硫酸盐干湿循环下带冷缝混凝土能量演化研究北大核心CSCD

为探究硫酸盐干湿循环作用下带冷缝混凝土受荷作用时的能量演化规律,制作了整浇和浇筑间隔0.25 d、0.5 d、1 d、7 d和28 d的带冷缝混凝土,基于单轴压缩实验及能量计算原理,研究了硫酸盐干湿循环对带冷缝混凝土强度和能量演化规律的影响。结果表明:带冷缝混凝土强度及损伤应力和峰值应力处弹性应变能与耗散能均随干湿循环呈先增大后减小的趋势,随着新混凝土与母体浇筑间隔的增加呈现减小的趋势;随着干湿循环次数的增加,损伤应力处储能水平Kad先减小后增加,说明损伤应力处储能水平越高,带冷缝混凝土越容易产生损伤,Kad可以作为混凝土破坏的预警指标。

Energy evolution of concrete with cold joints under sulfate admixture wet-dry cycling

Concrete specimens with cold joints are manufactured with one-piece pouring and multiple pouring at the intervals of 0.25 d, 0.5 d, 1 d, 7 d, and 28 d to investigate their energy evolution under loads and the cycling of sulfate solution wetting and drying. The cycling effect on the strength and energy evolution are examined by conducting a uniaxial compression experiment and energy calculations. The results show that for the concrete with cold joints, the wet-dry cycling causes a first-increase-then-decrease trend in the time development of its strength, elastic strain energy, dissipation energy at damage stress, and peak stress. All these parameters present a declining tendency with the increasing pouring interval. And as the number of wet-dry cycles increases, the energy storage level Kad at damage stress first decreases and then increases, showing a larger Kad is related to higher susceptibility of concrete to damage. Thus, Kad can be used as an indicator for concrete damage early warning.