Basalt fiber is a continuous fiber drawn from natural basalt rock melted at about 1,450 °C. This article explains its strengths through four indicators (typical industry values; actual figures subject to test reports).

1. Mechanics: high specific strength

Basalt fiber has a tensile strength of about 3,500–3,800 MPa, a density of about 2.65 g/cm³ and an elastic modulus of about 90 GPa. Converted to specific strength (strength/density), that is about 20–35× that of steel, meaning a lighter structure reaches a similar strength level, with 30–50% weight savings in lightweight applications.

2. Heat and flame: born fireproof

Basalt comes from melted volcanic rock and is inherently non-combustible. Its long-term service temperature is about −260 °C to 700 °C (higher for short periods), with a limiting oxygen index ≥68%, reaching Class A non-combustible level, and it retains more than 80% of its strength at high temperature, which organic materials struggle to match.

3. Weather and corrosion: unafraid of water or salt

24h water absorption <0.5% and salt-spray resistance over 3,000 hours. For bridges, ships, coastal works and chemical environments, corrosion resistance means lower whole-life cost.

4. Electromagnetics: signal-friendly

A dielectric loss tangent below 0.01, about 50% lower than glass fiber, and wave transmittance above 98% make it a natural fit for 5G communications, radomes and similar applications.

How does it compare with common materials?

In one sentence: carbon fiber performs well but costs a lot (about RMB 150–300/kg); glass fiber is cheap but has performance limits. Basalt fiber sits between them: at RMB 30–80/kg it covers many applications where glass fiber falls short and carbon fiber is unaffordable.

Note: figures in this article are typical industry values for illustration; formal selection is subject to actual test reports and prototype data.