Effect of alkalinity on early-age hydration in calcium sulfoaluminate clinker

Early-age hydration with neutral or alkaline (0 M to 8 M) solutions was studied in calcium sulfoaluminate clinker (CSA) using isothermal conduction calorimetry, X-ray diffraction (both continuous and discontinuous, i.e., after detaining isopropanol) infrared spectroscopy. Hydration 0.1 NaOH observed be similar water. At the next highest concentration (1 M), however, reaction rate slower, due primarily lower AFt stability that medium. Faster but less total heat pastes hydrated 2 NaOH, a finding associated presence of metastable compound, U-phase, subsequently transitioned AFt, C3AH6 thenardite. highly (4 inhibited formation completely, although ye'elimite reacted more vigorously (particularly NaOH) form katoite, AH3