孔的分布,阻抑最可几孔径和临界孔径的增长;SEM分析发现,掺入硅粉能够改善纤维-水泥石与骨料-水泥石的界面区结构,提高玄武岩纤维路面混凝土的抗冻性能。

Research on Frost Resistance of Silica Powder Reinforced Basalt Fiber Pavement Concrete in Cold Regions

To explore the enhancement effect and modification mechanism of silica powder on the frost resistance of basalt fiber pavement concrete, the decay law of mass loss, relative dynamic elastic modulus and flexural tensile strength of basalt fiber reinforced concrete with different freeze-thaw cycle times were studied by quick freezing method. By means of mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM), the evolution of pore structure and interface structure before and after freeze-thaw cycle were analyzed, and the strengthened mechanism of silica powder reveals from the microscopic level. The research results show that 9% (mass fraction) silica powder has the best effect on improving the frost resistance of basalt fiber pavement concrete, the mass loss reduces by 62.35%, the relative dynamic elastic modulus increases by 14.68%, and the flexural tensile strength is improved 43.89% after 320 times freeze-thaw cycles. The MIP results indicate that the addition of silica powder refines the internal pore structure of the basalt fiber pavement concrete, reduces the number of pores, optimizes the distribution of pores suppresses the growth of mean pore-size and critical pore size. SEM images reveal that the addition of silica powder improves the interface zone structure between fiber-cement stone and aggregate-cement stone, and improves the frost resistance of basalt fiber pavement concrete.