Water Migration Phenomenon in Concrete in Postpeak Region

An experimental and analytical study on pore-water pressure occurring in the postpeak region of concrete due to the external load is performed to investigate the mechanism of water migration in concrete. In the experiment, an apparatus is developed that can measure the pore-water pressure in concrete under the control of lateral pressure. Concrete strain, stress, and pore-water pressure are measured; the experimental parameters are the loading age, lateral pressure, and curing method. The effects of each parameter on pore-water pressure generation are discussed. Further, the main factor that influenced the pore-water pressure is investigated. As a result, it becomes possible to measure the pore-water pressure occurring in concrete under the arbitrary stress state due to the development of a cell that imitates the triaxial, almost undrained condition. The pore-water pressure occurring in concrete due to the external load divides the high rate compared with the concrete stress. In the prepeak region, i.e., volumetric contraction of concrete, the positive pore-water pressure increment occurs, while in the postpeak region, i.e., volumetric expansion of concrete, the negative pore-water pressure increment occurs.