What does calcination refer to in a fire context?

In the context of fire investigation, calcination refers specifically to the process of driving out chemically bound water from materials, most notably gypsum, when exposed to high temperatures. This process occurs when materials like gypsum, which contain water in their chemical structure, are subjected to heat. As the temperature rises, the water is released as steam, leading to a change in the structure of the material.

Calcination is important for fire investigators to understand because it can provide valuable clues about the temperature and duration of the fire, as well as the extent of damage to building materials. The presence of calcined materials can indicate areas that were subjected to intense heat, helping to establish the fire's behavior and potentially its origin.

Other options do not correctly define calcination; the destruction of a building structure is a broader outcome of fire, but it does not specify the chemical processes involved. Preventing fires in buildings pertains to fire prevention techniques rather than the effects of heat on materials. The cooling phase of a fire aftermath refers to the state after a fire has been extinguished, not the specific chemical reactions occurring during a fire's heat. Thus, the focus on the chemical reaction pertaining to gypsum effectively highlights the significance of calcination in fire investigations.