FRHPC在冻融与腐蚀共同作用下的强度变化

Strength Development of FRHPC Subject to the Combined Action of Freezing-thawing Cycles and Chemical Attack

目的研究纤维增强高性能混凝土(FRHPC)在恶劣环境下的强度规律,解决FRHPC承受冻融破坏和化学腐蚀问题.方法测定了高性能混凝土(HPC)、钢纤维增强高性能混凝土(SFRHPC)和高强高模聚乙烯纤维增强高性能混凝土(PFRHPC)在冻融与卤水化学腐蚀共同作用下的强度变化.结果结果表明:HPC在青海和新疆盐湖卤水腐蚀条件下的冻融后强度很高,在内蒙古和西藏盐湖卤水腐蚀下则略低.SFRHPC明显改善了HPC在内蒙古和西藏盐湖卤水腐蚀条件下的抗冻性,PFRHPC在新疆盐湖卤水腐蚀条件下的抗冻性明显优于SFRHPC.延长混凝土的养护龄期,能够明显提高HPC和SFRHPC在盐湖卤水腐蚀条件下的冻融抗折强度.此外,随着在盐湖卤水腐蚀条件下冻融循环次数的增加,HPC和SFRHPC的强度基本上是降低的,而PFRHPC的强度则表现出一定程度的增长.结论综合分析指出,FRHPC适合于同时承受冻融破坏和化学腐蚀的严酷环境.

Strength development of high performance concrete （HPC）, steel fiber reinforced high performance concrete （SFRHPC）, and high elasticity module polyethylene fiber reinforced HPC （PFRHPC） subjected to the combined actions of freezing-thawing cycles and bittern chemical attack was investigated. Results show that HPC exhibits excellent freezing-thawing durability when exposed to bitterns from Oinghai or Xinjiang salt lakes, while its freezing-thawing durability is relatively poor when exposed to bitterns from Neimeng or Xizang salt lakes. Freezing-thawing durability of HPC exposed to bitterns from Neimeng or Xizang salt lakes was remarkably improved by the addition of steel fibers. While freezing-thawing durability of HPC exposed to bitterns from Xinjiang salt lakes was considered, the addition of high elasticity module polyethylene fibers was more effective than that of steel fibers. Flexural strength of HPC and SFRPHC subjetted to bittern attacks could be notably improved by extending the curing time. With the increasing of freezing-thawing cycles, strength of both HPC and SFRHPC declined, while that of PFRHPC increased a bit. Generally speaking, FRHPC is more applicable to the combined actions of freezing-thawing cycles and bittern chemical attack.