Which material is preferred for constructing overcasts?

In constructing overcasts, incombustible materials are preferred due to their safety and structural integrity in underground mining environments. Overcasts are structures built to divert air flow and allow for the passage of materials and personnel while ensuring adequate ventilation.

Using incombustible materials minimizes the risk of fire in the underground setting, where conditions can be hazardous and difficult to control. These materials do not burn and contribute to fire resistance, which is crucial in preventing fire hazards that can arise from machinery, electrical components, or other potential ignition sources in a mining operation.

In contrast, while wood and certain plastics may be lighter and easier to handle, they pose significant fire risks as they are combustible. Metal can also be used for overcasts; however, it is often heavier and may not provide the same level of protection from fire that incombustible materials deliver. Therefore, the use of incombustible materials is the most effective choice for ensuring the safety and functionality of overcasts in underground mines.