Concrete is a mixture of aggregates, cement, water and admixtures. The sizes and specific gravity of these components vary. For example, the specific gravity of aggregate is usually 2.6 to 2.7, while the specific gravity of most cement is 3.1 to 3.2. Differences in size and specific gravity give these components a tendency to separate from each other. If errors occur during production and construction, segregation will occur.
The main causes of segregation include:
1. Unreasonable aggregate gradation and excessive water consumption are the main reasons for segregation.
2. The concrete mix ratio is improper, and the cementitious material is too small to fully wrap the coarse aggregate, causing the coarse aggregate to settle and segregate.
3. Insufficient mixing of concrete.
4. During the construction process, the vertical drop of concrete is too large, causing segregation.
5. When mixing concrete on site, if the quality of the mixer is poor or the blades are severely worn, it may easily lead to concrete segregation.
6. High slump concrete or pumped concrete will cause segregation if there is excessive vibration or improper use of vibrators.
7. Surface smoothing and polishing operations immediately after concrete pouring may cause the coarse aggregate to settle and the cement slurry to float, leading to segregation.
8. Too dense reinforcement can easily lead to segregation.
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