Laboratory investigation of RAP aggregates for dry lean concrete mixes

•Mechanical properties of RAP of different age is studied.•Coarse RAP has more potential to be used in DLC mixes than fine RAP.•OLD RAP can be used up to 75% in DLC mixes.•NEW RAP can be again utilized in Bituminous mixtures. In the present study, the suitability of coarse (C) and fine (F) RAP aggregates extracted from two flexible pavements (OLD (O) & NEW (N)) having different service (20 yrs. & 2½ yrs.) and stockpiling life (8 months & 0 months) for productions of Dry Lean Concrete (DLC) and bituminous mixtures is assessed. For the same, a total of 15 DLC mixes were cast, consisting of 9 mixes containing different proportions (25–100%) of CO and CN aggregates and 6 mixes containing FO (25–100%) and FN aggregates (25% and 50%). The effect of both fractions of RAP on optimum moisture content (OMC), maximum dry density (MDD), compressive strength, water absorption and permeable voids were studied. Volumetric properties of compacted bituminous mixes containing aggregates milled from new pavement were also investigated. It was found that aggregates obtained from old pavement have the potential to replace 75% coarse and 50% fine natural aggregates whereas 25% CN and zero FN aggregates may be utilized for DLC mixes. Contrary, aggregates obtained from new pavement were found to be suitable for construction of base and wearing course of flexible pavements whereas aggregates from older pavement could not be even molded while preparing test sample due to loss of binding properties of asphalt mixtures by virtue of oxidation process.