1. Definition and composition
Refractory concrete
Refractory concrete is a special concrete that can withstand high temperatures. It is usually made of refractory aggregates (such as refractory brick sand, alumina clinker, etc.), cementitious materials (such as Portland cement, aluminate cement, etc.) and appropriate amounts of admixtures and water in a certain proportion. It is essentially a special application form of concrete, which emphasizes performance under high temperature environments.
Refractory castables
Refractory castables are a type of amorphous refractory material, mainly composed of refractory aggregates, powders, binders and admixtures. Compared with refractory concrete, its binder types are more diverse. In addition to cement binders, there are also a variety of inorganic binders such as water glass and phosphoric acid. Moreover, the combination of each component can be flexibly adjusted according to specific usage requirements to adapt to different high temperature conditions.
2. Differences in construction technology
Refractory concrete: Generally, the construction method of conventional concrete is followed. First, the ingredients are mixed and then vibrated to make it dense and formed. However, during the construction process, more attention should be paid to the control of environmental conditions such as temperature and humidity to ensure that its fire resistance is not affected. Moreover, refractory concrete needs to be cured for a certain period of time after construction. For example, when silicate cement is used as a cementitious material, it is usually necessary to keep it moisturized for several days so that its strength can develop normally.
Refractory castables: During construction, the raw materials are fully mixed and evenly mixed, and then poured, rammed, etc. are used to fill them into the required parts for molding. Its construction flexibility is relatively higher, and some parts with complex and irregular shapes can be filled well. And the appropriate construction method can be selected according to the actual situation. For example, self-flowing castables can rely on their own gravity to flow and fill the mold or construction site without additional vibration, and the construction efficiency is high.
3. Differences in performance characteristics
Refractory performance
Refractory concrete: Its refractory temperature is limited to a certain range. Generally speaking, the temperature that ordinary refractory concrete can withstand is relatively not particularly high. It is mostly suitable for medium and low temperature industrial kilns and other occasions. It mainly depends on the refractory performance of the selected cementitious materials and aggregates. However, through reasonable material selection, its refractory temperature can be improved to a certain extent.
Refractory castables: Due to the flexibility of the selection of binders and aggregates, the refractory performance of refractory castables can be adjusted in a wide range and can meet the use requirements of different levels from low temperature to high temperature. For example, some high-purity corundum refractory castables can withstand extremely high temperatures and are often used in high-temperature key parts such as steel and non-ferrous metallurgy.
Strength performance
Refractory concrete: The strength development is similar to that of ordinary concrete. The early strength growth mainly depends on the hydration of cementitious materials, and the later strength is relatively stable. Its strength indicators such as compression and flexural strength can meet certain use requirements at room temperature, but as the temperature rises, the strength may decrease to varying degrees, especially under the action of high temperature for a long time, the strength loss may be more obvious.
Refractory castables: Different types of refractory castables have different strength characteristics. For example, some castables using high-strength binders and high-quality aggregates have higher strength at room temperature. In high-temperature environments, some castables can rely on high-temperature sintering and other effects to maintain good strength, and even the strength will be improved within a certain temperature range. The overall strength performance is more controllable.
Wear resistance
Refractory concrete: The wear resistance mainly depends on factors such as the hardness and grading of the aggregate. The overall wear resistance is at a standard level. It can meet the use requirements in some occasions where the material scouring is relatively not severe. However, if it faces high-speed and large-scale material scouring, its wear resistance may not be enough to maintain structural integrity for a long time.
Refractory castables: The wear resistance can be improved by adjusting the type and particle size of aggregates and adding wear-resistant enhancers. Some refractory castables specifically used for wear-resistant parts can show good wear resistance in the face of harsh working conditions such as material scouring in blast furnaces and material friction in cement kilns, ensuring the service life.
Different application scopes:
Refractory concrete is often used in some industrial furnace foundations, flues and other parts that have high requirements for shape regularity and relatively mild temperature conditions, such as the bottom foundation of small brick kilns, and the lining of some civilian heating furnaces, etc., relying on its relatively simple construction process and certain fire-resistant and heat-insulating capabilities.
Refractory castables have a wider range of applications, whether it is blast furnaces and converters in the metallurgical industry, rotary kilns in the cement industry, and various high-temperature kilns in the ceramic industry. There are a large number of applications in parts with complex shapes, high temperatures and strict requirements for fire resistance and wear resistance. It can provide materials with corresponding performance according to specific working conditions and ensure the smooth progress of industrial production.