Water reducing agent is a concrete admixture that can reduce mixing water consumption while maintaining the slump of concrete basically unchanged. Most of them are anionic surfactants, including lignin sulfonate, naphthalene sulfonate formaldehyde polymer, etc. After being added to the concrete mixture, it has a dispersing effect on the cement particles, which can improve its workability, reduce the unit water consumption, and improve the fluidity of the concrete mixture; or reduce the unit cement consumption and save cement.

1. Steric hindrance: The hydrophilic branched chain in the superplasticizer structure stretches in the aqueous solution, thereby forming a certain thickness of hydrophilic three-dimensional adsorption on the surface of the adsorbed cement particles. layer. When the cement particles are close together, the steric hindrance between the cement particles is greater, and the obstruction to the cohesion between the cement particles is also greater, so that the slump of the concrete is maintained well.

2. Lubricant effect: The hydrophilic group in the water-reducing agent is very polar, so the water-reducing adsorption film on the surface of the cement particles can form a stable solvated water film with water molecules. This layer The water film has a good lubrication effect and can effectively reduce the sliding resistance between cement particles, thereby further improving the fluidity of concrete.

3. Dispersion (electrostatic repulsion): After adding the water-reducing agent, the water-reducing agent molecules can be directionally adsorbed on the surface of the cement particles, so that the surfaces of the cement particles have the same charge (usually negative charge) , forming electrostatic repulsion, causing the cement particles to disperse with each other, the flocculation structure to disintegrate, releasing part of the wrapped water to participate in the flow, thereby effectively increasing the fluidity of the concrete mixture.