Jeong Jong-Hyun, Park Yeong-Seong, Lee Yong-Hak
Department of Civil Engineering, Konkuk University, 120 Neungdong-ro Gwangjin-gu, Seoul 143-701, Korea.
Materials (Basel). 2015 Nov 16;8(11):7780-7794. doi: 10.3390/ma8115421.
The variation of shrinkage strain within beam depth was examined through four series of time-dependent laboratory experiments on unreinforced concrete beam specimens. Two types of beam specimens, horizontally cast and vertically cast, were tested; shrinkage variation was observed in the horizontally cast specimens. This indicated that the shrinkage variation within the beam depth was due to water bleeding and tamping during the placement of the fresh concrete. Shrinkage strains were measured within the beam depth by two types of strain gages, surface-attached and embedded. The shrinkage strain distribution within the beam depth showed a consistent tendency for the two types of gages. The test beams were cut into four sections after completion of the test, and the cutting planes were divided into four equal sub-areas to measure the aggregate concentration for each sub-area of the cutting plane. The aggregate concentration increased towards the bottom of the beam. The shrinkage strain distribution was estimated by Hobbs' equation, which accounts for the change of aggregate volume concentration.
通过对无筋混凝土梁试件进行的四组与时间相关的实验室试验，研究了梁深度范围内收缩应变的变化情况。测试了两种类型的梁试件，即水平浇筑和垂直浇筑的试件；在水平浇筑的试件中观察到了收缩变化。这表明梁深度范围内的收缩变化是由于新拌混凝土浇筑过程中的泌水和捣实造成的。通过两种类型的应变片，即表面粘贴式和嵌入式应变片，测量了梁深度范围内的收缩应变。两种类型应变片测得的梁深度范围内的收缩应变分布呈现出一致的趋势。试验完成后，将试验梁切成四段，切割面分为四个相等的子区域，以测量每个切割面子区域的集料浓度。集料浓度朝着梁底部增加。收缩应变分布由考虑集料体积浓度变化的霍布斯方程估算得出。
