Refractory cements are formulated to maintain structural integrity at high temperatures (typically above 1,000 °C) and are based on materials such as calcium aluminate or silicon carbide rather than Portland clinker. Ordinary hydraulic cements that are not designed for high-temperature service classify in the chapter covering cement and building materials, not here.

Heading 3816 covers unfired or chemically bonded refractory compositions in bulk, bagged, or paste form. Pre-formed, fired refractory bricks and shapes are classified in the chapter on ceramic products. If a product arrives as a shaped article that has been fired, it should be reviewed against the ceramics chapter rather than 3816.