Experimental Evaluation of Thermo-mechanical and Hygroscopic Properties in Earth Blocks Reinforced with Date Palm Fibers and Hybrid Stabilizers

Abstract

Despite the growing use of natural fibers and mineral stabilizers in earth construction, the combined influence of fiber reinforcement and stabilizer type on the thermo-mechanical and hygroscopic behavior of stabilized earth blocks (SEBs) remains insufficiently understood, particularly regarding pore structure evolution and moisture transport mechanisms. This study addresses this gap through a comprehensive experimental investigation. Mixtures incorporated cement (5%, 10%), lime (5%, 10%), and a hybrid stabilizer (5% cement + 5% lime), combined with date palm fibers (DPFs) at 0%, 0.25%, and 0.5%. The experimental program included mechanical characterization (compressive and flexural strength), physical and hygric assessment (total, open, and water-accessible porosity, water absorption, and capillary water uptake), durability-related transport properties (water vapor transmission and water permeability under pressure), as well as complementary non-destructive and thermal analyses using ultrasonic pulse velocity and Hot Disk thermal conductivity measurements. Results showed that DPFs significantly enhanced thermal insulation but increased porosity and permeability due to greater pore interconnectivity. Although fiber incorporation caused a slight reduction in mechanical strength, the 10% cement-stabilized formulation exhibited the best overall performance, combining the highest strength with the lowest water absorption and permeability. The hybrid formulation (5% cement + 5% lime) did not surpass the 10% cement mixture in durability-related indicators; however, it remains a viable compromise by reducing cement content while maintaining acceptable mechanical performance compared with lime-only and unstabilized mixtures. These findings provide valuable guidance for developing sustainable, thermally efficient, and locally sourced earth-based building materials suited to hot and arid regions.