Assessment of workability and mixing – compaction temperatures of LDPE-modified binders

This research study evaluates the workability and production temperature of low-density polyethylene (LDPE)-modified asphalt binders incorporating sulphur (S) and maleic anhydride (MAH) as stabilising additives. The primary objective is to assess the efficacy of dynamic shear rheometer (DSR)-based approaches for determinin0g mixing (MT) and compaction temperatures (CT) of LDPE-modified binders and to evaluate the workability of mixtures prepared with these binders. A VG 30 base binder was modified with 1.5%–7.5% (LDPE + S/MAH) by weight of the base binder. The production temperatures of the virgin binder were first determined using the equiviscous method, and the corresponding torque values were measured. The production temperatures for LDPE-modified binders were subsequently determined using the phase angle method, steady shear flow method, and a torque-based workability approach employing an equal-torque criterion. The steady shear flow method yielded production temperatures 15–20 °C lower than those obtained using the workability framework and was found to be ineffective for LDPE-modified binders. The workability-based approach produced 10%–12% higher MT at ≤ 3% LDPE and 4%–5% higher MT at > 3% LDPE compared with the phase angle method. Recommended MT and CT ranges of 165–175 °C and 150–165 °C, respectively, are proposed.