1. What is a high-efficiency water-reducing agent?
A water-reducing agent is a kind of agent that can reduce the amount of mixing water while maintaining the slump of concrete basically unchanged. Concrete admixtures have a dispersing effect on cement particles after being added to concrete mixtures, which can improve their workability, reduce unit water consumption, and improve the fluidity of concrete mixtures; or reduce unit cement consumption and save cement.
High-efficiency water-reducing agent is a water-reducing agent that can significantly reduce the amount of mixing water under the condition that the slump of concrete is basically the same. Its water-reducing rate can reach more than 20%, which can significantly reduce water consumption, thereby significantly improving the strength of concrete at all ages.
2. What are the types of high-efficiency water reducing agents
High-efficiency water-reducing agents are different from ordinary water-reducing agents. They have a higher water-reducing rate and lower air entrainment capacity. The main types of high-efficiency water-reducing agents currently used include the following:
1. Naphthalene-based water-reducing admixtures
Naphthalene-based high-efficiency water-reducing admixtures can be divided into high-concentration products (Na2SO4 content 10%). Naphthalene-based water-reducing agents are the most produced and widely used high-efficiency water-reducing agents in my country (accounting for more than 70% of the water-reducing agent dosage). They are characterized by high water-reducing rates (15% to 25%) and no air entrainment. , has little impact on the setting time, has relatively good adaptability to cement, can be used in combination with various other admixtures, and is relatively cheap.
2. Melamine and modified melamine water-reducing agents
It is the product of melamine sulfonated with sulfuric acid and then condensed with formaldehyde. Therefore, the chemical name is sulfonated melamine formaldehyde resin, which is an anionic surfactant. This type of water-reducing agent appears as white powder, is easily soluble in water, has good dispersion of powder materials, has a high water-reducing rate, and has good fluidity and self-healing properties.
3. Sulfamate water-reducing agent
Sulfamate high-efficiency water-reducing agent is a monocyclic aromatic hydrocarbon-type high-efficiency water-reducing agent. , mainly composed of p-aminobenzenesulfonic acid, monocyclic aromatic hydrocarbon derivatives phenolic compounds and formaldehyde, which are heated and condensed under acidic or alkaline conditions. The molecular structure of sulfamic acid-based high-efficiency water-reducing agents is relatively complex, and differentThe monomers have different molecular structures. The main chain of the amino acid sulfonate superplasticizer is alternately linked by phenyl and methylene groups. The main chain contains a large number of sulfonic acid groups, amino groups, hydroxyl groups and other hydrophilic groups. Functional group branching.
4. Aliphatic (aldehyde and ketone condensate) water-reducing agent
Aliphatic high-efficiency water-reducing agent is carbonyl pyroaldehyde synthesized by polymer sulfonation. , the hydrophobic main chain is aliphatic hydrocarbons. This high-efficiency water-reducing agent has wide applicability to cement, obvious reinforcement effect on concrete, small slump loss, and no sodium sulfate crystallization phenomenon at low temperatures. It is widely used in the preparation of pumping agents. , retarding, early strength, antifreeze, air entraining and other types of personalized water-reducing agents, which can also be used in combination with naphthalene-based water-reducing agents, amino water-reducing agents, and polycarboxylate water-reducing agents.
5. Anthracene water-reducing agent
A tan powder made by sulfonation, hydrolysis condensation, neutralization, atomization and drying of crude anthracene. Toxic, odorless, and does not contain chloride ions. It has high water reduction rate in concrete mixing, low air entrainment volume, high reinforcement, good workability in concrete mixture construction, and is not easy to bleed or segregate. It is suitable for C10~C60 strength. grade of concrete.
6. Washing oil-based water-reducing agent
Using coking washing oil, another by-product of coal coking, as raw material, it is mixed with naphthalene-based water-reducing agent. The production process is similar to the water agent, and the polycyclic aromatic hydrocarbon sulfonate formaldehyde condensate is produced, and its performance is similar to that of the naphthalene series water reducing agent. It is a water-reducing agent with wide sources of raw materials, low cost and great industrial value.
3. What is the difference between high-efficiency water-reducing admixtures and ordinary water-reducing admixtures?
Both high-efficiency water-reducing admixtures and ordinary water-reducing admixtures can effectively improve concrete. The rheological properties of the mixture have similar functions, but in other aspects, the two water-reducing agents are different:
1. The water-reducing rate of ordinary water-reducing agents is usually 5% to 10%; while the high-efficiency water-reducing agent The water reducing rate of water reducing agent can reach 12%~25%, or even higher.
2. High-efficiency water-reducing admixture can greatly improve the workability of concrete under the condition that the water-cement ratio remains unchanged. For example, adding high-efficiency water-reducing admixture can prepare high-fluidity concrete with a slump of 25cm. , and at the same time, it will not entrain excessive air, nor will it cause excessive retardation of concrete; and under the condition that the cement dosage remains unchanged, the slump of concrete mixed with ordinary water-reducing agent is usually about 10cm.
3. Under the condition that the slump is basically the same, high-efficiency water-reducing admixtures can significantly reduce the mixing water consumption of concrete and significantly reduce the water-cement ratio, thus greatly increasing the strength of concrete. Therefore, high-efficiency water-reducing admixtures It is mainly used to prepare fluid concrete with high strength level and high water reduction requirements; while the water reducing rate of ordinary water reducing agent is relatively low and is mainly used to prepare concrete with low strength level and low water reduction requirements.
4. In terms of preparation cost, polycarboxylate high-efficiency water-reducing agent has a high solid content, so the price is relatively high; while ordinary water-reducing agent has a low solid content, and the price will be low.
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