What type of cement would be least appropriate for environments with high temperatures during hydration?

Type III cement, also known as high-early-strength cement, is formulated to hydrate quickly and achieve strength at a faster rate than other types of cement. While this characteristic can be advantageous in certain situations, it can also lead to excessive heat generation during the hydration process. In high-temperature environments, the rapid heat buildup can exacerbate the risk of issues such as thermal cracking and reduced workability of the concrete mixture.

In contrast, Type I cement has a standard hydration rate suitable for general construction, Type II cement is designed to resist moderate sulfate attack and endure higher temperatures, and Type IV cement is specifically formulated to have a lower heat of hydration, making it more appropriate for use in structures where temperatures may significantly rise during the curing process. Thus, when working in environments with high temperatures during hydration, using Type III would indeed be the least appropriate choice due to its potential to generate excessive heat and create complications.