Curing in concrete continues until the relative humidity in the concrete drops below what percent?

Curing in concrete continues until the relative humidity in the concrete drops below what percent?

• A. 40
• B. 50
• C. 80
• D. 90

Answer: (C)

Curing keeps concrete moist so the cement paste can fully hydrate. The interior moisture of the concrete is measured as relative humidity in the pores. As curing proceeds, moisture is lost and the internal RH drops. The standard guideline is to continue curing while that internal relative humidity stays at or above eighty percent because, at or above this level, there is enough water for ongoing hydration to develop strength and reduce early cracking. Once the internal RH falls below eighty percent, hydration slows significantly and keeping the concrete moist offers diminishing returns, so curing is considered effectively complete. The other percentages don’t align with this practical threshold for moisture-driven strength gain.

Curing keeps concrete moist so the cement paste can fully hydrate. The interior moisture of the concrete is measured as relative humidity in the pores. As curing proceeds, moisture is lost and the internal RH drops. The standard guideline is to continue curing while that internal relative humidity stays at or above eighty percent because, at or above this level, there is enough water for ongoing hydration to develop strength and reduce early cracking. Once the internal RH falls below eighty percent, hydration slows significantly and keeping the concrete moist offers diminishing returns, so curing is considered effectively complete. The other percentages don’t align with this practical threshold for moisture-driven strength gain.