Experimental Evaluation of Low Density Polyethylene and Styrene-Butadiene-Styrene Modified Asphalt Concrete Mixtures with Reclaimed Asphalt Pavement

Abstract

Pakistan is currently grappling with economic challenges due to increased price hikes. To address this issue, it is essential to design pavements that are cost-effective and environmentally friendly. In my research, I explore the use of polymers such as LDPE and SBS as binder replacements, and Hydrated Lime and RAP as aggregate mix replacements, to evaluate pavement performance, including distress analysis after the design life period. Both conventional and modified asphalt mixes underwent performance tests, including the Simple Performance Test (SPT). The results were analyzed using the NCHRP master solver 09-29 2.2, and master curves were prepared as input data for MEPDG AASHTOWare application for pavement design. The optimal combination was observed with 5% LDPE and 2% SBS content by weight of bitumen, along with 2% Hydrated Lime and 15% RAP in asphalt mixtures, outperforming other SBS percentages. The MEPDG application provided distress condition analysis after the pavement's life period. This analysis showed a decrease of 2.87 in./mi in IRI, a decrease of 0.06 in. in total rut, and a decrease of 0.06 in. in pavement deformation of asphalt concrete, a reduction of 0.08% in bottom-up fatigue cracking with 0.18% damage, 83.93 ft./mile in top-down fatigue cracking with 0.3% damage, and an increase of 0.4*10^6 Psi in mid-Quintile sub-layer modulus compared to conventional samples. It was observed that the addition of 15% RAP and 2% Hydrated Lime improved results accordingly. However, higher percentages of LDPE-SBS were not as effective as the combination of 5% LDPE and 2% SBS. Overall, the asphalt mixtures consisting of 5% LDPE along with 2% SBS as bitumen modifier and 2% Hydrated Lime and 15% RAP as aggregate modifier had the best results.