Construction Technology and Requirements of Concrete Foundation When the length of raft foundation and box foundation of high-rise building exceeds 40 m, the post-pouring construction joint (post-pouring belt) should be set through, and the post-pouring bandwidth should not be less than 80 cm. At the post-pouring construction joint, the reinforcing bar must be through. Concrete Engineering (2) Concrete mixing The order of concrete mixing charge is: stone cement sand water admixture. Mass concrete engineering (1) Pouring scheme of mass concrete 1. Overall stratification: when the plane size is small and the thickness is large, it is adopted. 2. Segmentation and stratification: It is suitable for use when the thickness of the structure is not large and the area is large or the length is long. 3. Slope stratification: It is suitable for mass concrete with large plane and thickness. The concrete pouring of the lower layer must be carried out before the initial setting of the previous concrete. (3) Maintenance of mass concrete 2. Maintenance time.After pouring, it should be covered and watered within 12 hours. The curing time of ordinary Portland cement concrete should not be less than 14 days. The curing time of concrete mixed with slag cement and pozzolanic cement should not be less than 21 days. (4) Control of cracks in mass concrete 1. Select slag cement mixing concrete with low hydration heat preferentially and use retarder and water reducer appropriately. 2. Proper water-cement ratio of precipitation to reduce cement consumption; 3. Control the temperature of injection mould, control the temperature difference between inside and outside of concrete, control within 25 degrees. 4. Insulation and maintenance in time; 5. Pre-embedded cooling water pipe for artificial heat conduction; 6. When mixing concrete, appropriate amount of micro-expansive agent or expansive cement can be added to reduce the temperature stress of concrete. 7. Setting up post-pouring joints; 8. Mass concrete must be applied twice to reduce surface shrinkage cracks.

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