Electrical resistivity of wood–cement biocomposites of Pinus pseudostrobus

Abstract This study investigates the influence of incorporating 5% gray and white Portland cement on the electrical resistivity of wood–cement biocomposites manufactured from Pinus pseudostrobus sawdust and a wheat-protein adhesive. Three composite formulations were prepared: a control (no cement), gray-cement (MCgray), and white-cement (MCwhite) composites. Test specimens were fabricated under controlled thermal and humidity conditions and evaluated for density and electrical resistivity in transverse and parallel directions. Statistical analyses revealed that the addition of cement significantly affected both density and electrical resistivity. The density increased by approximately 7% for MCgray and 2.3% for MCwhite compared with the control. Electrical resistivity decreased markedly for both cement-containing composites: gray cement reduced resistivity by approximately 70%, while white cement achieved up to 75% reduction, with lower values in the parallel direction. These differences were attributed to the formation of conductive pathways associated with hydrated cement phases and ionic migration within the wheat-protein matrix. The results confirm that even low cement dosages of 5% substantially alter the microstructural compactness and conduction mechanisms of lignocellulosic composites. Notably, the comparable conductivity performance of white and gray cements suggests that oxide purity (Fe₂O₃ content) is not the only determining factor in electrical transport. This work provides at quantitative comparison of gray and white cements in wood-based biocomposites, contributing to the development of multifunctional, bio-based materials with tunable electrical properties.