Effect of alkaline additives on the physiochemical properties of high-volume slag cement

The objective of this study is to examine the physiochemical changes that occur in high-volume slag cement when additives with varying levels of alkalinity are introduced. The high-volume slag cement blends were made by substituting 70% Portland cement with slag. For the additives, three different alkaline materials, namely volcanic ash, red mud, and cement kiln dust, were considered. The additives were added at 0%, 5%, 10%, and 15% by mass of high-volume slag cement. The characteristics of high-volume slag cement blends were examined by compressive strength, isothermal calorimetry, x-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and porosity measurement. The results indicated that the alkaline additives have a beneficial effect on the early-age strength development. However, the long-term strength is compromised due to the alkalinity of the paste blends.