Preparation and mechanical characterization of pressed carbonized wood sawdust bio-composite

This study investigates the development and performance of carbonized bio-composites derived from wood sawdust, integrated with sustainable binders such as cement, lime, and shale ash, to create environmentally friendly construction materials. The research systematically optimizes mix compositions and curing techniques to enhance mechanical properties, softening, and sustainability, with a focus on reducing cement content and mitigating CO₂ emissions. Wood sawdust, treated with various solutions (water, Al₂(SO₄)₃, CaCl₂, Ca(OH)₂), was combined with binders and additives (sand, shale ash) in precise proportions, followed by a controlled carbonization process (19% CO₂, 65% RH). Compressive strength tests revealed that cement-based composites with water-treated sawdust and 20% sand achieved a 44% strength increase (up to 9.6 MPa), while 30% cement replacement with shale ash yielded a 55% strength gain and improved water resistance (softening coefficient: 0.55). Carbonization, preceded by air-drying, further enhanced strength by 12% and density by 2%, demonstrating superior durability under moisture exposure. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the formation of calcite and a cohesive microstructure, respectively, underpinning the mechanical improvements. CO₂ emissions were reduced by up to 65% in optimized formulations compared to traditional cement production, aligning with circular economy principles. These bio-composites, suitable for lightweight masonry applications, outperform prior sawdust-based materials (1-3 MPa) in strength and sustainability. This work advances the field of sustainable construction by offering a scalable, high-performance alternative to conventional materials, with rigorous methodology and robust data supporting its potential for industrial adoption.