## 2 Acoustic Emission Based Evaluation of Embrittlement Temperatures
### Testing Asphalt Binders
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{2}{c}{**AE-Based Embrittlement**} & \multicolumn{2}{c}{**BBR Cracking**} & \\
**Asphalt Binder *** & \multicolumn{2}{c}{**Temperatures (\({}^{\circ}\)C)**} & \multicolumn{2}{c}{**Temperatures (\({}^{\circ}\)C)**} & \\ \cline{2-5}  & **TENB (\({}^{\circ}\)C)** & **COV \# (\%)** & **TBBR (\({}^{\circ}\)C)** & **COV \# (\%)** & **TBBR-T\({}_{\text{EMB}}\) (\({}^{\circ}\)C)** \\ \hline TANK AAA1 (PG58-28) & \(-37.58\) & \(2.98\) & \(-34.69\) & \(7.54\) & \(2.89\) \\ RFFO AAA1 (PG58-28) & \(-35.78\) & \(3.68\) & \(-32.83\) & \(5.34\) & \(2.95\) \\ PAV AAA1 (PG58-28) & \(-32.09\) & \(3.68\) & \(-32.83\) & \(8.07\) & \(1.20\) \\ TANK AAB1 (PG58-22) & \(-30.46\) & \(3.56\) & \(-27.81\) & \(14.34\) & \(2.65\) \\ RFFO AAB1 (PG58-22) & \(-29.45\) & \(2.21\) & \(-26.32\) & \(3.27\) & \(3.13\) \\ PAV AAB1 (PG58-22) & \(-24.33\) & \(3.25\) & \(-23.13\) & \(7.92\) & \(1.20\) \\ TANK AAC1 (PG58-16) & \(-29.36\) & \(3.77\) & \(-24.90\) & \(8.99\) & \(4.46\) \\ RFFO AAC1 (PG58-16) & \(-27.77\) & \(1.26\) & \(-21.37\) & \(11.86\) & \(6.40\) \\ PAV AAA1 (PG58-16) & \(-21.86\) & \(5.30\) & \(-19.90\) & \(11.66\) & \(1.96\) \\ TANK AAD1 (PG58-28) & \(-39.09\) & \(2.66\) & \(-34.17\) & \(9.87\) & \(4.92\) \\ RFFO AAD1 (PG58-28) & \(-37.93\) & \(2.07\) & \(-30.24\) & \(5.13\) & \(7.69\) \\ PAV AAD1 (PG58-28) & \(-35.19\) & \(2.79\) & \(-27.03\) & \(3.35\) & \(8.16\) \\ TANK AAF1 (PG64-10) & \(-24.47\) & \(4.74\) & \(-16.49\) & \(7.35\) & \(7.99\) \\ RTFO AAF1 (PG64-10) & \(-22.29\) & \(3.35\) & \(-10.47\) & \(14.33\) & \(11.82\) \\ PAV AAF1 (PG64-10) & \(-17.30\) & \(5.15\) & \(-8.31\) & \(10.63\) & \(8.98\) \\ TANK AAG1 (PG58-10) & \(-26.48\) & \(3.56\) & \(-19.63\) & \(17.05\) & \(6.84\) \\ RTFO AAG1 (PG58-10) & \(-24.12\) & \(2.55\) & \(-16.63\) & \(10.45\) & \(7.49\) \\ PAV AAG1 (PG58-10) & \(-19.54\) & \(5.39\) & \(-11.08\) & \(5.77\) & \(8.46\) \\ TANK AAK1 (PG64-22) & \(-31.76\) & \(3.24\) & \(-32.12\) & \(9.00\) & \(-0.36\) \\ RTFO AAK1 (PG64-22) & \(-30.15\) & \(2.76\) & \(-29.29\) & \(3.94\) & \(0.83\) \\ PAV AAK1 (PG64-22) & \(-25.95\) & \(5.03\) & \(-24.63\) & \(6.21\) & \(1.32\) \\ TANK AAM1 (PG64-16) & \(-28.01\) & \(2.67\) & \(-24.32\) & \(4.58\) & \(3.70\) \\ RTFO AAM1 (PG64-16) & \(-26.52\) & \(3.60\) & \(-21.01\) & \(7.32\) & \(5.52\) \\ PAV AAM1 (PG64-16) & \(-19.98\) & \(4.40\) & \(-13.40\) & \(9.81\) & \(6.58\) \\ \hline \hline \end{tabular}  
* TANK, Rolling Thin-Film Oven (RTFO), and Pressure Aging Vessel (PAV) stand for unaged, i.e., virgin, short-term, and long-term aging, respectively.
* A minimum of four replicas was used to estimate average values and corresponding Coefficients of Variation (COVs).  
\end{table} 
Table 1: AE-based embrittlement temperature and BBR cracking temperatures of several different binders, each with three aging levels. The promising AE results for low-temperature cracking performance of asphalt materials suggests that AE could be considered as a viable alternative for the ASHTO protocols, which estimate the low-temperature performance based upon the rheological binder properties. Furthermore, the AE approach has the advantage of being faster, having less variability, and capable of being used for all types of binders, including modified binders.