Which material is known for not greatly expanding or losing strength when exposed to heat?

Concrete is known for its ability to withstand heat without significantly expanding or losing strength. This characteristic makes it a preferred construction material in fire-resistant applications. Unlike wood, which can warp and weaken under high temperatures, or asphalt, which can soften and deform when heated, concrete maintains its structural integrity. Moreover, insulation materials often have varying degrees of thermal resistance and may degrade under extreme temperatures, making them less reliable as fire-safe options. The stability of concrete under fire conditions is a critical factor for ensuring safety in buildings and structures, helping to prevent the spread of fire and providing valuable time for evacuation and response efforts.