Beijing Dongke United Technologies Co.,Ltd.

Concrete plasticizer additives

Water reducer is a concrete admixture that can reduce the water consumption for mixing while maintaining the slump of concrete basically unchanged. Most of them are anionic surfactants, such as lignosulfonate, naphthalenesulfonate formaldehyde polymer and so on. After adding the concrete mixture, it can disperse 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.

The appearance form is divided into liquid and powder. The solid content of water is generally 20%, 40% (also known as mother liquor), 60%, and the solid content of powder is generally 98%. According to the water reducing and enhancing ability of water reducing agent, it can be divided into ordinary water reducing agent (also known as plasticizer, water reducing rate is not less than 8%, represented by lignosulfonate), high efficiency water reducing agent ( Also known as superplasticizer, the water reducing rate is not less than 14%, including naphthalene, melamine, sulfamate, aliphatic, etc.) and high-performance water reducing agent (the water reducing rate is not less than 25%, with Polycarboxylic acid water reducing agent is representative), and are divided into early strength type, standard type and retarded type.

After the cement is mixed with water, due to the hydration effect of the cement particles, the cement particles show the formation of an electric double layer structure, which makes it form a solvated water film, and the surface of the cement particles has an opposite charge to cause the association between the cement particles and make the cement The slurry forms 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, thus 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 cement particles, the surface of the cement particles is charged with the same charge (usually negative charge), which forms electrostatic repulsion, which promotes the mutual dispersion of cement particles and the disintegration of the flocculation structure. , Release part of the water that is wrapped, participate in the flow, thereby effectively increasing the fluidity of the concrete mixture.

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 lubricating effect and can be effective Reduce the sliding resistance between cement particles, thereby further improving the fluidity of concrete.

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 lubricating effect and can be effective Reduce the sliding resistance between cement particles, thereby further improving the fluidity of concrete.

The hydrophilic branch in the water reducer 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, the adsorption layer begins to overlap, that is, steric hindrance is generated between the cement particles. The more overlap, the greater the steric hindrance repulsion, and the greater the obstacle to the cohesion between the cement particles, causing the concrete to collapse The degree is maintained well.

In the process of preparing new water-reducing agents such as polycarboxylic acid water-reducing agents, some branched chains are grafted on the molecules of the water-reducing agent. This branching chain can not only provide steric hindrance, but also, in the cement hydration In a high-alkalinity environment, the branch chain can also be slowly cut to release polycarboxylic acid with dispersing effect, which can improve the dispersion effect of cement particles and control slump loss.

It is suitable for pumping or normal concrete projects with strength grades of C15~C60 and above. It is especially suitable for the preparation of concrete projects with high durability, high fluidity, high slump retention, high strength and high appearance quality requirements. It is extremely beneficial for the preparation of high-fluidity concrete, self-compacting concrete and fair-faced concrete.

Ordinary water reducing agent should be used for concrete constructed with daily minimum temperature above 5℃. High-efficiency water reducing agent is suitable for concrete construction with daily minimum temperature above 0℃, and is suitable for preparing high-fluidity concrete, high-strength concrete and steam-cured concrete.

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