A study to compare virgin and target asphalt binder obtained from various RAP blending charts

Abstract

Use of reclaimed asphalt pavement (RAP) material in mixes is on the rise. Currently, RAP proportion to reach the target binder grade is determined by absolute viscosity and performance grade (PG) methods. However, it is necessary to compare the RAP proportion recommended by the two methods. Further, it is essential to ascertain whether the RAP blended target binder is equivalent to virgin target binder based on various rheological and chemical properties. In this study different percentages (i.e. 0%, 15%, 25%, 40% and 50% by weight of binder) of RAP binder was blended with base binder (AC10). RAP proportion to achieve target grade (AC30) was determined based on absolute viscosity, PG, LAS and MSCR tests. Absolute viscosity and PG methods recommended the RAP proportion of 48% and 32% respectively. Thereafter, average of the two RAP proportions was blended with AC10 binder to obtain target grade of AC30 (AC30_RAP). AC30_RAP was observed to have a higher fatigue life than AC30 binder at lower strains and the trend reversed at higher strain. Higher recovery (R) and lower non-recoverable creep compliance value (Jnr) was exhibited by AC30. FTIR spectroscopy indicated that AC30_RAP had higher sulphoxide and carbonyl content. LAS and MSCR tests recommended the RAP proportion of 35% and 48% based on fatigue and rutting performance respectively.