Structural behaviour of geopolymer concrete beams reinforced with bamboo bars

Global warming has emerged as a critical environmental issue. The primary cause is carbon dioxide (CO₂), and the construction industry is responsible for significant CO₂ emissions during the production of cement and steel. In recent years, there has been an increasing trend toward manufacturing methods that do not utilize steel or cement. In this study, we investigate the structural performance of "bamboo-reinforced concrete," which employs bamboo reinforcement in place of steel bars and combines it with geopolymer concrete that does not require cement. Although this technology is based on the use of natural and rustic materials, it is anticipated that such nature-based solutions may be recognized as leading-edge technologies in the future. To explore the structural performance of bamboo-reinforced concrete, beam-shaped specimens were fabricated and subjected to flexural tests. The experimental results revealed the following: (1) Geopolymer concrete was trial-produced using glass powder as a binder. The results confirmed that it is possible to produce geopolymer concrete with a setting time exceeding 2 h and a 28-day compressive strength of 15 N/mm² or more. (2) Due to the lower bond strength of bamboo reinforcement, the failure mode of bamboo-reinforced concrete beams was found to differ from that of steel-reinforced concrete beams. (3) The strength of bamboo-reinforced concrete beam members could be accurately evaluated using values calculated from existing steel-reinforced concrete design equations. However, it was also confirmed that strength evaluation considering bond strength is necessary for bamboo-reinforced concrete beams.