纤维增强高性能混凝土在西部盐湖中的抗冻性

采用普通水和我国西部4种典型盐湖卤水为冻融介质,用快冻法研究了钢纤维与高强高模聚乙烯纤维对高性能混凝土抗冻性的影响,探讨了纤维增强对高性能混凝土抗冻性的作用机理.结果表明,在水中冻融时,钢纤维的阻裂作用限制了冻融时混凝土内部裂纹的引发与扩展,在一定程度上提高了高性能混凝土的抗冻性;高强高模聚乙烯纤维因其存在表面微裂纹,对高性能混凝土的抗冻性具有明显的不利影响.阐述了西藏、内蒙古、新疆和青海盐湖卤水中冻融时,纤维增强高性能混凝土内部不能形成足以导致结构破坏的盐结晶压,具有很高的抗卤水冻蚀性.因此,在我国西部盐湖地区,纤维增强高性能混凝土属于高耐久性的混凝土,适用于不同类型的盐湖环境.

Freezing-thawing durability of fiber reinforced high performance concrete exposed to salt lakes

Freezing-thawing durability of fiber reinforced high performance concrete (HPC) exposed to pure water or Xinjiang,Qinghai,Inner Mongolia and Tibetan salt lakes were studied by accelerated freezing-thawing method.Effects of addition of high Young's modulus polyethylene fibers or steel fibers on freezing-thawing durability of HPC were investigated and the influence mechanism was also discussed.When the freezing-thawing medium was pure water, the results showed that steel fibers prevented the generating and expansion of crackles while high Young's modulus polyethylene fibers demonstrated disadvantageous effects on Freezing-thawing durability of HPC,due to tiny flaws on the surfaces of polyethylene fibers.When the freezing-thawing medium was bitterns from Xinjiang,Qinghai,Inner Mongolia or Xizang salt lakes,addition of fibers prevented the formulation of salt crystal,which would lead to fracture of concretes,in fiber reinforced HPC that resulted in the high bittern-freezing-thawing durability of fiber reinforced HPC exposed to salt lakes.Consequently,fiber reinforced HPC is applicable to the various types of salt lakes in the west of China.