This study investigates the thermophysical, mechanical, and durability performance of adobes reinforced with Juncus maritimus fibres, a natural material recently considered for sustainable construction. The composites were prepared by mixing clay with different fibre volume fractions (20%, 40%, and 60%). Prior to fabrication, the raw materials were thoroughly characterised through physical, chemical, thermal, geotechnical, and mineralogical analyses to ensure a comprehensive understanding of their intrinsic properties. The elaborated adobe blocks were then subjected to a series of tests to evaluate their thermal performance using the Hot Disk method, as well as their mechanical behaviour through compression and flexural strength tests.

To assess durability, capillary water absorption experiments were conducted to examine the influence of fibre content on water resistance. The incorporation of fibres led to a significant improvement in thermal insulation, reducing heat transfer and increasing the material’s heat storage capacity. However, a progressive decrease in mechanical strength was observed with higher fibre content. In contrast, water resistance was enhanced, particularly with higher fibre incorporation, indicating better performance under humid conditions.

These findings demonstrate the potential of Juncus maritimus fibres as an effective natural reinforcement for adobe, resulting in composite materials that are not only more thermally efficient but also more durable, offering promising applications in sustainable and eco-friendly building practices.