# Permeability and Stiffness Assessment of Paved and Unpaved Roads with Geocomposite Drainage Layers
## 2 Descriptions of Materials and Test Sections  
In this study, the two different geocomposite materials (GC-1 and GC-2) consisting of two layers of non-woven geotextile with synthetic polymer geonet cores were evaluated. The properties of the two materials provided by the manufactures are shown in Table 1. Geocomposite GC-1 (Figure 1a,b) possessed a thicker non-woven geotextile and a stiffer geonet core than GC-2 (Figure 1c,d). The stiffness values of the geocomposite materials were not provided by the manufacturers.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Property** & **GC-1** & **GC-2** & **Testing Method** \\ \hline Thickness (mm) & \(11\) & \(9\) & NA (used Calipers) \\ Strength (kN) & Exceeds Class 2 & \(17\) & AASHTO 2 M 288 [8] for GC-1 \\  & & & ASTM 3 D5035 [9] for GC-2 \\ Water Flow Rate (L/min/m\({}^{2}\)) & \(4481\) & \(4100\) & ASTM D 4491 [10] \\ AOS 1 of the Geotextile (mm) & \(0.212\) & \(0.212\) & ASTM D 4751 [11] \\ \hline \hline \end{tabular} \({}^{1}\) AOS stands for apparent opening size; \({}^{2}\) AASHTO is the abbreviation of American Association of State Highway and Transportation Officials; \({}^{3}\) ASTM is the abbreviation of American Society for Testing and Materials.  
\end{table}
Table 1: Properties of the GC-1 and GC-2 geocomposite materials.  
A total of six test sections were constructed at two different sites, with the Portland cement concrete (PCC) and warm-mixed asphalt (WMA) sections located at the same site. The nominal cross-section profiles of the test sections are shown in Figure 2. For the paved test sections, GC-1 was installed at the top of the base layer (directly beneath the pavement layer) prior to paving. For the unpaved test sections, GC-2 was placed at the interface of the subgrade and surface aggregate layers. The soil index properties of the geomaterials used in this study are summarized in Table 2.  
Figure 1: Photos of the (**a,b**) Roadrain RD-5 (GC-1) and (**c,d**) Macdrain W 1091 (GC-2) geocomposite materials placed beneath paved and unpaved surface courses, respectively.  
Figure 2: Nominal cross-section profiles (not to scale) of the (**a**) Portland cement concrete (PCC) paved; (**b**) warm-mixed asphalt (WMA) paved and (**c**) unpaved test sections.  
For the PCC-paved sections, discrete fibrilated polypropylene (PP) fibers with 5% Portland current (PC) were used to stabilize the reclaimed subbase layer. Two WMA sections were constructed at the same site as the PCC sections (Figure 2). The top 30 cm of natural subgrade of the WMA sections were stabilized with 10% Portland cement. The detailed test section designs, construction processes, material properties, and costs are beyond the scope of this paper but are reported in [12; 13].  
The unpaved road test sections were constructed at a different site. The final thickness of the surface aggregate layer after construction ranged between 10 and 15 cm, and the subgrade had a slightly higher fines content than the subgrade of the paved test sections. The GC-2 geocomposite was placed at the interface of the surface aggregate layer and subgrade. The construction processes and costs of the test sections are described in detail in [14].