LayGrade: Design and fabrication of a layer-graded bio-based composite from wood waste

Abstract

This study introduces a fully bio-based functionally graded composite developed from pine processing waste to enable structural and optical performance control in architectural components. Rosin, beeswax, and sawdust were combined in defined ratios to produce stratified composites exhibiting spatially tunable stiffness and translucency. Mechanical characterisation showed a progressive increase in tensile strength from 1.21 to 2.89 MPa and compressive strength from 9.19 to 39.27 MPa with increasing sawdust content (0–60 wt%), accompanied by a corresponding decrease in light transmittance. Mix-specific calibration of CNC milling parameters ensured dimensional precision and defect-free surfaces across gradients. These data informed a voxel-based computational workflow coupling material composition with adaptive machining parameters to achieve local control of mechanical and optical behaviour within a single artefact. A graded tile demonstrator validated the framework, demonstrating continuous variation in stiffness and translucency through depth-controlled fabrication. The work establishes a reproducible pathway linking bio-composite formulation, digital design, and adaptive manufacturing, advancing wood-waste upcycling toward performance-driven applications in sustainable architecture.