A Calculation of Theoretical Temperature Rise of Concrete by One-Dimensional Difference Method Considering Cement Hydration
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摘要: 由于混凝土内部温度场的不均匀分布,使得大体积混凝土容易产生不同程度的温度裂缝,而这些温度裂缝往往直接影响着混凝土的施工质量,关系建筑物的结构安全。因此,对于大体积混凝土温度场的准确计算就显得尤为重要,能够为温度裂缝的控制提供有效的依据和措施。在温度场的计算中,一维差分法作为混凝土施工常用的便捷计算方法,因其计算简便、原理易于理解,被广泛应用于各类复杂施工条件下的大体积混凝土温度场计算。但是,传统的一维差分法并没有考虑混凝土热力学参数随胶凝材料水化反应而变化的特点,使得计算结果与实际温升值存在较大的差距。基于不同热力学参数随水泥水化度的变化特点,建立热力学参数调整系数,并纳入环境温度的周期变化影响,研究提出了一种基于一维差分法考虑水泥水化度的大体积混凝土理论温升预测的改进优化方法。通过对比分析现场大体积混凝土试块的测温数据,表明提出的方法能够更加准确地反映混凝土中心点处最高温升值以及其出现的时间。Abstract: Due to the uneven distribution of the temperature field inside the concrete, mass concrete is prone to produce temperature cracks of varying degrees. These temperature cracks often directly affect the construction quality of concrete and the structural safety of buildings. Therefore, it is particularly important to accurately estimate the temperature field of mass concrete, which can provide effective basis and measures for the control of temperature cracks. However, traditional one-dimensional difference method does not take into consideration the fact that thermal parameters of concrete change with the hydration reaction of cementitious materials, which makes some disparities between the calculated result and the actual temperature. Incorporating thermal parameters changes during cement hydration, a phase adjustment coefficient of thermal parameters was proposed. Based on one-dimensional difference method, a new method for calculating theoretical temperature of mass concrete by incorporating the cement hydration and periodic variation law of ambient temperature was proposed. Through the comparison and analysis of the results from mass concrete cube temperature test, it showed that the proposed method could more accurately reflect the maximum temperature at the center of concrete and the time when the maximum temperature occurred.
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