THE DURABILITY DETERIORATION MODEL BASED ON CARBONATION FOR UNDERGROUND CONCRETE STRUCTURES

Carbonation is one of the important influence factors on underground concrete structures’ durability. The deterioration of concrete structures by carbonation can be expressed by the carbonation depth of the protection layer. Indoor fast carbonation experiment was designed and the model of carbonation depth is set up in this paper, which considers diverse stress levels, different water-cement ratio and various operation periods. The model shows: concrete’s carbonation rate decreases with time slowly; tension stress can accelerate carbonation rate of concrete while compression stress can restrict it; in a certain range, carbonation rate of concrete increases with water-cement ratio. A durability judgment rule is proposed and the corresponding limit condition equation is established for the prediction of the service life of concrete structures.