Precautions for Fire Brick Joints When High Alumina Refractory Bricks are Built
There will be brick joints in the middle of high alumina refractory brick masonry buildings. Although firebrick mortar is used for jointing and filling, due to some reasons, the joints of bricks are more serious than wear and tear, which will affect the service life of the overall lining. Therefore, handling the brick joints is also an important part. Fire Brick joints and expansion joints are two completely different concepts. Expansion joints are deliberately reserved to prevent the expansion of high-alumina refractory bricks, and brick joints exist naturally. The smaller the requirements, the better. When laying, high alumina refractory bricks are divided into several categories according to the required construction fineness
In actual masonry, the following masonry principles must be met to meet the requirements of the refractory industry. The joints of high alumina refractory bricks for masonry must be full, the mortar should be squeezed out of the joints, no gaps are allowed, and the mortar should not be poured into the mortar joints. The fullness of the mortar must be greater than 95%. Fire Brick joints of masonry are filled with refractory mud, but because the density and strength of refractory mud are too different from the product, it is easy to be eroded during use, so fire brick joints should be better. This requires that the high alumina refractory brick products must not have large deformation, missing edges, corners, melting holes and cracks, and the dimensional tolerances should meet the specified requirements. In the same way, brick joints are the weak link of blast furnace bricklaying. The erosion and damage of the furnace lining starts from the brick joints.
Therefore, the quality of the refractory mortar used for joint filling bricks directly affects the service life of the furnace lining. The material of refractory mud should be the same as that of high alumina refractory brick products.
The thickness of the brick joints of various types of high alumina refractory brick masonry is shown in the following table: type, brick joint thickness, special masonry 0, 5 mm, class masonry 1 mm, class masonry 2 mm, class masonry 3 mm, class Masonry 3 mm. When building industrial furnaces, thermal insulation, diatomaceous earth bricks and clay, the thickness of the brick joints has the following aspects.
When masonry is built with phosphate mud, the thickness of the ring joint of the blast furnace and hot blast stove ring wall masonry is allowed to increase, but it shall not exceed 5mm;
When using non-phosphorus mud for masonry, it is allowed to increase the thickness of the joints of high-alumina refractory bricks, but the increased value shall not exceed 50% of the prescribed joints;
When the allowable deviation of the outer dimensions of the carbon block is 0, 5 mm, the allowable thickness of the joint between the blast furnace bottom and the hearth masonry high-alumina refractory brick shall not exceed 1 mm;
When using aluminum carbon or silicon carbide products to build the hearth and shaft of a blast furnace, the thickness of the joints between high-alumina refractory bricks shall not exceed 2mm.
In order to prevent the lining of high-alumina refractory bricks from thermal expansion, resulting in high-pressure stress and damage between the lining bricks, it is necessary to calculate the thermal expansion of each brick according to the thermal expansion coefficient and the temperature that can be withstood, so as to determine the appropriate brick joint size and eliminate the expansion of the lining brick Thermal stress caused.
Therefore, the brick joints of high-alumina refractory bricks are calculated according to the working conditions of refractory materials. This requires us to adopt reasonable high-alumina refractory brick masonry technology and use appropriate refractory mortar for treatment to ensure high-alumina refractory brick products Service life.
