Introduction of calcium lignosulfonate to delay aging in bituminous mixtures

This study examines the merits of using calcium lignosulfonate (CLS) to mitigate negative effect of aging on bituminous mixtures. To do so, we studied how fracture energy and fracture toughness of the bituminous mixtures containing CLS change when exposed to long-term aging. Aging is implicated in premature cracking including but not limited to top-down cracks and low-temperature cracks which negatively impact road roughness, and subsequently ride quality and driver safety. Considering that latter cracks are induced by tensile and shear forces, we used semi circular bending (SCB) test to quantify fracture energy and fracture toughness of mixtures containing 5-20% CLS under both mode I and II. Each mixture was exposed to short and long term aging and tested at temperature of +15 degrees C and -15 degrees C. The study results showed that introduction of CLS increased the fracture energy and fracture toughness of the mixtures under both modes I and II. The study outcomes provides insights for advancing socioeconomics of pavements by mitigating surface cracks which in turn enhances the driver safety, ride quality and maintenance cost of pavements.