List the common problems that occur during the concrete production process when using water reducing agents.

Concrete is used in various tensile strength applications such as highways, high-speed rail lines, bridges, tunnel construction, nuclear power plants, hydropower installation projects, multi-story buildings, public buildings, etc. In grade concrete projects, the role of concrete admixtures is to reduce the water consumption of concrete mixing stations while keeping the slump of concrete basically unchanged, and can significantly improve the process performance and performance of concrete. However, during the storage and application process, some problems are generally encountered, which make the expected effect of concrete water-reducing agent worse or even invalid, causing unpredictable negative effects.

1. The concentration of water reducing agent is reduced

Due to the influence of weather factors such as heavy rain that may occur during transportation, if the water-reducing agent tank is not tightened or other factors cause the concentration of the water-reducing agent to decrease, the water-reducing rate will decrease. If this type of water-reducing agent is used , which may cause the concrete slump to be smaller. In order to prevent this from happening, after the feeding agent pumps the water-reducing agent into the tank, the upper outer cover should be tightly closed first, and the material personnel should pay more attention to inspection.

2. The water-reducing agent is uneven

During the production process , The mixing device of the water-reducing agent tank may have a mechanical failure, resulting in uneven accumulation density of the water-reducing agent. The accumulation density of the water-reducing agent below is slightly larger and the condensation time is too long. The mass concentration above is smaller and the condensation time is shorter. During the construction process, the slump may be slightly larger and the initial setting time may exceed 20 hours. In order to prevent this from happening, the water-reducing agent should be restarted regularly and stirred evenly. Material operators should pay more attention to inspections. If the mixing device stops, report the problem first.

3. Water-reducing agents are interchangeable

Because carboxylate water-reducing agents and naphthalene Water-reducing agents are immiscible when used with each other, resulting in poor concrete cohesion. The on-site inspectors did not have sufficient knowledge of new technologies and new professional skills, resulting in a relatively small on-site slump. In order to prevent this kind of situation from happening, it is necessary to improve the training of on-site quality inspectors in the laboratory, and different water-reducing agents cannot be used interchangeably.

4. Mixed application of water-reducing agents

Although water-reducing agents all have water-reducing effects , but the water reducing rates of different brands of water reducing agents are different. If mixed, the water reduction rate cannot be accurately predicted and the expected effect cannot be achieved. This type of water reducing agent may cause a slightly larger slump when used in concrete. In order to prevent this from happening, it is forbidden to mix water reducing agents. </p