## 1 Introduction
### Moisture damage mechanisms and common influential factors  
Moisture usually reaches asphalt mixes through different mechanisms, including surface water infiltration, capillary rise action, and water diffusion. Infiltration is considered the primary source of moisture in asphalt pavements [3; 8], while diffusion is the most common mechanism of moisture transport where molecules move from a high to a low concentration region, and hence durability damage in asphalt pavements occurs [26; 27]. Moisture damage, however, starts with the moisture transport mechanisms by which the moisture gets into the asphalt mixture's structure. A process of change in conditions at the aggregate-binder interface then occurs, adversely affecting the integrity and capacity of asphalt mixes [1]. Typically, six mechanisms contribute to moisture damage in asphalt mixes: asphalt film detachment and displacement, mastic dispersion and desorption, film microcracks, and spontaneous emulsification [1; 28]. The fundamental causes of moisture damage in asphalt pavement have been vastly investigated. Some causes can be related to aggregate mineralogy and binder characteristics [27; 29; 30], while others refer to environmental and traffic conditions, volumetric properties, and a construction process [12; 31]. [PERSON] and [PERSON] [2] conducted an in-field investigation of asphalt pavement cores to determine the most influential parameters for moisture damage. They found that air void content, pavement structure, pavement age, and overall rainfall significantly influence moisture damage [2]. High air void contents in an asphalt mix not only increase the tendency of mixes to moisture damage but also could result in early aging and low fatigue resistance [7]. [PERSON] et al. [32] evaluated the durability of HMA at different air void contents ranging from 4% to 9%. The study showed a proportional relationship between the air void percentage and HMA permeability, which is the ability of a porous medium such as an asphalt mix to transmit water [33]. However, vulnerable mixes to moisture damage have been achieved at air void contents beyond 6% [32]. Invisible cracks, known as \"checks\", with a length of 1-4 inches and 1-3 inches apart, are typically propagated while paving asphalt mixes in fields [6]. These checks, however, increase the permeability of the mixes by connecting the entrapped air voids and making effective routes for surface water to infiltrate inside the pavement structure, which leads to less durable mixtures prone to moisture damage [6,7]. In addition, moisture damage is influenced by the internal composition of the mixes. Insufficient asphalt cement contents in HMA can provide a relatively thin asphalt film coating the aggregate particles, promoting cohesive damage within the mastic and/or adhesive damage at the aggregate-bitumen interface in the presence of water [31,33]. However, aggregates' mineralogy is much more dominant in moisture damage than asphalt cement types [27,29,31]. For instance, siliceous-type (acid) aggregates such as gravel and granite are more prone to moisture damage than high-carbonate (basic) aggregates like limestone [1,29]. The limestone aggregate is mainly composed of calcite, a moisture-resistant mineral, whereas the granite aggregate is composed of albite, quartz, and K-feldspar, which are sensitive to moisture damage [30]. Therefore, selecting proper types of aggregate with good compatibility with asphalt cement is imperative for designing asphalt mixes that are less sensitive to moisture damage [34]. Further, the moisture-absorption property of aggregates is an important factor that significantly influences moisture attack in asphalt mixes [29,30]. Aggregates with high affinity to water impose an adhesive failure at the aggregate-binder interface [3]. This is because of the required short time for water diffusion in such porous aggregates [27,30].