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Several destructive factors that may cause corrosion to stone

Stone is one of the relatively high-end materials in the current decoration field. The pure natural texture and various surface treatment effects can increase the indoor and outdoor decoration effects to several levels.At the same time, compared to other decorative materials that are difficult to clean up when stained and easily shattered when hit by heavy objects, stone is obviously much more solid. It is not only hard in structure, able to resist heavy objects, and has a smooth surface,can resist the intrusion of ordinary dirt.It can be described as a very cost-effective decoration material.


But this does not mean that the stone is impeccable. In the actual application of stone, there are still many destructive factors that can cause erosion in the general environment. Therefore, do not think that as long as you choose stone as a decoration material, you can be completely at ease. To extend its service life as much as possible, we still need to have a simple understanding of the destructive factors that affect the life of stone, and do some nursing work accordingly.


1. Water

In the eyes of the public, water is the source of life, but for stone people, to a certain extent, water is the out-and-out "source of all evil". Because water is the most difficult substance in life, this also causes various stone products to be relatively susceptible to water erosion in many details, which in turn causes various problems. The culprit of various common phenomena is often water.Water will transport the chemical properties and salts of oxidized or reduced minerals into the stone, and will also bring various modern industrial pollutants into it.This will accelerate the dissolution and destruction of the stone, or cause the loss of calcium carbonate and other components to make the stone lose its luster, or cause the formation of gel inside the stone to produce water spots, or cause the internal calcium components to be brought to the surface of the stone to form a whitening phenomenon,or make the iron in the stone rust, forming rust spots.


On the other hand, rainwater, condensed water, and groundwater enter the stone through the micropores. As the temperature changes, the volume of the stone will shrink or expand repeatedly, and the stress can cause the stone to crack. Especially for outdoor stone that has been in a humid environment for a long time and has a large temperature difference between day and night, water repeatedly and unevenly absorbs, penetrates, and dissolves, constantly shrinks and expands, and it is easy to crack the rock. In addition, in places where the weather is relatively cold. When the pores of the stone absorb enough water, once the temperature drops below 0°C, the water in the stone begins to freeze and the volume expands. When the expansion force of the ice is greater than the structural force of the stone, the stone will be damaged, which is the phenomenon of frost damage.


It is also worth noting that water is also an indispensable condition for the growth of microorganisms and other organisms. The growth of microorganisms will also cause great damage to the stone.


2. Salt crystals

Natural stone will produce salt crystals in the natural formation process. After being mined and processed by humans, the content of salt crystals may increase due to the penetration of cement, mortar, dust, moisture, sea water and polluted liquids into the micropores. On the one hand, salt will generate a lot of pressure during the crystallization process. If the temperature of the stone rises greatly, the salt will expand in volume. On the other hand, under certain conditions, some salts can also recrystallize to form new hydrates, occupying a larger volume and generating greater pressure. These conditions may cause the internal damage of the stone.


In general usage scenarios, salt crystallization is harmful to the stone, and it is often inseparable from the wind. The salt crystals inside the stone dissolve in the water (moisture) and spread to the surface. The wind accelerates the evaporation of water, thereby promoting the accumulation of salt and the formation of crystals. Repeated salt dissolution and salt crystallization will cause the surface of the stone micropores to be powdered or scaled off. If it is washed by rain, after long-term action, deep grooves are easily formed on the surface of the stone, which affects the aesthetic effect.


In addition, some decorative stones will show the phenomenon that the surface does not dry under constant humidity. The reason is often caused by the moisture absorption of salt. In real life, we need to pay more attention.


3. Acid rain

From ancient China, to the ancient Mabylon in the Mesopotamia, to ancient Greece, ancient Egypt, and ancient Rome along the Mediterranean coast, a large number of stone imprints have been left on the long journey of mankind from wildness to civilization. Because of this, there are many great stone buildings and carvings around the world that have been preserved to this day. However, the details of most of the relics have so far been dirty and obscure, and the culprit is acid rain.


The combination of oxides such as carbon dioxide and sulfur dioxide in the air with rain water will increase the acidity of the water and become more corrosive. This acidic liquid is extremely harmful to stone, especially carbonate stone.When it rains, the calcium carbonate in the stone will chemically react with acid rain containing sulfur dioxide to produce calcium sulfate. Part of the calcium sulfate will enter the gaps between the grains of the stone, deposit on the surface of the marble in the form of crusts, and then gradually fall off,and then affect the stone curtain wall. The remaining soluble salts may further attack the stone through recrystallization or hydration.


4. Smoke

Smoke is a mixture of moisture, dust and various chemical fuels. Soot, like a sponge, absorbs various gases and forms an acidic solution when mixed with water. Severe industrial pollution, automobile exhaust emissions and blocked atmospheric circulation are the main reasons for the formation of industrial smog. Smoke is not only harmful to organisms, but also defaces and corrodes stone buildings and decorative stones.


5. Biology

Generally speaking, compared with other destructive factors, the stone erosion directly caused by organisms or their metabolites is much smaller. However, the erosion and destruction of stone by organisms, especially microorganisms, still cannot be ignored. The products of biological metabolism include oxygen, carbon dioxide, and organic acids. Dissolving in water will increase the corrosivity of water. At the same time, in the process of organicization, organisms will also promote the oxidation-reduction reaction of minerals and consume minerals, thereby promoting the decomposition of rocks. In addition, the excrement of birds and other animals will also cause certain damage to the stone.


The surface of unprotected new stone is more likely to be occupied by organisms, such as algae, bacteria, and lichens. Once these organisms occupy the surface of the stone, the biodegradation will continue to develop in depth, causing irreversible damage to the stone itself. In addition, some plants, such as creeper, ivy, etc., can grow from cracks in the stone and cause stress damage directly.


Of course, the various factors that cause the stone to be corroded are not isolated, they are carried out at the same time and promote each other. Therefore, in the actual use process, we need to carefully analyze the local climate and geological conditions, and adopt the most appropriate method to maintain the stone, so as to avoid the erosion of the stone.