Development of sustainable and high-performance polymer composite rebar using vegetable waste biochar and areca fiber as reinforcement materials for green construction

Abstract

This study explores the mechanical, thermal, and water absorption properties of environmentally friendly polymer composite rebar, created using locally discarded vegetable waste biochar and areca fiber. The material underwent various characterization following ASTM standards in order to evaluate its suitability for construction applications. The integration of biochar and areca fiber aims to improve both the sustainability and performance of the composite rebar. Scanning electron microscopy (SEM) images were analyzed to offer insights into the material's microstructure and morphology behind the performance change. From rebar composite ‘C,’ with 2 wt% biochar and 40% areca fibers, superior load-bearing capacity was observed with a tensile strength of 58 MPa, flexural strength of 99 MPa, and compression strength of 75 MPa, indicating enhanced mechanical performance. In contrast, rebar composite ‘E’ exhibited notable shore-D hardness of 81 due to excessive biochar content, enhancing material rigidity. The increased biochar content positively influenced the thermal conductivity of the composite rebar material, with the collaborative effect of areca fibers and biochar particles enhancing overall thermal performance. Consequently, rebar composite ‘E’ displayed a thermal conductivity value of 0.544 W/mK. Water absorption behavior in the rebar composites was influenced by 1 µm-sized biochar particles, rendering them hydrophobic. Despite the natural hydrophilic nature of areca fibers, the biochar content intensified hydrophobic behavior. Rebar composite ‘E,’ with 8 wt% biochar, exhibited minimal water absorption at 0.0009. In the three-point bending strength analysis of beams constructed with rebar composites, ‘C’ rebar-made beams demonstrated robust bending strength at 29.6 MPa. This heightened strength is attributed to the structural strength inherent in the ‘C’ rebar composite, enabling effective resistance and absorption of applied loads. Therefore, this overall characterization provides valuable insights into the performance of the eco-friendly polymer composite rebar, establishing their potential for sustainable construction practices.