Effect of Delayed Water Curing on the Compressive Strength of Concrete with Different Water–Cement Ratios

Abstract

Curing is a critical factor governing the development of concrete strength, as adequate moisture availability is necessary for continued cement hydration. However, delays in initiating water curing may occur under practical construction conditions and can adversely affect concrete strength development. This study experimentally investigates the effect of delayed water curing on the compressive strength of concrete with different water–cement ratios. Twelve concrete mixes were prepared using water–cement ratios of 0.50, 0.55, and 0.60, with water curing initiated immediately after casting or delayed by 12, 24, and 48 h. Compressive strength was evaluated at 7 and 28 days. The results showed a consistent reduction in compressive strength with increasing curing delay at all investigated water–cement ratios. After a 48 h delay, the reduction in 7-day compressive strength ranged from approximately 8.5% to 16.4%, while the corresponding reduction at 28 days ranged from approximately 10.2% to 20.6%, depending on the water–cement ratio. Increasing the water–cement ratio generally reduced compressive strength at both testing ages. However, the sensitivity to curing delay did not follow a simple trend with water–cement ratio, indicating that the magnitude of strength loss depended on both mixture proportion and curing delay. The findings emphasize the importance of initiating water curing as early as practicable, particularly under hot and dry environmental conditions.