## 3 Results
### Pavement Fatigue Life under Environmental Conditions  
To investigate the impact of water, frost, or road salt on the selected construction fatigue life, FEM modeling was performed considering the degradation index value. Based on the catalog solutions and modeling tips [46], a typical flexible pavement construction for heavy traffic in the KR-5 traffic category was applied. Construction consisted of 3 layers made from MMA and soil subgrade, characterized by the following thicknesses and parameters:  
* surface course (thickness: 4.0 cm, stiffness modulus-7300 MPa, Poisson's ratio-0.30),
* binding course (thickness: 8.0 cm, stiffness modulus-10,300 MPa, Poisson's ratio-0.30),
* base course (thickness: 18.0 cm, stiffness modulus-9800 MPa, Poisson's ratio-0.30),
* subgrade (thickness: 2.0 m assumed, secondary module-120 MPa, Poisson's ratio-0.35  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Mix** & **Binder Type** & \begin{tabular}{c} \(V_{b}\) \\ [\%] \\ \end{tabular}  & \begin{tabular}{c} \(V_{m}\) \\ [\%] \\ \end{tabular}  & **Variant** & \begin{tabular}{c} \(E^{*}_{0,1}\) \\ [MPa] \\ \end{tabular}  & \ \begin{tabular}{c} \(E^{*}_{0,2}\) \\ [MPa] \\ \end{tabular}  & \begin{tabular}{c} \(DI_{(S)}\) \\ [\%] \\ \end{tabular}  \\ \hline A4 & 35/50 WMA & 3.82\% & 6.22\% & **f-t** & 9948 & 8468 & \(\mathbf{-14.87\%}\) \\ \cline{3-6}  & & & **rs** & 9400 & 8274 & \(\mathbf{-11.99\%}\) \\ \hline B4  
The durability of the pavement structure was determined using the AASHTO 2004 fatigue criterion in accordance with Formula (3). Fatigue damage equal to the occurrence of 5% of alligator cracks was assumed in the calculations. \[N_{f}=D_{FC}\cdot 7.3557\cdot 10^{-6}\cdot C\cdot k^{\prime}\cdot\left(\frac{1}{ \varepsilon_{t}}\right)^{3.9492}\cdot\left(\frac{1}{E_{0}^{*}}\right)^{1.281} \tag{3}\]  
where:  
\(D_{FC}\)-fatigue damage, taking into account asphalt layer thickness and the assumed percentage value of alligator cracks [-],  
\(N_{f}\)-number of repetitive loads until fatigue cracks occur [repetitive loads],  
\(C\)-volumetric properties MMA coefficient [-],  
\(k^{\prime}\)-calibration factor, depending on the asphalt layers thickness and the type of the cracks (down-top) [-],  
\(\varepsilon_{t}\)-critical tensile strain level in pavement asphalt layers [-],  
\(E_{0}^{*}\)-asphalt layer stiffness modulus [MPa]. To determine the durability of the structure using the criterion, modeling was carried out in the Abaqus program using the finite element method (FEM). An elastic model of the layered half-space, commonly used for dimensioning flexible and semi-rigid pavement constructions, was used. General assumptions based on catalog data [46] were made for modeling related to the load level (57.5 kN per wheel and 115 kN per axle (EU standard)), shape and application surface, and layer-to-layer interaction. Assumptions were presented in Table 4. The designed 3  
For pavement fatigue life analysis employing the criterion, 12 models were made in the Abaqus program for 4 mixes differing in the type of asphalt and the impact case (reference model, model considering degradation caused by water, frost, or road salt). The investigation was carried out on the previously analyzed level of binder content in mixtures A4, B4, C4, and D4 equal to \(V_{b}=3.82\%\). It is a value that corresponds to the binder level content commonly used in mixtures dedicated to this type of pavement construction (binding and base course layers). For the calculations, the same level of void content in mixtures, equal to \(V_{m}=6.2\%\), was assumed. In this way, among others: imperfections resulting from compaction on the construction site, the low temperature of the utilized mixes, and the air void content test results of the A4, B4, C4, and D4 mixtures were considered. Referring to the adopted layer's parameters, in order to take into account the degradation caused by water and frost or road salt, the previously calculated degradation ratio \(DI_{(S)}\) was used.