Acid-resistant refractory castables are commonly used in areas that require acid and corrosion resistance, such as anti-corrosion flue, chimney lining, acid storage tanks, pickling tanks, and some furnace linings that are subject to acid gasification erosion or corrosion. The anti-thermal shock resistance of acid-resistant castables is not very good, so try not to use them in areas with large temperature difference between quenching and quenching. There are 9 suggestions for finding refractory nets for the construction of acid-resistant refractory castables:
1. During the construction of acid-resistant and refractory castables, it is necessary to ensure that no power is cut off and construction is not interrupted.
2. The template for the construction of acid-resistant castables can be made of steel or hardwood. The template should have sufficient strength, good rigidity, no shape, no displacement, no leakage. The steel formwork should be coated with a release agent, and the wooden formwork should be painted with a waterproof paint. Reusable templates should be cleaned before painting.
3. The amount of water added to the castable should be strictly controlled according to the instruction manual and must not exceed the limit. Under the premise of ensuring the construction performance, the amount of water should be less and less.
4. The mixing time of the castable should be no less than 5 minutes. Use a forced blender when operating. When mixing, it is advisable to dry mix beforehand, and then add 80% water to stir, then slowly add the remaining water according to the dryness and wetness, and continue to stir until a suitable working consistency is obtained. The mixer should be cleaned before mixing different castables.
5. The castable must be used in whole bags. The stirred castables are typically used up within 30 minutes. In the high temperature and dry working environment, it is necessary to shorten this time. Castables that have been initially condensed or even agglomerated shall not be poured into the mold frame, and shall not be mixed with water.
6. The acid-resistant castable poured into the mold frame should be layered and shattered with a vibrating rod immediately. The height of each layer should be no more than 300mm, and the vibration spacing should be about 250mm. Try to avoid touching the anchor when shaking, and do not shock or tremble in the same position. After seeing the surface of the castable material, the vibrating rod should be slowly extracted after the slurry is returned to avoid segregation and voiding in the castable layer.
After the pouring is completed, the cast body can no longer be pressed and shocked before solidification.
7. When pouring large areas, it is necessary to divide the blocks. The area of each casting area is about 1.5m2. Expansion joints shall be left in design and shall not be missed. The expansion joints should be left at the anchor spacing.
8. After the surface of the acid-resistant castable is dry, immediately cover the exposed part of the air with a plastic film or a straw bag. After the initial condensation arrives, it should be regularly sprinkled and maintained to keep the surface moist. The curing time is at least two days, and the first day should be watered. After the castable is finally set, the side mold can be removed and the water spray can be maintained. However, the load-bearing formwork must be 70% after the strength can be removed.
9. The cast body should be inspected in time after the template is removed. It is found that quality problems such as honeycomb, spalling and voids should be handled and repaired in time. When the problem is serious, the defect part should be chiseled to expose the anchor, and then the same quality of the solid material should be used to fill the compaction, and the maintenance should be continued. It is forbidden to cover the problem with the cement mortar.
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