## 1 Introduction  
The durability of flexible pavement is affected by several factors over its service life. Much research has been carried out to investigate the ageing of asphalt mixture in the laboratory by simulating ageing and factors such as heat, oxidation, time, and sunlight. At least fifteen mechanisms have been identified; however, the most common are the following four: oxidation (in darkness or direct light), loss of volatiles by evaporation, loss of volatiles by exudation, and steric or physical hardening [1]. It is stated that volatilization is the main ageing mechanism for bitumen during mixing and construction, while oxidation and some steric hardening are the main reasons for ageing during service life [2]. Oxidation is considered the main cause of hardening of bitumen, and it is considered one of the ageing mechanisms that has a serious influence on bitumen properties [1, 3, 4, 5]. Although bitumen is the main material in asphalt mixtures affected by ageing, with demonstrated chemical changes that are reflected in its physical properties [6, 7], the aggregate and the designation of the asphalt mixture with high void content also play a significant role in acceleratingpavement ageing [1; 4]. Furthermore, one study showed that asphaltene-rich bitumen tends to age faster than bitumen with low asphaltene content [1]. Elevated temperatures in very hot and dry places, such as desert regions, lead to an increase in pavement temperature resulting in chemical changes to bitumen bulk, leading to hardening, especially on the surface. The hardening rate increases due to increased temperature and also due to exposure to sunlight during the summer [4; 7]. These two factors are considered the main reasons for early ageing of the surface layer of pavement, even if there is no traffic load in the desert region. Like any organic material, bitumen changes physically after a change in its chemical composition. Oxidation changes the functional groups inside the bitumen, where new polar groups containing oxygen are formed, such as carbonyl, and results in an increase in sulfoxide groups. As reported previously, the reaction of oxygen with bitumen molecules results in larger and more complex molecules that make the bitumen harder and less flexible. Where there is an increased content of asphaltene, this leads to increased viscosity and stiffness, which are considered to be the main reasons for fatigue and thermal cracking [1; 4; 7; 8; 9; 10; 11]. As ageing pushes pavement to the end of its service life, especially in hot regions such as southern Libya, many studies have been carried out regarding delaying ageing. Various types of additives are used to modify bitumen, such as thermoplastic elastomers like polyurethane, polyether-polyester copolymers and olefinic [12], and high- and low-density polyethylene [13], polyvinyl chloride, polystyrene, polypropylene and ethylene-vinyl acetate [14], which are considered plastomers, natural rubber, crumb rubber and more [1; 12; 14; 15; 16]. Recently, nanomaterials have attracted the interest of pavement researchers due to their unique properties and incredible features, which make it possible for them to be used as an additive in asphalt mixtures [17]. The presence of nanomaterials could improve asphalt material properties such as viscoelasticity and high temperature properties as well as resistance to fatigue, ageing and moisture damage [17; 18; 19]. Many types of nanomaterial have been introduced in previous studies, such as nano-clay, nano-carbon, nano-zinc and more [17; 18; 20]. However, fewer studies have been based on nano-modified asphalt mixtures than on nano-modified binders. Furthermore, factors such as environmental effects, cost, and the economic and ecological assessments of nano-modified asphalt also need to be considered [4; 7; 18; 21].