Morphology of microdefects in asphalt concrete at the early stage of operational degradation

Introduction. The operational durability of asphalt concrete pavements is largely determined by degradation processes occurring in the microstructure of the material under the influence of moisture and alternating temperatures. At the early stages of deterioration, microdefects are formed, which subsequently lead to crack development and a decrease in the performance characteristics of the pavement. Despite numerous studies devoted to the durability of asphalt concrete, the morphological features of the initial stage of operational degradation remain insufficiently studied. The aim of this work is to identify early morphological indicators of damage in the asphalt concrete structure and to quantitatively assess changes in the defect space of the material at the initial stage of operational deterioration.

Materials and methods. The object of the study is stone mastic asphalt SMA-16 specimens. Microscopic imaging of areas with pronounced microdefects was performed for specimens in the initial condition and after water saturation followed by cyclic freezing and thawing. The morphology of the defect space was analyzed using digital microphotographs with automated image processing methods. A set of morphological parameters was used to quantitatively characterize the defect structure, including the fraction of the defective area and parameters describing the shape and extent of defect boundaries.

Results. A total of 40 representative microstructural zones were analyzed. Quantitative estimates of defect evolution after exposure to water and alternating temperature cycles were obtained. It was established that stable features of primary structural degradation appear after five freeze–thaw cycles, manifested by an increase in integral defectiveness and changes in pore-crack morphology. It is shown that at the early stage of degradation, mechanisms of defect network branching and merging of defect regions with their enlargement occur simultaneously.

Conclusions. The obtained results confirm the possibility of diagnosing the early stages of operational damage in asphalt concrete based on morphological analysis of its microstructure. The necessity of combined use of areal and linear morphological parameters for quantitative assessment of the defect space is demonstrated.

1. Kiryukhin G.N. On the theory of asphalt concrete structure. Roads and Bridges. 2019; 1(41):247-261. EDN STEFLF. (rus.).

2. Yu J., Feng Zh., Chen Ya., Yu H., Korolev E., Obukhova S. et al. Investigation of cracking resistance of cold asphalt mixture designed for ultra-thin asphalt layer. Construction and Building Materials. 2024; 414:134941. DOI: 10.1016/j.conbuildmat.2024.134941. EDN KEMLMO.

3. Shestakov N.I., Chertes K.L., Tkach E.V. Comparative analysis of biopositiveness of design solutions of objects of the road and transport complex. Biosphere Compatibility: Human, Region, Technologies. 2022; 3(39):106-120. DOI: 10.21869/2311-1518-2022-39-3-106-120. EDN VIHOAQ. (rus.).

4. Obukhova S.Yu., Budkina A.O., Korolev E.V. Structure formation of modified binder in the presence of crumb rubber part 1. Compatibility of crumb rubber and hydrocarbon plasticizers. Regional Architecture and Engineering. 2024; 1(58):24-32. DOI: 10.54734/20722958_2024_1_24. EDN SOSNAR. (rus.).

5. Korolev I.V. Model of the structure of bitumen film on mineral grains in asphalt concrete. News of Higher Educational Institutions. Construction and Architecture. 1981; 8:63-67. (rus.).

6. Yadykina V.V. Management of formation processes and quality of building composites considering the surface state of dispersed raw materials. Moscow, ASV Publishing House, 2009; 374. EDN SAPOYD. (rus.).

7. Yadykina V.V., Trautvain A.I. Influence of mechanical activation of mineral powders on interaction with bitumen and on structure formation of asphalt binder. Association of Asphalt Concrete Researchers : Proceedings of the Annual Scientific Session. 2013; 26-32. EDN ZIXYOP. (rus.).

8. Bratchun V., Pshenichnykh O., Romasyuk E., Ponomarenko P., Vasilyeva T., Koval D. et al. On the formation of the structure of adsorption-solvate layers of asphalt chrysotile binder on the surface of mineral materials of road asphalt concrete. Proceeding of the Donbas National Academy of Civil Engineering and Architecture. 2022; 1(153):114-121. EDN VWEBYO. (rus.).

