Whether the concrete strength has regular occurrence and development, whether the concrete surface defects can be controlled, whether the concrete durability can meet the service life, these are closely related to the construction technology, construction details and the maintenance of concrete on the construction site
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And the habit of, a quality problem is often pushed to the concrete mixing station, according to the following construction, can blame the laboratory concrete control is not good? 1
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Improper concrete vibration sequence and method, concrete vibration not in accordance with the specified sequence, improper vibration method or local missing vibration, will lead to local sand and stone concentration, so that the concrete is loose and not dense, honeycomb holes or local holes will appear, especially in the parts with dense reinforcement, which is prone to honeycomb, exposed reinforcement and other adverse diseases
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2
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It is a necessary condition for cement hydration reaction that concrete members are not cured
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Therefore, the ambient humidity has a significant impact on the normal development of concrete strength
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If the humidity is not enough, the concrete will lose water and dry, which will affect the normal hydration of cement, or even stop hydration
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The earlier the drying time, the more serious the shrinkage cracking, the looser the structure, the greater the loss of strength, the greater the carbonation of concrete surface, and the lower the durability
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3
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When pouring concrete, the falling distance or the thickness of pouring layer is too large
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When pouring concrete, the reinforced concrete column, wall and other projects poured from the top, if it is too high, the coarse aggregate in the concrete will separate from the concrete and fall on the outside or bottom of the concrete pile, or in the process of pouring, the coarse aggregate will fall first, and the mortar will fall behind, causing the segregation of the concrete and squeezing the coarse aggregate In the corner of the floor, it is easy to form “honeycomb”, “pockmarked surface”, “rotten root” or cause uneven distribution of sand and stone
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Moreover, if the free falling height is too high, the concrete will have great impact force, which will bend the reinforcement and make the stirrups of the vertical members dislocation, which will affect the mechanical performance of the members
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