In the whole application process of refractory brick products, the index value of linear and volume transformation is the key wire expansion and re-burning volume transformation. The refiring volume of refractory brick products is an irreversible volume transformation process, and the thermal deformation of the product is a reversible volume transformation. Refractory brick products are often used as raw materials for the construction of thermal insulation machinery and equipment, and are often applied under the standard of changing high temperature and temperature, and the key to the volume change of raw materials lies in the linear expansion characteristics of the product. Therefore, in the whole process of application, even if the product is reburned and closed, the expansion joint must be embedded to accommodate the linear expansion caused by the continuous temperature change of the product. Due to the difference in composition and physical structure, the refractory material of the industrial furnace where the expansion joint is stayed, and the difference between the wall building method and the raw materials of the wall, there is also a certain difference in the amount of surge after heat. The setting of expansion joints for large-volume refractories should be clarified according to the above factors. Generally, the interval between expansion joints should be 15-1m in the middle. The operating temperature is less than 800 refractory clay brick wall, red brick wall and attapulgite brick wall, because the surge is small, the absorption force itself is strong, and there is no expansion joint within the length of 2m. Under normal conditions, the total width of the expansion joint should be 50% of the basic theoretical surge at the high temperature of the heating surface. The following is the standard value (mm m) of the total width of the expansion joint of the lining of common refractory materials
The part of the expansion joint of the total width of the expansion joint of the refractory brick masonry of different materials should be around the bearing position, such as the eyelet of the furnace wall frame and the lining, so as to prevent the overall compressive strength of the refractory from being endangered, and be evenly set under the premise that the expansion joint maintains an effective interval. The expansion joints of the refractory brick masonry at the intersection are set as shown in the following figure: the expansion joints of the furnace bottom should be overlapped in the middle of the left and right brick layers and the bottom of the furnace. The expansion joint of the furnace body should be overlapped in the middle of the inner surface layer and the middle of the upper and lower layers. The annular arch wall can be filled with mud refractory material or insulation material by leaving an expansion joint between the infill wall and the casing. For the case that can rise with the surge, the heat pipe heat dissipation regulations are not too high, and it is also possible not to fill with refractory materials or insulation materials. The vault is generally vacated on both sides of the expansion joints, leaving to take into account the surging in each direction, the vault height to width ratio of more than 25m, in addition to leaving expansion joints on both sides, should also be based on the length of the arch according to the section, in the middle of the vault to leave expansion joints. The vault of the overlapping masonry wall can leave a direct expansion joint, and it can also leave overlapping expansion joints. To reach the vault of the masonry wall, overlapping expansion joints should be selected. Expansion joints of double-layer vaults should be set on top of each other. Expansion sewing requires a cover with a certain bending stiffness, like a hoop. For silica bricks and magnesia bricks, in addition to the expansion joints above, a 1 3mm thick cardboard should be changed in the middle of 3 5 bricks to increase the compensation for the surge. For suspended kilns, in addition to setting expansion joints along the perimeter of the kiln, the gap that should be vacated when the lower furnace body rises upwards should also be considered. At the junction of the wall and the roof, an expansion joint should be set in both the vertical and horizontal directions of digestion and absorption. For the rotary kiln with a large diameter, when the concrete pouring of the refractory concrete casting material is performed, the manipulation expansion joint is set as much as possible, and the rotary kiln is divided into fan-shaped or bow-shaped residential quarters with a straight line length of no more than 1m, and the concrete is poured in systematic partitions. For some key positions, in order to prevent it from cracking and endangering the overall compressive strength, the control joint can be set at the less critical position around it, digest and absorb the in-situ stress caused by the volume transformation of the key position, prevent the cracking of the key position, avoid the cause of the crack of the special position with the preset gap, and the preset gap is generally also called the control joint.