In this study, the effects of blast furnace slag content and water/cement ratio at cement pastes on the electrical resistivity were investigated. Admixtures having different water/cement ratios and admixtures having binder at different dosage levels were prepared. The blast furnace slag was used in the admixtures by replacing the cement in ratio of 0%, 10%, 20% and 30% by weight. Electrical current was applied to the fresh cement pastes in the molds. The measurements were done at room temperature. The differences between electrical resistivity and hydration time with and without electric current application on the specimens were investigated. As a result, adding blast furnace slag at a high proportion and application of electrical current to the cement pastes shorten the setting time.