Behavior Under Compression and Bending of Bamboo Filled with Plant-Based Cementitious Composites

Introduction: Bamboo exhibits favorable physicomechanical properties and significant potential for application in civil construction as an alternative to conventional materials. This study aimed to evaluate the geometric, physical, and mechanical characteristics of Bambusa vulgaris culms along their longitudinal axis, in addition to investigating bamboo absorption behavior, differential shrinkage of the culms, and the effect of filling with a sisal fiber-reinforced cementitious composite under compressive and flexural loads, in accordance with Brazilian and international standards. For this purpose, culms were harvested from Bambusa vulgaris specimens at the State University of Feira de Santana (UEFS), followed by cleaning, drying, and subsequent characterization. Results indicated that after 89 days of ambient air drying, the specimens attained constant mass and exhibited a reduction in external culm diameter from base to apex, with spatial variability in physical and mechanical properties along the culm length. Bamboo demonstrated higher water absorption compared to the fiber-reinforced composite. Structural performance of the filled bamboo was assessed through compressive and flexural testing of specimens measuring 12 cm and 20 cm, respectively, with and without composite filling. Specimens incorporating the composite exhibited enhanced crack propagation resistance attributable to the reinforcing effect of the vegetal fibers embedded within the matrix, thereby substantiating the efficacy of the filling technique, as corroborated by load-displacement response curves. Objective: The objective of this study is to investigate the structural behavior of Bambusa vulgaris bamboo culms filled with a sisal fiber-reinforced composite, subjected to compressive and flexural loads. Theoretical Framework: Initially, the potential of bamboo as an alternative construction material is described, highlighting its favorable physicomechanical properties and environmental advantages. The properties of natural fiber-reinforced composites, such as those reinforced with sisal fibers, and their applications in enhancing structural performance are also discussed. Method: An experimental methodology was used, starting with the collection of Bambusa vulgaris culms at the State University of Feira de Santana (UEFS). The culms were cleaned, air-dried for 89 days until constant mass was reached, and then analyzed for their geometric, physical, and mechanical properties along their length. Specimens measuring 12 cm for compression tests and 20 cm for flexural tests were prepared, both with and without sisal fiber-reinforced composite filling. Testing adhered to Brazilian and international standards for absorption, shrinkage, compressive strength, and flexural strength analysis. Results and Discussion: Results showed that Bambusa vulgaris culms exhibit variations along their length, with a reduction in external diameter from base to apex and stabilization of mass after 89 days of air drying. Bamboo absorption was higher than that of the sisal fiber-reinforced composite, which, when used as filling, significantly improved the structural behavior of the specimens under compression and flexion by enhancing crack containment, as evidenced by load-displacement curves. Research Implications: This research offers practical implications for civil construction, suggesting that filling bamboo culms with fiber-reinforced composite can increase the durability and structural resistance of construction elements. Theoretically, it contributes to the understanding of the combined behavior of bamboo and natural composites, encouraging the sustainable use of alternative materials. The results may impact sectors related to sustainable civil engineering, composite materials, and eco-friendly construction technologies. Originality/Value: This study contributes to the literature by integratively investigating the properties of bamboo along its length and the effect of filling with a sisal fiber-reinforced composite under mechanical loads—an innovation not previously explored in bamboo filling research. The detailed experimental approach and use of natural fibers as reinforcement add value to advancing sustainable solutions in civil construction, demonstrating the viability of bamboo as a technically and environmentally advantageous alternative.