## 3 Results
### Moisture Susceptibility Test Results  
Moisture susceptibility represents the capacity of an asphalt mixture to resist damaging effects caused by water. The bonds between the aggregates and asphalt binder weaken due to moisture accumulation within the mixture. This situation led to the rapid development of multiple types of strain and deformation, such as rutting, cracking, ravelling, and potholes. Pavement distress is mainly related to the presence of water and leads to costly maintenance solutions. A moisture susceptibility test was conducted to evaluate the tendency of SMA mixtures containing CBA towards moisture-induced deterioration. Figure 14 illustrates the tensile strengths of the CBA mixtures in both unconditioned (dry) and conditioned (wet) states. The results demonstrated that the wet-conditioned CBA mixtures consistently exhibited lower values than the dry-unconditioned CBA mixtures. The presence of water has been shown to reduce the tensile strength of CBA mixtures. The results in Figure 14  
Figure 13: Ultimate strain for CBA mixtures.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Mixture** & **Ultimate Strain (\(\upmu\)s)** & **Normalized** \\ \hline CBA-0 & 32,906 & 1.00 \\ CBA-10 & 21,535 & 0.65 \\ CBA-20 & 20,667 & 0.63 \\ CBA-30 & 20,400 & 0.62 \\ CBA-50 & 13,747 & 0.42 \\ CBA-70 & 26,170 & 0.80 \\ CBA-100 & 32,070 & 0.97 \\ \hline \hline \end{tabular}
\end{table}
Table 9: Normalized ultimate strain of CBA mixtures.  
indicate that the CBA-10 and CBA-20 mixtures demonstrated higher tensile strengths under both wet and dry conditions than the control mixture. The coarse texture and angular shape of the CBA enhance interlocking and bonding within the asphalt mixture. Previous research indicated a comparable trend in tensile strength, in which the incorporation of up to 20% CBA resulted in an initial increase in tensile strength, followed by a decline with a subsequent rise in CBA content [43].  
The tensile strength ratio (TSR) for all CBA mixtures was calculated, with the normalised value being presented in Figure 15 and Table 10, respectively. The data indicate that all CBA mixtures, except for CBA-70 and CBA-100, satisfied the minimum tensile strength ratio (TSR) requirement of 80%, which is recommended by AASHTO T283 and the Malaysian Public Works Department for road construction. The findings demonstrated that the CBA-10 mixture displayed a TSR value similar to that of the control mixture. As the CBA content increases, there is a corresponding decrease in the TSR value. The TSR value of CBA-20 is 86.4%, which is 0.99 times the value of the control mixture. The TSR value for CBA-30 is 84.3%, whereas the TSR value for the CBA-50 mixture is 84.1%. This value indicates a 0.01-0.03% reduction relative to the control mixture. A decrease in the TSR value suggests that the CBA mixture has less ability to resist moisture-induced deterioration [70]. The porous and absorptive characteristics of CBA facilitate increased water infiltration into the mixture. A recent study [71] found that substituting 20% CBA in both hot and warm mix asphalt reduced the TSR value of both mixtures. Previous research [72] observed comparable results when employing CBA as a replacement for fine aggregate in HMA to create the wearing course of an asphalt mixture.  
\begin{table}
\begin{tabular}{c c c} \hline
**Mixture** & **TSR (\%)** & **Normalized** \\ \hline CBA-0 & 86.9 & 1.00 \\ CBA-10 & 86.9 & 1.00 \\ CBA-20 & 86.4 & 0.99 \\ CBA-30 & 84.3 & 0.97 \\ CBA-50 & 84.1 & 0.97 \\ CBA-70 & 77.7 & 0.89 \\ CBA-100 & 75.6 & 0.87 \\ \hline \end{tabular}
\end{table}
Table 10: Normalized tensile strength ratio (TSR) of CBA mixture.  
Figure 14: Tensile strength of CBA mixtures.