The Influence Of The Selection Of Concrete Admixtures On The Performance Of Concrete

The functions of concrete admixtures:

The functions of concrete admixtures vary depending on the type of admixture. Generally speaking, when the water or cement usage per cubic meter of concrete remains unchanged, they can improve the fluidity of the corresponding concrete; when the cement usage remains unchanged or the slump of the concrete remains the same, they can reduce the water usage, increase the concrete strength, and improve the durability of the concrete; when the designed strength and the slump of the concrete remain unchanged, they can save the cement usage and reduce costs, etc. Accelerators can increase the early strength of concrete and are mainly used in emergency projects and concrete construction in winter; water reducers, while maintaining the workability of the concrete unchanged, have the effect of reducing water usage and enhancing performance; air-entraining agents mainly reduce the segregation caused by bubbles generated during the mixing of concrete, improving the workability of the concrete; retarders can delay the setting time of concrete and have the dual effects of retardation and water reduction. They are mainly used for large-volume concrete, concrete constructed under high-temperature conditions, or concrete transported over long distances.

Analysis of the impact of admixtures and water reducers on concrete performance:

Concrete admixtures and water reducers are mainly composed of surfactants. This type of surfactant belongs to anionic surfactants. Essentially, the concrete alkali-water agent does not undergo a chemical reaction with cement. Its effect on concrete mainly lies in the plasticization of freshly mixed concrete. Plasticization is a process of wetting, adsorbing, dispersing and lubricating.

The adsorption, dispersion, lubrication and wetting effects of admixtures and water reducers enable only a small amount of water to be used for uniform mixing of concrete, thereby improving the workability of freshly mixed concrete. This is the plasticization effect of admixtures and water reducers on freshly mixed concrete.