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What are the mechanism of high efficiency water reducing agent?

Release time:

2022-06-18

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　　SuperplasticizerWhat are the mechanisms of action?

Under the condition that the slump of concrete is basically unchanged, the admixture that can greatly reduce the mixing water consumption is called high-efficiency water reducing agent. Admixtures that can reduce the mixing water consumption by more than 15%. So, what is the mechanism of action of superplasticizer?

　　SuperplasticizerWhat are the mechanisms of action?

1. The action mechanism of water reducing agent is that the hydrophilic group in water reducing agent is strong, so the adsorption film of water reducing agent on the surface of cement particles can form a stable solvated water film with water molecules, which has good lubrication effect and can effectively reduce the sliding resistance between cement particles, so as to further improve the fluidity of concrete.

2. Due to the hydration of cement particles, the cement particles show the formation of an electric double layer structure, which forms a solvated water film. And the surface of the cement particles with different charges associated with each other, so that the cement slurry to form a flocculation structure, so that 10% to 30% of the mixing water wrapped in the cement particles, can not participate in free flow and lubrication, thus affecting the fluidity of the concrete mixture.

3. When the water reducing agent is added, the molecules of the water reducing agent can be adsorbed on the surface of the cement particles, so that the surface of the cement particles has the same charge (usually negative charge), forming electrostatic repulsion, promoting the mutual dispersion of the cement particles, disflocculating the structure of the tile, releasing the part of the wrapped water and participating in the flow, thus effectively increasing the fluidity of the concrete mixture.

　　SuperplasticizerWhat are the applications?

1. It is suitable for prefabricated and cast-in-place reinforced concrete in various industrial and civil buildings, water conservancy, transportation, ports, municipal engineering, etc.

2. It is suitable for high-strength and medium-strength concrete, as well as concrete with early strength, moderate frost resistance and large fluidity.

3. Precast concrete components suitable for steam curing process.

4. It is suitable for reducing water and reinforcing components of various composite admixture.

　　SuperplasticizerWhat should be paid attention to in the application of construction?

1. Amino water reducing agent is sensitive to dosage. When the amount of powder is less than 0.5%, the slump loss is very large. When used in high doses, it is easy to bleed, easy to separate, and cannot be used alone. Amino water reducing agent has large retarding effect, poor compatibility with air-entraining agent, and rapid loss of air content after compounding with air-entraining agent.

2, tea-based and melamine-based water reducing agent on the cement fluidity and concrete slump loss is larger, with coal grinding stone, tuff, pyrite slag and zeolite as the admixture of cement should be more mixed. After adding tea-based and melamine-based water reducing agent, the concrete bleeding is obvious. The tea-based water reducing agent will precipitate when it meets calcium ions, is selective to the compound, and is not suitable for use as a water reducing agent.

3. The content of sodium sulfate in onion-based water reducing agent is very high, and it is easy to precipitate crystals at low temperature. The air-entraining performance of onion-type water-reducing agent is not high, but the bubble diameter is large and the stability is poor. When it is used in concrete with high surface quality requirements, a small amount of defoaming agent needs to be compounded.

4. Ketone-based water reducing agent has a large loss on the slump of concrete dam and needs to be compounded with condensation regulator. Ketone water reducing agent will produce chloasma pattern in the early hardening stage of concrete, and concrete bleeding will increase color pollution, so it is not suitable for the preparation of structural concrete with unfinished surface. A decrease in the amount of doping can be avoided.

5. The polygalacturonic acid series water reducing agent is a chemical synthesis additive, and the defoaming agent should be compounded according to the construction needs.

Key words:

Superplasticizer

The main function of high efficiency water reducing agent

What are the classification of superplasticizer?

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