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大体积混凝土产生裂缝的原因是多方面的,必须从结构设计、温度控制、原材料选择、施工安排和施工质量等方面采取综合性措施。由于温度变化和混凝土收缩而产生的温度应力和是导致大体积混凝土出现裂缝的主要原因,所以在制定温控措施时,必须把控制混凝土的最高温度作为主要方面。这就要从降低混凝土出机口温度和降低水化热温升入手,抓住主要矛盾的主要方向,从而结合工程的实际情况,采取切实可行的具体措施。在降低水化热温升方面:可以采用混凝土“双掺”(掺粉煤灰、掺外加剂),合理选择混凝土配合比,尽量降低单位水泥用量,尽量选用低流态和大级配混凝土。在降低混凝土出机口温度方面:主要从降低对混凝土出机口温度影响最大的石子温度和拌和水温度方面下功夫。经验表明:石子温度每下降1℃,混凝土出机口温度大约可降低0.55℃,水温下降1℃,混凝土温度可下降0.2℃。同时在制定温控措施时,必须结合工地实际情况,采用技术上可行、操作上简便实用、经济上节省的措施。运输上,采用混凝土罐车,尽量减少曝晒时间和停歇,从而降低温升。
The causes of cracks in mass concrete are manifold, and comprehensive measures must be taken from structural design, temperature control, raw material selection, construction arrangements, and construction quality. Because the temperature stress and the temperature stress and the shrinkage of the concrete are the main causes of the cracks in the mass concrete, the control of the maximum temperature of the concrete must be taken as the main aspect when setting the temperature control measures. This will start with reducing the temperature at the concrete exit and reducing the temperature rise of heat of hydration, and grasp the main directions of the main contradiction, so as to take practical and practical measures in light of the actual conditions of the project. In the aspect of reducing the temperature rise of hydration heat: concrete can be used with “double-doped” (with fly ash, mixed admixtures), and the concrete mix ratio can be reasonably selected to reduce the amount of cement per unit, and the low flow regime and large gradation should be used as far as possible. Concrete. In the aspect of reducing the temperature of the concrete exits, efforts are mainly made to reduce the temperature of the stones and the temperature of the mixing water, which have the greatest influence on the exit temperature of the concrete. Experience has shown that for every 1°C decrease in the temperature of the stone, the temperature at the concrete exit can be reduced by approximately 0.55°C, the water temperature can drop by 1°C, and the concrete temperature can drop by 0.2°C. At the same time, in the formulation of temperature control measures, it is necessary to combine the actual conditions of the construction site and adopt measures that are technically feasible, simple and practical in operation, and economical. In transportation, concrete tankers are used to minimize the exposure time and stop, thereby reducing the temperature rise.