Study on the formation of xonotlite during dynamic hydrothermal synthesis and effect of Sr(NO3)2 addition

The formation of xonotlite during dynamic hydrothermal synthesis was studied with XRD, SEM and TEM. Due to the fact that C-S-H gel is unstable at temperature above 200°C, the formation course of xonotlite during dynamic hydrothermal synthesis at 180°C is different from that at 220°C. By adding Sr(NO3)2 as a mineralizer, the ionic strength of slurry is increased and the formation rate of C-S-H gel is decreased, thus the formation of xonotlite is delayed. During the dynamic hydrothermal synthesis of xonotlite, the ξ potential of solid particles in the slurry varies with the reaction time. The absolute value of the ξ potential of solid particles in the slurry is decreased with the addition of Sr(NO3)2. At the same time, both the growth of fibrous crystal and the formation of spherical agglomerates of xonotlite are promoted.