## 4 Summary and Conclusions  
In conclusion, this study evaluated the feasibility of mudstone aggregate as an alternative material in the construction of colored asphalt pavement. Based on the test results, the following findings were drawn from the study:  
* The results of the aggregate quality tests indicate that mudstone aggregates satisfy the criteria established by the Ministry of Land, Infrastructure and Transport (MOLIT) of South Korea. The mudstone aggregate exhibited excellent abrasion rate, stability, and  
Figure 12: Dynamic modulus master curve in log–log scale.  
Figure 13: Phase angle of the test specimens.  
coating rate, meeting standards. These results show that the mudstone aggregate possesses high durability, stability, and resistance to deformation and moisture damage, making it suitable for use in asphalt pavement.
* The Kim test results revealed that the colored asphalt mixture exhibited superior deformation strength, which resulted from the multifaceted and rounded shape of the mudstone aggregates that enhance aggregate-to-aggregate interaction. However, the addition of pigment to the asphalt binder was found to decrease the deformation resistance of the colored asphalt pavement due to the reduced stiffness of the binder.
* In the IDT strength test, all materials tested surpassed the IDT strength criterion for surface pavement layers. Furthermore, the colored asphalt pavement, regardless of the presence of pigment, was found to have superior crack resistance when compared to typical SMA. However, when colored asphalts with and without pigment were compared, similar to the Kim test results, the addition of pigment was observed to lower the IDT strength due to the reduced stiffness of the binder.
* Dynamic modulus test results show that typical SMA has a higher elastic modulus across various temperatures compared to colored asphalt mixtures, indicating greater stiffness and brittleness, potentially reducing crack resistance. At elevated temperatures, all mixtures have similar elastic moduli, suggesting comparable resistance to plastic deformation. The phase angle trends indicate that all three mixtures exhibit elastic behavior at low temperatures, shifting to aggregate-dominated behavior at higher temperatures.  
Overall, the mudstone aggregate demonstrated excellent properties for use in asphalt pavement, including high durability, stability, and resistance to deformation and moisture damage. The colored asphalt mixtures showed superior performance in terms of deformation strength and crack resistance, although the addition of pigment reduced these properties. Additional tests should be performed to thoroughly examine the effects of additional pigment in the performance of colored asphalt pavement. Nonetheless, these findings suggest that mudstone aggregate is a viable alternative in constructing colored asphalt pavement. For future studies, the effectiveness of the mudstone aggregate replacement with respect to the color retention of colored asphalt shall be evaluated.  
Conceptualization, J.W.K. and C.E.; methodology, J.W.K. and C.E.; validation, J.W.K. and C.E.; formal analysis, C.E.; investigation, J.W.K. and C.E.; resources, J.W.K.; data curation, C.E.; writing--original draft preparation, C.E.; writing--review and editing, J.W.K.; visualization, C.E.; supervision, J.W.K.; project administration, J.W.K.; funding acquisition, J.W.K. All authors have read and agreed to the published version of the manuscript.  
This research was conducted under the KICT Research Program (Project No. 20240499-001, Development of a mobile plant equipped with smart devices and machines for the production and maintenance of 3 ton/h asphalt mixtures for emergency road maintenance and excavation-restoration work) funded by the Ministry of Trade, Industry, and Energy.  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
The authors declare no conflicts of interest.