Evaluation of Stiffness and Fatigue Cracking Resistance of Post-Consumer Recycled (PCR) Plastic-Modified Asphalt Mixes

Among different recycled materials, use of post-consumer recycled (PCR) plastics in asphalt mixes provides several benefits, including economic, environmental, and improvement in performance. Resistance to fatigue cracking of asphalt mixes is used in the design and performance assessment of asphalt pavements. The purpose of this study was to evaluate the effect of PCR plastics on the stiffness and resistance to fatigue cracking of asphalt mixes. Specifically, this study addressed the changes in the dynamic modulus, cracking tolerance index (CTIndex) and percent loss (%Loss) from Cantabro abrasion test with the addition of PCR plastic in different amounts. For this purpose, a surface mix (NMAS of 9.5-mm) with PG 64-22 binder was modified using three different percentages (0.25%, 0.5%, and 1% of aggregate) of PCR plastic. Two different PCR plastics, namely low-density polyethylene (LDPE) and linear lowdensity polyethylene (LLDPE), were incorporated in the asphalt mix using the dry process. Dynamic modulus test, indirect asphalt cracking test (IDEAL-CT), and Cantabro test were performed on both control and plastic-modified mixes. The stiffness, resistance to fatigue cracking, and %Loss of plastic-modified mixes were compared with those of the control mix as well as between mixes with two different types and amounts of PCR plastics. In addition, laboratory performance of the plastic-modified mixes was compared with performance of a typical pavement under traffic loading analyzed using the AASHTOWare Pavement Mechanistic-Empirical Design (PMED) software. The findings of this study are presented in this paper.