What Is a Cement Water Reducer?

A cement water reducer is a chemical admixture that decreases the amount of water used in concrete. This decrease in water allows the concrete to hydrate at a lower rate, giving it better strength and durability.

Low-range water reducers, also known as normal water reducers or regular plasticizers, typically lower the amount of water in a mix by 5 to 10%. These water reducers are often used in everyday concrete applications such as driveways, sidewalks, and basement walls.

Mid-range water reducers, also called plasticizers or intermediate plasticizers, typically lower the amount of concrete that needs to be mixed by 15 to 20%. These admixtures are often used in concrete for flatwork, such as driveways and sidewalks, because they reduce the water needed to produce a good-quality surface.

High-range water reducers, also known to be superplasticizers or high range admixtures, are synthetic water-soluble organic compounds that decrease the amount of water in concrete by 25 to 30%. This results in a higher fluidity of the concrete, allowing it to flow better and provide more flexibility for placements.

These admixtures are usually added to the concrete mixture at a low dosage rate, although some high-range admixtures require a higher dose for optimal performance.

Most of these admixtures have no effect on the hydration of the cement, but some - like polycarboxylates - may increase air entrainment. This will vary depending on the chemistry of the admixture and its dosage rate. It is important to select the proper admixture for the application.