Refractories and Bricks Applications 

BRICKS. . . as a plasticizer

Both powdered and granular sodium bentonites are used in the production of common and face brick. As a bonding agent, bentonite assists in the elimination of “bats” or chipped brick when used in shale brick. Volclay bentonite also adds plasticity, thus reducing the moisture in the formulation. The increased plasticity results in longer die life, and reduces power requirements on the extrusion equipment.

REFRACTORIES...as a lining
Linings are used in furnaces to prevent molten metals from destroying them. In general, linings consist of ganisters, silica stone, quartz pebbles, or refractory grog. Most of the linings consist of graded sizes of ganisters in which the voids between large grains are filled with progressively smaller grains creating a firm, yet brittle body. Increasing the plasticity of linings enhances durability and performance. This can be accomplished by adding sodium bentonites, and, for greater performance - adding hectorites.

Bentonites and hectorites are used as a binder in high temperature furnace cements, mortars, and furnace gun mixtures. Other clays are used in the manufacture of these products, however, bentonites and hectorites provide higher stickiness per pound, reduce cracking at high temperatures, and supply more coverage per pound -- qualities not found in other clays.

CEMENTS AND PLASTER...as a plasticizing agent
One pound of Volclay bentonite added to each sack of cement increases the plasticity and improves the handling of the mixture, without reducing the set strength. As the amount of Volclay per sack is increased - up to 20% -- more water is required for the cement mixture, making a “fat” mixture for filling large voids. Acoustical plaster is applied over ceilings or walls to absorb sound. The base of acoustical plaster is either vermiculite, perlite, or synthetic fibers. A typical formula would consist of 70% vermiculite or perlite, 10% synthetic shorts and 20% Volclay bentonite. When this is mixed with water to create a plastic mass, when applied over a ceiling, the Volclay causes it to adhere. As it dries it shrinks, and the shrinkage causes cracks in the product which entrap sound.