Is the phenomenon of mortar efflorescence related to hydroxypropyl methylcellulose?
August 7, 2020
The phenomenon of efflorescence is: ordinary concrete is silicate. When it meets the air or water vapor in the wall, the silicate ion undergoes a hydrolysis reaction, and the generated hydroxide combines with metal ions to form a hydroxide with less solubility (the chemical nature is Alkaline). When the temperature rises, the water vapor evaporates and the hydroxide is precipitated from the wall. With the gradual evaporation of the water, the hydroxide is precipitated on the surface of the concrete and cement. Or paint and other things are lifted up and no longer adhere to the wall, whitening, peeling, and peeling occur. This process is called "efflorescence." Therefore, it is not efflorescence caused by hydroxypropyl methylcellulose.
The customer said a phenomenon: the shotcrete he made will have efflorescence on the concrete wall, and no efflorescence will appear on the fired brick wall, which shows that the cement used on the concrete wall is silicic acid There is too much salt (strong alkaline salt). Efflorescence caused by the evaporation of water used in spraying. However, efflorescence will not occur without silicate on the fired brick wall. Therefore, the occurrence of efflorescence has nothing to do with spraying.
1. The silicate content of the base concrete cement is reduced.
2. Use anti-alkali backcoating agent, the solution penetrates into the stone to block the capillary tube, so that water, Ca(OH)2, salt and other substances cannot penetrate, cutting off the path of efflorescence.
3. Prevent water intrusion and do not spray a lot of water before construction.
Treatment of efflorescence
Can use the stone efflorescence cleaning agent on the market, the cleaning agent is a colorless translucent liquid made of non-ionic surfactants and solvents, etc. It has a certain effect on the cleaning of some natural stone surfaces. But before use, be sure to make a sample test block to test the effect and decide whether to use it.