Appraising bitumen coverage, workability, and production temperatures of warm asphalt-aggregate blends

In this study, temperature-dependent high and low shear-rate workability indices (WIs) proposed from a developed workability tester, were employed respectively to determine suitable mixing and compaction temperatures for 12 warm mix blends. An automated procedure was also developed to determine the percentage of coated aggregates using a computer analysis code and set additional possible mixing temperatures for the blends. Two base binders, three representative warm asphalt technologies, and two gradations of basaltic aggregate were involved in the experimental work. Additionally, a framework of WI was introduced. The warm mixed blends were coated at lower temperatures compared to hot mixes. The workability of mixture is not controlled by binder viscosity only; rather it is dominated by the interwoven characteristics of asphalt-aggregate components. The proposed methodology helped in determination of reduced production temperatures for warm mix blends, and the reduction degree is affected by technology type and rate, and binder grade.