Property

Industrial Gypsum

Standard Gypsum

Plaster Gypsum

Forming Gypsum

Quick  Setting Gypsum
(Plaster of Paris)

Slow Setting Gypsum

Color

Grey – Light Pink or Yellowish - Homogeneous

homogeneous bright white

homogeneous bright white

homogeneous bright white

Fineness (By Weight)

Whole amount  passes  through a standard 1.18 mm . mesh - The retained amount in 150 micron mesh should not exceed  25%

Retained amount  by a standard 1.18 mm . mesh - should not exceed  5%

Retained amount  by a standard 1.18 mm . mesh - should not exceed  1%

Whole amount  passes  through a standard 0.595 mm . mesh - The retained amount in 150 micron mesh should not exceed  5%

Setting Time      ( minutes)

Not less than 6 & not more than 15

Not less than 8 & not more than 15

Not less than 60 & not more than 180

Not less than 15 & not more than 40

Failure Resist-ance by Bending (N/mm2)

Not less than 1 for 24 days & 2 for 7 days

-

-

Not less than 1.5 for 1 hr. & 4 for 7 days

Volume  Stability

-

the cast plaster in molds does not show signs of decomposition, swelling, or holes when exposed to saturated vapor pressure equal to one atmospheric pressure

-

Longitudinal  Expansion

-

-

Not more than 0.2% at 24 hours in a closed humid atmosphere

-

Transverse force

-

Not less than  2.5 N/mm2

Not less than  1.2 N/mm2

-

Mechanical resistance

-

Does not exceed 5 mm

-