What is a water reducer? What's the use?

Water reducer is a kind of concrete admixture which can reduce the mixing water consumption while keeping the slump of concrete basically unchanged. Most of them belong to anionic surfactants, such as lignosulfonate, naphthalene sulfonate formaldehyde polymer and so on.

Function:

Adding concrete mixture can disperse cement particles, improve its workability, reduce unit water consumption and improve the fluidity of concrete mixture, or reduce unit cement consumption and save cement. ?

Mechanism of action

(1) Decentralization

After cement is mixed with water, due to the hydration of cement particles, the surface of cement particles forms an electric double layer structure, which makes them form a solvated water film, and the surface of cement particles has opposite charges, which makes cement slurry form a flocculation structure, so that 10% ~ 30% of mixed water is wrapped in cement particles and cannot participate in free flow and lubrication, thus affecting the fluidity of concrete mixture.

(2) Lubrication

The hydrophilic groups in the water reducer are very polar, so the water reducer adsorption film on the surface of cement particles can form a stable solvated water film with water molecules, which has a good lubricating effect and can effectively reduce the sliding resistance between cement particles, thus further improving the fluidity of concrete.

(3) steric hindrance

Hydrophilic branches in the structure of water reducer extend in aqueous solution, thus forming a hydrophilic three-dimensional adsorption layer with a certain thickness on the surface of adsorbed cement particles.

(4) Sustained-release effect of grafted multi-branches

In the preparation process of new water reducer, such as polycarboxylic acid water reducer, the water reducer molecules are grafted with some branched chains, which not only can provide steric effects, but also can be slowly cut off in the high alkalinity environment of cement hydration, releasing polycarboxylic acid with dispersion effect, thus improving the dispersion effect of cement particles and controlling slump loss.

Refer to the above? Baidu encyclopedia-water reducer