Research on the flexural behavior of sawdust-magnesium oxychloride composite beams strengthened with FRP

Sawdust-magnesium oxychloride cement composite (SMOCC) is a novel low-carbon material whose beams exhibit inadequate flexural capacity due to premature sawdust fiber fracture. This study investigates the flexural behavior of SMOCC beams strengthened with FRP. A total of 6 groups of 13 beam specimens with dimensions of 2300 mm × 200 mm × 100 mm were designed for four-point bending loading tests. The design parameters include the type of FRP material (CFRP or BFRP), the number of FRP flexural reinforcement layers (1, 2, or 4), and the configuration of FRP shear reinforcement (4 or 6 stirrups). The results show that FRP reinforcement promotes a more ductile failure compared to unreinforced beams. Increasing CFRP layers improves flexural performance, but excessive layers (more than two) cause over-reinforcement, reducing efficiency. Additional CFRP hoops do not enhance bearing capacity or initial stiffness but effectively improve ductility. CFRP reinforced beams achieve higher peak loads and stiffness than those with BFRP. Strain measurements confirm deformation compatibility between FRP and the SMOCC matrix, validating the plane-section assumption. Theoretical predictions of the flexural capacity of the SMOCC beams based on a sectional analysis were found to be in good agreement with the experimental results and were within 5% on average.