Many water treatment chemicals are used in admixtures for concrete, such as chelating agents, polymeric dispersants, biocides, etc.

ISO 19596-2017
Admixtures for concrete

3.2 Specific definitions
3.2.1 admixtures for concrete
material added during the mixing process of concrete in a quantity not more than 5 % by mass of the cement content of the concrete, to modify the properties of the mix in the fresh and/or hardened state

3.2.2 water reducing/plasticizing admixture
admixture which without affecting the consistence, permits a reduction in the water content of a given concrete mix, or which, without affecting the water content increases the workability/consistency or produces both effects simultaneously

3.2.3 high range water reducing/super plasticizing admixture
admixture which, without affecting the consistence, permits a high reduction in the water content of a given concrete mix, or which, without affecting the water content increases the workability/consistency considerably, or produces both effects simultaneously

3.2.4 water retaining admixture
admixture which reduces the loss of water by a reduction of bleeding

3.2.5 air entraining admixture
admixture which allows a controlled quantity of small, uniformly distributed air bubbles to be incorporated during mixing which remain after hardening

3.2.6 set accelerating admixture
admixture which decreases the time to commencement of transition of the mix from the plastic to the rigid state

3.2.7 hardening accelerating admixture
admixture which increases the rate of development of early strength in the concrete, with or without affecting the setting time

3.2.8 set retarding admixture
admixture which extends the time to commencement of transition of the mix from the plastic to the rigid state

3.2.9
water resisting admixture
waterproof admixture
admixture which reduces the capillary absorption of hardened concrete

3.2.10 set retarding/water reducing/plasticizing admixture
admixture which produces the combined effects of a water reducing/plasticizing admixture (primary function) and a set retarding admixture (secondary function)

3.2.11 set retarding/high range water reducing/superplasticizing admixture
admixture which produces the combined effects of a high range water reducing/superplasticizing admixture (primary function) and a set retarding admixture (secondary function)

3.2.12 set accelerating/water reducing/plasticizing admixture
admixture which produces the combined effects of a water reducing/plasticizing admixture (primary function) and a set accelerating admixture (secondary function)

3.2.13 slump and air retentions/high range water reducing/air entraining admixture
admixture that enable reduction in the water content, while providing slump and air retentivity, without affecting the consistence

3.2.14 viscosity modifying admixture
admixture incorporated in concrete to limit segregation by improving cohesion

3.2.15 antiwashout admixture
admixture that significantly reduces the washout of cement during underwater placing and hardening of concrete

3.2.16 antifreezing admixture
admixture which allows concrete to set and develop compressive strength at temperatures below freezing