Classification of decorative stones and five characteristics of natural stones

At present, there are four kinds of common stones in the market: marble, granite, terrazzo and synthetic stone. Among them, marble is made of white marble; Granite is harder than marble; Terrazzo is forged from cement, concrete and other raw materials; Synthetic stone is made of crushed stone of natural stone as raw material, plus adhesive, etc. through pressurization and polishing. Because the latter two are made manually, their strength is not as high as that of natural stone.

Marble refers to sedimentary or metamorphic carbonate rocks, including marble, dolomite, limestone, sandstone, shale and slate.

1. Fire resistance

All kinds of stones are different. Some stones undergo chemical decomposition under the action of high temperature.

(1) Gypsum: decompose when it is greater than 107c.

(2) Limestone and marble: decompose when it is greater than 910c.

(3) Granite: cracks due to uneven heating of constituent minerals at 600C.

2. Expansion and contraction

Stone also expands and shrinks with heat, but if it is heated and then cooled, its shrinkage cannot return to its original volume, but must retain a part to become permanent expansion; American Arsenal has tested from 00C to 1000C and then reduced to 00C. It is measured that the degree of increase of permanent expansion is 0.02-o.045%.

3. Frost resistance

At minus 20 degrees Celsius, freezing occurs, and the water expansion in the pores is 1 / 10 larger than the original volume. If the rock cannot resist the force caused by this expansion, damage will occur. Generally, if the water absorption is less than 0.5%, its frost resistance will not be considered.

4. Compressive strength

The compressive strength of stone varies due to mineral composition, crystal thickness, uniformity of cementitious material, load area, angle of load action and cleavage, etc. If other conditions are the same, usually the dense materials with fine crystalline particles bonded to each other have high strength. There is no difference in compressive strength (extremely low water absorption) of dense volcanic rocks after drying and saturated water. If they are porous and water resistant cemented rocks, there is a significant difference in dry and wet strength.