Moisture transports in high-cycle compressive fatigue-damaged concrete

Concrete structures in marine environments, e.g. bridges, usually undergo fatigue loads induced by vehicle transportations. Fatigue loads may lead to growth of micro-cracks in concrete which would initiate the additional transport channels and thus accelerate the penetration of moisture and some other aggressive agents into concrete This paper presents an investigation on the moisture transports in fatigue-damaged concrete. Axial compressive fatigue tests were conducted to obtain concrete with uniform compressive fatigue damage and residual strains were used as indexes to estimate the fatigue damage degrees of concrete. Water absorption and air drying tests were subsequently designed and carried out on fatigue-damaged concrete. Test results showed that the absorption rate increased with the residual strain and moisture could evaporate out of the exposed surface more easily of fatigue-damaged concrete than non-damaged concrete, which indicated that degradation of impermeability performance of fatigue-damaged concrete. In addition, prediction model of moisture transport in fatigue-damaged concrete was developed based on assumption of fictitious crushing band, and the accuracy of model was verified based on experimental results. The moisture transports in gradient fatigue-damaged concrete were further investigated based on the validated model with two damage indexes, i.e. residual strain at the exposed edge and residual curvature. The numerical results showed that the moisture transport rates are slightly decrease by the increase of residual curvature as the residual strain at the exposed edge was fixed. As compared to residual curvature, the rates of moisture transport in gradient fatigue-damaged concrete were more sensitive to the residual strains at the exposed edges.