为改善超高性能混凝土(ultra-high performance concrete,简称UHPC)的收缩性能,研究了钢纤维掺量为 1.5%、2.0%、2.5%的UHPC在自然养护、标准养护、热水养护 3 种养护条件下的收缩性能变化,通过X射线衍射(X-ray diffraction,简称XRD)和扫描电镜(scanning electron microscopy,简称SEM)分析,进一步分析了影响其收缩性能变化的微观因素.结果表明:标准养护和热水养护条件下对UHPC的收缩抑制作用比较显著,随着钢纤维掺量的提高,UHPC的收缩性能会降低,钢纤维掺量为 2.5%时UHPC的收缩性能仍满足要求,且在热水养护中混凝土的收缩率最小;此外,加入矿物掺合料可以促进水泥二次水化,形成致密的微观结构,使钢纤维与基体黏结更紧密.
Improvement of shrinkage properties of ultra-high performance concrete by different curing conditions and steel fiber contents
In order to improve the shrinkage properties of ultra-high performance concrete(UHPC),this experiment investigated the changes of shrinkage properties of UHPC with steel fiber content of 1.5%,2.0%,and 2.5%under three curing conditions(natural curing,standard curing,and hot water curing),and further analyzed the microscopic influencing factors on the changes of shrinkage properties by X-ray diffraction(XRD)and scanning electron microscopy(SEM)analysis.The results show that the shrinkage inhibition effect on UHPC under standard curing and hot water curing conditions is relatively significant,and with the increase of steel fiber content,it will reduce the shrinkage performance of UHPC.The shrinkage properties of UHPC still meet the requirements when the steel fiber content is 2.5%,and the shrinkage of the concrete is the smallest in the hot water curing.In addition,the addition of mineral admixtures can promote the secondary hydration of cement,forming a dense microstructure,so that the steel fibers are more closely bonded to the matrix.
NETL
NSTL
万方数据
维普
