Admixture is the material added to improve and adjust the performance of concrete. As an important part of the concrete industry, it has played a more and more important role. Adding proper amount of admixture in concrete can improve concrete quality, improve concrete performance, reduce concrete water consumption, save cement, reduce cost and speed up construction progress. It is the least amount of concrete material but has a great impact on its performance of the component.
Classification of concrete admixture and its principle of action:
Early strength agent
Generally mixed into cement mortar or concrete can accelerate cement mortar or concrete hardening, improving concrete strength, especially the early strength of the admixture called early strength agent. More commonly used early strength agents are chlorine salts, sulfate early strength agent, triethanolamine complex early strength agent. Each component of the composite early strength agent acts at a different stage of the structure formation of the cement set. Through the proper combination of various admixtures, the reaction properties of liquid and solid phases and the physical and mechanical properties of crystal structure of cement stone can be affected in the most effective way.
Water reducing agent
Water reducing agent is used to reduce water consumption per unit, and can improve the fluidity of concrete mixture. The development of water-reducing agents has experienced the lignosulphonate in the 1930s, naphthalene and melamine in the 1960s, and the polycarboxylic acid series of high performance water reducing agents developed in Japan in the 1990s. In recent years, polycarboxylic acid water-reducing agents are the best prospect in research and application. A large number of studies have been carried out at home and abroad, and also obtained rapid development.
Water reducing agent plays a very important role in the development of new concrete technology all over the world, promoting the application of industrial by-products in the cementitious material system, and has gradually become an essential material for high quality concrete. In addition to the extensive use of polycarboxylic acid water-reducing agents, there is also a widespread use of lignosulphonate in Malaysia.
Retarders are divided into organic retarders and inorganic retarders. The inorganic retarder mainly includes phosphate, metaphosphate, borax, sodium fluorosilicate and so on. Organic retarders mainly include hydroxyl carboxylic acids, amine carboxylic acids and their salts, polyols and their derivatives, sugars and other compounds. It is used to prolong the hardening time of concrete mixture.
It is also known as an aerating agent. In the process of mixing, it can produce a large number of tiny bubbles, can improve the workability, water retention and cohesion of concrete mixture, and improve fluidity.
The admixture that can improve concrete pumping performance is called pumping agent. It has the effect of reducing water and delaying coagulation.
It speeds up the hardening of concrete.
Waterproof agent can play a waterproof, anti-freeze crack function.
Rust and corrosion inhibitor
It prevents steel from rusting.
Expansion agent is a kind of material which can cause volume expansion through physical and chemical reactions. It is mainly used to compensate for shrinkage during hardening of materials and prevent cracking.
A substance that prevents moisture in concrete from freezing at low temperatures.
It is used to prepare concrete with stable color.
Different admixtures have different functions. This is a basic raw material industry in the construction industry, and is an extremely important branch. Within the prescribed dosage, admixtures generally have few side effects.