The destructive effect of salt on stone

The damage of salt to stone is the second factor after water. Its destructive power to stone is concentrated in: stress caused by crystallization weathering, crystallization pressure, hydration pressure, moisture absorption and expansion, and temperature expansion. Due to the role of salt, the stone becomes loose and forms the main weathering cause of the stone. The existence of salt: one is the crystal salt attached to the stone itself, and the other is the salt formed by the combination of the acquired stone components and the acid gas in the air.

In the construction of stone, the salt in cement, lime, soil, food, sea water, industrial production, etc., and some cleaning agents will enter the stone through the micropores and cracks of the stone. After the salt forms crystals in the stone, a great pressure is produced, that is, the crystallization pressure. The greater the crystallization pressure, the greater the destructive power of the stone. Some salts are also transformed into recrystallized hydrates under certain conditions, which then occupy a larger volume and generate additional pressure, namely hydration pressure.

　　The molecular formula of gypsum has large water molecules. As the temperature changes, the pressure changes correspondingly, and the repeated stress changes. Finally, the local stone changes into powdery, broken nitrate, and scales.

　　The damage of salt to the stone is often caused by repeated dissolution, precipitation, and precipitation on the surface of the stone with the help of moisture and wind, and finally the stone is broken.