Specialty cement, concrete and mortar contain specialized binders such as K silicate, calcium aluminate, sulfur, and oxysulfate or polymer resins. They cure or set through film drying (air setting), chemical reactions, thermoset bonds, hydraulic bonds, hot melting, and multiple component binder systems. Unlike conventional construction products, specialty concrete is not based on Portland cement. Instead, specialty concrete consists of specialty cement such as potassium silicate that is mixed with water, a coarse aggregate such as gravel or crushed stone, and a fine aggregate or sand. Specialty mortar is a mixture of a specialty binder or clinker and a fine aggregate. Specialty cement, concrete and mortar are used to join components and form structures. Products such as grout and caulk are used to fill gaps between tiles and bricks. Thin set materials such as dry set mortar and dry bond mortar include cement and are used in coating products. Cement-based liners or lining systems are much heavier or are applied in thicker layers than thin set materials. Pre-cast shapes such as blocks and sheets are commonly available.