## 4 UV Prevention Strategies Based on Aging Equivalence Relationships
### Equivalent Relation of UV Aging of Asphalt  
At present, the anti-UV aging asphalt and related projects in China have mostly stayed at the level of the trial road, and there are no UV-resistant aging pavement projects on a provincial scale. This is mainly limited by the benefit ratio, that is to say, in a large range of China, especially in the UV radiation climate zone I, the promotion of anti-UV aging technology is of low benefit and difficult. Therefore, this paper puts forward the concept of equivalent UV aging of asphalt, i.e., taking the dividing line of UV radiation climate zone I and zone II (69.4 kW\(\cdot\)h/m\({}^{2}\)) as the benchmark, with the help of the relationship between the maximum UV radiation and the benchmark radiation in zone II and zone III and the UV aging equation of asphalt, the equivalent UV aging of asphalt (i.e., the same UV radiation amount) can be converted with the equivalent time of zone II and zone III (laboratory time and outdoor time). In the same way, the amount of UV radiation and asphalt aging can also be calculated under the same UV radiation time. In this paper, six months of outdoor irradiation in zone I is selected as the baseline UV irradiation time and amount, and the relationship between the equivalent time and the equivalent radiation amount of different UV climatic zones is shown in Tables 3 and 4.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Asphalt** & **Indexes** & **Dynamic UV Aging Equation** & \(\mathbf{R^{2}}\) \\ \hline \multirow{2}{*}{50\({}^{\#}\)} & Penetration at 25 \({}^{\circ}\)C, 0.1 mm & \(\mathrm{P}(t)=-0.0830/(1-1.0016\times\mathrm{e}^{0.0080t})\) & 0.93 \\  & Ductility at 10 \({}^{\circ}\)C, cm & \(\mathrm{P}(t)=-0.0037/(1-1.0002\times\mathrm{e}^{0.0090t})\) & 0.95 \\ \hline \multirow{2}{*}{70\({}^{\#}\)} & Penetration at 25 \({}^{\circ}\)C, 0.1 mm & \(\mathrm{P}(t)=-0.0070/(1-1.0001\times\mathrm{e}^{0.0070t})\) & 0.96 \\  & Ductility at 10 \({}^{\circ}\)C, cm & \(\mathrm{P}(t)=-0.0385/(1-1.00144\times\mathrm{e}^{0.0103t})\) & 0.98 \\ \hline \multirow{2}{*}{90\({}^{\#}\)} & Penetration at 25 \({}^{\circ}\)C, 0.1 mm & \(\mathrm{P}(t)=3.7597/(1-0.9590\times\mathrm{e}^{0.0060t})\) & 0.97 \\  & Ductility at 10 \({}^{\circ}\)C, cm & \(\mathrm{P}(t)=-0.0440/(1-1.0013\times\mathrm{e}^{0.0114t})\) & 0.96 \\ \hline \multirow{2}{*}{110\({}^{\#}\)} & Penetration at 25 \({}^{\circ}\)C, 0.1 mm & \(\mathrm{P}(t)=-0.3276/(1-1.0300\times\mathrm{e}^{0.0040t})\) & 0.98 \\  & Ductility at 10 \({}^{\circ}\)C, cm & \(\mathrm{P}(t)=-0.0327/(1-1.0007\times\mathrm{e}^{1.01087t})\) & 0.99 \\ \hline \multirow{2}{*}{SBS I-C} & Penetration at 25 \({}^{\circ}\)C, 0.1 mm & \(\mathrm{P}(t)=0.0247/(1-0.99966\times\mathrm{e}^{0.0033t})\) & 0.97 \\  & Ductility at 5 \({}^{\circ}\)C, cm & \(\mathrm{P}(t)=0.0055/(1-0.99843\times\mathrm{e}^{0.0475t})\) & 0.94 \\ \hline \multirow{2}{*}{SBS I-D} & Penetration at 25 \({}^{\circ}\)C, 0.1 mm & \(\mathrm{P}(t)=4.2360/(1-0.92311\times\mathrm{e}^{0.0027t})\) & 0.96 \\  & Ductility at 5 \({}^{\circ}\)C, cm & \(\mathrm{P}(t)=-30.8858/(1-2.1110\times\mathrm{e}^{0.0056t})\) & 0.95 \\ \hline \hline \end{tabular} P(\(t)\) represents penetration or ductility under UV aging at time \(t\).  
\end{table}
Table 2: UV aging equations of various asphalt involved in this paper.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**UV Climatic Zones** & \begin{tabular}{c} **Time of Outdoor,** \\ **months** \\ \end{tabular} & \
\begin{tabular}{c} **UV Radiation** \\ **in Laboratory,** \\ **kW\(\cdot\)h/m\({}^{2}\)** \\ \end{tabular} &
\begin{tabular}{c} **Equivalent Test Time** \\ **in Laboratory,** \\ **