Industry News
Pay attention to the block construction of castables
Castable, also known as refractory castable, is a mixture of granular and powdery materials made of refractory materials and binders. It is stirred to a certain extent during use to make it homogenized, and it has a certain flowability, and also has a suitable construction time and hardening time. Shaped refractory. The castable may not go through the firing process, and the castable needs to be baked when it is used. Compared with refractory bricks, it is more suitable for complex and special-shaped structure construction. It has the characteristics of simple production process (since no fixed size requirements, eliminating the need for machine pressing and firing processes), easy mechanized construction, and fast construction speed. The effect on the equipment is better than that of refractory bricks.
The biggest advantage of castables is good integrity, but when the construction area is too large, such as when the area is greater than 2 square meters to 3 square meters, the castables without expansion joints may cause irregular fractures. The generation of such cracks is caused by the thermal expansion of the refractory material or the cooling and shrinkage of the refractory material after use. According to the different structure of the castable construction site, the more complex the structure of the castable construction site, the more irregular the cracks will be. If these cracks are not treated in time, they will gradually expand with the extension of use time. The cracks are usually narrow in width, but the depth is easy to penetrate, and the resulting cracks usually cannot be completely repaired. The only way to repair the cracks is to fill refractory fibers and apply refractory mud in tanks. The above methods are usually difficult to apply, and it is difficult to completely repair the damaged cast. Even if it is repaired, if the expansion joint is not reserved, cracks will still occur in other parts.
In order to avoid cracks, especially through cracks, castables are usually cast in blocks. The block construction of the castable should be set in combination with the working conditions, construction thickness, construction difficulty, material characteristics, etc., usually set aside according to the side length of no more than 2 meters to 3 meters, and the shorter the expansion joint spacing, the less irregularity can be reduced. Cracks may occur, but too small expansion joint spacing will greatly increase the difficulty of construction, and through joints should be strictly prohibited when expansion joints are left. During the construction of a single-layer structure, the expansion joints of the castable should be reserved in the form of "Z"-shaped "concave-convex". The expansion joints of different refractory layers of the multi-layer structure shall be constructed in a staggered manner. The expansion joint support material should be soft and high temperature resistant materials such as expansion joint board and fiber felt. When using corrugated board, attention should be paid to straightening the corrugations on the heating surface side when laying on the heating surface, so as to avoid local shedding caused by the corrugation pressing the heating surface. The expansion joints should also bypass special structures such as anchors, burners, manholes, thermocouple holes, etc., which should be fully considered before design and construction, and key inspections should be carried out after the formwork is supported to avoid the improper setting of expansion joints in special parts. Defects.
The castable for block construction reduces the occurrence of irregular cracks and prolongs the service life; Of course, the block construction also increases the difficulty of construction, and attention should be paid to the reasonable design of the block size and the appropriate formwork method.
