Laboratory investigation on the effect of rejuvenator in Reclaimed Asphalt Pavement based Stone Mastic Asphalt Mixes

Abstract

The present study discusses the characteristics of Reclaimed Asphalt Pavement (RAP) materials in bituminous mixtures. RAP is a material extracted from worn out or distressed pavement. These materials possess a valuable component such as aggregates and aged bituminous binder which has a potential to be reused or recycled. At present the field engineers are facing lot of problems to get quality aggregate for road construction. Due to the scarcity of this material, the cost is escalating. The government of India is insisting to use marginal or reclaimed materials in road construction based on investigations in the laboratory. These materials are incorporated as a replacement to conventional bitumen binder and also the aggregates in both coarse and fine fractions. The mix design for conventional and RAP based Stone Matrix Asphalt (SMA) mixes are optimised to obtain sufficient strength, durability based on the standards suggested by relevant codes to be used as a bituminous layer in flexible pavement. The RAP materials are incorporated at different replacement levels (0%, 30%, 50%, and 70% by weight of total aggregate gradation content in the mix). Various mechanical, durability and performance properties are studied in detail and compared to conventional SMA mix. It was found that the RAP based SMA Mix displayed better strength when compared to that of conventional mixes. Whereas, the durability and fatigue performance was found to decrease with the increase in RAP content. To overcome the problems of durability and fatigue performance of RAP materials, rejuvenators were used. The rejuvenators used in the present study are bio based and another petroleum based viz., Waste Cooking Oil (WCO) and Waste Engine Oil (WEO). The rejuvenators are added to reduce the stiffness and viscosity with improved workability. The test results of rejuvenated RAP based SMA Mix exhibited better strength than the conventional mix. The durability and fatigue performance of the rejuvenated mix also improved even at higher levels of replacement of RAP, indicating the significance of rejuvenation and utilization of higher RAP content in the mix.vi The use of rejuvenated RAP in bituminous mixes would lead to lower production cost of bituminous mixes as compared to the conventional type.