Seven Misunderstandings of Polycarboxylic Acid Superplasticizer
Publish Time: 2020-01-10 Origin: Site
Polycarboxylic acid water reducing agent is a commonly used cement and concrete water reducing agent, which has the effect of reducing water and slumping. The rational use of polycarboxylic acid water reducer is more effective.
1. The water reduction rate fluctuates, which is not easy to control in the project.
Polycarboxylic acid water reducing agent has been proved to have a better water reducing effect at lower dosages, and its water reducing rate is much larger than other varieties of water reducing agents. But it must be noted that compared with other water reducing agents, the water reducing effect of polycarboxylic acid type water reducing agents is more affected by the test conditions and is not easy to control.
2. The greater the amount of water reducing agent, the better the water reducing effect.
In order to configure high-strength concrete and reduce the water-cement ratio, engineers and technicians often have to continuously increase the amount of polycarboxylic acid water reducer in order to obtain good results. However, the water-reducing effect of the polycarboxylic acid-based water-reducing agent is highly dependent on the amount of the water-reducing agent. Generally, as the amount of the water-reducing agent increases, the water-reduction rate increases. But after a certain amount of addition, even with the increase in the amount of addition, the water reduction effect actually "decreased". This is because the concrete has a serious bleeding phenomenon at this time, the concrete mixture is set, and the fluidity is difficult to be reflected by the slump method.
3. The concrete formulated with polycarboxylic acid water reducing agent has serious bleeding.
Concrete formulated with polycarboxylic acid-based water reducer does not always fully meet the requirements for use, and problems such as this often occur. The commercial concrete mixing station is not strict in the detection and control of the moisture content of the aggregate, so it is easy to cause too much water in the production and cause the concrete mixture to leak and segregate.
4. High-flow concrete is easy to be separated and separated.
In most cases, high flow concrete prepared with polycarboxylic acid-based water reducer, even though the amount of water reducer and the control of water consumption are the best, it is very prone to delamination and segregation. Specific performance The coarse aggregate sinks, and the mortar or slurry floats up. The reason is mainly due to the sharp decrease in the viscosity of the slurry when the fluidity of the concrete mixed with this polycarboxylic acid water reducing agent is large.
5. Used in combination with other varieties of water reducing agents, no superimposed effect.
We all know that traditional water reducing agents can be compounded in any proportion to meet the special formulation requirements of different projects or to obtain better economics. However, it is not easy to obtain a superimposed effect when the polycarboxylic acid type water reducing agent is used in combination with other types of water reducing agents, and the mutual solubility of the polycarboxylic acid type water reducing agent solution and other types of water reducing agent solutions is itself poor.
6.No modification effect after adding commonly used modification components.
The diversity and instability of cement, admixtures, and aggregates in the project. It is very important for the admixture production supplier to modify the polycarboxylic acid-based water reducer products according to the needs of the project. The test proves that the past modification technology measures are not necessarily suitable for polycarboxylic acid-based water reducer, and may require deeper exploration and research to modify and supplement.
7, The performance stability of the product is too poor.
As far as production control is concerned, the instability of raw material sources and quality has always been a major factor that plagued the performance of polycarboxylic acid water reducers.
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