Overview Marble: Also known as marble, it is recrystallized limestone as long as its composition is CaCO3. Limestone softens under high temperatures and pressures and recrystallizes to form marble when the minerals it contains change. The main components are calcium and dolomite, with many colors, usually obvious patterns, and many mineral particles. Mohs hardness ranges from 2.5 to 5. Marble is a metamorphic rock formed by the action of high temperature and high pressure in the earth's crust from the original rocks in the earth's crust. The internal forces of the earth's crust cause the original types of rocks to undergo qualitative changes, that is, the structure, structure and mineral composition of the original rocks change. New rocks formed after qualitative changes are called metamorphic rocks. Marble is mainly composed of calcite, limestone, serpentine and dolomite. Its main component is calcium carbonate, accounting for more than 50%. Since marble generally contains impurities, and calcium carbonate is affected by carbon dioxide, carbides, and water vapor in the atmosphere, it is also easily weathered and corroded, causing the surface to quickly lose its luster. Marble is generally softer than granite. In interior decoration, marble is suitable for TV table tops, window sills, indoor floors, etc. Marble is a trade name, not a petrological definition. Marble is a category of natural architectural decorative stones. It generally refers to metamorphosed or unmodified carbonate rocks that have decorative functions and can be processed into building stones or handicrafts. It is named after the brilliantly colored and patterned stone produced in Diancang Mountain, Dali City, Yunnan, China. Marble generally refers to marble, limestone, dolomite, and skarn and marble formed by different alterations of carbonate rocks. Marble is mainly used to process into various shapes and plates for walls, floors, platforms, and columns of buildings. It is a precious material for furniture inlays. It is also commonly used as a material for monumental buildings such as monuments, towers, statues, etc. Marble can also be carved into arts and crafts, stationery, lamps, utensils and other practical works of art. Marble has a soft texture, beautiful appearance and solemnity, elegant style and various colors. It is an ideal material for decorating luxurious buildings and a traditional material for artistic sculpture.
Marble classification
Marble is divided into three categories:
Dolomite: Magnesite (calcium magnesium carbonate) content is more than 40%
Forsterite: Magnesite (calcium magnesium carbonate) content between 5 and 40.
Calcite: Magnesite (calcium magnesium carbonate) content is less than 5
Characteristics of ore raw materials
(1) Process classification
Marble is a type of rock represented by marble, including carbonate rock and related metamorphic rocks. It is generally softer in texture than granite. Common rocks include marble, limestone, dolomite, skarn, etc. The classification of marble varieties has different naming principles. Some are named after the place of origin and color, such as Dandong green, Tieling red, etc.; some are named after patterns and colors, such as snowflake white, mugwort green; some are named after pattern images, such as autumn scenery. , waves; some have traditional names, such as white marble, crystal black jade, etc. Therefore, due to different origins, there are often synonyms for the same type of rocks or the same name for different rocks.
The marble produced in my country can be roughly divided into seven series: white, yellow, green, gray, red, coffee and black according to the basic color of its polished surface. Each series can be divided into several subcategories according to the color and pattern characteristics of its polished surface, such as: white marble, rosin yellow, Dandong green, Hangzhou gray, etc. The patterns and crystal grain sizes of marble are ever-changing, including landscape type, cloud type, pattern type (threads, willow leaves, cultural images, paleontology, etc.), snowflake type, etc. Modern architecture is colorful and constantly changing. Therefore, decorative marble also requires multiple varieties and colors that can be used in different parts of the building. Generally, monochrome marble requires uniform color; colorful marble requires a gradual transition of patterns and shades; patterned marble requires clear patterns, bright colors, and strong pattern regularity. In short, it is better if the colors are beautiful, easy to splice and decorate in large areas, and can be supplied in batches with the same color. The classification of Chinese marble technology is shown in Table 4.25.1.
(2) Mineral composition and main characteristics
The mineral composition and ore characteristics of marble are directly related to the performance and decorative effect of its products.
(3) Chemical composition and physical properties
The chemical composition of marble generally does not play a major role in whether it can be utilized, but it can directly explain the lithology and indirectly affect the physical properties. Chemical properties have certain significance in evaluating the processability, weathering resistance and corrosion resistance of marble.
