Investigation of Thermo-Mechanical Behavior of Bitumen Composite Structures

Abstract

The growing demand for sustainable, eco-friendly materials in civil engineering has prompted the exploration of natural additives in conventional bituminous binders. This study investigates the mechanical performance and thermal behavior of bitumen–Acacia sap composites, with the goal of improving the durability, workability, and environmental sustainability of flexible pavements. Acacia sap, a natural polymeric exudate, was incorporated into bitumen at varying concentrations (2%, 4%, 6%, and 8% by weight of binder). The modified binders were subjected to a series of tests, including penetration, softening point, ductility, Marshall stability, indirect tensile strength, and dynamic shear rheometer (DSR) analysis. Additionally, thermal properties were evaluated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Results indicated that the addition of Acacia sap improved stiffness and resistance to rutting at higher temperatures while enhancing tensile strength and reducing susceptibility to thermal cracking at low temperatures. Optimal performance was observed at 6% Acacia sap addition, beyond which excessive brittleness was noticed. Thermal analysis confirmed enhanced thermal stability, indicating suitability for diverse climatic conditions. The study concludes that Acacia sap is a promising renewable additive for producing sustainable bituminous composites with balanced mechanical and thermal properties.