膨胀剂和纤维及其复合对混凝土抗冻性的影响

Effect of Expansive Agent,Fiber or Their Combination on Freezing-Thawing Durability of High Performance Concrete

用快冻法研究了铝酸盐膨胀剂(A lum inate expans ive agen t,AEA)、钢纤维和高强高模聚乙烯纤维(H ighe lastic ity m odu le po lyethy lene fiber,HEM PF)及其复合对双掺硅灰与粉煤灰的高性能混凝土(H igh perform anceconcrete,HPC)抗冻性的影响。结果表明,强度等级C 80的非引气HPC具有较好的抗冻性,但是其抗冻性对养护环境的相对湿度(re lative hum id ity,RH)具有敏感性。AEA和HEM PF对HPC的抗冻性存在负效应,钢纤维则对HPC的抗冻性存在正效应。在改善HPC抗冻性及其对养护环境湿度的敏感性方面,AEA和钢纤维复合的改善效果明显好于AEA和HEM PF复合。AEA和钢纤维的综合效应可以保证HPC的抗冻融循环次数不低于750次,在30%RH环境养护时的抗冻融循环次数能够达到标准养护时的80%以上。

Effects of the addition of aluminate expansive agent （AEA）, steel fiber, or high elasticity module polyethylene fiber （HEMPF） on freezing-thawing durability of high performance concrete （HPC） mixed with both silica fume and fly ash, are studied. Results show that the non-air-entrained C80 HPC mixed with both silica fume and fly ash exhibits excellent freezing-thawing durability, and the durability is sensitive to the relative humidity （RH） of its cure environment. The addition of AEA or HEMPF impairs the freezing-thawing durability of HPC while the addition of the steel fiber can improve the freezing-thawing durability. The addition of the combination of AEA and the steel fiber is better than the combination of AEA and HEMPF in the improvement of the freezing-thawing durability and alleviation of the sensitivity to cure RH. The freezing-thawing durability of HPC containing both AEA and the steel fiber is not less than 750 cycles. When cured in an environment with 30%RH, the freezing- thawing cycles are more than 80% of those standard cured one.