Castables with a bulk density less than 1.5 specific gravity are lightweight castable refractory, mainly for thermal insulation. The castables with a bulk density greater than 1.5 and less than 1.8 can be called semi-light castables, and those with a bulk density greater than 1.8 are heavy castables.
The raw materials of the lightweight castable refractory are aggregates and powders that are added in proportion with a density and light weight, and the binder is also combined with high-alumina cement. There is also a combination of water glass and phosphoric acid, but the binder of the lightweight castable refractory is large, and the proportion of water added to the construction is also larger than that of the heavy castable.
Lightweight castable refractory are characterized by low density, light weight, low thermal conductivity and good thermal insulation effect. There are many varieties of lightweight castables, and the properties are also divided into neutral and acidic.
The lining of the kiln basically has an insulating layer. The lightweight castable refractory used for the insulating layer cannot be directly flamed. The outer layer of the insulating layer generally has castables or refractory bricks for the working layer, which are lightweight and refractory. The castable has good thermal insulation effect, slow heat dissipation and good thermal insulation effect. And it can save the use of fuel in the kiln. In different furnace linings, different lightweight castables or lightweight castables with different properties are used.
Some high-grade lightweight castables refractory can also be used as working layers in the furnace lining, such as acid-resistant light-weight castables with a specific gravity of 1.5, which are used in chimneys or flues, and the effect is quite good. Will make the chimney lightweight and reduce stress. There are also alumina hollow ball refractory castables, which are high-grade materials in lightweight castables and can be used in special light-duty kiln linings. They are not only resistant to high temperature, but also light in weight.
Lightweight castables are lightweight, have low thermal conductivity, are easy to use and are inexpensive. Moreover, according to the different needs of the market, lightweight castables are constantly developing composite lightweight refractory castables to meet the use of furnace linings.
