ABSTRACT
ABSTRACT: For environmental reasons, low installation cost and initial investment; low energy infrastructure materials are becoming of high interest. A potential option to replace current hot mix asphalts is emulsifications, where bitumen binder is dispersed in a water phase aided by emulsifier and shear forces, and mixed at ambient temperature with unheated stones. Long term performance must, however, be guaranteed, otherwise the application benefits will be significantly diminished. In this paper, the main issues of cold mix (emulsion based) asphalt, like wetting in the presence of moisture and dust, and coalescence issues are discussed. Since both bitumen droplets and mineral surfaces were upscaled, pure mineral surfaces were investigated as stone material consists of different minerals. As a measure of the interfacial bond strength, surface free energies of different mineral aggregates and bitumen have been investigated in this paper as a stepping stone for further analyses of emulsions. From the analyses it was found that bitumen has only dispersive forces whereas most of the minerals surfaces have polar nature. According to Fowke’s additive nature of the forces, bitumen and water are roughly equally strongly adsorbed to plagioclase and calcite, whereas water will displace bitumen from quartz, gypsum, potassium feldspar and mica surface.
