Multiscale Coupled-Hygromechanistic Approach to the Life-Cycle Performance Assessment of Structural Concrete

Moisture and cracks are scourges of structural concrete, and understanding the multiscale interactions between the two is key to determining long-term durability performance. This paper uses three-dimensional integrated micromaterial structural modeling to address moisture migration/balance and associated volume changes of concrete with creep in prestressed concrete bridge viaducts that are experiencing excessive deflections. It is found that moisture migration-related deflections driven by the capillary surface tension and disjoining pressures in cement micropores account for 25 to 45% of the macroscopic deflections. These apparent kinematics can be approximated by adding the moisture-related time-dependent deflections to the mechanistic-induced creep by external loads. This paper also addresses water-crack interaction in cracked RC bridge decks under moving loads in view of the coupled hygromechanics. It is found that the water presence on the upper deck parts, when subjected to high-speed traffic, can shorten the fatigue life of the deck by one-and-a-half order of life span. This reduction in life is discussed in terms of high-water pressure developing over large numbers of wheel passages, in addition to the reduced shear transfer along crack planes.