Rheological characteristics of bitumen mastic depending on composition and filler dispersity

Abstract

As fillers in asphalt concrete are used for bitumen viscosity increase, structure modi-fication it is necessary to estimate the filler structuring effect in bitumen binder. For this pur-pose the influence of phase and size parameters of fine-dispersed powdered fillers on rheologi-cal characteristics of bitumen mastics (bitumen–filler composition) is studied. Maximal effect for bitumen properties is observed for such fillers as kaolin and chalk-stone. These two fillers have the highest specific surface area (SSA) and the highest void content. So, they are able to absorb a higher content of bitumen vs. fillers with lower SSA and void content values. Varia-tions in Delta Ring and Ball values for kaolin- and chalk stone-based mastics at 83°С and 24°С, respectively are significant vs. other compositions (up to 8–10°С). It can be associated with structuring effect under high temperature. Significant change in bitumen physical and me-chanical properties can be occurred when kaolin application is connected with thin flake form of its particles. Study of rheological characteristics of bitumen mastics by the dynamic shift remoter under high temperatures demonstrates lower values of complex modulus for bitumen mastics containing lime stone and sand fillers with medium and high dispersity vs. chalk-stone-and kaolin based analogues.