It is very common to use acid-resistant lightweight castables for lining chimneys. But if the castables still have no strength a few days after being poured, or become soft when pressed by hand after condensation, what is the reason?
1. First, make a small test block of the remaining material of the light acid-resistant refractory castable. You can also use a mineral water bottle. Add the material to the binder and high alumina cement in proportion, and pour it into the bottle. There is a handle to hold the material in the bottle. Pound the material on the ground a few times and place it in a place where it cannot be exposed to rain. See how it condenses after 4-12 hours? If there is no problem with the initial setting, it means that there is no problem with the acid-resistant lightweight castables.
2. In addition, drinking water must be used during construction, and the amount of water added must be in accordance with the castable manufacturer's instructions. Do not add too much water. If too much water is added, the setting speed of the castable will be affected and the strength will be affected.
3. It depends on the construction conditions at the time, whether the temperature is too low. If the temperature is low, measures must be taken to ensure that the construction temperature cannot be lower than 5℃.
If the construction temperature and construction conditions are within the normal range, the light acid-resistant castable will still appear to be non-condensing or have no strength. It depends on whether there is no air circulation after construction is completed. If there is no air circulation, the castable will lose strength for a few days after construction.
If there is no strength, first check whether the acid-resistant lightweight castables can initially set. Press with your hands to see if there are fingerprints on the castable. If there are fingerprints on the castable even though it has condensed, it means the strength is low. In this case, check whether both ends of the chimney at the construction site are blocked and there is no ventilation. If both ends are blocked and there is no ventilation, initial condensation will occur, but there will be no strength.
After this phenomenon occurs, remove the blockage at both ends of the chimney and allow it to ventilate. Another method is to bake it. After baking, it will gain strength, indicating that the light acid-resistant castable has no air circulation after construction.
