Water reducing agent action mechanism
Dispersion: After the cement is mixed with water, due to the hydration of the cement particles, the cement particles show the formation of an electric double layer structure, which causes it to form a solvated water film, and the surface of the cement particles has a heterogeneous charge to cause association between the cement particles. To make the cement slurry form a flocculating structure, so that 10% to 30% of the mixing water is wrapped in the cement particles, which cannot participate in free flow and lubrication, thereby affecting the fluidity of the concrete mixture. When the water reducing agent is added, because the water reducing agent molecules can be adsorbed on the surface of the cement particles in a directional manner, the surface of the cement particles has the same charge (usually a negative charge), forming an electrostatic repulsion effect, promoting the dispersion of the cement particles and the disintegration of the flocculated structure , Release part of the wrapped water, participate in the flow, thereby effectively increasing the fluidity of the concrete mixture.  Lubricating effect: The hydrophilic group in the water reducing agent is very polar, so the water reducing agent adsorption film on the surface of cement particles can form a stable solvated water film with water molecules. This layer of water film has a good The lubricating effect can effectively reduce the sliding resistance between the cement particles, thereby further improving the fluidity of the concrete. Steric hindrance: Hydrophilic branches in the structure of the water reducing agent stretch in the aqueous solution, thereby forming a hydrophilic three-dimensional adsorption layer with a certain thickness on the surface of the adsorbed cement particles. When the cement particles approach, the adsorption layer begins to overlap, that is, steric hindrance occurs between the cement particles. The more overlap, the greater the steric repulsion force, and the greater the obstacle to the cohesion between the cement particles, making the concrete slump. Degree remains good. Slow-release effect of graft copolymerized branched chains: During the preparation process of new water-reducing agents such as polycarboxylic acid water-reducing agents, some branches are grafted on the molecules of the water-reducing agent. The branches not only provide space In addition, in the high alkalinity environment of cement hydration, the branch chain can be slowly cut off to release polycarboxylic acids with a dispersing effect, which can improve the dispersing effect of cement particles and control slump. Slope loss.