Effect of aging on characteristics of bitumen modified with waste lime sludge
Advances in Civil Engineering Materials
School of Engineering
The design of pavement must be carried out to make it capable of evenly transferring the wheel load to the subgrade soil without exceeding its bearing capacity. However, failure occurs before the design life because of structural defects shown by pavements, such as low skid resistance, fatigue, and rutting. Because low-temperature cracking is more predominant in cold-temperature regions, this aspect of failure is considered within the future scope of study. To address this concern, waste lime sludge was added to improve the properties of bitumen in the present research work. In order to examine the effect of aging, the rolling thin-film oven test was conducted to replicate the short-term aging process, and pressure aging vessel test was used to resemble long-term aging. The viscosity test, softening point test, and penetration test were carried out to assess the physical properties, whereas the dynamic shear rheometer test was conducted to investigate the rheological properties of aged and unaged bitumen binders. It is observed that sludge acts as an aging inhibitor. The complex modulus was enhanced as a result of addition of sludge up to 20%, which also lowered the values of phase angle, depicting high resistance to permanent deformation. The rutting and fatigue resistances of the binder improved, and soft grade bitumen was converted to hard grade bitumen.