Description:
<jats:p>This note describes an autoclave chamber developed and constructed by Anton Paar and its application for <jats:italic>in situ</jats:italic> experiments under hydrothermal conditions. Reactions of crystalline phases can be studied by successive <jats:italic>in situ</jats:italic> measurements on a conventional laboratory X-ray diffractometer with Bragg–Brentano geometry at temperatures <483 K and saturated vapour pressure <2 MPa. Variations in the intensity of X-ray diffraction reflections of both reactants and products provide quantitative information for studying the reaction kinetics of both dissolution and crystal growth. Feasibility is demonstrated by studying a cementitious mixture used for autoclaved aerated concrete production. During a period of 5.7 h at 466 K and 1.35 MPa, the crystallization of torbermorite and the partial consumption of quartz were monitored.</jats:p>