Durability of Concrete Under the Combined Action of Carbonization and Fatigue Loading of Vehicles

Abstract

Natural factors such as environments gradually cause the aging of structural materials of concrete bridges and mechanical properties of the components are constantly degraded. When highway bridge structures are under the combined with vehicle loading and environmental diversities, the degradation of structural performance is further aggravated. In this study, according to the deterioration trend of concrete durability in atmospheric environment, durability tests for concrete under the combined action of fatigue loading of vehicles and carbonization were performed by artificial climate simulation. A bending fatigue test for concrete under vehicle loading was carried out, and the trend of fatigue life change with vehicle loading level and the trend of fatigue strain development were obtained. The results show that the fatigue life increases with the decrease in fatigue loading level of vehicles, and the logarithmic value of fatigue life Nf is linear with the fatigue stress level S. Fast carbonization tests for concrete were performed with respect to the fatigue damage degree D of 0, 0.2, 0.4, 0.6, and 0.8. It was found that the carbonization trend of fatigue damaged concrete under vehicle loading follows the Fick first law. The carbonization depth increases with the increase in carbonization time, relatively fast at the initial stage and then slowly at the later stage. When the fatigue damage degree D is less than 0.4, the effects of fatigue damage on carbonization is relatively small. When D is more than 0.4, the effect of fatigue damage on carbonization is relatively significant. The extension of interior micro-cracks and micropores caused by fatigue damage is a significant factor affecting the carbonization performance of fatigue damaged concrete. The change trend of carbonization depth of damaged concrete with time was fitted and analyzed. An influencing factor of fatigue damage was introduced, and a durability prediction model for concrete under the combined action of carbonization and fatigue loading of vehicles was established.