Natural stone is divided into slate and granite according to its physical and chemical characteristics and quality. Artificial stone is divided into terrazzo and synthetic stone according to the process. Terrazzo is made by forging and pressing raw materials such as cement and concrete; synthetic stone is made by using crushed natural stone as raw material and adding adhesives and then being pressed and polished. The latter two are artificially made, so their strength is not as high as the value of natural stone. Stone is a high-end product of building decoration materials. Natural stone is generally divided into granite, slate, sandstone, limestone, volcanic rock, etc. With the continuous development and progress of technology, artificial stone products are also constantly changing with each passing day, and their quality and beauty are no less than those of natural stone. With the development of architectural design, stone has long become one of the important raw materials for building, decoration, road and bridge construction.
Identification methods：observing the surface structure, measuring the size and specification, listening to the knocking sound, etc.
Inspection methods：test methods such as bulk density, true density, true porosity, water absorption rate, etc.
Definition： A building decoration material is applied in indoor and outdoor decoration design, curtain wall decoration and public facility construction.
Industry development
For industrial upgrading, China's stone industry needs technological transformation in product innovation, management innovation and marketing innovation. At the same time, it must meet the needs of building a beautiful China and give prominence to resource conservation and clean production.
Applications
Since different parts of buildings are decorated with natural facing stones, different types of stones are selected. When used for the decoration of outdoor buildings and exposed to long-term wind, rain, sunlight and other elements, granite is the best choice as it does not contain carbonates, has low water absorption and strong weather resistance. Granite stones of various types should be selected. For facing stones used for the decoration of hall floors, which require stable physical and chemical properties and high mechanical strength, granite stones should be preferred. For the decoration of wall skirts and bedroom floors at home, where the mechanical strength is slightly lower, marble with beautiful patterns can be used.
Physical properties
Fire resistance
Various stones are different. Some stones undergo chemical decomposition under the action of high temperature.
(1) Gypsum: Decomposes at temperatures greater than 107 °C.
(2) Limestone and marble: Decompose at temperatures greater than 910 °C.
(3) Granite: Cracks at 600 °C due to uneven heating of constituent minerals.
Expansion and contraction
It is also thermal expansion and contraction. However, if it is cooled after being heated, its contraction cannot return to its original volume, and a certain part must be retained as permanent expansion. The US arsenal once tested from 0°C to 100°C and then back to 0°C.
Frost resistance
When the temperature reaches minus 20 degrees Celsius, freezing occurs. The water in the pores expands to 1/10 larger than the original volume. If the rock cannot resist the force generated by this expansion, damage will occur. Generally, if the water absorption rate is less than 0.5%, its frost resistance performance is not considered.
Durability
Stone has good durability. Structures built with stone have the possibility of being permanent. Ancient people have long recognized this. Therefore, many important buildings and commemorative structures are built with stone.
Compressive strength
The compressive strength of stone will vary due to factors such as mineral composition, crystal fineness, uniformity of cementing material, load area, load action and the angle formed by joints. If other conditions are the same, usually dense materials with fine crystal particles and bonded together usually have higher strength. There is no difference in compressive strength between dense volcanic rocks after drying and being saturated with water (extremely low water absorption rate). For porous and water-sensitive cemented rocks, there is a significant difference in strength between dry and wet conditions.
There are two major categories of stone for building decoration: natural stone and artificial stone. Natural stone is mainly used. It is a high-grade decoration material and is mainly used in projects with high decoration grade requirements.
