Experimental investigation of hydration temperature variation in reinforced concrete beam construction under winter conditions

This study investigates the early-age thermal behaviour and hydration process of large-scale reinforced concrete beams cast under both winter and summer conditions, with a focus on the influence of fresh concrete temperature, admixture use, and environmental factors. Temperature monitoring was conducted for a minimum of 72 h using embedded sensors, and special attention was given to winter concreting under natural atmospheric conditions. Two winter casting scenarios were defined: Winter-1, with ambient temperatures below –15 °C, and Winter-2, ranging between –15 °C and +5 °C. Results show that fresh concrete temperature is the dominant factor in initiating hydration, with admixtures alone proving insufficient at low temperatures. Solar exposure and daytime casting significantly improved hydration behaviour, especially when specimens were covered with greenhouse plastic. In contrast, night-time casting under sub-zero temperatures delayed hydration by several hours, particularly in unheated conditions. Summer specimens exhibited consistent hydration aligned with reference laboratory behaviour. The temperature–time factor development of the without admixture winter group specimens average decreased by 39 % after 48 h. The findings highlight the importance of controlling fresh concrete temperature and utilizing environmental aids in cold weather concreting.