Full-Scale Evaluation of Balanced Cold in-Place Recycling (CIR) Asphalt Mixtures Using a Heavy Vehicle Simulator

Abstract

This study was initiated with the goal of evaluating the impact of binder content on the field performance of Cold In-Place Recycling (CIR) asphalt mixtures. Three CIR sections were constructed at the Center for Research and Education in Advanced Transportation Engineering Systems (CREATEs) through reclaiming the existing asphalt pavement structure. All CIR sections were prepared using foamed asphalt (PG 64-22) at 2% (rut resistant), 3% (balanced), and 4% (crack resistant) recycling agent contents. The preparation of the CIR mixes (or sections) also involved adding 3% water by weight of reclaimed asphalt pavement with no virgin aggregates added into the mix. In addition, each of the sections was instrumented with four asphalt strain gauges and two pressure cells; placed at the bottom of the CIR layer. When the CIR layer cured sufficiently (after a week of construction), a thin hot mix asphalt (HMA) overlay (4.75 mm nominal max. aggregate size) was placed on the CIR layer. A Heavy Vehicle Simulator was used to apply accelerated loading on the balanced CIR section for: (1) 150,000 cycles using a truck tire to simulate low to medium traffic level and (2) 50,000 passes using a truck tire to simulate airfield pavements. A laser profiler was used as HVS loading progressed to measure the extent in pavement deformation. Based on the preliminary testing results, the binder content did not present a strong impact on rutting susceptibility of CIR mixtures under both accelerated truck and aircraft loading.