Enhancing the Durability and Mechanical Performance of Bamboo Fiber-Reinforced Concrete Through Magnesium Hydroxide Modification Under Wet-Dry Cycles

This study systematically investigates the effects of different treatment methods (untreated and magnesium hydroxide [Mg(OH)₂] treated fibers) and varying fiber dosages (0, 1.2, 1.8, 2.3 and 2.8) % on the mechanical properties and durability of bamboo fiber-reinforced concrete (BFRC). Compressive, tensile, and flexural strength tests were conducted before and after 16 wet-dry cycles, and scanning electron microscopy (SEM) was used to analyze the microstructure of bamboo fibers and their interfacial bonding mechanisms, establishing the durability of BFRC. The results indicate that as the bamboo fiber content increases, the compressive strength of BFRC decreases, while the tensile and flexural strengths reach their optimal values at a 2.3 % fiber content. Untreated bamboo fibers contain surface impurities, leading to weak interfacial bonding with the cement matrix, whereas Mg(OH)2-treated fibers exhibit a cleaner surface and significantly enhanced interfacial adhesion. After 16 wet-dry cycles, BFRC with untreated fibers showed a flexural strength loss of 11.5–12.7 %, compared to 17.4 % for plain concrete. BFRC with Mg(OH)2-treated fibers further reduced the loss to 8.2–8.9 %, confirming the treatment’s effectiveness. This study provides new insights into the development of high-durability and sustainable bamboo fiber-reinforced composites and establishes a theoretical foundation for their application in civil engineering.