WATER PERMEABILITY OF REINFORCED CONCRETE MEMBER WITH NON-PENETRATION CRACK.

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Experiments were carried out to investigate the influence of the non-penetration crack formed in reinforced concrete member on the water permeability of the member. Beam type specimen which has one bending crack was used. The crack formation was controlled by a notch cut on the tension side of the beam at the center of the span. The beam was loaded by sustained loading. A ionized solution of x-ray contrast medium was injected into the crack and x-ray technique was used to inspect the penetrated area of the contrast medium in the concrete.As results of experiments, the following conclusion can be drawn :(1) By new x-ray technique, the penetrated area of contrast medium in concrete through a crack could measure.(2) When the contrast medium was injected into a crack by the pressure of 245 kPa, the pressure at the tip of the crack in the concrete was 225 kPa. The pressure loss was 8 %.When the contrast medium was injected into a crack by the pressure of 490kPa, the penetration area in the concrete was about two times of that obtained by the pressure of 245 kPa. It can be said that when the injection pressure of contrast medium is higher, the penetration speed of the contrast medium into the concrete through a crack becomes higher.(4) The penetration area of the contrast medium in the specimen which surface was sealed by coating material becames smaller than that of non-sealed specimen at the same injection test period. It can be said that when the concrete is more dry, the penetration speed becomes more high.(5) Results for permeability obtained by the x-ray technique using contrast medium were not the same value as that obtained by the direct splitting observation test using real water. Experiments were done to clear reasons whey the differences occurred. One of the reasons is supposed that the dynamic coefficient of viscosity of the contrast medium (1.06, density : 50 %) is higher than that of water (1.00).