How to treat alkali return on walls?

Surface return to base

If there is a back-alkali reaction only on the surface, it is because the various substances in the material have poor density and are easy to absorb moisture. When the material contains chemically unstable alkaline impurities exceeding the specified value (marble and most tiles are alkaline). When encountering acidic substances such as acid rain. They will react to form salts, such as carbonates. After the water evaporates, white crystals precipitate on the surface of the brick.
Solution: The solution to this type of problem is usually surface cleaning, which is to use a certain proportion of oxalic acid solution to arrange regular cleaning based on the surface contamination during the use of the material and the seasonal acid rain reaction.

Osmotic crystallization

If it is penetration crystallization. The main reason is that the water absorption rate of the exterior wall material (stone or tiles) is too high and the alkali content of the cement in the paste is too high. The crystallization of natural stone is relatively thick, and there are many capillaries that are invisible to the naked eye (the water absorption rate of tiles is even higher, and ceramic tiles are relatively better than ceramic tiles). Chemical substances that are soluble in water can be infiltrated into the stone through the capillaries in the stone. (or facing brick) the other side.
With water as the carrier and the fine pores of the surface material as channels, water, alkali, salt and other substances in the bonding material penetrate and precipitate. After the water evaporates, the white salt-alkali crystalline substance stays on the surface of the stone (mainly mortar) Precipitation, calcium hydroxide or calcium carbonate after reacting with carbon dioxide in the air) is back to base.
Solution: First, purchase surface materials with higher density and use less alkaline cement materials (preferably non-alkaline gel materials) when pasting.
Secondly, dry hanging construction technology is used to avoid wet sticking.
Finally, it is treated with waterproofing. Generally, waterproof materials are applied to the concrete or cement plaster base. After water sealing treatment, use non-alkaline adhesive for bonding construction.
For situations where you are often in a humid environment. In addition to the water sealing treatment of the base layer. The stone also needs to be sealed in an all-round way. And all surface layers of the stone should be treated with special waterproof materials before starting the pasting construction.

Treatment methods for wall alkali return

Once anti-alkali occurs on the wall, it is difficult to remove. Therefore, we should focus on prevention, and only the following remedies can be taken after alkaline reaction occurs.
1. Carry out comprehensive waterproofing treatment as soon as possible to prevent further intrusion of moisture and prevent the expansion of the anti-alkali area.
2. You can also use anti-alkali cleaning agents on the market. These cleaning agents are colorless and translucent liquids made of non-ionic surfactants and solvents. It has a certain effect on the anti-alkali cleaning of some walls. However, before use, a small sample test block must be made to test the effect and decide whether to use it.
So if alkali return on walls is in your house, you can do solve it as above.