The effect of water reducing agent on bleeding water

2019-06-13 11:33:01

What is the definition of water reducer?

Water-reducing agent is a kind of concrete admixture, which can improve the workability of concrete, reduce construction energy consumption and improve construction efficiency. In the concrete, water reducing agent is added to the mixture of cement particles dispersion effect, which can optimize the working performance of cement. Under the condition of keep the concrete slump constant,  mixing and subtract agent can greatly reduce the unit water use of concrete mixture and reduce the water cement ratio of concrete and improve the strength and stability of the reinforced concrete. Or under the same condition of the concrete workability and strength, adding water reducing agent can reduce the unit of cement so as to save cement. However, there are also some problems in the application of superplasticizer in concrete. For example, when the majority of superplasticizer ions are anionic surfactants, there will present some materials such as lignin sulfonate, naphthalene sulfonate formaldehyde polymer, etc..

How to make the water reducing agent?

Using methyl naphthalene and sulfur trioxide as raw materials, through sulfonation, condensation, neutralization and other reactions, finally through drying the product.

Common problems of pumping concrete: the effect of water reducing agent on bleeding water!

According to the action mechanism of water-reducing agent, polar molecules adsorb around cement particles, making the particles repel each other, reducing flocculation, releasing the water covered by cement particles, and thinning the adsorbed water layer on the surface of cement particles, greatly reducing the wetting water required. According to this mechanism, the water-reducing agent can increase the free water amount in fresh concrete and increase the bleeding water. But on the other hand, because of the water-reducing effect of water-reducing agent, the mixing water needed for concrete with the same slump degree greatly reduces the water, so that the concrete can extract free water to reduce water. The final bleeding condition depends on which function is dominant.

The adaptability of admixtures and cement also affects the bleeding of concrete.

What are the main research directions of concrete water reducer in the future?

(1) The production of water reducer materials can be further optimized the synthesized. Through the selection of production materials and the change of production technology, the molecular structure of water reducer is optimized to improve the adaptability between water reducer and cement, so as to enhance the effect of water reducer.

(2) Two or more high-efficiency water-reducing agents should be compound prepared in a certain proportion, so as to change the performance of each part at the same time and to bring internal coordination to produce a superposition effect. 

(3) From the direction of polymer development of new efficient water reducer, comprehensively optimize the concrete strength and durability, etc, so as to reduce production costs.

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