Marble

Six major qualification index characteristics of stone

Gloss

Gloss is one of the important contents to evaluate the quality of facing stone. Besides the color and variety, it is the main basis to measure the quality of the stone.

According to the standard of “jc79-92 natural marble building plate”, the minimum gloss requirements (qualified products) of marble mirror plate shall be no less than 70, 60, and 40 gloss units according to the different chemical principal components.

According to the “jc205-92 natural granite building plate”, the minimum gloss shall not be less than 75 gloss units.

Black Marble

Bulk density and water absorption

The bulk density is the ratio of the mass to the volume of the stone. High density means that the specific gravity and capacity of rock are large, and it has high stability in the process of sawing, grinding, polishing, and cutting.

Water absorption refers to the water absorption capacity of stone, which reflects the number, size, distribution, and connectivity of pores contained in the stone.

Generally, the water absorption rate of rock is less than 1.5%, and those less than 0.5% can be regarded as having good weathering resistance and freezing resistance, so the frost resistance test is not required.

China Black Marble

Bending strength and bending resistance

The bending strength is equivalent to the bending resistance, which refers to the ability of the facing plate of a certain specification to resist fracture at two supporting points.

The bending strength of the stone is much lower than the compressive strength, which is about 1 / 14 ~ 1 / 8 of the compressive strength after the test. Generally, the compressive strength can be roughly estimated as the bending strength. Generally, the greater the bending strength, the less likely the plate is to break.

According to the standard of “jc205-92 natural granite building plate”, the bending strength shall not be less than 8.0MPa; according to the standard of “jc79-92 natural marble building plate”, the bending strength shall not be less than 7MPa

Compressive strength and stone compression resistance

Compressive strength refers to the anti-destructive capacity of rock under uniaxial compression. The compressive strength indicates the hardness of the rock.

Compression strength is expressed in MPa, 1MPa = 10.2kg/c ㎡ (kgf / cm2)

One standard atmospheric pressure = 760 mm Hg = 76 cm Hg = 1.013 × 105 Pascal = 10.336 m water column.

To ensure that the standard atmospheric pressure is a fixed value, the resolution of the Tenth International metrology conference in 1954 stated that the standard atmospheric pressure is 1 standard atmospheric pressure = 101325 Newton / m2

According to the standard of “jc205-92 natural granite building plate”, the dry compression strength shall not be less than 60.0mpa.

According to the standard of “jc79-92 natural marble building plate”, the dry compression strength of marble shall not be less than 20.0Mpa.

The compressive strength of granite is between 110-245mpa, and that of marble is between 70-110mpa

China Marble

Physical performance index of marble plate

Bulk density ≥ 2.60g/cm3

Water absorption ≤ 0.5%

Dry compression degree (compression resistance) ≥ 50MPa

Bending degree (bending resistance) ≥ 7.0Mpa

Physical performance index of granite plate

Bulk density ≥ 2.56g/cm3

Water absorption ≤ 0.60%

Dry compression degree (compression resistance) ≥ 100MPa

Bending degree (bending resistance) ≥ 8.0MPa

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