Unique Effects of Hydrated Lime Filler on the Performance-Related Properties of Asphalt Cements: Physical and Chemical Interactions Revisited

Abstract

Hydrated lime is evaluated as a filler in bitumen and is compared to similarly sized filler comprised of calcium carbonate, limestone. Extensive laboratory testing is considered, including rheological testing of mastics (with a dynamic shear rheometer, a dynamic mechanical analyzer, and a bending beam rheometer); low temperature elongation and fracture tests on mastics; torsional fatigue testing of mastics; fatigue testing of mixtures; and permanent deformation testing of mixtures. These tests confirm that hydrated lime as a filler significantly impacts the rate and level of microcrack-induced damage, microdamage healing, and plastic and viscoelastic flow in both mastics and mixtures across a wide range of temperatures (from low to high temperatures, representative of the pavement environment). Hypotheses are presented based on rheological models of filled liquids and bitumen microstructure to explain the test results and the fact that the response of hydrated lime as a filler in bitumen requires an understanding of the physical and chemical interactions on both the micro- and nanoscale. Furthermore, the impact of hydrated lime as a filler is dependent on its interaction with a specific bitumen.