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

通过试验研究了钢筋混凝土构件中形成的非穿透裂缝对构件透水性能的影响。试件采用具有一条弯曲裂纹的梁式试件。裂缝的形成是由跨中梁受拉侧的缺口控制的。梁是通过持续加载来加载的。将x射线对比剂电离溶液注入裂缝中，用x射线技术检测对比剂在混凝土中的穿透面积，实验结果表明：(1)利用新的x射线技术，可以测量对比剂在混凝土中的穿透面积。(2)当对比剂以245kpa的压力注入裂缝时，混凝土中裂缝尖端的压力为225kpa。压力损失为8%，当对比剂以490kPa的压力注入裂缝时，混凝土内的渗透面积约为245kPa时的两倍。可以说，当对比剂的注入压力越高，对比剂通过裂缝侵入混凝土的速度就越大。(4)在相同的注射试验周期内，对比剂在被涂层材料封闭的试件中的渗透面积比未密封的试件的小。可以说，混凝土越干，渗透速度就越快。(5)用对比剂X射线法测得的渗透率与用实水直接劈裂观测得到的渗透率值不同。为了弄清出现差异的原因，进行了实验。其中一个原因是造影剂的动态粘度系数(1.06，密度：50%)高于水的动态粘度系数(1.00)。

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).