Summary of five types of concrete water reducer

 Overview of superplasticizer

The superplasticizer can significantly improve the fluidity of the mixing slurry so that the foam mud can reach self-leveling in the mold and reduce or even no bread. It can greatly reduce water consumption while maintaining the slump of concrete. Water reducers are also called dispersants or plasticizers. It is the most commonly used admixture.

Principle of water reducing agent:

The specific surface area of cement is generally 350-400m2/kg, and more than 90% of the cement particles have a particle size in the range of 7-80 microns, which belongs to the category of fine powder particles. For cement-water systems, the surfaces of cement particles and hydrated cement particles have a slightly polar surface and are highly hydrophilic. Fine cement particles have considerable specific surface energy (solid-liquid interface energy). In order to reduce the total heat on the surface solid and liquid, fine cement particles tend to spontaneously condense into flocs to minimize the interface energy of the system and make the system thermodynamic. keep it steady. At the same time, in the early stage of cement hydration, the surface of C3A particles is positively charged, while the surfaces of C3S and C2S particles are negatively charged.

There are three watering methods in concrete: free water combined with water and adsorbed water. In the initial stage of cement mixing, there is less chemically bound water and adsorbed water, and the mixed water mainly exists in the form of free water. However, due to the flocculating structure of cement particles, 10%-30% of the open water is wrapped in them, thereby severely reducing the fluidity of the concrete mixture. The main function is to destroy the flocculation structure of cement particles, keep them in a dispersed state, and release free water in the packaging and flocs, thereby improving the fluidity of fresh concrete.

The role of superplasticizer:

1. Reduce the solid-liquid interface energy of cement particles

2. Electrostatic repulsion

3. Spatial repulsion

4. Lubrication effect of hydration film

According to the effect of water reducer, it can be divided into the following three categories: (1) Ordinary water reducer, also known as a plasticizer, its water reducing rate is not less than 8%, and its main component is lignosulfonate; (2) ) High-efficiency water-reducing agent, also known as high-efficiency water-reducing agent, the water-reducing rate is not less than 14%, and its main component is represented by tea water-reducing agent; (3) High-performance water-reducing agent, its water-reducing rate is not less than 25 %, represented by polycarboxylic acid series water reducer

Five main types of new superplasticizers

(1) Polycarboxylic acid type water reducing agent: The polycarboxylic acid type water reducing agent molecule has many chains. In the main chain, there are some strong polar anions that combine with the surface of the electric layer to form a hydrated film. Due to the above reasons, it not only enhances the adsorption between molecules but also produces steric hindrance, so it has a good plasticizing effect. However, this kind of water reducing agent is very expensive, so its application is limited to a certain extent. At present, the polycarboxylate superplasticizer with comprehensive efficiency and high performance is the best superplasticizer.

(2) Naphthalene-based superplasticizer: Naphthalene-based superplasticizer has electrostatic repulsion and mutual repulsion of molecules between charges. Since cement will decompose to a certain extent during the hydration process of self-flocculation, the free water contained in the cement can be discharged. Therefore, it can be seen that the water reduction effect is obvious. Compared with polycarboxylic acid superplasticizers, naphthalene superplasticizers have relatively mature technology and low prices.

(3) Sulfamic acid series superplasticizer: Modified amino sulfonic acid series superplasticizer is a kind of non-air-entraining resin type superplasticizer, its water reduction rate can reach more than 25%, and it is effective for concrete. Processability and durability have been significantly improved. However, the production cost of sulfamic acid-based superplasticizers is relatively high. When the molecular weight is too small or too large, it is easy to cause bleeding, segregation, and hardening. At present, the research on this type of water-reducing agent is mainly through modifying sulfamic acid and dispersing cement particles, effectively reducing the shortcomings in use and expanding the market prospects.

