What type of material does NOT support combustion even under accelerated conditions?

A fire break is a physical gap or barrier used to stop the lateral spread of fire, not a classification describing the combustibility of a material.

Fireproof materials are inherently non-combustible and will not ignite, burn, or support combustion regardless of the intensity or duration of fire exposure, including accelerated test conditions. This represents the highest classification of fire material behavior, meaning the material itself contributes no fuel to a fire. Examples include concrete, masonry, and certain mineral-based materials used in construction and firestop assemblies.

Fire-resistant materials can withstand fire exposure for a specified rated period but may eventually degrade, char, or fail under prolonged or accelerated conditions.

Fire-retardant materials are treated or formulated to slow the rate of flame spread and burning, but they can still combust under sufficiently intense or sustained fire conditions.