​What is the mechanism of action of water reducing agents

1. Lubrication effect
Due to the strong hydrophilic polarity of water reducing agents, the adsorption film of water reducing agents on the surface of cement particles can form a stable solvation water film with water molecules. This water film has a good lubricating effect and can effectively reduce the sliding resistance between cement particles, further improving the fluidity of concrete.

2. Dispersion
After mixing cement with water, under the hydration of cement particles, the cement particles form a double-layer structure of solvated water film. The surface of the cement particles has opposite charges, which cause bonding between the cement particles and form a coagulation structure in the cement slurry. 10% to 30% of the mixed water is surrounded by cement particles and cannot participate in free flow and lubrication, thereby affecting the concrete. Because after adding a water reducing agent, the water reducing agent molecules are directionally adsorbed on the surface of cement particles, carrying the same charge (usually negative) on the surface of cement particles to form electrostatic repulsion, causing the cement particles to disperse and the cohesive structure to disintegrate, releasing some of the packaged water and participating in the flow, which can effectively increase the fluidity of the concrete mixture.

3. Grafted copolymer branched chain slow-release
New water reducing agents, such as polycarboxylate water reducing agents, have a spatial resistance effect on the molecules of the water reducing agent during the preparation process. Moreover, cement can slowly cut in a highly alkaline environment of hydration, thus releasing dispersed polycarboxylates, improving the dispersion effect of cement particles, and controlling slump loss.

4. Spatial hindrance
In the structure of water reducing agents, hydrophilic limbs extend into the aqueous solution and form a certain thickness of hydrophilic three-dimensional adsorption layer on the surface of adsorbed cement particles. When cement particles approach, the adsorption layer begins to overlap. That is to say, there will be spatial resistance between cement particles. The more overlap there is, the greater the spatial resistance, and the greater the interference on the cohesion between cement particles. The slump of concrete is maintained in a good state.

The water reducing agents used in handmade concrete in the past were generally ordinary water reducing agents such as pulp waste liquid, wood calcium, and molasses, with a low reduction rate of 5% to 10% With the increasing demand for the quality of hydraulic concrete, the quality requirements for water reducing agents are also becoming higher and higher. The naphthalene high-efficiency water reducer widely used in large-scale hydropower projects such as the Peat Three Gorges, with a reduction rate of 20% to 30%, is mainly used to prepare high-strength and high flow concrete or concrete that requires a significant reduction in water consumption. Efficient water reducing agents have a significant effect on improving the efficiency of cement use, saving about 20% of cement usage