## 3 Experimental Methods
### Finite Element Analysis of Accelerated Pavement Test  
Finite element analysis of APT, which was performed in the first part of the study, was conducted in order to estimate the rut depth of surface structure depending upon the cumulative number of ESALs. The commercial FEM analysis program ABAQUS was adopted for the numerical analysis. The mechanical properties of materials used in each course of the testing pavements are summarised in Table 3. Those material characteristics were referred by the previously conducted studies [15; 18; 19].  
As illustrated in Figure 4, the contact area and a load of a single tire of heavy vehicle simulator, which was 0.0459 m\({}^{2}\) (0.18 m \(\times\) 0.255 m) and 4.1 ton, respectively, were considered for the computational simulation in order to demonstrate the APT completed in the first part of the study. To simulate the dynamic wheel load, the load was gradually imposed onto the surface with a speed of 0.41 ton/s for 10 s. Once the wheel load was fully exerted on, the imposed load was dislodged with the same ratio and those steps for 20 s were dealt with a single loading cycle. The target loading cycles were 1.97 million cycles which were equivalent to 1.97 million ESALs.  
Figure 3: Falling weight deflectometer and operation.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Layer**} & \multirow{2}{*}{**Layer**} & \multirow{2}{*}{\begin{tabular}{c} **Unit Weight** \\ **(ton/m\({}^{3}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Young’s** \\ **Modulus (MPa)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Poisson’s Ratio** \\ **(v)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Friction Angle** \\ **(\(\Phi\))** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Cohesion** \\ **(MPa)** \\ \end{tabular} } \\ \hline \multirow{3}{*}{**Surface course**} & **Asphalt** & 2.35 & 6000 & 0.3 & - & - \\ \cline{2-7}  & **Concrete block [11; 23]** & 2.0 & 25,000 & 0.2 & - & - \\ \cline{2-7}  & **Stone [33]** & 2.65 & 83,000 & 0.2 & - & - \\ \hline \multirow{3}{*}{**Laying course**} & **Sand [11; 23]** & 1.8 &
\begin{tabular}{c} 50 (\(\leq\)5000 ESALs) \\ 350 (\(>\)5000 ESALs) \\ \end{tabular} & 0.3 & 35 & 0.01 \\ \cline{2-7}  & **Mortar [33]** & 2.1 & 25,000 & 0.15 & 50 & - \\ \hline \multirow{3}{*}{**Base course**} & **Concrete [12; 23]** & 2.5 & 27,000 & 0.15 & - & - \\ \cline{2-7}  & **Asphalt [11]** & 2.35 & 300 & 0.3 & - & - \\ \hline \multicolumn{2}{c}{**Sub-base course**} & 1.8 & 48 & 0.4 & 35 & 0.01 \\ \hline \hline \end{tabular}  
* 1) Development of Performance Prediction Model for Discrete Layer of Concrete Block Pavement [18]. 2) Accelerated pavement testing on slab and block pavements using the New Mobile Load Simulator [15]. 3) Inc. Architectural Design Information [19].  
\end{table}
Table 3: Material properties for FEM modelling.  
To model the testing pavements, the eight-node brick element with reduced integration (C3D8R) that is the element family provided by ABAQUS software was introduced. Normally, it is used in stress analysis and continuum element. As indicated in Table 4, the surface layer for asphalt and stone pavements was used as an elastic material model. Additionally, concrete damaged plasticity and Mohr-Coulomb material models were assigned for the concrete and asphalt layers respectively. A Drucker-Prager-type concrete plasticity model was selected for the mortar for joint and laying course.