(4) Modified lignosulfonate superplasticizer: The modified lignosulfonate superplasticizer is made by modifying lignosulfonate. The new modified lignosulfonate is a high-efficiency water-reducing agent, and its water-reducing rate is 1.5 times that of other common water-reducing agents. Changing the hydration heat and collapse degree of cement effectively guarantees the excellent performance of concrete, has low production cost, and is conducive to construction.

(5) Hybrid water-reducing agent: a water-reducing agent made by mixing a quaternary ammonium salt acrylate graft copolymer containing aminobenzenesulfonic acid maleic amide and vinyl pyrrole copolymer. And at the same time, due to the combination of other copolymers containing sulfonic acid and carboxylic acid groups, their different anionic functions and functional polarities can be used as superplasticizers for various polymers and copolymers, so it can have a Cement particle effect. The production process of the mixed superplasticizer is more complicated, and the optimization of the mixing amount still requires a lot of experiments

Application of superplasticizer

With the continuous improvement of society and production technology, in the construction industry, the quality and performance requirements of concrete are becoming more and more stringent, and the quality of buildings is directly affected by the performance of concrete.

The invention of concrete admixture greatly improved this problem. Commercial concrete mixed with a water-reducing agent greatly improves the work performance, increases the strength of the concrete, and improves the durability and service life of the concrete. This is a remarkable achievement. Used in the construction industry.

Water reducing agents are widely used in various key infrastructures, especially high-rise buildings, super high-rise buildings, high-speed railways, highways, subway stations, nuclear power plants, etc., which promote the rapid development and strong protection of the construction industry. industry.

The water-reducing agent is an additive, which can significantly reduce or greatly reduce the mixing water of concrete in the concrete mixing process, and improve the fluidity and strength. It has been proved that if the water-reducing agent is added to the concrete if it is not necessary to increase the strength, it can greatly reduce the amount of cement and improve the compactness of concrete. Therefore, water reducing agent is an indispensable additive in commercial concrete.

In order to further improve the economic benefits of commercial concrete, concrete manufacturers like to use water-reducing agents with higher water-reducing properties to increase the strength of concrete or greatly reduce the amount of cement and reduce production costs.

In fact, this is a major misunderstanding. Although water reduction is beneficial to improve the compressive strength of concrete, excessive water reduction can also adversely affect the flexural strength of concrete.

Although proper water reduction is conducive to reducing the shrinkage of concrete, it must be noted that when designing the concrete mix, the water-reducing function of the water-reducing agent has been considered, and the water-cement ratio in the overall design is low, such as further reducing. The amount of water used will increase the shrinkage rate of the concrete and increase the shrinkage rate of the concrete.

When commercial concrete greatly reduces the amount of cement, although the compressive strength does not decrease, as the volume of hardened cement stone in the concrete decreases, the tensile strength will decrease.

Due to the reduction of cement consumption, the concrete grouting layer is too thin, which will cause more micro-cracks in the concrete. Of course, the micro-cracks have little effect on the compressive strength of concrete, but they cannot affect the tensile strength and other properties of concrete. The large reduction in neglected cementitious materials will also affect the elastic modulus and creep of concrete, making it easier to crack. In commercial concrete production, the water reduction rate of concrete and the number of cementitious materials must be considered comprehensively. Do not reduce the moisture or excessively reduce the cementitious material.

The price of superplasticizer

The price of superplasticizers varies randomly with production costs, transportation costs, international conditions, exchange rates, and market supply and demand of superplasticizers. Tanki New Materials Co. Ltd aims to help all industries and chemical wholesalers find high-quality products by providing a full range of products. If you are looking for a superplasticizer, please contact us for the latest price.

Suppliers of superplasticizers

As a global supplier of superplasticizers, Tanki New Materials Co., Ltd. Has extensive experience in the performance, application, and cost-effective manufacturing of advanced and engineering materials. The company has successfully developed a series of foam concrete additives (including lightweight concrete, CLC blocks provide concrete foaming agents, superplasticizers, foam concrete strength enhancers, etc.), high-purity targets, and functional materials. Ceramics and structural equipment, and provide OEM services.