基于温度影响下早期变形特征的混凝土凝结时间的确定

通过模板侧压力实验和温度实验,监测新浇混凝土24 h模板侧压力和24 h混凝土内部温度变化过程,研究由混凝土水化时释放的热量引起温度的变化而造成混凝土初凝前后的变化特征。将工程实验测得的初凝时间与贯入阻力法测得的初凝时间进行对比,结合混凝土早期变形特征,提出了确定混凝土凝结时间的新方法。实验结果显示:随着浇筑高度的增大混凝土模板侧压力也增大,当混凝土浇筑完成到混凝土初凝这段时间模板侧压力出现减小趋势,混凝土初凝后因温度升高发生膨胀,模板侧压力也随之增大;将混凝土模板侧压力再次增大的时间点定为混凝土初凝时间与贯入阻力法测试得到的初凝时间有良好的相关性。

Determination of concrete setting time based on early deformation characteristics caused by temperature

The change process of the 24h formwork lateral pressure of the new concrete was monitored through the lateral pressure test of the formwork, and the temperature of the hydration heat release of concrete was studied before and after the initial setting of the concrete. By comparing the initial setting time measured in the engineering test with the initial setting time measured through the penetration resistance method, and combining with the early deformation characteristics of concrete, a new method for determining the setting time of concrete was proposed. The experimental results showed that: with the increasing of the height of pouring concrete formwork, lateral pressure increased, when the pouring height reached a certain value the formwork lateral pressure would not increase, when the concrete sets up, it expands because of the increase of temperature, the lateral pressure of formwork increased. The initial setting time of concrete defined by the lateral pressure of concrete formwork increased again and the time gained from the penetration resistance test have good correlation.