Fiber comparison
Basalt fiber vs E-glass fiber
Every value below is a typical room-temperature figure with its source, test method and conditions — the same dataset that drives the calculators.
Which to choose
Basalt is spun from melted volcanic rock rather than a glass batch, and comes out slightly stiffer and stronger than E-glass with better resistance to heat and alkaline attack. E-glass has the wider supply chain, far more published data and lower cost. Basalt is the interesting substitute where temperature or alkali resistance matters.
| Property | Basalt fiber | E-glass fiber | Difference |
|---|---|---|---|
| Density | 2.67 g/cm³ | 2.54 g/cm³ | Basalt fiber — 5% higher |
| Young's modulus E | 89 GPa | 72.4 GPa | Basalt fiber — 23% higher |
| Tensile strength | 2900 MPa | 3450 MPa | E-glass fiber — 19% higher |
Where these numbers come from
- Fiore et al., Composites Part B 74 (2015) — basalt fibre review
- Daniel & Ishai, Engineering Mechanics of Composite Materials, 2nd ed.
Typical room-temperature values for learning and preliminary design; grades vary widely and a supplier datasheet always overrides a textbook figure. Confirm against the datasheet before design work.