The physical properties of marble are an important indicator for judging its processability, as well as an important reference for performance and scope of use.
Uses of marble
Marble has beautiful colors and patterns, high compressive strength and good physical and chemical properties. Its resources are widely distributed and easy to process. With the economic development, With the development of marble, the application scope of marble is constantly expanding, and its usage is increasing, playing an important role in people's lives. Especially in the past 10 years, large-scale mining, industrial processing, and international trade of marble have enabled marble decorative plates to enter the building decoration industry in large quantities. They are not only used in luxurious public buildings, but also in homes. decorate. Marble is also widely used in the manufacture of exquisite appliances, such as furniture, lamps, smoking sets and artistic sculptures. Some marbles (including limestone, dolomite, marble, etc.) can also be used as alkali-resistant materials. The gravel and leftover materials generated during marble mining and processing are also commonly used in the production of artificial stone, terrazzo, stone rice, and stone powder, and can be used as fillers in coatings, plastics, rubber and other industries.
Industrial technical requirements
Due to different applications, the industrial technical requirements of natural marble have different emphasis.
1. Main requirements for natural marble blocks
The main requirements for natural marble blocks in the building materials industry standard (JC202-92) are as follows:
Block materials Must have the shape of a rectangular parallelepiped.
The specifications and dimensions of the blocks require that the length is greater than or equal to 100cm, the width is greater than or equal to 50cm, and the height is greater than or equal to 70cm.
Appearance quality requires that the tone and pattern of the same batch of blocks should be basically the same; the appearance quality grade of missing corners, missing edges, cracks, etc. of the blocks should comply with the provisions of Table 4.25.6.
Physical performance requirements: bulk density is not less than 2.6g/cm3; water absorption is not greater than 0.75; dry compressive strength is not less than 20MPa; flexural strength is not less than 7.0MPa.
2. Marble quality requirements for craft carving
It is required that the marble structure is dense, the particles are uniform and not easy to fall off, there are no cracks, no inclusions, and the color, pattern, blockiness, and shape meet the shaping requirements. , the general requirement is greater than 0.15m3. If used outdoors, the rock surface does not need to be fresh, but it requires good weather resistance and low water absorption.
3. Quality requirements for electrical insulation boards
Many non-ferrous metals, rare metals, precious metals and non-metal minerals are related to marble in origin. It is also an excellent building material and raw material for arts and crafts. Marble is not very hard and is a medium-hard stone that is easy to mine and process. After polishing, the board will show decorative patterns or color textures, which are very beautiful and can be used as indoor and outdoor decoration materials. The waste materials from mining and processing can be made into handicrafts or crushed to produce high-quality aggregates such as terrazzo and terrazzo. A small number of highly dense and homogeneous materials can be used for artistic carving and decoration. Since marble is basically composed of pure calcium carbonate or magnesium carbonate, it is extremely sensitive to the dissolution of acid-polluted air. There are usually carbonic acid separated from carbon dioxide and sulfuric acid generated from smoke in the urban atmosphere, which constantly interact with marble. Contact will cause marble products to be affected to varying degrees. In any case, marble is still an ideal material in architectural decoration and sculpture.
Resource status
my country is extremely rich in marble mineral resources, with large reserves and many varieties, and the total reserves rank among the top in the world. According to incomplete statistics, it has been initially determined that there are nearly 400 varieties of domestic marble, among which the more expensive varieties include the following.
● Pure white ones include: Beijing Fangshan white marble; Anhui Huaining and Guichi white marble; Hebei Quyang and Laiyuan white marble; Sichuan Baoxing Shu white marble; Jiangsu Ganyu white marble; Yunnan Dali Cangshan white Marble; Shandong Pingdu and Yexian Xuehuabai, etc.
