The Mechanism Of Action Of The Water Reducer

Post Date:5,Jan,2026

1. Dispersion effect: After cement is mixed with water, the hydration of cement particles forms a double-layer structure on their surface, generating a soluble water film. The opposite charges on the surface of cement particles cause them to aggregate, forming a flocculation structure. This results in 10% to 30% of the mixing water being trapped inside the cement particles, unable to flow freely and act as a lubricant, thus affecting the fluidity of the concrete mixture. When a water reducer is added, its molecules are oriented and adsorbed on the surface of cement particles, giving the particles a uniform charge (usually negative). This electrostatic repulsion promotes the dispersion of cement particles, breaks down the flocculation structure, and releases some of the trapped water, effectively enhancing the fluidity of the concrete mixture.

2. Lubrication effect: The hydrophilic groups in the water reducer have strong polarity. Therefore, the film adsorbed on the surface of cement particles forms a stable solution water film with water molecules. This film has excellent lubricity, effectively reducing the sliding resistance between cement particles and further improving the fluidity of concrete.

3. Spatial steric hindrance: The hydrophilic side chains in the structure of the water reducer extend into the aqueous solution, forming a hydrophilic three-dimensional adsorption layer of a certain thickness on the surface of cement particles. When cement particles approach each other, the adsorption layers begin to overlap, creating spatial steric hindrance between the cement particles. The greater the degree of overlap, the stronger the spatial repulsive force, and the greater the resistance to the aggregation of cement particles, thereby maintaining the good slump of concrete.

4. Slow-release effect of grafted copolymer side chains: New types of water reducers, such as polycarboxylate superplasticizers, have side chains grafted onto their molecules during the preparation process. These side chains not only provide spatial steric hindrance but also slowly break down in the highly alkaline environment during cement hydration, releasing polycarboxylates with dispersion effects. This helps improve the dispersion of cement particles and control the loss of slump.