Effects of Postmanufacture Conditioning on the Mechanical and Hygroscopic Properties of Extrusion Printed Wood–Sodium Silicate Composites

Abstract

Additive manufacturing of wood–sodium silicate composites could aid in mitigating the carbon footprint of the building and construction industry. However, the effect of postmanufacture conditioning on the mechanical and physical properties of additively manufactured wood–sodium silicate composites is not well understood. This study investigated eight different postmanufacture drying processes, including: ambient indoor and outdoor conditions, oven-drying at two different temperatures, microwave drying, alcohol-induced dehydration using ethanol and denatured alcohol, and desiccant drying. Each postmanufacture conditioning treatment was assessed in terms of total moisture extraction and moisture extraction rate as well as the flexural strength, flexural stiffness, and hardness of the wood–sodium silicate samples after drying. In addition, the water absorption and volumetric swelling properties of the additively manufactured wood–sodium silicate samples were assessed via water submersion tests. The postmanufacture conditioning treatments were found to significantly affect the mechanical and physical properties of the samples. A universal ranking system was established based on cumulative rankings of each evaluated characteristic. Samples dried in ambient outdoor conditions achieved the best overall ranking and had the smallest carbon footprint. However, ovendried samples had the best flexural properties. Future studies investigating hybrid approaches in which composites are sequentially subjected to different drying methods will likely provide the most desirable mechanical and physical properties of wood–sodium silicate composites.