Kaolin–Cellulose–Lignin Biocomposites Inspired by Termite Mounds for Sustainable Structural Materials

Abstract This study presents a bioinspired structural material that mimics the chemical composition and preparation process of termite mounds by fabricating a composite of kaolin, cellulose microfibrils, and lignin without any additional thermal energy. We investigated the roles of each component in the composites: kaolin as the matrix, cellulose as the filler (reinforcement), and lignin as the binder. Our findings revealed that cellulose and lignin contents tuned the mechanical properties and the wettability of the biocomposites, attributed to their dense intertwined structure and hydrophobicity, respectively. At an optimal composition, namely, C49-K/L40 (49 wt % cellulose at kaolin/lignin = 40 w/w), the composite achieves a compressive strength of 148 MPa and a strain at maximum stress of 37%, exhibiting much higher stress than conventional concrete yet significantly higher strain and, consequently, superior toughness. This composite material exceeds the performance of most other biobased alternatives, representing a significant step toward developing sustainable, high-performance materials.