Dynamic mechanical analysis and thermal properties of bitumen-acacia sap composites

Abstract

Bitumen binder mechanical and thermal properties have been unsatisfactory. Different synthetic binder modifies that have been used to improve its performance have led to environmental problems such as incineration and landfill. Acacia sap, a natural and environment-friendly polymer, has been used successfully as a modifier. Composites of bitumen-acacia sap with different composition of sap percentage ranging from 0% to 62.5% cell sap were prepared by injection drawing process. The composites were analyzed by dynamic mechanical analysis (DMA) for mechanical properties and Thermogravimetric Analysis for thermal properties. Storage modulus and Loss modulus of bitumen binder increased with acacia sap loading. Glass transition temperatures were found to shift to higher values as acacia sap loading increased. Activation energies were determined from the thermogravimetric data of the bitumen-acacia composites using the Broido model. Pure bitumen binder had the highest thermal stability. Modification of bitumen binder with 25% acacia sap loading gave optimum mechanical properties. Further studies should dwell more on understanding morphological properties of bituminous binding elements and using different kinds of natural polymers and different grades of bitumen obtained from different crudes.