Fourteen problems to be paid attention to in the construction of refractory castables for magnesia bricks

Fourteen problems of magnesium-aluminum bricks to be paid attention to in the construction of refractory magnesia bricks

First, preparation before construction, inspection content:

The equipment to be poured and the site cleaning; the construction machine is in good condition; the anchor material, type, size, arrangement and welding (fixed) quality, the magnesium brick metal anchor is used for expansion compensation treatment; and the surrounding refractory brick and other castable wet water Precautionary measures; pre-test castables are ineffective; water quality should meet drinking water standards; the above experience is acceptable and ensures that construction is not interrupted. The main items examined are:

1. Check the site cleaning status of the construction site to be poured;

2. Check the preparation of construction equipment and spare parts;

3. Check the specification, size, arrangement and fixed form quality of the anchor, in which the metal anchor must be compensated for expansion;

4. Check the refractory bricks in contact with the construction of the castables, and prevent the water loss measures of the moisturizing materials;

5. Check the construction water, the water quality must meet the drinking water standard;

6. Check if the castable expires.

All the above-mentioned inspections can be accepted after acceptance, and it is necessary to ensure that no power is cut off during construction and construction is not interrupted.

Second, construction requirements:

1. Molding: It is made of steel plate or hard wood board, the steel plate is coated with release agent, and the wooden board should be brushed with waterproof paint without leakage. It should have sufficient strength.

2. Stirring: use a forced mixer, first pour the castable into the machine, and take out the additive pouch and pour it into it. Mix it for 2-3 minutes, add water to wet for 3-5 minutes, add water should be less, and add more. The amount of water is 7.0-7.5%.

3. Vibrating: The pouring material poured into the mold should be stratified and tapped immediately with the vibrating rod. It must not leak and vibrate and re-vibrate at the same position to avoid segregation and holes in the castable. The stirred castable must be removed from the water to the end of 20-30 minutes, and the initial aggregate should be discarded. The expansion joint is designed to be left behind.

4. Maintenance: After the surface of the castable is dry, it can be demolded with 70% strength. The mold removal time is ≥24 hours, and the curing time is ensured ≥24 hours.

5. Drying: According to the different grades and the thickness of the castable lining and the climatic conditions of the site, the user must provide sufficient baking time to ensure that the water is not bursting. The required baking time is ≥72 hours.

Third, note:

1. Strictly control the amount of water added. The room temperature in winter must be greater than 5 °C, and there are certain antifreeze measures.

2, must use a forced mixer mixing, artificial mixing is strictly prohibited.

3, anchor nails must be added with an expansion cap or brush asphalt paint.

4. This product is strictly prohibited to be mixed with other grades of castables.

5. The retention period is March.

Fourth, the construction template can be used for steel plates and hardwood boards. The formwork should have sufficient strength and the quality of the formwork should be such that it does not shift or leak. The release agent should be brushed on the contact surface with the castable.

5. The amount of water to be poured and poured should be strictly controlled. The amount of water supplied by the manufacturer of the castable should be referred to. Under the premise of ensuring performance, the amount of water should be less and less.

6. For the mixing of castables, a forced mixer should be used. It should be cleaned before use. After mixing, mix dry and then add 80% water, then add the remaining water until the suitable construction consistency is obtained.

7. The poured castables must be used up within 30 minutes. The castables that have been initially set or even agglomerated shall not be used.

8. The pouring material poured into the mold should be layered and shattered immediately. The height of each layer should be no more than 300mm, and the spacing should be about 250mm. It is not possible to touch the anchor and the insulation layer during vibration. It must not be shocked or trembled at the same position. . When the surface of the castable is returned to the slurry, the vibrating rod is slowly withdrawn after the bubbles are reduced, so as to avoid segregation and voids in the castable layer.

Nine, large-area pouring should be divided into blocks, each area is 1.5 square meters. The expansion joints shall be left in the center of the anchor spacing as required by the design and shall not be missed.

10. After the surface of the material to be cast is hardened, the strength can reach 70% to remove the mold. The curing time is determined according to the type of casting material and the construction design requirements and the strength of the castable body required by the manufacturer of the castable.

XI. After the template is removed, the castable should be inspected in time, and the quality problems such as honeycomb, spalling and holes should be dealt with and repaired in time. When the problem is serious, the defective part should be cut out, filled with tapping with the same grade of pouring material, and continue to be maintained.

12. Design and maintain the baking time according to the pouring thickness of the castables and the temperature conditions on site. When baking, strictly follow the heating curve. It is forbidden to heat up too fast. It should be ensured that the water is slowly discharged to prevent the pouring material from bursting due to too fast heating.