An inorganic hydrophobic layer connected by rivets endows the bamboo with high fire retardant, mechanical, and mold-proof properties

This study investigated the mineralization process of calcium carbonate on bamboo surfaces using aqueous solutions of calcium propionate and sodium carbonate as precursors. The mineralization process was carried out once, three times, and five times, and its effects on fire-retardant, mechanical, and mold-proof properties were examined. Scanning electron microscopy revealed that calcium carbonate bonded with bamboo cells through a rivet structure, resulting in a pronounced roughness of the mineralized layer. Mineralized bamboo exhibited improved fire-retardant properties, with decreases of the maximum heat release rate and total heat release rate by 20-32 % and 8-13 %, respectively. Additionally, mineralized bamboo displayed enhanced mechanical properties, increase of modulus of elasticity (MOE) and modulus of rupture (MOR) by 1-3 % and 3-10 %, respectively. After five cycles of deposition, the initial contact angle of the mineralized bamboo became 159 degrees, and the infestation value of Aspergillus niger mold was almost zero, indicating satisfactory hydrophobicity and mold-proof properties. Mineralization of bamboo surfaces with calcium carbonate substantially improved the properties of bamboo and extended its application in various fields.