Effect of ground granulated blast-furnace slag on the hydration and properties of cement paste

The hydration process of cement paste blended with ground granulated blast-furnace slag (GGBS) was investigated using calorimetric and electrical methods. The effect of GGBS on early-age hydration was studied by examining electrical resistivity curves, heat of hydration curves and their rate curves. Through comparisons of the setting time and four other critical moments in early-age hydration evolution obtained from electrical resistivity and hydration heat tests, the application of electrical resistivity to characterise the setting behaviour of cement paste was proven to be effective, through the peaks on the rate curve of resistivity and the inflection point on the electrical resistivity–log time curve. The effects of GGBS on autogenous shrinkage and compressive strength development were also studied. It was found that compressive strength at 3 d could be predicted by electrical resistivity at 1 d. A positive linear correlation between autogenous shrinkage and compressive strength before 28 d was found. A relationship relating GGBS content to 28 d autogenous shrinkage and 28 d compressive strength was also developed. Scanning electron microscopy observations confirmed the macroscopic experimental results.