Which curing methods are approved for cylinder specimens?

• A. Dry curing in air.
• B. Immersion in hot water.
• C. Moist curing or sealed curing.
• D. No curing required.

Answer: (C)

Keeping cylinder specimens properly cured ensures continued hydration and the development of their designed strength. The approved methods are moist curing, which maintains surface moisture through water or humidity, and sealed curing, which uses plastic or another impermeable wrap to prevent moisture loss. Dry curing in air dries the surface and can lead to lower strength than expected, so it isn’t approved. Immersion in hot water can alter hydration conditions and introduce thermal effects that aren’t part of the standard curing process, and no curing required would fail to preserve moisture, giving an inaccurate representation of the concrete’s performance. Therefore, moist curing or sealed curing are the acceptable methods.