1. Dispersion effect. The water-reducing agent molecules can be directionally adsorbed on the surface of cement particles, so that the surfaces of the cement particles carry the same charge (usually negative charge), forming an electrostatic repulsion that promotes the cement particles to disperse each other, the flocculation structure to disintegrate, and the trapped water is released. Participate in the flow, thereby effectively increasing the fluidity of the concrete mixture.
2. Lubricating effect. The hydrophilic group in the water-reducing agent is very polar, so the water-reducing agent adsorption film on the surface of the cement particles can form a stable solvated water film with water molecules. This 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. Steric hindrance. The hydrophilic branched chain in the superplasticizer structure stretches 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 are close to each other, the adsorption layers begin to overlap. The more overlap, the greater the steric repulsive force, and the greater the obstruction to the cohesion between cement particles, so that the slump of concrete is maintained well.
4. The sustained-release effect of grafted copolymer branches. The molecules of the new water-reducing agent are grafted with some branched chains, which not only provide steric hindrance effect, but also can be slowly cut off in the high alkalinity environment of cement hydration, thereby releasing Polycarboxylic acid with dispersing effect is produced, which can improve the dispersion effect of cement particles and control slump loss.
How to use water reducing agent:
(1) Naphthalene series high-efficiency water reducing agent
1. Dosage range: powder: 0.75-1.5%; liquid: 1.5-2.5%.
2. When using porous aggregates, it is advisable to add water and stir first, then add water-reducing agent.
3. When the slump is large, attention should be paid not to vibrating for too long to prevent bleeding and delamination.
(2) HSB aliphatic superplasticizer
1. Find out through experiments The optimal dosage is 1.5-2%;
2. Add HSB to the concrete together with the mixing water, or you can add it later. The mixing of HSB concrete should be extended for 30 seconds;
3. Due to the large water reduction rate of HSB, before the initial setting of the concrete, a layer of yellow slurry will be secreted on the surface. normal phenomenon. The color will disappear after the concrete is pounded and grouted, or the color will disappear naturally after the concrete is strengthened. The color will disappear faster through watering and curing without affecting the internal and surface properties of the concrete. </p
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