Moisture damage in hot-mix asphalt (HMA) occurs because of a loss of adhesion and/or cohesion, resulting in the reduced strength or stiffness of the HMA and the development of various forms of pavement distress. There are several different approaches for improving adhesion and reducing moisture sensitivity in asphalt mixtures. One convenient approach is coating the aggregate surface with a suitable agent to reverse the predominant electrical charges at the surface and reduce the surface energy of the aggregate. In this research, the effects of two types of polyethylene (PE), namely high-density polyethylene (HDPE) and low-density polyethylene (LDPE), were added to coat the aggregate, and the moisture damage to the asphalt mixtures was evaluated. Three types of aggregates representing a considerable range in mineralogy (limestone, granite, and quartzite) were evaluated during the course of this study. This paper explains the theoretical and experimental concept of predicting moisture damage in asphalt conc...

With increasing interest in the use of warm mix asphalt (WMA) in the paving industry, more studies in this field for improvement of WMA properties seem to be necessary. In past decade, several studies focusing on use of Sasobit and asphamin as warm additives in asphalt mixtures have been conducted; however, the effects of these additives on moisture susceptibility of asphalt mixture are still not fully understood. In this study, the moisture susceptibility of WMA evaluated with and without a new nanotechnology material as antistrip additive (namely Zycosoil) by determining the micromechanisms that affect the adhesion bond between the aggregate and asphalt binder and the cohesion strength of the asphalt binder using the surface free energy (SFE) concept and laboratory testing analysis. Indeed, the primary goal of this research was to decrease the moisture damage in WMA. Two types of aggregates, limestone and granite, and two types of WMA additives, namely Sasobit and aspha-min, in addition to as Zy...

Nowadays, saving energy and recycling materials are becoming priorities in the road construction industry. This paper presents an experimental study to characterise permanent deformation of a warm mix asphalt (WMA) mixture containing reclaimed asphalt pavement (RAP). The WMA mixtures containing 0%, 15%, 30%, 50% and 60% of RAP were plant prepared. To assess the impact of RAP on rutting properties of hot mix asphalt, mixtures were tested using Marshall and dynamic creep tests. It was found that replacing up to 60% of the virgin aggregate with RAP improved rutting properties of the asphalt mixtures because RAP increased asphalt binder's viscosity as a main factor of rutting, especially at high temperatures. However, replacement of too much RAP in asphalt mixtures can increase moisture sensitivity of flexible pavements. Therefore, an indirect tensile strength test was conducted to evaluate moisture damage of the mixtures. The results showed that the minimum permissible tensile strength ratio (TSR) of 70% was satisfied by replacing up to 50% of the virgin aggregate by RAP; but the mixtures with 60% RAP had a TSR of less than 70%. Accordingly, 50% replacement of RAP was found to be the optimal replacement level.