Agave Americana fibers for sustainable construction: An integrated evaluation of Thermo-mechanical properties, carbon footprint, and life cycle cost

Earthen materials offer a low-carbon, locally available alternative for sustainable construction. In this study, we explore how Agave americana (AA) fibers improve the thermal and mechanical behavior of clay-based earth bricks. AA fibers were mixed into clay at 2, 4, and 6 wt% relative to the dry mass of soil, and the resulting composites were characterized for density, thermal conductivity (Hot Disk method), and compressive and flexural strength. Fiber addition reduced dry density from 1994 kg/m³ (control) to 1824, 1696, and 1622 kg/m³, respectively, while thermal conductivity fell by up to 41% (from 0.845 to 0.501 W/m·K) and diffusivity dropped by 53%. Specific heat capacity increased from 572 to 877 J·kg^-1·K^-1 (≈53%), indicating enhanced heat storage capacity on a mass basis. Mechanically, compressive strength rose from 1.26 ± 0.09 MPa to a peak of 2.45 ± 0.12 MPa (≈94% increase) at 4 wt% fiber content, while flexural strength increased from 1.23 ± 0.07 MPa to 1.41 ± 0.10 MPa, reflecting improved crack-bridging and stress redistribution within the earthen matrix. The 4 wt% formulation provided the best thermo-mechanical compromise, combining a 36% reduction in thermal conductivity with the highest compressive strength. Complementary carbon footprint and life-cycle cost assessments further indicate that this optimized formulation offers environmental and economic advantages compared to conventional mineral-based materials. Overall, AA fiber-reinforced earth bricks demonstrate strong potential as low-carbon, thermally efficient materials for sustainable construction.