First of all, we should know what is the concrete segregation phenomenon, that is, the main material in the concrete mortar and sand appear separation. The more professional explanation from Baidu Encyclopedia is: the cohesion between the components of concrete mixture is not enough to resist the sinking of coarse aggregate, which makes the components of concrete mixture separate from each other, resulting in the phenomenon of uneven internal composition and structure.
The main reason for concrete segregation is the problem of mixing station. Different levels of concrete have strict specifications. Improper use of water, cement, aggregate and additives may cause concrete segregation.
Mainly by the following and several situations:
1. Improper proportioning of raw materials, including more water or less cement will cause segregation of finished concrete.
2. Sand quality is not good, too high water content will also cause segregation. Concrete mixer truck
3. The segregation of concrete is easily caused by poor grading of crushed stone, the increase of crushed stone particle size, poor grading and single grading.
4. Excessive addition of additives, retarder and other additives, or poor adaptability of additives and cement will also cause concrete segregation.
Of course, there are also reasons for improper use of concrete mixer, which we can not ignore in daily use.
1. In the process of concrete transportation, when the road is long, we should add water in the tank to prevent the concrete from setting. However, if the amount of water is not well controlled, it will also cause segregation of concrete. This is a mistake that some novice drivers are particularly prone to make, or they do not strictly follow the mixing process. When washing the car on the first day, the water in the mixing tank is not drained, or they feed directly before they finish. Small concrete mixer
2. During the transportation of concrete, the segregation phenomenon is caused by the long-time stop of the mixing tank. The mixing tank must not be stopped for a long time during the transportation. If there is no effective mixing during the transportation, the sand, stone and cement will separate from each other, and the coarse aggregate will sink, resulting in segregation. But at this time, we need to worry about the phenomenon of stuffy tank caused by concrete condensation.
3. If the speed of mixing tank is too fast, it will also cause concrete segregation. In the process of concrete transportation, if the driver makes the mixing tank rotate too fast, heavy gravel will sink under the action of centrifugal force.
4. The last is the unreasonable design of the tank. If the design of the mixing tank is unreasonable, it will also cause the segregation of concrete. The main reasons are the installation design angle of the mixing blade inside the tank and the poor workmanship, which will cause the uneven mixing of concrete and cause the segregation of concrete during transportation.