9. Inozemtsev S.S., Korolev E.V. Evaluation of the influence of the degree of hydration of cement on the properties of the mineral filler for asphalt concrete. The Russian Automobile and Highway Industry Journal. 2017; 4-5(56-57):77-84. EDN ZHMYTR. (rus.).

10. Vysotskaya M.A., Rusina S.Yu., Reznikov A., Khlevnoy I. Porous dispersed fillers in binary compositions. Effective building composites : scientific and practical conference dedicated to the 85th anniversary of the Honored Scientist of the Russian Federation, Academician of the Russian Academy of Architecture and Construction Sciences, Doctor of Technical Sciences Yuri Mikhailovich Bazhenov. 2015; 95-99. EDN UDANSF. (rus.).

11. Nikolsky V.G., Dudareva T.V., Krasotkina I.A., Zvereva U.G., Bekeshev V.G., Rochev V.Ya. et al. Development and properties of new nanomodifiers for road pavement. Khimicheskaya Fizika. 2014; 33(7):87. DOI: 10.7868/S0207401X14070073. EDN SGVXUL. (rus.).

12. Levkovich T.I., Worobjev E.G., Teresina Yu.W. Features of the structure and properties of modified asphalt concrete and bitumen. Scientific Almanac. 2024; 2-3(112):30-35. EDN IHQPCN. (rus.).

13. Shestakov N.I., Urkhanova L.A., Buyantuev S.L., Semenov A.P., Smirnyagina N.N. Asphalt concrete using carbon nanomodifiers. Bulletin of Belgorod State Technological University named after V.G. Shukhov. 2015; 6:21-24. EDN ULFTKT. (rus.).

14. Samarov A.S. Asphalt concrete of dense structure with improved properties. Science Bulletin. 2024; 4(7)(76):284-289. EDN KVOVCG. (rus.).

15. Khodan E.P., Kravchenko S.E. Investigation of the influence of changes in physical and mechanical properties on structure formation and compaction of freshly laid asphalt concrete. Road Construction and its Engineering Support : Proceedings of the International Scientific and Technical Conference. 2020; 84-89. EDN YMXDMV. (rus.).

16. Guba V.V., Guba K.R., Tretiakova L.N. Changes in the asphalt concrete composition, structure and texture during operation. Bulletin of the Automobile and Road Institute. 2023; 3(46):17-24. EDN QLGXDH. (rus.).

17. Zhevanov V., Bratchun V., Postoenko V. Increasing the fatigue life of asphalt concrete by complex modification of their structure. Proceeding of the Donbas National Academy of Civil Engineering and Architecture. 2023; 4(162):70-75. EDN DVNNDU.

18. Certificate of state registration of the database No. 2023624277. Database of types of two-component asphalt concrete structures according to the features of structure formation / Potapova A.S. 2023.

19. Wang L., Yao Y., Li Ju., Tao Y., Liu K. Review of visualization technique and its application of road aggregates based on morphological features. Applied Sciences. 2022; 12(20):10571. DOI: 10.3390/app122010571. EDN JHBVDP.

20. Lomov S.V., Morkovkin A.I. Study of the microstructure of asphalt concrete using X-Ray computed tomography. Industrial Laboratory. Diagnostics of Materials. 2024; 90(7):40-47. DOI: 10.26896/1028-6861-2024-90-7-40-47. EDN PKRWUQ. (rus.).

21. Shakiba M., Darabi M.K., Abu Al-Rub R.K., You T., Little D.N., Masad E.A. Three-dimensional microstructural modelling of coupled moisture–mechanical response of asphalt concrete. International Journal of Pavement Engineering. 2015; 16(5):445-466. DOI: 10.1080/10298436.2015.1007239

22. Du C., Liu P., Sun Y., Chen J., Liu Q., Oeser M. Characterizing asphalt mixtures with random aggregate gradations based on the three-dimensional locally homogeneous model. Computer-Aided Civil and Infrastructure Engineering. 2022; 37(13):1687-1702. DOI: 10.1111/mice.12796. EDN TLYITA.