Effect of internal curing on internal relative humidity and shrinkage of high strength concrete slabs
Effect of internal curing on internal relative humidity and shrinkage of high strength concrete slabs
复制标题
内部养护对高强混凝土板内部相对湿度和收缩的影响
DOI：
10.1016/j.conbuildmat.2014.02.060
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发表时间：
2014-06-30
影响因子：
7.4
通讯作者：
Hao, Tingyu
中科院分区：
文献类型：
--
作者：
Han, Yudong;Zhang, Jun;Hao, Tingyu
本文通过连续测量板坯浇筑后即刻至28天的混凝土内部湿度，研究了在正常室内环境下，添加和未添加预浸轻骨料（PSLWA）的高强混凝土板的内部含水量（以相对湿度表示）。分析了内部养护对高强混凝土板内部相对湿度和自由收缩发展的影响。试验结果表明，高强混凝土自浇筑以来，内部相对湿度随混凝土龄期的增加而降低。混凝土内部相对湿度随龄期的发展趋势为相对湿度达到100%的蒸汽饱和阶段（I阶段）和相对湿度逐渐降低阶段（II阶段）。早期高强混凝土沿板厚存在湿度梯度。随着PSLWA的加入，第二阶段室内湿度的降低率明显降低，随年龄的降低趋势由非线性转变为近似线性。PSLWA的加入显著延长了内部湿饱和阶段的持续时间。湿度梯度和相应的沿板坯厚度的收缩梯度也减小了。高强混凝土浇筑28 d内湿度的最大降幅为中等PSLWA掺量时的46.5% ~ 26.2%，高PSLWA掺量时的7.9%。在一定加入范围内，PSLWA加入量越大，上述正向内固化效应越强。(C) 2014 Elsevier Ltd.版权所有。
In the paper, the moisture content, in terms of relative humidity, inside of high strength concrete slab, with and without addition of pre-soaked lightweight aggregate (PSLWA), exposed to normal indoor environment is investigated by continually measuring the interior humidity of concrete immediately after slab casting until 28 days. The effects of internal curing on the developments of internal relative humidity and free shrinkage in high strength concrete slab are analyzed. The experimental results show that the internal relative humidity of high strength concrete decreases with concrete age since casting. The developing tendency of the relative humidity inside of concrete with age follows a vapor-saturated stage with 100% relative humidity (stage I) and a stage that relative humidity gradually decreases (stage II). A humidity gradient along the thickness of slab exists in early age high strength concrete. As PSLWA is added, the reduction rate of interior humidity in stage II is obviously reduced and the reduction trend with age changes from non-linear pattern to almost linear pattern. The duration of the internal humidity-saturated stage I is noticeably prolonged by addition of PSLWA. The humidity gradient together with the corresponding shrinkage gradient along the thickness of the slab is reduced also. The highest reduction on internal humidity at 28 days since casting in high strength concrete slab is changed from 46.5% to 26.2% with a medium PSLWA addition ratio, and finally to 7.9% with a high PSLWA addition level. Within present addition range, the more the PSLWA added, the stronger the above positive internal curing effects. (C) 2014 Elsevier Ltd. All rights reserved.