Time： 2019-03-20 00:00:00
People often think that stone is a long-term high-grade decorative materials, adopt stone decoration can once and for all. In fact, in the natural environment, dust, exhaust gas, acid rain, freezing and other pollutants can easily cause discoloration, pollution and even damage to the stone materials used in buildings, greatly reducing the decorative effect and service life of the stone materials. At the same time, due to the errors in construction methods, the decorative effect of the stone materials will also fail, which will have to be heavy on the buildings in the short term. New decoration has resulted in a great waste of manpower and material resources.
There are many reasons that cause various pathological changes and shorten the service life of stone. Generally speaking, the main reasons are: internal reasons: changes caused by both the structure and chemical composition of stone; external reasons: factors such as mining and processing methods, installation and construction technology, use environment and so on.
The main reasons affecting the service life of stone materials and causing stone diseases are as follows: common stone diseases include: dry spots, salting out and alkali return, white flowers, yellow rust spots, frost damage, surface corrosion, pigment pollution (including oil stains), moss growth and powder peeling. There are many reasons that cause various pathological changes and shorten the service life of stone, which can be summarized into two aspects: one is the internal reasons, i.e. the changes caused by the structure and chemical composition of stone; the other is the external reasons, i.e. the influence of mining and processing methods, installation and construction technology and use environment.
1. Reasons from inside of stone
(1) Structural structure of stones: There are micro-cracks and capillaries in natural stones, which will absorb fine dust and dirt in the air for a long time, and gradually infiltrate into the interior of stones due to capillary action, thus greatly reducing the decorative performance and service life of stones. The smaller the pore size, the stronger the capillarity and surface adsorption.
(2) Relatively complex chemical composition: Some components in stone are easy to interact with the external environment, resulting in erosion or variation of stone. Stones generally contain iron in varying degrees, and rust will occur when corroded by moisture. The higher the iron content in stone, the easier the rust yellow will be produced. In addition, most natural marbles are mainly composed of carbonates, such as calcium carbonate and magnesium carbonate, and a small amount of alkaline oxides. Calcium carbonate and magnesium carbonate are relatively stable compounds, but the chemical properties of some alkaline oxides are unstable. In humid environment, they can easily react with acidic oxides such as carbon dioxide, sulfur dioxide, sulfur trioxide and nitrogen dioxide in the air to change the physical structure of marble. Similar chemical damage can also occur on other stones, light will make the stone surface lose luster, or even color fade, there are spots; heavy will make the hardness of natural stone decline, surface weathering and peeling.
2. Reasons from outside of stone
There are many external factors affecting the decorative effect and service life of stone materials, such as improper maintenance during mining, processing, storage and transportation, the influence of bonding materials used for installing stone materials and natural environmental factors.
(1) The influence of mining, processing and storage and transportation: for example, the cracks of stone may be related to improper mining methods; the iron tools used in processing may also cause rust and yellowing of stone, and improper cooling liquid of stone may pollute stone; improper maintenance during storage and transportation may also cause pollution of stone such as rust spots and straw rope yellowing.
(2) Influences of installation technology and bonding materials: If the wet bonding method of cement mortar is used in stone installation, alkaline soluble substances in cement will seep out along the capillary pore of stone due to the erosion of rainwater, while alkaline compounds such as Ca(OH)2 will react with CO 2 and H 2 in the air to form CaCO 3 crystallizing on the surface of stone, resulting in salting out and alkaline return. Elephant. In addition, due to the hygroscopicity of some salts produced by cement hydration, water spots will be formed on the surface of stone after infiltration into stone, which seriously affects the aesthetics. In addition, improper use of pasting materials, such as some stone pasting glue, may also cause yellowing of stone.
(3) The impact of environmental factors: environmental factors include environmental pollution, acid rain erosion and freezing damage. Polluted air, acid rain and other man-made pollutants in the natural environment can cause pollution and corrosion of stone materials. In addition, freezing damage is also an environmental factor that can not be neglected, because stone has water absorption (even if it is constructed by dry hanging). In cold winter, freezing accelerates its weathering process and reduces its strength, which not only affects its service life, but also threatens personal safety.