不同配比下超早期混凝土与模板之间侧向作用

Test Study of Lateral Interaction Mechanism at Different Concrete Mixes Between Very EarlyAge Concrete and Structures

摘要:

超早期混凝土对模板的侧向压力直接影响到模板设计，其大小受浇筑速度、混凝土配比、温度、模板表面性态、尺寸、形状、浇筑深度等诸多因素影响，作用机制非常复杂.在理论分析的基础上，设计了一个可以测量不同配比下混凝土对模板侧向压力的模型试验，并对试验结果进行了分析.试验结果表明,侧向压力竖向分布与静水压力相似，但明显小于静水压力；混凝土水灰比(质量比)越大，模板初始侧向压力越接近静水压力，侧向压力下降速度越快；超早期混凝土侧向压力的消散发生在潜伏期之后的水化反应阶段，此阶段水化产物的加速形成使材料具有自承载能力，因此侧向压力迅速下降并最终消失.

关键词:超早期混凝土; 模板; 侧向压力; 模型试验; 配比

Abstract:

The lateral pressure of very earlyage concrete on the formwork directly affects the formwork design, whose numerical size is controlled by the casting rate, concrete mix，temperature, surface characteristics, size and shape of formwork and the depth of the casting concrete and so on. Therefore, the influencing mechanism is quite complicated. Based on theory analysis, a model test which can obtain the lateral pressure under the condition of different concrete mix was designed, and the measuring results were analyzed. The test results show that the vertical distribution of lateral pressure is similar to the hydrostatic pressure, but significantly less than the hydrostatic pressure. As the concrete watercement ratio increases, the initial template lateral pressure gets closer to the hydrostatic pressure, and the lateral pressure drops faster. The cancellation of lateral pressure occurs after the end of the dormant period of cement hydration. The accelerated rate of formation of hydrates enables the material to become selfbearing, which leads the rapid decrease of lateral interaction towards zero.

Key words:very earlyage concrete; formwork; lateral pressure; model test; concrete mix