常温养护超高性能混凝土受压性能研究

Compressive Behavior of Ultra-High Performance Concrete at Room Temperature Condition

超高性能混凝土(UHPC)通常采用蒸汽和蒸压养护,更适合于桥梁等预制结构的工程应用,但也限制了其在建筑结构领域的发展。以现浇施工性和环境养护为目标,配制出适合于结构应用的超高性能混凝土。研究了水胶比、钢纤维类型和钢纤维掺量对于超高性能混凝土受压强度的影响。结果表明,水胶比越低,新拌浆体内部更加致密,UHPC的受压强度越高;端钩型钢纤维与混凝土浆体之间的黏结力更强,可获得较直线型纤维UHPC更高的受压强度。随着纤维掺量的增加,UHPC受压强度也随之增加,建议不超过3%掺量。此外,为了研究UHPC在现浇状态下的流动性和施工性,进行了UHPC塌落度试验。结果表明,水胶比0.16、掺入3%钢纤维的新拌混凝体浆体的塌落度为242 mm,流动性能良好。

Ultra High Performance Concrete(UHPC)usually pheed steam and autoclave curing.It is more suitable for engineering applications prefabricated bridges and other structures,but also limits its development in building structures.In this paper,with cast construction and environmental conservation as the goal,UWPC was desiqned for the application in building structures.The effect of water-binder ratio,the type of steel fiber and steel fiber volume compressive strength was analysized.The results showed that the UHPC with lower waterbinder ratio had denser paste inside fresh,and had the denser and the higher compressive strength of UHPC;It had stronger adhesion between the hooked steel fiber and concrete slurry and higher compressive strength than UWPC with straight short fibers.With the increase of fiber volume,the compressive strength of UHPC increased.It is recommended volume ratio no larger than 3%.Further,in order to study the fluidity and constructability of UHPC under the condition of cast-in-situ,the collapse degree test of UHPC was carried out.The results showed that the newly mixed coagulant slurry mixed with 3% steel fiber under the water-binder ratio of 0.16 had a 242 mm slump and good flow performance.