Plasticizers or high-range water reducers (HRWR) constitute a special class of water-reducers .

•  HRWRs reduce the water content of a given concrete by 12 to 30%, which increases strength.

•  Essential for use in high strength and high performance concrete mixtures.

•  HRWRs can also greatly increase the slump to produce "flowing" concrete. A normal dosage will increase slump from 3-4 inches up to about 8 inches. Flowing concrete is a highly fluid but workable concrete that can be placed with little or no vibration or compaction.

•  Flowing concrete will return to its original slump within 30 to 60 minutes, so HRWRs are usually added at the job site.

•  HRWRs are covered by ASTM C494 and C 1017.