Monolithic refractories are used to advantage over brick construction in various types of furnaces. Their use promotes quick installation, avoiding delays for the manufacture of special brick shapes. Using monolithics frequently eliminates difficult bricklaying tasks, which may be accompanied by weakness in construction. They are of major importance in the maintenance of furnaces because substantial repairs can be made with a minimum loss of time and, in some cases, even during operations. Under certain conditions, monolithic linings of the same chemical composition as firebrick provide better insulation, lower permeability, and improved resistance to the spalling effects of thermal shock.
Types of Monolithics
Plastic refractories are used to form refractory monolithic linings in various kinds of furnaces, and are especially adaptable for making quick, economical emergency repairs. They are easily rammed to any shape or contour. The high refractoriness, the range of compositions, and the ease with which they can be rammed into place make plastics suitable for many important applications.
Alumina-based patches and plasters are useful for a variety of refractory repairs, including ladle lips, boiler doors and other high-temperature applications where the repair requires only a thin layer of material. These finely ground materials and moderate moisture content give them excellent workability compared to plastics.
The purpose of the mortar is to fill the joints and bond the individual brick together. It should protect the joints from attack by slag and other fluxes and provide resistance to infiltration by cold air and to the outward flow of gases.