Tensile and Flexural Characterization of Bamboo and Rattan as Alternative Reinforcing Bars to Conventional Steel in Concrete

The practical utilization of bamboo (Bambusa vulgaris) and rattan (Calamuc deerratus) as alternative for the conventional deformed steel reinforcement in concrete is essential for environmental, social and economic sustainability. For this reason, a systematic experimental study of the tensile properties of bamboo and rattan as well as the flexural behaviour of concrete beams reinforced with these alternative materials in comparison with the conventional steel bars was conducted and presented in this chapter. A universal testing equipment was used to assess the yield strength (YS), ultimate tensile strength (UTS), and elongation of 50 specimens of the three materials. Three beams of concrete strength 20 N/mm2 were reinforced individually at age 28 days with the same amount of bamboo, rattan, and steel bars, while the stirrups were largely mild steel bars. To analyze the flexural behavior, the beams were subjected to BS 1881 centre-point flexural loading. Bamboo, rattan, and steel bars had mean YS of 201.1 N/mm2, 58.5 N/mm2, and 442.7 N/mm2, respectively, while their UTS were 335.2 N/mm2, 85.4 N/mm2, and 540.1 N/mm2, in that order. The mean elongation of bamboo, rattan and steel were 7.42, 10 and 14.7% respectively. The load-deflection plots of bamboo and steel RC beams were quadratic, while rattan RC beams had curvilinear trend. The flexural stiffness of bamboo RC beams (BB) and rattan RC beams (RB) were 32 and 13.5% of the stiffness of steel RC beams (SB). The post-first crack residual flexural strength was 41% for BB and SB, while RB was 25%. Moreover, the moment capacities of BB and RB corresponded to 51 and 21% respectively of the capacity of steel RC beams. The significant difference in flexural capacity between natural rebars and steel can be attributed not only to tensile strength, but also to inadequate interfacial bonding between bars and concrete. It can be concluded that bamboo bars are ideal rebars for non-load bearing and lightweight RC flexural constructions, but rattan requires additional pre-strengthening treatment for increased interfacial bonding and load-carrying capability.