Basalt ropes for marine applications: Mechanical performance and seawater durability

Synthetic ropes are widely used in the marine industry, but are known to impact the environment in various ways such as microplastics production during use. This study examines the potential of basalt ropes for use in marine applications through the investigation of a basalt braid. First, mechanical properties at both yarn and rope scales were investigated, demonstrating the material’s sensitivity to the braiding process. Alternatives to this braid were then tested: adding a coating and increasing the lay length. Adding a coating increased the strain at break, while increasing the pitch resulted in greater specific strength and specific stiffness. Finally, the durability of the reference braid was evaluated through ageing in seawater at 15 °C and 40 °C for up to 3 years. Both temperatures led to two-stage degradation: a rapid loss of strength (-30% at 15 °C, -60% at 40 °C). After 3 years at 40 °C, the loss of strength remained stable. This previously observed degradation phenomenon could be explained the corrosion of the basalt fibre surface, which then acts as a protective layer. The data obtained through this study could serve as a basis for integrating basalt ropes into marine applications where synthetic ropes cannot be used.