Fatigue pull-out failure of deformed bars in concrete under the effect of liquid water

To investigate the pull-out behavior of deformed bars subjected fatigue loading in the simultaneous presence of liquid water, fatigue pull-out tests were carried out. Experimental parameters were the presence/absence of liquid water, matrix type, loading pattern, and the presence of a mechanical anchorage. It was found that the matrix in the vicinity of the deformed bar was converted into sludge by the complex interaction of liquid water and fatigue, and pull-out failure of the deformed bar occurred without accompanying macro cracks, resulting in significantly reduced fatigue life. Pull-out failure associated with the formation of sludge occurred at a comparatively low load level, and tended to occur when the water-cement ratio was high and under reversal loading. A further finding is that mechanical anchorages have the effect of reducing the conversion to sludge and have the beneficial effect of preventing pull-out failure.