Influence of Additives from Hydrocarbon-Origin on the Surface Free Energy (SFE) of Asphalt Binder

Abstract

Enhancing the quality of asphalt binder with additives improves the quality and durability of flexible pavements. In the present work, two types of additives from hydrocarbon origin are implemented (carbon black and crumb rubber) for modification of asphalt cement and to influence the required surface free energy (SFE). The prepared modified binders were subjected to SFE and determination of static and dynamic contact angles using the Sessile drop (SD) and Wilhelmy plate (WP) techniques. It was observed that for SD test, carbon black reduced the acid and Lifshitz-van Der Waals (LW) component elements of static contact angle (SCA) by 32.5% and 5.8% respectively, however, crumb rubber exhibited increments in the SCA component element by 2.4, 3, and 3.9% for LW, acid, and base component elements respectively as compared with the control binder. For WP method, implication of carbon black exhibited higher dynamic contact angles (DCA) components by 0.9, 1.9, and 1.3% for LW, acid, and base component elements respectively while implementation of crumb rubber modifier exhibited decline in the DCA components of 3.2, 2.7, and 1.5% for LW, acid, and base component elements respectively as compared with the control binder. Implementation of 10% carbon black had increased the SFE of the binder by (17.39 and 7.69%) for SD and WP methods, respectively, as compared with the control binder. WP method exhibited higher SFE than that of SD method regardless of the implemented additives.