Influence of Bitumen Modification and Gradation on Performance Characteristics of Asphalt Pavements

In the mix design process, as gradation has a significant effect, the selection of suitable aggregate gradation plays a vital role on the performance of the pavement during its service life. In India, many researchers and practitioners are following the midpoint blending process suggested by the Ministry of Road Transport and Highways (MoRTH), Government of India. Bailey’s method of aggregate blending was developed based on the strong philosophy that the coarse aggregates form the interlocked skeleton while the fine aggregates help in subsequent packing of the aggregates in the mix. It is with this premise that the current experimental investigations were taken up to study the efficacy of bituminous concrete mixes prepared with Bailey’s blend vis-a-vis the standard mixes prepared with MoRTH’s midpoint blending guidelines. MoRTH’s Bituminous Concrete-1 mix was chosen for the current investigation. Both the mixes were prepared in strict conformity with the standards and were tested for their volumetric properties, tensile strength, resilient modulus, rut resistance and stripping properties. Additionally, a stripping nullifying strategy of adding shredded plastics to the mix was also tried during the current investigation. Mix combinations having MoRTH’s midpoint and Bailey’s blends, with and without shredded plastics, totaling to four different mixes, were prepared. These mixes were initially investigated to arrive at optimum binder as well as plastic contents using Marshall’s mix design process. Further, these optimized bituminous concrete mixtures were assessed for indirect tensile strength, resilient modulus and rutting tests which were performed under wet conditions at 50 °C. Bailey’s blended mixes with and without shredded plastics were found to be clearly outperforming the corresponding MoRTH’s mixtures with and without shredded plastics. © 2019, The Institution of Engineers (India).