When is the hydration activity in bridge deck concrete at its highest?

The hydration activity in concrete, particularly in a bridge deck, is at its highest during the first few hours after placement. This is because the hydration process is a chemical reaction between water and cement that begins as soon as water is added to the mix. During these initial hours, there is an abundance of moisture and the cement particles are actively reacting with the water, which leads to rapid setting and hardening of the concrete.

At this stage, the heat generated by the exothermic reaction of hydration can be quite significant, and this is critical in the curing of the concrete. As hydration progresses, the rate of reaction gradually slows down. After this initial peak, hydration continues but at a decreasing rate; hence, activities occurring 24 hours or even 7 days after placement do not exhibit the same level of high activity as seen in the first few hours.

Understanding this peak hydration period is crucial for concrete inspectors as it informs decisions about curing practices, minimizing cracking, and ensuring the overall strength and durability of the concrete structure.