What are Concrete Admixtures and What are They for?

concrete mixture

A concrete admixture is a material added to the concrete before or after the mixing process. It helps modify the concrete’s properties for constructions with special requirements. It is also used to enhance or retard the setting time of concrete, which is especially useful when being transported over a long distance.

Air-entrainers

Air-entrainers are used to enhance the workability and ease of placing of fresh concrete. It also makes concrete more durable and resistant to frost, as well as reduces bleeding. Examples of air-entraining agents are neutralized vinsol resins, wood resins, sulphonated compounds, and polyethylene oxide polymers.

Retarders

A concrete retarder delays or extends the setting time of the cement paste, which is helpful when transporting it over a long distance. It also helps make it easier for the concrete to be placed at high temperatures.

Accelerators

Accelerating admixtures are used to expedite the setting time of concrete. It also provides strength to concrete in its early stages of casting. Accelerators are mostly used for emergency repair work and early formwork removal. It is also suitable for concreting during winter.

Water reducers

Water reducing admixtures make it possible for the cement to achieve greater workability with less water. This increases the strength of the concrete without the need for more cement, which helps reduce cost.

Superplasticizers

This type of concrete admixture is a synthetic chemical that works similarly with a water reducer but better. It can reduce the water content of concrete by 25% to 35% more than regular water reducers.

Benefits of using concrete admixtures

Concrete admixtures are used to enhance the workability and strength of concrete. And because of its ability to resist water, strength loss of the concrete is not an issue. Additionally, they prevent the need for more cement, making them a very cost-effective option. They are also known to resist frost, corrosion, and abrasion. They also prevent a building from overheating, which leads to fewer cracks in the concrete.

Concrete admixtures allow a more even and compact cement particle distribution, which significantly improves the concrete’s durability. A cement mix will work fine without adding concrete admixtures, but more and more are choosing to do so anyway because of their physical and economic benefits.