Mineral Board
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Composition
Predominant component or mineral fibre is mineral wool (90 to 99.8% by weight). Other components include:
- 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:
1. Glass wool; a mineral wool usually made from borosilicate glass with a mean fibre diameter of 4-9 µm.
2. Rock wool; a mineral wool made from naturally igneous rock (such as basalt or diabase) with a mean fibre diameter of 4-9 µm.
Chemical 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 |
Thermal Conductivity
Density and temperature differential affect the thermal conductivity of mineral fibre material: 0.03-0.05 W/m.K
Working Temperature
The performance of mineral wool product is unaffected below 230ºC. At temperature above 670ºC softening of glass may commence. The breakdown process is one of softening rather than combustion; at no stage does any significant toxicity occur.
Fire Properties
- Non-combustible and not add to the fire load of the building.
- Slow and reduce heat transfer between surfaces, giving protection to structural elements and preventing fire spread.
- Resist the spread of flame surface of the unfaced product