What are Admixtures?

Admixtures are additional materials that are added to the mix constituents to improve the properties of the concrete. A selection of admixtures and their uses are listed below:

Superplasticisers
Give a high workability concrete without the need for excess water in the mix. Very good in applications where placing of the concrete is difficult, i.e. heavily reinforced areas etc.

Retarders
These are particularly useful for hot weather concreting as they delay the initial set of the concrete. A normal dose will retard the concrete for 2-4 hours. Also used to produce an exposed aggregate finish on concrete surfaces.

Accelerators
Increase the rate of chemical reaction which aids the development of early strength in concrete. Particularly useful in the winter where conditions often require rapid strength in concrete in order to withstand effects of low temperatures.

Air Entraining Agents
Improve workability and durability of concrete. Cohesion is also increased which reduces the risk of segregation and bleeding.

Expanding Agents
Used to avoid cracking and to compensate for water loss and plastic settlement.

Fibres
Assist in crack control and increase durability.

Waterproofers
Reduce the rate at which water can penetrate into or through concrete.

Colour Pigments
Produce decorative coloured concrete. Available in a variety of colours.