https://orcid.org/0000-0001-8904-2706
Abstract
The hydration performance of cementitious pastes containing ground granulated blast furnace slag (GGBS) during the first 72 h was studied by the isothermal calorimeter and noncontact resistivity methods. The early electrical resistivity of the cement-GGBS pastes was higher than that of the plain cement paste because of less soluble ions in GGBS particles and higher tortuosity calculated based on the electrical resistivity. However, the cement-GGBS pastes have lower resistivity after the dissolving period, suggesting lower hydration activity of GGBS in 72 h. The hydration heat of the cement-GGBS pastes was always lower than that of the plain cement paste, and the order of the rate of hydration heat of the pastes is the same as that of the rate of the electrical resistivity; the plain specimen has the highest value, the specimens with GGBS have lower values, and the higher GGBS replacement has the lowest test results. GGBS activity in water, CH water, and cement water was investigated. The heat development of the GGBS-water mix shows the increase of 18.75 J/g from 1 to 72 h, which is much lower compared with the GGBS CH-water and GGBS cement-water mixes. The electrical resistivity results show only the dissolution process of GGBS in water. The GGBS in the CH-water solution, which was prepared with CH-to-GGBS ratios of 0.05 at a water-to-GGBS ratio of 0.5, shows obvious reaction activity; the increase value is 119.44 J/g in 72 h. The electrical resistivity shows a lower increase with time than that found with GGBS in the cement-water system. It is found that GGBS has no chemical activity in plain water and has a certain activity with CH. Cement-hydration–dominated electrical resistivity, heat development, and GGBS gave a little contribution during the hydration process. There was a good logarithmic correlation between the electrical resistivity and hydration heat during the deceleration period for the cement-GGBS specimens.
