Lilis Nurhayati, Sri Murni Dewi, Wisnumurti, Devi Nuralinah
In this research, the mechanical properties and the reinforcement mechanism of finger-jointed laminated Merbau beams processed from wood-industry wastes are investigated and unreinforced specimens and externally U-shaped carbon fiber reinforced polymer (CFRP) strengthened beams are compared. The problem to be solved is the brittle failure and reduced flexural capacity of finger-jointed glulam; hence, it determines the combined impact of joint orientation (face-finger and face-butt), the number of lamination (three and five layers), and CFRP reinforcement on block-assembled beams with randomly distributed finger joints through four-point bending tests. The outcome of the study reveals that the use of CFRP has a huge impact on the flexural performance of the material, with the ultimate load being increased by 27.4–48.8% and the maximum bending moment being raised by 45.3% when compared to non-reinforced beams. The mid-point deflection at the maximum load has also increased by 6.5–51.4%, which shows a higher capacity for deformation and better ductility of the material. The noted enhancements are credited to the successful shifting of the stress from the timber tension zone to the CFRP, lessening of stress concentration at the finger-joint discontinuities, and the crack initiation and propagation taking longer time in random locations which together change the structural response from sudden brittle fracture to more stable damage progression leading up to failure. Among the tested configurations, face-butt beams have obtained the highest modulus of elasticity of 20.46 GPa (an 8.8% increase), while the five-lamina face-butt configuration strengthened by CFRP has reached the greatest modulus of rupture of 55.85 MPa (a 33.4% increase). The three-lamina face-finger beams showed the highest increase of MOR after reinforcement, being at 48.30 MPa (a 46.4% increase). Changing lamination from three to five layers raised flexural strength by 18.9%, suggesting a homogenization effect that improves stress distribution in laminated beams composed of blocks. All in all, the collaboration of finger-joint configuration, number of lamination, random block assembly, and CFRP strengthening has opened a door to convert Merbau wood waste into higher-performance engineered timber elements for low-carbon structural applications Copyright © 2025, Authors.
Department of Industrial Engineering, Universitas Katolik Darma Cendika, DR. Ir. H. Soekarno str., 201, Surabaya, 60117, Indonesia; Department of Civil Engineering, Universitas Brawijaya, M.T. Haryono str., 167, Malang, 65145, Indonesia
