How is a water reducing admixture defined?

How is a water reducing admixture defined?

• A. An admixture that decreases the amount of water needed for a given workability in concrete, improving strength and durability without greatly affecting setting time.
• B. An admixture that increases water demand for easier finishing.
• C. An admixture that solely improves color of concrete.
• D. An admixture that delays strength development.

Answer: (A)

Water reducing admixtures lower the amount of water needed to achieve a given workability in concrete, so you can keep the same slump with less water, which leads to higher strength and better durability. They generally do not greatly change the setting time, though small variations can occur depending on the specific chemical and dosage. This makes the statement describing lower water demand for the same workability—and not greatly affecting setting time—the best definition. The other ideas miss the core purpose: some describe increasing water demand, others focus on color, and others describe delaying strength development seen with retarders rather than with water reducers.

Water reducing admixtures lower the amount of water needed to achieve a given workability in concrete, so you can keep the same slump with less water, which leads to higher strength and better durability. They generally do not greatly change the setting time, though small variations can occur depending on the specific chemical and dosage. This makes the statement describing lower water demand for the same workability—and not greatly affecting setting time—the best definition. The other ideas miss the core purpose: some describe increasing water demand, others focus on color, and others describe delaying strength development seen with retarders rather than with water reducers.