Early-age shrinkage development of ultra-high-performance concrete under heat curing treatment
Early-age shrinkage development of ultra-high-performance concrete under heat curing treatment
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DOI：
10.1016/j.conbuildmat.2016.11.024
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发表时间：
2017-01-30
影响因子：
7.4
通讯作者：
Shah, Surendra P.
中科院分区：
文献类型：
--
作者：
Li, Wengui;Huang, Zhengyu;Shah, Surendra P.
试验研究了新型热养护制度和纵向配筋率对超高性能混凝土（UHPC）早期收缩的影响。采用扫描电镜、压汞法和热分析等方法对不同热固化时间后UHPC的微观结构、孔隙率和氢氧化钙含量进行了表征。结果表明，当热养护时间小于60 min，养护温度达到48℃时，早期收缩率略有下降，而当热养护时间接近70 min，养护温度在55℃左右时，早期收缩率急剧上升。热固化48h后的早期收缩率约为450 μ epsilon。纵向配筋率从2.0增加到4.52%，UHPC的早期收缩率显著降低33 ~ 60%。同时，热养护10 h后，UHPC中的水泥水化和二次水化趋于结束，导致UHPC的微观结构致密，CH含量较低。(C) 2016 Elsevier Ltd.版权所有。
The effects of a novel heat curing regime and longitudinal reinforcement ratio on early-age shrinkage of ultra-high performance concrete (UHPC) were experimentally investigated in this study. The microstructure, porosity and calcium hydroxide (CH) content of UHPC after different heat curing durations were characterized with scanning electron microscopy, mercury intrusion porosimetry and thermal analysis. The results indicate that slight shrinkage was observed when the heat curing duration was less than 60 min and curing temperature reached 48 degrees C. However, when the heat curing duration approached 70 min and curing temperature was around 55 degrees C, the early-age shrinkage increased dramatically. It was found that the early-age shrinkage is approximately 450 mu epsilon after 48 h of heat curing. The results also show that the early-age shrinkage of UHPC significantly decreased by percentage of 33-60% with the increase of longitudinal steel reinforcement ratio from 2.0 to 4.52%. Meantime, after 10 h of heat curing, the cement hydration and secondary hydration in UHPC tend to finish, which consequently leads to dense microstructure and low CH content in UHPC. (C) 2016 Elsevier Ltd. All rights reserved.