[Note: The information in this article is from the Internet, and is presented by Longmeida Stone Group, the first brand of Seiko Stone and an expert in hotel stone engineering. It is shared with you to create classics and inherit precious stones.]
Section I Overview
People often think that stone is a kind of long-term high-grade decorative material, which can be used for decoration once and for all. In fact, in the natural environment, dust, waste gas, acid rain, freezing and other pollutants are very easy to fade, pollute and even destroy the stone used in buildings, greatly reducing the decorative effect and service life of the stone. At the same time, due to the mistakes in the construction methods, the stone decoration effect will also fail, and the buildings will have to be redecorated in a short period of time, resulting in a large waste of human and material resources.
There are many reasons for stone to have various pathological changes and shorten its service life, which can be summed up as internal and external causes: internal causes (changes caused by the structure and chemical composition of stone) and external causes (effects of mining and processing methods, installation and construction technology, service environment and other factors). It is described in detail below.
Section II Main causes affecting stone service life and stone diseases
Common stone diseases mainly include: water spots are not dry, salting out and alkali returning, white flowers, rust spots spit yellow, frost damage, surface corrosion, pigment pollution (including oil stain), moss growth and powdery peeling, etc.
1. Reasons from the interior of stone
(1) Structure and structure of stone materials: there are micro cracks and pores in natural stone materials, which will absorb fine dust and dirt in the air over a long period of time, and slowly penetrate into the interior of stone materials due to capillarity, thus greatly reducing the decorative performance and service life of stone materials. The smaller the pore size, the stronger the capillarity and surface adsorption.
(2) Relatively complex chemical composition: some components in the stone are easy to interact with the external environment, causing erosion or variation of the stone. Stone materials generally contain iron in varying degrees, and rust yellow will be produced due to the erosion of moisture. The higher the iron content in the stone, the easier the rust yellow will occur. In addition, most natural marble is mainly composed of carbonate, such as calcium carbonate and magnesium carbonate, and a small amount of alkaline oxide. Calcium carbonate and magnesium carbonate are relatively stable compounds, but the chemical properties of some alkaline oxides are unstable. In a humid environment, they are easy to react with acidic oxides in the air, such as carbon dioxide, sulfur dioxide, sulfur trioxide, nitrogen dioxide, etc., to change the internal physical structure of marble. Similar chemical damage will also occur on other stones, and the light ones will make the stone surface lose luster, even the color will fade, and there will be spots; If it is heavy, the hardness of natural stone will decrease, and the surface will be weathered and peeled off.
2. Reasons from outside of stone
There are many external reasons that affect the decorative effect and service life of stone, such as improper maintenance during mining, processing, storage and transportation, the impact of bonding materials used for installing stone, and natural environmental factors.
(1) The impact of mining, processing, storage and transportation process: for example, the cracks of stone may be related to improper mining methods; The iron tools used for processing may also leave hidden dangers for the stone to rust yellow, and improper stone cooling fluid may pollute the stone; Improper maintenance during storage and transportation will also cause rust spots and yellow straw rope on stone.
(2) Impact of installation and construction technology and bonding materials: If the wet pasting method of cement mortar is used for stone installation, alkaline soluble substances in cement will seep out along the pores of stone to the surface due to rain erosion, and alkaline compounds such as Ca (OH) 2 will react with CO2 and H2O in air, forming CaCO3 crystals on the stone surface, forming the phenomenon of salting out and alkali returning. In addition, due to the hygroscopicity of some salts generated after cement hydration, they will absorb water in the air and form water spots on the stone surface after penetrating into the stone, seriously affecting the aesthetics. In addition, the use of inappropriate paste materials, such as some stone paste glue, may also cause the stone to turn yellow.
(3) Impact of environmental factors: environmental factors include environmental pollution, acid rain erosion and freezing damage. The polluted air, acid rain and other man-made pollutants in the natural environment will pollute and corrode the stone. In addition, frost damage is also an environmental factor that can not be ignored. Because stone materials have water absorption (even if dry hanging construction is used), in cold winter, the weathering process is accelerated due to frost, which reduces its strength, not only affecting the service life, but also threatening personal safety.
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