Comparison of Surface Energy Values of Limestone with Respect to Different 3D Surface Roughness Measurements

Moisture damage is one of the most important factors affecting durability of asphalt pavements. Selection of appropriate aggregates with optimum properties will help to improve the quality and durability of pavements. Recent studies showed that contact angle measurement using sessile drop instrument is an economical and convenient method for determining the surface energy of solid aggregates. However, there are few studies which compared contact angle measured on aggregate surface with varying surface roughness. Therefore, the present study is intended to compare contact angles measured on limestone which is polished with different grade Silicon carbide grits to reduce surface roughness. Contact angles were measured at selected points using probe liquids such as water, ethylene glycol and diiodomethane. In addition, measurements of surface roughness were made using three-dimensional optical profilometer. Also, using the contact angle measured, surface energy components were calculated. Energy ratio and compatibility ratio parameter of limestone with PG 64-22 were determined using the surface energy components. From present study, it was observed that surface roughness could cause variations in contact angle measurements which could be minimized by appropriate polishing of aggregate surface.