Thermo-hygro-mechanical behavior of an innovative bio-based building material incorporating date palm shives

This study explores the use of date palm shives as a bio-based aggregate for lightweight insulating concretes, addressing the need for low-impact construction materials to reduce the carbon footprint of the building sector. A comprehensive multi-scale experimental approach was adopted, including: the extraction and physico-microstructural characterization of date palm shives; the formulation of bio-based concretes with different shive incorporation rates (8%, 12%, and 16%) using two distinct binders : Tradical PF 70 for the CTF formulation and CEM II + hydraulic lime for the CCF formulation; the evaluation of physical, thermal, hygrothermal, and mechanical properties; and an optimization phase followed by comparison with reference bio-based concretes reported in the literature. The results show that date palm shives exhibit a highly porous lignocellulosic alveolar structure, a particle size distribution mainly between 1 and 34 mm, and a high water absorption capacity, reaching approximately 492% by mass. These intrinsic characteristics result in concretes with low apparent density and enhanced thermal and hygrothermal performance. CTF formulations demonstrate superior thermal insulation, with thermal conductivity values ranging from 79.86 to 90.89 mW·m -1 ·K -1 , together with high water vapor permeability (1.97–3.07 ×10 -11 kg·m -1 ·s -1 ·Pa -1 ) and a moisture buffering capacity (MBV) reaching 2.21 g·m -2 ·%RH -1 . In contrast, CCF formulations exhibit higher compressive strength, reaching up to 1.40 MPa, but at the expense of hygrothermal performance. The optimized CTF formulation with 12% shives provides the best balance between hygrothermal performance and mechanical resistance, outperforming comparable bio-based concretes by 6–15% and confirming the strong potential of date palm shives for sustainable, high-performance construction materials.