Basalt Fiber (Inorganic / Natural Volcanic Mineral Fiber)
Basalt fiber is made from a single natural raw material — volcanic basalt rock — melted at ~1400–1500°C and extruded through platinum-rhodium bushings into continuous filaments. Unlike glass fiber, it requires no chemical additives: the natural mineral composition of basalt (SiO₂ ~50%, Al₂O₃ ~15%, FeO/Fe₂O₃ ~10%, CaO ~8%, MgO ~5%) directly becomes the fiber. The result is an inorganic fiber with higher strength (3.0–4.8 GPa) and better thermal resistance (~650°C continuous) than E-glass, plus excellent alkali resistance — making it the preferred reinforcement for cement and concrete applications where glass fiber would degrade. It is 100% natural, single-ingredient, and recyclable.
Quick Facts
| Type | Inorganic; melt-spun from natural volcanic basalt rock — no additives needed |
| Raw material | Basalt rock (volcanic origin; SiO₂ ~45–52%, Al₂O₃ ~10–17%, FeO/Fe₂O₃ ~8–15%, CaO ~7–12%, MgO ~3–8%) |
| First commercialized | 1980s (USSR military); civilian applications from 1990s onward |
| Density | 2.6–2.8 g/cm³ (slightly heavier than E-glass at 2.5) |
| Tensile strength | 3.0–4.8 GPa (comparable to S-glass; better than E-glass) |
| Service temperature | Continuous: ~650°C (vs. E-glass ~600°C); short-term: 800–1000°C |
| Chemical resistance | Excellent alkali resistance (natural stone chemistry); better than E-glass in corrosive environments |
Properties
| Property | Rating | Engineering implication |
|---|---|---|
| Strength | ★★★★☆ | Higher than E-glass; comparable to S-glass; natural material, not engineered |
| Heat resistance | ★★★★☆ | ~50°C higher continuous rating than glass; key advantage |
| Alkali resistance | ★★★★★ | Excellent — natural basalt is alkaline rock; superior to most glasses in cement |
| Eco-profile | ★★★★☆ | No chemical additives; 100% natural; single-ingredient melt; recyclable |
| Brittleness | ★★☆☆☆ | Same brittle failure as glass; surface-sensitive |
| Cost | ★★★☆☆ | Higher than E-glass; lower than carbon/aramid; limited production scale |
Yarn Engineering Guide
| Application | Form | Key criteria |
|---|---|---|
| Cement/concrete reinforcement | Chopped basalt fiber or rebar | Alkali-resistant; bridges cracks; replaces steel rebar in corrosive environments |
| High-temp insulation | Basalt wool; needle mat | Superior to glass wool at elevated temperatures; fire protection |
| FRP composites | Basalt roving/woven | Chemical plant pipes/tanks; marine; where glass is inadequate but carbon is overkill |
Summary
Basalt fiber is a natural inorganic reinforcement — stronger and more heat-resistant than E-glass, with better alkali resistance for cement, at a moderate cost premium. Its limitation is production scale, not performance. See the Textile Material framework.