Refractory concrete is an unshaped refractory material that is prepared by adding water or other liquids to refractory aggregates, powders, and cement and is used directly without calcination. Also known as refractory castable, generally, most of this material is constructed by pouring. So it is also called refractory castable. It can be divided into the following types. ① Ordinary refractory concrete. The aggregates used are high alumina, clay, siliceous, alkaline materials (magnesia, chromite, dolomite, etc.) or special materials (carbon, silicon carbide, zircon, etc.). Several combinations of refractory aggregates can also be used. ②Insulation refractory concrete. It is mainly formulated with refractory light aggregate. The light aggregates used include expanded perlite, vermiculite, ceramsite, porous clay clinker, hollow alumina balls, and so on. It can also be combined with several refractory lightweight aggregates, or combined with refractory aggregates. The cement used in refractory concrete includes high alumina cement, phosphate cement, water glass cement, clay, and so on.
Advantages of Refractory Concrete
Refractory concrete (https://refractorycastablecement.com/high-heat-refractory-concrete/) is a non-burning product, with a simple production process and energy saving. It can be shaped according to needs, the integrity is better than the brick lining, suitable for mechanized construction, and the life of the lining can be prolonged when it is reasonably used. Refractory concrete is mainly used in industrial kilns such as metallurgy, petroleum, chemical industry, building materials, and machinery. The general use temperature is 1300～1600°C. The refractory concrete whose service temperature is lower than 900°C is called heat-resistant concrete, which is mainly used in the foundations of thermal equipment, chimneys, flues, and other structures.
Performance Comparison of Refractory Concrete and Refractory Bricks
- The refractoriness is similar to that of refractory bricks of the same material. However, because the refractory concrete (castable) is not sintered, it shrinks greatly during the initial heating, so the load softening point is slightly lower than that of refractory bricks. Nevertheless, in general, the performance is better than refractory bricks.
- Refractory concrete is superior to low-temperature cementitious materials and has higher compressive strength at room temperature. At the same time, because the integrity of the masonry is good, the furnace is airtight and not easily deformed. Therefore, the outer furnace shell steel plate can be eliminated, and the furnace has better resistance to mechanical vibration and impact than brick masonry. For example, it is used on the sidewall of the soaking furnace. The mechanical abrasion and collision at this place are relatively severe, and the life span is several times longer than that of bricks.
- Good thermal stability. Most of all of the aggregate are clinker, and the expansion is offset by the shrinkage of the cement. Therefore, the thermal expansion of the masonry is relatively smaller than that of the brick, and the temperature stress is also smaller. Moreover, there are various network, needle, and chain crystal phases in the structure. Strong resistance to low-temperature stress. For example, it is used for pouring the furnace mouth and furnace cover of the soaking furnace, and the service life is extended to one and a half years.
- The production process is simple, and the complicated brick-making process is eliminated. It can be made into a variety of prefabricated blocks and can be mechanized for construction, which greatly accelerates the furnace building speed and increases the efficiency of bricklaying by more than ten times. You can also use waste bricks as aggregates to turn waste into profit.
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