What is added to concrete to reduce water requirements by up to 30%?

What is added to concrete to reduce water requirements by up to 30%?

• A. fly ash
• B. air entrainment
• C. super plasticizer
• D. more cement

Answer: (C)

The key idea is that concrete can keep its workability while using much less water by using a high-range water-reducing admixture. A superplasticizer is designed for this purpose: it disperses cement particles so they flow more easily, allowing you to reach the same slump with significantly less water—often up to about 30% less. This improves strength and durability because the water-to-cement ratio is lower, without sacrificing workability. Fly ash is a supplementary cementitious material that can improve durability and sometimes workability, but it isn’t primarily used to cut water demand by such a large amount. Air entrainment adds tiny air voids to enhance freeze‑thaw resistance and doesn't reduce water required. Adding more cement would actually increase, not decrease, the water needed.

The key idea is that concrete can keep its workability while using much less water by using a high-range water-reducing admixture. A superplasticizer is designed for this purpose: it disperses cement particles so they flow more easily, allowing you to reach the same slump with significantly less water—often up to about 30% less. This improves strength and durability because the water-to-cement ratio is lower, without sacrificing workability.

Fly ash is a supplementary cementitious material that can improve durability and sometimes workability, but it isn’t primarily used to cut water demand by such a large amount. Air entrainment adds tiny air voids to enhance freeze‑thaw resistance and doesn't reduce water required. Adding more cement would actually increase, not decrease, the water needed.