Green and sustainable production of waste styrofoam-modified bitumen: a laboratory-based investigation on physical, rheological properties, and storage stability.

The motivation of this study was to investigate the feasibility of production of green and sustainable bitumen modified with waste styrofoam (WS) that contributed to the base bitumen in certain rate. To achieve it, not only basic but also rheological properties and storage stability of WS-modified bitumen were taken into consideration. In this respect, bitumen with 70/100 penetration grade was modified with WS in different rates ranging from 1 to 5% with 1% increment. Basic test methods including penetration, softening point, rotational viscometer were conducted on the bitumen samples to analyze physical properties, while dynamic shear rheometer and bending beam rheometer tests were performed on the samples for rheological assessment. Rolling thin film oven and pressure aging vessel tests, which are aging methods in rheological evaluation, were followed to supply short- and long-term aged samples, respectively. Storage stability test was conducted on the modified samples to determine the compatibility between the two materials at different contribution WS rates. The results showed that significant changes occur on both physical and rheological properties of WS-modified bitumen. Compatibility between WS and bitumen was not observed except of the bitumen modified up to 2% WS as examined with softening point, but up to 3% WS as examined with penetration test. Overall, disposal of WS within bitumen modification can be a green and sustainable as considering the ecological and economic aspects.