Flexible Mineral Wool
Property
Composition
| Component | Content (% wt) | |
| Glass wool | Rock wool | |
| Silica (SiO2) | 53-65 | 45-54 |
| Alumina (Al2O3) | 2-5 | 8-15 |
| Titania (TiO2) | < or = 0.2 | 0.6-3 |
| Ferric Oxide (Fe2O3) | < or = 0.35 | 1.8-12.5 |
| Ferrous Oxide (FeO) | < or = 0.35 | 1.8-12.5 |
| Lime (CaO) | 6.5-23.5 | 8-21 |
| Magnesia (MgO) | 2-5 | 3-14 |
| Manganese Oxide (MnO) | 0.05 | 0.2 |
| Sodium Oxide (Na2O) | 9-18 | 1.6-16 |
| Potasium Oxide (K2O) | 0.8-1.7 | 0.4-1.6 |
| Boric Oxide (B2O3) | 2-8 | <0.2 |
Source: Doran, DK, Newnes Construction Material Pocket Book; Gutterworth-Heinemann Ltd, Oxford, 1994 [13]
Other components include [13]:
- Phenol formaldehyde resin (often modified with urea or lignosulphonates): 10% nominal
- Mineral oil: 1% nominal
- Silane: 0.02% nominal
- Polydimethylsiloxane (or water repellent base on this): 0.1% nominal
The two most common type of mineral fibre are [13]:
- Glass wool: a mineral wool (usually borosilicate glass) with a mean fibre diameter of 4-9 µm.
- Rock wool: a mineral wool made from naturally occurring igneous rock (such as basalt or diabase) with a mean fibre diameter of 4-9 µm.
Thermal Conductivity [13]
Density and temperature differential affect the thermal conductivity of mineral fibre material.
It ranges from about 0.03 to 0.05 W/ mK
Working Temperature [13]
The performance of mineral wool product is unaffected at temperatures up to 230ºC. Softening of glass may initiate at above 670ºC. The breakdown process is one of softening rather than combustion; at no stage does any significant toxicity occur.
Fire Properties [13]
- Mineral wool is non-combustible, and does not add to the fire load of the building.
- Good thermal insulation properties which slow and reduce heat transfer between surfaces, giving protection to structural elements and preventing fire spread.
- The surface of the unfaced product act to resist the spread of flame.
* The various methods of installing acoustical material affect the NRC values. When an installation system is selected, a much closer NRC value can be obtained. The range is from 250 to 2000 Hz.