混凝土超早期收缩试验与模拟

通过测定混凝土早期变形随龄期的发展规律,定义了基于变形的凝结时间和基于内部湿度发展的临界时间,研究了3个强度等级混凝土的凝结时间和临界时间随水胶比的变化规律,并对湿度饱和期收缩进行了模拟。结果表明：混凝土水胶比越大,凝结时间越长,临界时间也越长,湿度饱和期收缩越小;凝结时间与临界时间之差随水胶比的减小而减小;基于水泥水化程度和刚度修正的混凝土早期收缩模型,能够反映混凝土早期收缩发展特征,模拟结果与试验结果吻合良好,模型可以较好地预测混凝土湿度饱和期收缩的发展。

Tests and Simulations on Shrinkage of Concrete at Early-Age

The deformation determined setting time and interior humidity based critical time both were defined via the measurements of free deformation and interior humidity.The relationship between setting time or the critical time and the water to binder ratio of concrete with three strength grades was investigated.Also,the shrinkage produced within the stage of interior humidity of 100% was simulated with respect of the effect of matrix stuffiness.The results show that a greater water to binder ratio leads to the longer setting time and the critical time.The difference between the critical time for the decreased humidity and the setting time is gradually reduced with the decrease of water to binder ratio.Within the moisture saturated stage,the characteristic of the shrinkage development with age can follow the shrinkage model.The experimental results are in a reasonable agreement with the calculated data by the model.