Water Reducers/Retarders

Publisher Summary This chapter examines water reducers/retarders admixtures. A water reducer can be defined as an admixture that reduces the amount of mixing water for concrete for a given workability. It improves the properties of hardened concrete and, in particular, increases strength and durability. Usually, according to standards the reduction of mixing water by the use of these admixtures must be at least 5%. However, commercial water reducers can reduce mixing water up to 10 to 15%.There is another mode of use of these admixtures, involving reduction of both water and cement, so that workability and strength of concrete containing admixtures are similar to those of the control concrete. Admixtures could thus act as cement reducers. Besides allowing cement saving, these admixtures are capable of reducing the heat of hydration, a property that is useful for concreting in hot climates or massive structures. If water reducers are added without modifying mix proportions, concrete workability improves; in this case they act as plasticizers. This is particularly useful for placing concrete in areas of high steel content thatrequire a more workable concrete.

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