Raw material of CSA cement
Sand: The amount of mud in the washed sand is less than 3%. The gravel is between 16 mm and 30 mm. The mud content is less than 0.8%. The antifreeze is of the NC type.
Concrete construction uses a comprehensive thermal storage method using hot water (55 ° C) and hot sand (40 ° C). The concrete mold temperature is controlled between 9 °C and 15 °C, and the concrete outlet temperature is controlled between 13 °C and 19 °C. At the same time, the concrete is loaded strictly according to the concrete mix ratio.
After the concrete is introduced into the mold, since the initial setting time of the CSA cement is 45 min, the vibration must be timely. For the parts with dense spacing of the steel bars, it is necessary to repeatedly vibrate back and forth to prevent the generation of honeycomb and pockmarks. The root of the column should be dense to prevent "bad roots". After the concrete is initially set, it is covered with plastic cloth and straw bag for heat preservation. Before the temperature measurement personnel are on duty, the technicians will control the technical safety before the post, and the measurement points will be arranged. The insulation and temperature measurement of concrete should continue until the temperature difference between the concrete temperature and the atmosphere is within 15 °C. The concrete strength reaches 85% of the design strength and the technical department agrees. Measuring temperature can be stopped. Since the strength of the CSA cement concrete can reach more than 70% of the design strength on the first day, more than 70% of the hydration heat is released on the first day. Therefore, temperature control and measurement on the first day are very important. According to the temperature measurement data of the temperature measurement personnel, the insulation and maintenance are carried out. In order to limit the crack caused by the temperature stress of the concrete, after the concrete is demolished, it is still necessary to maintain the heat preservation. When the temperature difference between the concrete temperature and the atmosphere is within 20 °C, the heat preservation can be stopped.
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