Comparative Analysis of Wood Waste Species on the Mechanical Performance of Sustainable Cement-Based Mortars

The use of wood waste as a component in cementitious composites represents a promising strategy for reducing environmental impact and promoting circular economy principles in the construction sector. This study examines the influence of five types of wood waste, spruce sawdust, spruce shavings, oak, beech, and oriented strand board (OSB), on the properties of Portland cement mortars. A constant 5% by mass of sand was replaced with each wood residue, and mixtures were tested for flowability, density, flexural, and compressive strength at 7, 14, and 28 days. Our results show that wood addition reduces density by 20–36% and compressive strength by 70–85%, depending on species and particle morphology. Denser materials (oak and OSB) resulted in composites with higher mechanical strength, suggesting a more effective particle packing and interfacial interaction compared to porous particles (spruce sawdust, shavings), which led to higher water demand and reduced strength. Beech showed the highest flexural strength, indicating potential for bending-dominated applications. The study demonstrates the feasibility of using selected wood residues for lightweight, non-structural cement composites and outlines the need for future microstructural validation through SEM and porosity analyses.