What are the characteristics of natural stone?

1. Fire resistance Various stones are different, and some stones are chemically decomposed under the action of high temperature.

(1) Gypsum: Decomposes when it is greater than 107 C.

(2) Limestone, marble: decomposes when it is greater than 910 c.

(3) Granite: At 600 C, it is cracked due to uneven heating of the constituent minerals.

2. Expansion and contraction

Stone is also thermal expansion and contraction, but if it is cooled after heating, its shrinkage can not return to its original volume, and some must remain a permanent expansion; the US arsenal has tested from 00C to 1000C, then down to 00C, and measured permanent. The degree of expansion increases from 0.02 to 0.045%.

3. Frost resistance

When the stone is in a wet state, it can resist freezing and thawing without causing significant damage. This property is called freeze resistance. The water in the pores of the rock freezes when the temperature is as low as minus 20 degrees Celsius, and the water swelling in the pores is 1/10 larger than the original volume. If the rock cannot resist the force generated by such expansion, the phenomenon will be destroyed. Generally, if the water absorption rate is less than 0.5%, the frost resistance is not considered.

4. Compressive strength

The compressive strength of stone varies depending on factors such as mineral composition, crystal thickness, uniformity of cemented material, load area, load and angle of cleavage. If other conditions are the same, a dense material in which the crystal grains are fine and bonded to each other generally has a high strength. Dense volcanic rocks have no difference in compressive strength after drying and saturated water (water absorption is extremely low). If it is porous and water-resistant cemented rock, its drying and moisture intensity are significantly different.