Stone can be divided into natural stone and artificial stone (also known as artificial stone). Stone is a high-grade product of architectural decoration. Natural stone is divided into granite, boulder, sandstone, limestone, volcanic rock, etc. With the continuous development and advancement of technology, artificial stone The products are also constantly changing, and the quality and beauty are not inferior to natural stone. With the development of the economy, stone has already become one of the important raw materials for construction, decoration, roads and bridge construction.
The advantages and disadvantages of selecting and distinguishing the facing stone, in addition to the color pattern can be intuitively measured, the rest must rely on physical and chemical performance testing to understand. These properties have an important relationship to the use, durability, processability, and transportation of the facing stone. Foreign countries, especially developed countries, must carry out rigorous testing on each variety. This information should also be attached to the facing stone in China's postal service, and it must be provided during the negotiation. Many domestic products in China have also done this, but most products, especially township and village enterprises, have been neglected for various reasons. The leaders of relevant departments have repeatedly stressed the importance of attaching importance to the testing of the physical properties of decorative stone, but it is not enough. The physical and chemical performance test can reflect the pros and cons of the stone, the performance is as follows:
1, usability:
Any stone on the building, any piece of stone on each building, must have a certain degree of mechanical, such as compressive strength, bending strength and mineral composition, structural composition, structural structure, water saturation, etc., such as compression The strength, quartz and feldspar are higher than calcite and dolomite, so granite generally has higher compressive strength than marble. Granite and marble itself have different mechanical strengths due to different compositions. Granite is generally higher than gabbro, different structures of the same kind of rock, and different compressive strengths. For example, fine-grained stone is higher than coarse-grained structure, etc. Higher than unequal. The acid and alkali resistance of stone has a close relationship with chemical composition. Generally speaking, the content of SiO2 is high and the acid resistance is good, while the content of CaO and MgO is high and alkali resistance.
2, durability:
For any building, it is expected to be used for a long time, and the facing stone is also required to be beautiful for a long time. Therefore, it must have certain weathering resistance, frost resistance, anti-wear and other properties, and these properties are related to the water absorption rate and porosity in the stone. Certain metal sulfides, such as pyrite, are easily oxidized to limonite or ferrous sulfate in the atmosphere, thereby reducing the strength and aesthetics of the stone. Therefore, the determination of mineral composition is also important for understanding the durability of stone. Radioactive elements are directly related to human health, especially for interior decoration, and there must be strict restrictions on their radioactive attempts.
3. Processability:
The mining, sawing, grinding and polishing of stone is itself a process of resisting external mechanical forces. The mineral is easy to process because of its low hardness, single composition and uniform structure. There are flaws that can only adapt to rocks of a certain strength. For example, diamond frame saws are suitable for sawing marble. ZBQ sand saws are not good for cutting strong stone. Different mineral components also have an effect on the glossiness. Dark minerals are easy to polish and light colors are difficult. The difficulty of polishing is also related to the chemical composition. For example, in the original TC79-92 natural marble building board standard, the mirror gloss has different requirements for different marbles. Therefore, according to the mineral composition and chemical composition, it is also known whether the gloss of the processed product has reached the required level. Different chemical compositions are also required to choose different grinding heads.
I beam has different sizes and very versatile, which is widely used for building construction, bridge, vehicle, bearing bracket, machine etc. 30# I beam with thick flange is specialized in electric hoist crane which is easy for electric hoist crane to operate.
The I-beam is mainly divided into three types: ordinary I-beam, light I-beam and low alloy light i-beam.
Ordinary I-beam, light steel flange is a variable cross-section of the thick web, the external thin; H steel: HW HM HN HEA HEB HEM, etc. the flange is a constant cross-section
Application scope
Because of the relatively high and narrow section size, the ordinary steel beam and the light steel beam have a large difference in the moment of inertia of the two main sleeves. The use of I-beam should be selected according to the requirements of the design drawings.
I Beam
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