● Pure black ones include: Guilin black from Guilin, Guangxi; black marble from Shaoyang, Hunan; Shandong Cangshan Moyu and Venus King; Henan Anyang Moyu black, etc.;
● Red ones include : Anhui Lingbi red Anhui snail; Nanjiang red from Nanjiang, Sichuan; Laishui red from Laishui, Hebei and Fuping red from Fuping; Northeast red from Tieling, Liaoning, etc.;
● Gray ones include: Hangzhou, Zhejiang Hang gray; Yun gray in Dali, Yunnan, etc.;
● Yellow ones include: Henan Zhechuan rosin yellow, rosin jade and beige, etc.
● Green ones include: Dandong Green from Dandong, Liaoning; Laiyang Green from Laiyang, Shandong and Wave Jade from Qixia; Bibo from Huaining, Anhui;
● Colored ones include: Yunnan Green Spring flowers, autumn flowers, ink flowers; plum blossoms on a snowy night in Quzhou, Zhejiang, etc.
Evaluation method
Choose the grade: According to the allowable deviation of specifications and dimensions, the allowable tolerances of flatness and angle, as well as the appearance quality, surface finish and other indicators, marble slabs are divided into superior products There are three levels: first-class product and qualified product; the grading and identification of marble slabs are mainly through the detection of instruments and measuring tools.
Check the appearance quality: Different grades of marble slabs have different appearances. Because marble is naturally formed, defects are inevitable. At the same time, the quality of processing equipment and measuring tools is also the cause of plate defects. Some boards are not plump (warped or dented), have defects (cracks, blisters, stains, etc.), and have different specifications (such as missing edges and corners, irregular boards), etc. According to national standards, marble slabs of all grades are allowed to have certain defects, but they are not so obvious for high-quality products.
Choose patterns and colors: Marble slabs are colorful, with various tones and patterns. This is the precious charm of marble slabs. Basically the same tone, small color difference, and beautiful patterns are the specific manifestations of excellent varieties, otherwise the decorative effect will be seriously affected.
Detect surface gloss: The surface gloss of marble slabs will greatly affect the decorative effect. Generally speaking, the polished surface of high-quality marble slabs should have a mirror-like luster and can clearly reflect the scenery. However, due to different chemical compositions of marbles of different qualities, even products of the same grade will have great differences in gloss. Of course, there will also be certain differences in the surface gloss of boards between different grades of the same material. In addition, the strength and water absorption rate of marble slabs are also important indicators for evaluating the quality of marble.
Characteristics and advantages of marble:
1. No deformation, high hardness and strong wear resistance.
2. Anti-abrasion, high temperature resistance, maintenance-free.
3. Physically stable, well-structured, the grains fall off when impacted, the surface does not have burrs, does not affect its plane accuracy, the material is stable, can ensure no deformation for a long time, the linear expansion coefficient is small, and the mechanical precision is high , anti-rust, anti-magnetic and insulating.
1. After long-term natural aging, the rock has a uniform organizational structure, a very small linear expansion coefficient, and the internal stress completely disappears without deformation.
2. Good rigidity, high hardness, strong wear resistance and small temperature deformation.
3. It is not afraid of acid and alkaline liquid corrosion, will not rust, does not need to be oiled, is not easy to stick to dust, is easy to maintain, and has a long service life.
Fourth, it will not appear scratches, is not blocked by constant temperature conditions, and can maintain its original physical properties at room temperature.
5. It is not magnetized, can move smoothly during measurement, has no sluggish feeling, is not affected by moisture, and has a well-defined plane. Physical properties: Specific gravity 2970-3070kg/m3 Compressive strength: 2500-2600kg/cm3 Elastic coefficient: 1.3-1.5×106kg/cm2 Water absorption rate.
Maintenance of Marble
Marble is easy to stain. Use less water when cleaning. Wipe it regularly with a slightly damp cloth with mild detergent, and then wipe dry with a clean soft cloth. Polish.
Seriously worn marble furniture is difficult to handle. It can be wiped with steel wool and then polished with an electric polisher to restore its luster. Or wipe it carefully with a liquid scrubber. Lemon juice or vinegar can be used to clean the stains, but it is best not to leave the lemon on it for more than 2 minutes. Repeat the operation if necessary, and then clean and dry it. For minor scratches, special marble cleaners and conditioners are available. Old or valuable marble furniture should be handled by professionals.