Strength Properties of Lightweight Foamed Concrete with 15 kg/m³ of Kenaf Fiber

Abstract This comprehensive study investigates the reinforcement of Lightweight Foamed Concrete (LFC) with 15 kg/m 3 of untreated and treated Kenaf Fiber (KF) to improve its strength properties. Three different mix designs including control mix (LFC-CTR), LFC with untreated kenaf fiber (LFC-15UKF), and LFC with treated kenaf fiber (LFC-15TKF) were inspected to determine their strength properties including compressive strength, splitting tensile strength and flexural strength. The incorporation of KF with a length of 3 ± 1 cm did not significantly improve the compressive strength of LFC in both untreated and treated kenaf fiber condition. However, LFC-15TKF demonstrated the highest splitting tensile strength of 0.68 MPa. Identically, LFC-15TKF also exhibited the highest flexural strength at 2.52 MPa, attributed to the improved mechanical interlocking facilitated by the improved surface characteristics of treated KF. Scanning Electron Microscopy analysis revealed enhanced interfacial bonding in LFC-15TKF, emphasizing the role of the treatment purification process in promoting fiber surface adhesion with cement paste at Interfacial Transition Zone within the LFC matrix. Overall, despite a decrease in compressive strength compared to LFC-CTR, LFC-15UKF and LFC-15TKF demonstrated notable improvements in splitting tensile strength and flexural strength, indicating the effectiveness of KF in distributing and withstanding tension within LFC matrix.