Bron :  The Vermiculite Association

  • Chemical formula

    (Mg,Ca,K,Fe11)3 (Si,AL,Fe111)4O10(OH)2O4H2O


  • Typical chemical analysis

    ElementWeight percentage
    SiO238-46
    AL2O310-16
    MgO16-35
    CaO1-5
    K2O1-6
    Fe2O36-13
    TiO21-3
    H2O8-16
    Other0.2-1.2



  • Typical physical properties of exfoliated vermiculite

    Colour :

    Light to dark brown

    Shape :

    Accordion shaped granulate

    Bulk density (a):64-160 kg/m³
    Loss of moisture at 110 °C :4-10%
    pH (in water):6-9
    Combustibility :

    Incombustible

    MOH Hardness :1-2
    Melting temperature :1200-1320 °C
    Cation exchange capacity (b):50-150 me/100g
    Specific heat :0.84-1.08 kJ/kgK
    Water retaining capacity (a):220-325% (weight ratio)
    20-50% (volume ratio)
Notes :(a) Bulk density and water retaining capacity vary according to the granule size.
(b) Exchangeable ions are Mg+2 and Ca+2, sodium acetate saturation / ammonium acetate substitution method.



  • Thermal conductivity at several densities

    Bulk density
    (kg/m³)

    Thermal conductivity
    (W/mK)

    56-64

    0.058

    80-96

    0.064

    160-192

    0.071




  • Granule size of exfoliated vermiculite

Dimensions (mm)

Density (kg/m³)

Equivalent names/descriptions

 

 

System A

System B

0 - 16

56-72

NA

Premium (6)

0 - 8

64-85

1

Large (4)

0 - 4

72-90

2

Medium (3)

0 - 2

75-112

3

Fine (2)

0 - 1

80-144

4

Superfine (1)

0 - 0.5

90-160

5

Micron (0)