Deterioration mechanism of interface transition zone of concrete pavement under fatigue load and freeze-thaw coupling in cold climatic areas

In addition to stresses from dynamic loading, concrete pavements in cold climatic areas are often attacked by freeze-thaw cycling. The interface transition zone (ITZ) is the first section to deteriorate. To study the micro-structure changes of ITZ under the coupling function of fatigue load and freeze-thaw cycling, an indoor-accelerated coupling test was designed. The results show that the coupling effect accelerates the deterioration rate and increases the complexity of micro-crack structures with more pores including crack nucleation. Moreover, the coupling effect significantly reduces impermeability. DOD is the main factor that accelerates the speed of permeability attenuation of concrete.