# Construction of Geosynthetic-Reinforced Pavements and Evaluation of Their Impacts
## 1 Introduction  
Frost and thaw actions are one of the major causes of deterioration in pavement structures undergoing freeze-thaw cycles. As such, it is necessary to investigate useful and cost-effective techniques to mitigate freeze-thaw disturbances. Commonly, geosynthetic interlayers are one option that can provide reinforcement, separation, and filtration to pavements. Furthermore, geosynthetics can be used to mitigate freeze-thaw disturbances by minimizing the frost heaves and thaw settlements; they are also adaptable to many climates, easy to install, and cost-efficient. Geogrids are typically made by extruding Polyethylene or Polypropylene filaments or by weaving Polyester ribs into grid-like materials with openings [1]. Typically, there are three types of geogrids with uniaxial, biaxial, and triaxial grids offering reinforcement in one, two, or three directions, respectively. Geogrids have been widely used in civil engineering applications, such as in brick structures to mitigate the impact of seismicactivity [2], in pile-supported deep foundation structures to enhance their resilience [3], to reinforce and stabilize soils on slopes for building construction [4], and to reinforce weak subgrade materials in railway construction [5]. Geogrids are also widely applied in pavement structures as they can greatly strengthen an asphalt layer and mitigate reflective cracking. When placed between asphalt layers, the geogrid can function as a tensile element redirecting a crack horizontally along the interlayer [6]. The open apertures can also provide interlocking and effective bonding with the asphalt particles. Laboratory testing by [PERSON] et al. (2001) was used to create a theoretical model to study the mitigation of reflective cracking of geogrid in an asphalt layer [7]. A similar study used finite element modelling to investigate the Von Mises stresses in the geosynthetics-reinforced asphalt concrete layer [8]. The fatigue resistance of prismatic asphalt beams with and without geogrid reinforcement was also investigated by [PERSON] (2008), where it was demonstrated that geogrid-reinforced specimens exhibited significantly greater fatigue resistance compared to unreinforced control specimens [9]. [PERSON] (2008) also reported that the rate of upward crack propagation was decreased by the geogrid. Similar performance improvements were also observed in the study by [PERSON] et al. (2016), which used finite element modelling to demonstrate that the fatigue life of asphalt concrete could be increased with geogrid reinforcement [10]. Laboratory testing was also performed to verify the capability of geogrid to enhance the fatigue resistance of asphalt concrete by bending tests [11] as well as flexural testing combined with digital image correlation techniques [10; 11; 12]. [PERSON] et al. (2022) also found that the cracking resistance of asphalt specimens was enhanced by the installation of a geogrid interlayer when undergoing fatigue testing at lower temperatures [13]. A geogrid composite (i.e., a geogrid bonded to a geotextile) has the combined functions of separation, filtration, and drainage provided by the geotextile and reinforcement provided by the geogrid. These composites are more commonly used for weak subgrade and frost-susceptible soils. The usage of geogrid composites has been demonstrated to reduce stresses within the subgrade [14] as well as to save construction costs through the reduction of the granular base thickness [15]. Large-scale field tests have demonstrated that putting depths are significantly reduced with reinforcement at the base and subbase interfaces [16]. A long-term field trial conducted by [PERSON] (2006) from 1991 to 2005 demonstrated that the overall thickness of the base asphalt layer could be reduced when incorporating geogrid at the middle of the base layers, allowing for materials savings and with similar performance to the control sections [17].