In people's minds, stone is often considered to be a long-lasting high-grade decorative material. Stone decoration can be used once and for all. In fact, in the natural environment, dust, exhaust gas, acid rain, freezing and other pollutants are on the building. The stone used is very easy to cause fading, pollution and even damage, greatly reducing the decorative effect and service life of the stone. At the same time, due to the mistake of the construction method, the stone decoration effect will also fail, and the building has to be rebuilt in a short period of time. The renovation has caused a lot of waste of manpower and material resources.
First, the necessity of stone conservation
1 Overview
In people's minds, stone is often considered to be a long-lasting high-grade decorative material. Stone decoration can be used once and for all. In fact, in the natural environment, dust, exhaust gas, acid rain, freezing and other pollutants are on the building. The stone used is very easy to cause fading, pollution and even damage, greatly reducing the decorative effect and service life of the stone. At the same time, due to the mistake of the construction method, the stone decoration effect will also fail, and the building has to be rebuilt in a short period of time. The renovation has caused a lot of waste of manpower and material resources.
2. The main reason that affects the service life of stone and the cause of stone disease
Common stone diseases are: water spots are not dry, salting out pan-alkali (Baihua), rust spots yellow, frost damage, surface corrosion, pigment pollution (including oil pollution), moss growth and powder spalling. There are many reasons for the stone to produce various lesions and shorten the service life. There are two main reasons for the classification: one is the internal reason, that is, the structural structure and chemical composition of the stone; the second is the external reason: mining and processing methods, installation The impact of factors such as construction process and use environment.
2.1 Reasons from the inside of the stone
(1) Structural structure of stone: There are micro-cracks and capillary pores in natural stone. It will absorb fine dust and dirt in the air for a long time, and slowly penetrate into the interior of the stone due to capillary action, thus greatly reducing the decoration of the stone. Performance and service life. The smaller the pores, the stronger the capillary action and surface adsorption.
(2) Relatively complex chemical composition: Some components in the stone are easy to interact with the external environment, causing erosion or variability of the stone. Stones generally contain iron components to varying degrees, and are corroded by moisture to produce rust yellow. The higher the iron content in the stone, the more likely it is to produce rust yellow. In addition, most of the natural marble is mainly composed of carbonates such as calcium carbonate and magnesium carbonate, and a small amount of basic oxides. Calcium carbonate and magnesium carbonate are relatively stable compounds, but some basic oxides are chemically unstable. In humid environments, they are easily soluble in acidic oxides such as carbon dioxide, sulfur dioxide, sulfur trioxide, and dioxide in the air. A chemical reaction occurs in nitrogen to change the physical structure inside the marble. Similar chemical damage will occur on other stone materials. Lighter will make the surface of the stone tarnish, and even the color will fade and appear stains; in the case of heavy, the hardness of the natural stone will decrease and the surface will be weathered and peeled off.
2.2 Reasons from the outside of the stone
There are many external reasons that affect the decorative effect and service life of stone, such as improper maintenance during mining, storage and transportation, the influence of bonding materials used to install stone, and natural environmental factors.
(1) Influence of mining, processing and storage and transportation process: For example, the crack of stone may be related to improper mining method; the iron tool used for processing may also cause hidden danger to the rust of stone, and improper stone coolant may pollute. Stone; improper maintenance during storage and transportation will also cause rust and grass rope yellow pollution.
(2) Impact of installation and construction technology and bonding materials: If the cement is installed with cement mortar and paste, the alkaline soluble substances in the cement will ooze along the capillary pores of the stone due to the erosion of rainwater. The surface, while the basic compound such as Ca(OH)2 will chemically react with CO2 and H2O in the air, and CaCO3 will crystallize on the surface of the stone to form a salting-out and pan-alkali phenomenon. In addition, some of the salts formed after cement hydration are hygroscopic. After infiltrating into the stone, they will absorb the moisture in the air and form water spots on the surface of the stone, which seriously affects the appearance. In addition, improper use of adhesive materials, such as certain stone adhesives, may also cause yellowing of the stone.
(3) 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 to the stone. In addition, freezing damage is also an environmental factor that cannot be ignored. Because the stone has water absorption (even if it is made of dry hanging stone), in the cold winter, the weathering process is accelerated by freezing, so that the strength is reduced, which not only affects the use. Life expectancy also threatens personal safety.
Second, the cleaning treatment of stained stone and coloring renovation
In order to make the decorative stone always bright and beautiful, the effective method is to carry out the pre-protection treatment before the construction or installation, to prevent it from happening. However, some stone materials often do not cause sufficient attention in the installation and construction. Once the installation and construction is completed, the stone disease will follow, mainly represented by cement residue, Baihua, rust yellow, water spots, oil stains, cracks, and chalking. And faded and so on. Therefore, the treatment and renovation of diseased stone is also essential. Below we will explain the specific symptoms:
1. Baihua and cement residue
We often see some white matter hanging from the surface or gap of the stone. This is commonly known as “Baihuaâ€. The cause of Baihua is the soluble matter in the cement mortar during wet construction, along with the rain from the stone. The joints, cracks and pores leak out, and the white crystals formed by the combination of carbon dioxide in the air, or acidic rainwater dissolves the cement and oozes out to the surface of the stone, and recrystallizes as the rain evaporates. In addition, some rough surface and even smooth stone, due to the wet installation process, the cement mortar contaminated the surface of the stone and did not remove it in time. After the mortar was completely hardened, it remained permanently on the surface of the stone, seriously affecting the decorative effect of the stone. Some tiles, such as non-slip tiles and polished tiles, also suffer from contamination by cement residues. For thin-layer cement and early Baihua, it can be directly cleaned with Baihua scavenger Q-215B or strong cleaning agent Q-305C. For a large amount of cement residue and long-term thick white, in order to save cleaning costs, It can be removed with a tool first, then cleaned with a cleaning agent, or alternated with cleaning and cleaning to achieve a satisfactory cleaning effect.
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