Cement-free stabilization of compressed earth bricks using dredged dam sediments and milled date pits for arid and semi-arid regions

This study investigates a cement-free strategy for manufacturing compressed earth bricks (CEBs) by valorizing dredged dam sediments (DDS) and milled date pits (MDP), an abundant agricultural by-product. Three MDP size fractions (0–80 μm, 80–250 μm, 250–500 μm) were incorporated at substitution rates of 2.5–12.5 wt%, with a control sample (0%) for comparison. Each mixture was optimized for water content and compacted at 10 MPa. The best-performing formulation (5% MDP, 0–80 μm, 14% water content) reached a compressive strength of 12.79 MPa and low thermal conductivity (0.548–0.650 W/m·K), surpassing the unstabilized reference. Advanced characterization (XRD, FTIR, SEM, MIP) confirmed that no traditional cementitious phases developed. Stabilization was instead attributed to fine particle packing, selective moisture retention, and organic–mineral interphases such as whewellite (CaC₂O₄·H₂O) and glushinskite (MgC₂O₄·2 H₂O), coupled with mild clay activation under pressure. The dense shell and internal porosity of MDP enhanced cohesion, limited water absorption, and improved insulation. These results demonstrate the feasibility of producing non-hydraulic, thermally efficient CEBs from DDS and MDP, offering a sustainable construction material that balances strength, durability, and thermal performance.