## 2 Literature Review  
Incorporating a new material in the pavement structure requires evaluation of its performance not only in the laboratory but also in the field to determine its suitability for use. Currently, four types of pavement evaluation are performed by the Ministry of Transportation Ontario (MTO), in Canada, two of which include pavement roughness and pavement structural capacity evaluation [20]. Several factors influence flexible pavement properties, which could serve as an indication of its performance. According to the existing literature, pavement roughness measured as the international roughness index (IRI) (which is an important characteristic of a pavement's longitudinal profile) can be affected by the soil properties, freeze-thaw cycles, moisture content, thickness of the subbase and subgrade layers, and climatic factors [21; 22; 23; 24]. Specifically, [PERSON] and [PERSON] [25] found that an increase in freeze-thaw cycles results in a roughness increase, and greater roughness deterioration was observed for wet than dry regions. A study by [PERSON], [PERSON] and [PERSON] [26], concluded that the initial smoothness of new asphalt concrete (AC) pavements strongly influenced roughness advancement, while transverse cracks affected roughness over time for AC and AC overlaid pavements. Pavement roughness can be attributed to more pavement-related parameters such as surface material type, application methods, pavement design, the transition between sections, and pavement deterioration type over time, in terms of frequency, severity, and density [27]. Roughness, in turn, has a substantial impact on fuel consumption, vehicle maintenance costs, and the health of pavement users and their vehicles; therefore, it is a critical pavement measure. [PERSON] et al. [28] devised a method to determine approximate ranges of pavement roughness (IRI) in relation to road class and speed features like other studies [29; 30; 31; 32; 33]. The influence of pavement roughness is noted to be more significant at higher speeds. As IRIrises, the speed at which vehicles may safely utilize the roadway falls [27]. While an IRI value of 0 m/km denotes absolute smoothness, an IRI value of 8 m/km denotes a rough, unpaved road surface [34]. In Ontario, Canada, the recommended initial IRI values based on treatment while designing for new or reconstruction AC flexible pavements are 0.8 m/km, 1 m/km, and 1 m/km for freeways, arterial roads, and collector roads, respectively [35]. Local roads have no specified initial IRI; however, the closer to 1 m/km, the better. Similarly, MTO recommends terminal IRI values for a freeway, arterial, collector, and local roadways to be 1.9 m/km, 2.3 m/km, 2.7 m/km, and 3.3 m/km, respectively. However, according to [PERSON] and [PERSON], [34], newly constructed pavements should range between 1.5 and 3.5 m/km [28]. Automated road profilers like the automated or walking profilers are typically used to determine pavement roughness. Flexible pavement strength, on the other hand, is influenced by factors such as the quality of materials used and environmental conditions, particularly temperature. The modulus of elasticity (E), also known as stiffness, is commonly used as a measure of strength. A study reported that E increases at lower temperatures and decreases at higher temperatures [36]. The falling weight deflectometer (FWD) is widely used to determine the in-service pavement stiffness [37; 38; 39]. The FWD test is used to measure pavement performance by measuring vertical deflection under an impulse load. It uses falling weight and geophone sensors to determine deflections at specific distances from the impact point. The test results are used to estimate the pavement's structural capacity and determine if it's overloaded. The FWD test results are useful for planning future rehabilitation techniques and determining the pavement's capacity and performance life [40].