Concrete Admixtures

Concrete Admixtures

Concrete admixtures are liquids or powders which are added to the concrete during mixing in small quantities, normally based on the cement content. They influence the properties of the fresh and/or hardened concrete chemically and/or physically.

The standard includes the following under “Special Terms” (slightly abbreviated):

Admixtures – definitions and effects

·     Water reducer

Enables the water content of a given concrete mix to be reduced without affecting the consistence, or increases the workability without changing the water content, or achieves both effects.

·     Super plasticizer

Enables the water content of a given concrete mix to be greatly reduced without affecting the consistence, or greatly increases the workability without changing the water content, or achieves both effects.

·     Stabilizer

Reduces mixing water bleeding in the fresh concrete.

·     Air entrainer

Introduces a specific quantity of small, evenly distributed air voids during the mixing process which remain in the concrete after it hardens.

·     Set accelerator

Reduces the time to initial set, with an increase in initial strength.

·     Hardening accelerator

Accelerates the initial strength with or without an effect on the setting time.

·     Retarder

Retards the time to initial set and prolongs the consistence.

·     Water proofer

Reduces the capillary water absorption of the hardened concrete.

·     Retarder/water reducer

Has the combined effects of a water reducer (main effect) and a retarder (additional effect).

·     Retarder/super plasticizer

Has the combined effects of a super plasticizer (main effect) and a retarder

(additional effect).

·     Set accelerator/water reducer

Has the combined effects of a water reducer (main effect) and a set accelerator (additional effect).