For determining the chloride resistance of different concrete samples, the rapid chloride permeability test was used. This procedure has been established in the standard test method ASTM 1202 [1] For this purpose, national equipment was used. It follows the specifications of the method. The tested concretes had 6 different water/binder ratios (w/b) and three percentages of blast-furnace slag as a replacement of part of cement. Although the age of the concrete was the same in all the cases, the time of saturation in water was different.