Masterbatch natural rubber improved mechanical performance of asphalt concretes with various natural aggregates

This study evaluates the performance of Masterbatch Natural Rubber-modified asphalt concrete (MNR-AC) as a sustainable alternative to synthetic polymer-modified binders. The effects of aggregate type on the performance of MNR-modified asphalt concrete were investigated using basalt (B), granite (G), and limestone (L) aggregates. MNR was added at varying rubber-to-binder (r/b) ratios from 0% to 15%, and tested for Marshall stability, indirect tensile strength (ITS), indirect tensile resilient modulus (IT Mr), indirect tensile fatigue life (ITFL), and rutting resistance. The optimum r/b ratio was identified as 3%, at which the MNR-AC mixtures showed the best overall performance for all aggregate types. At this dosage, the minimum improvements were 7.8% in Marshall stability, 4.8% in ITS, 17.3% in IT Mr, and 10.6% in ITFL, while rut depth was reduced by at least 31.6%. These improvements are attributed to enhanced elastic recovery and the development of a latex-film network within the modified binder matrix. The sample with B aggregates yielded the greatest improvements due to their higher surface free energy. The unique fatigue distress model of MNR-AC for all aggregates was developed through the relationship between initial tensile strain ( ε t ) and ITFL. Compared with concentrated latex-modified asphalt concrete (CL-AC), MNR-modified asphalt concrete exhibited slightly lower ITFL under equivalent traffic loading levels, which was attributed to its lower ITMR. However, MNR offers considerable practical advantages due to its solid form. The application of MNR can reduce packaging requirements, minimize storage volume, and improve transportation efficiency compared with liquid natural rubber latex systems. These logistical efficiencies highlight MNR as a promising, sustainable alternative binder for asphalt pavement engineering in real-world applications.