Is the phenomenon of efflorescence in mortar related to hydroxypropyl methylcellulose?

The phenomenon of efflorescence is: ordinary concrete is silicate, and when it encounters air or moisture in the wall, the silicate ion undergoes a hydrolysis reaction, and the generated hydroxide combines with metal ions to form a hydroxide with low solubility (the chemical property is Alkaline), when the temperature rises, the water vapor evaporates, and the hydroxide is precipitated from the wall. With the gradual evaporation of water, the hydroxide is precipitated on the surface of the concrete cement. Over time, the original decorative paint Or paint and other things are lifted up and no longer adhere to the wall, and whitening, peeling, and peeling will occur. This process is called “pan-alkali”. So, it’s not the ubiquinol caused by hydroxypropyl methylcellulose.

The customer said a phenomenon: the sprayed grout he made will have pan-alkali on the concrete wall, but will not appear on the fired brick wall, which shows that the silicic acid in the cement used on the concrete wall Too much salt (strongly alkaline salt). Efflorescence caused by evaporation of water used in spray grouting. However, there is no silicate on the fired brick wall and no efflorescence will occur. Therefore, the occurrence of efflorescence has nothing to do with spraying.

Solution

1. The silicate content of base concrete cement is reduced.

2. Use anti-alkali back coating agent, the solution penetrates into the stone to block the capillary, so that water, Ca(OH)2, salt and other substances cannot penetrate, and cut off the way of pan-alkaline phenomenon.

3. To prevent water intrusion, do not sprinkle a lot of water before construction.

Treatment of pan-alkaline phenomenon

The stone efflorescence cleaning agent on the market can be used. This cleaning agent is a colorless translucent liquid made of non-ionic surfactants and solvents. It has a certain effect on the cleaning of some natural stone surfaces. But before use, be sure to make a small sample test block to test the effect and decide whether to use it.