Which effect can result from the calcination of gypsum?

The calcination of gypsum primarily involves the thermal decomposition of gypsum (calcium sulfate dihydrate) into calcium sulfate hemihydrate, commonly known as plaster of Paris. This process occurs when gypsum is subjected to high temperatures, typically around 150°C (302°F).

As a result of calcination, the structural integrity of gypsum is compromised, leading to thermal degradation and weakening of the material. This degradation can affect the overall fire resistance of buildings and materials where gypsum is used, as the material may lose its ability to provide thermal insulation and fire protection. This aspect is crucial in fire investigations, as understanding how different materials respond to heat can inform evaluations of fire spread and safety measures.

In contrast, the other effects mentioned do not directly relate to the calcination of gypsum. Increased flame propagation is influenced by different factors, such as fuel availability and material flammability, rather than the calcination process. Enhanced smoke production is generally associated with organic materials burning rather than the calcination of inorganic compounds like gypsum, and immediate fire ignition is typically linked to flammable materials that can ignite rapidly, which does not apply to calcined gypsum. Therefore, the weakening and thermal degradation caused by calcination is the correct focus in this context.