Precautions for High Alumina Brick Masonry

High alumina bricks have been widely used in the construction of various industrial kilns because of their special fireproof performance. However, due to its different performance from other bricks, it also has its own unique aspects that need to be paid attention to on the wall. High alumina brick lining can be divided into four categories according to the brick joint size and fineness level. The type and size of brick joints are Grades I ≤ 0.5mm; Grade II ≤ 1mm; Grade III ≤ 2mm; Grade IV ≤ 3mm. The mortar joints of the brick joints should be filled with fireproof mud, and the joints of the upper and lower bricks should be staggered.

First: The preparation of wall refractory mortar should follow the following principles:

1. Pre-test and pre-pave various refractory mortars before building walls to determine the bonding time, initial setting time, consistency, and water consumption of different mortars.

2. Different slurries need to be made with different instruments and should be cleaned immediately.

3. Different mortars should be mixed with clear water, the amount of water should be accurate, the mixing should be even, and it can be used at any time. The prepared hydraulic and pneumatic mortar cannot be used with water, nor can it be used with final setting mortar.

4. When preparing phosphate-bonded mud, the specified material retention time should be determined. The prepared mortar cannot be diluted with water. Due to the corrosive nature of the mud, it cannot come into contact with the metal casing.

Before the brick-lining construction, the site should be fully inspected and cleaned.

Before the construction of the brick lining, the lofting work should be done well, and the size and elevation of each part of the masonry should be checked according to the design drawings.

The basic requirements for bricklaying are: the bricks should be tightly attached, the joints should be straight, the circles should be accurate, the bricks should be locked firmly, and the masonry should be flat and vertical. High alumina bricks should be built with staggered joints, the mud in the brick joints should be full, the surface should be jointed, the brick joints should be horizontal and vertical, the arc surface should be smooth, and the masonry should be dense.

Second: What aspects should be paid attention to when building high alumina bricks?

According to the design plan, the layout of different high alumina brick varieties is carried out. When laying brick lining, the fullness of fireproof mud should be greater than 95%. The joints of facing bricks should be jointed with raw paste, but the excess paste on the surface of the brick lining should be removed in time.

Bricks should be handled with a flexible tool such as a wooden, rubber, or hard plastic hammer. Do not use steel hammers or cut bricks on masonry. Masonry must not be struck or aligned after the mortar has dried and hardened.

Bricks of different materials and types should be strictly separated, and bricks of the same quality, type, and length should be selected.

Generally, it is 1-1.2.2mm, and it is required to be flat, without curling, distortion, or burrs. The width of each board should be about 10mm less than the width of the bricks. During masonry, the steel plate shall not exceed the edge of the brick, and there shall be no sound of steel plates or bridging. Only one plate is allowed for each weld. Narrow steel plates for adjustment should be used as little as possible. Cardboard for expansion joints shall be placed as designed.

When locking bricks, flat bricks should be used for locking and finishing, and adjacent brick roads should be staggered by 1-2 bricks. It is strictly forbidden to use castables alone to lock bricks, but the last lock brick can be fixed with castables.

Third: When building refractory and heat-insulating linings, the following common problems should be avoided:

1. Misalignment: unevenness between layers and blocks.

2. Tilt: that is, the horizontal direction is uneven.

3. Uneven brick joints: The total width of brick joints is different, which can be adjusted through appropriate selection.

4. Climbing: that is, there are irregularities on the wall surface, which should be controlled within 1mm.

5. Separation: The brick ring and the shell in the arc masonry are not concentric.

6. Double seam: that is, the upper and lower brick joints overlap, and only brick joints are allowed between the double layers.

7. Through joints: that is, the joints of inner and outer bricks are not allowed to overlap, and even the outer shell is not allowed to be exposed.

8. Opening: In the curved masonry, the mortar joints are small inside and large outside.

9. Gaps: The mortar between layers, bricks, and shells is not full, and it is not allowed to appear in the lining of fixed equipment.

10. Coarse joints: The brick joints are not plastered, and the walls are not clean.

11. Serpentine bending: that is, the longitudinal seam, circular seam or transverse seam is not a straight line, but a wavy bend.

12. Masonry bulge: due to the deformation of the equipment, the surface of the equipment should be leveled during masonry. During the construction of double-layer lining, the insulation layer can be used for leveling.

13. Mud mixing: Do not misuse mud.

The fire-resistant and heat-insulating composite inner lining of the wall equipment should be layered and sectioned, and mixed layers and mortar walls are prohibited. Masonry insulation linings should also be filled with mortar and joints. When encountering holes and riveted parts, bricks or plates should be processed, and mud should be filled at the joints. It is strictly forbidden to pave randomly, leave space everywhere, and not use mortar. In the insulation layer, high-alumina bricks should be used to build walls and anchor bricks, behind the arch foot bricks, around the opening, and at the contact expansion.

For high alumina brick lining, expansion joints must be reserved according to the design. Expansion joint widths should not have a negative tolerance. Hard debris should not be left in the joint. The seams should be filled with refractory fibers to avoid the phenomenon of being full outside and empty inside. In general, expansion joints cannot be placed inside the insulation.

The lining of important parts and complex parts should be prefabricated first. Castable lining can be used for lining complex structures and large amounts of brick processing.

The exposed metal parts left in the brick lining, including brick backing boards, brick retaining boards, etc., should be sealed with special-shaped bricks, castables, or refractory fibers, and should not be directly exposed to high-temperature kiln gas during use.

Anchor bricks are masonry structural bricks and shall be reserved according to design regulations. Cracked anchor bricks shall not be used around hanging holes. Metal hooks should lie flat and hang securely. Hanging holes and hooks must not be stuck, and the gaps can be filled with refractory fibers.

When laying capping bricks, seam bricks, and curved bricks, if the original bricks do not meet the capping requirements, they should be finished with a brick cutter and manual processing of bricks is not allowed. Size of processed bricks: top bricks shall not be less than 70% of the original bricks; flat seam bricks and curved bricks shall not be less than 1/2 of the original bricks. It must be locked with the original brick. It is strictly forbidden to process the brick face. The processed side of the bricks must not face the furnace, work surfaces, or expansion joints.