Review on all kinds of water reducing agent for concrete

2019-06-13 11:16:54

What are the three types of water reducing agents with different water reducing effects?

According to the effect of water-reducing agents, they can be divided into the following three categories: (1) ordinary water-reducing agent, also known as plasticizer, its water-reducing rate is not less than 8%, and its main component is lignin sulfonate; (2) high-efficiency water-reducing agent, also known as superplasticizer, its water reduction rate is not less than 14%, and its main component is represented by tea water-reducing agent; (3) high-performance superplasticizer, its water reduction rate is not less than 25%, the polycarboxylic acid series superplasticizer is regarded as a representative.

What are the five main types of new efficient water reducing agents?

(1) Polycarboxylic acid series of water reducing agent: polycarboxylic acid type of water reducer molecules have a lot of chains. In the main chain there are some  strong polar anion and the surface of the electrical layer combined together, which  forms a hydrated film. Due to the above mentioned, it not only enhances the adsorption between molecules but also produces spatial steric resistance, and so it has a good plasticizing effect. However, this kind of water-reducing agent is very expensive, so its application is limited to some extent. At present, the polycarboxylate based superplasticizer with the comprehensive efficiency and high performance is the best water reducing agent.

(2) Naphthalene series efficient superplasticizer: naphthalene series efficient superplasticizer has electrostatic repulsion effect and molecular mutual repulsion between electric charges. Due to the certain decomposition on the cement in the hydration process of its own flocculation, the free water contained in it can be pushed out. Therefore, you can see the water reduction effect is obvious. Compared with polycarboxylic acid series superplasticizer, naphthalene series superplasticizer has a relatively mature technology with low price.

(3) Aminosulfonic acid series superplasticizer: modified amino sulfonic acid series superplasticizer is a non-air-entraining resin type high-efficiency superplasticizer, whose water reduction rate can reach more than 25%, to the concrete workability and durability have significant enhancement. However, the production cost of sulfamic acid series superplasticizer 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 of this kind of water-reducing agent is mostly effectively reduce the shortcomings in use and expand the market prospect through modifying aminosulfonic acid and dispersing cement particles.

(4) Modified lignosulfonate superplasticizer: modified lignosulfonate superplasticizer is obtained by modifying lignosulfonate. The new modified lignin sulfonate is a high-efficiency water-reducing agent, its water-reducing rate is 1.5 times higher than that of other ordinary water-reducing agents. The hydration heat and collapse degree of cement are changed to effectively ensure the excellent performance of concrete, and the production cost is low, which is conducive to construction.

(5) Hybrid water reducing agent: water reducing agent is blend by mixing the quaternary copolymer acrylate graft copolymer, which contains amino benzene sulfonic acid maleic acid amide and vinyl pyrrole copolymer. And at the same time due to other copolymer containing sulfonic acid and carboxylic acid based combining together, the functions of their different anion and polarity of functionality can be used as a super plasticizer of a variety of polymers and copolymers, and so it can have cement particle effects. The production of mixed superplasticizer is complicated, and the optimization of mixing amount needs a lot of experiments.

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