Surface interfacial dissolution phenomena of calcium silicates

About the Event

Alite (Ca3SiO5) and belite (Ca2SiO4) are the main components of cement clinker, which control the hydration kinetics and strength development of cements. Although their macroscopic properties are well-reported in literature, there is a phenomenon during the initial contact with water, when the reaction temporarily decelerates. Geochemical studies of natural silicates have shown the evidence of potential explanation of the reduced dissolution rate, which is argued to be due to the formation of altered surface silica-rich layers (ASSLs) during initial water contact through coupled interfacial dissolution–reprecipitation (CIDR). Using Transmission Electron Microscopy the ASSL morphology and passivating behavior of alite and belite were studied in this work. The morphology and passivating behavior of ASSLs seem to be dependent on crystallographic orientation, with Si-rich faces forming dense, passivating layers and Ca-rich faces remaining more reactive. These findings establish ASSL formation through CIDR as a key mechanism governing early-stage dissolution and reactivity of cement clinker phases.

About the Speaker

Aidyn Tugelbayev is a Ph.D. student at the Charles E. Via, Jr. Department of Civil and Environmental Engineering advised by Dr. Alexander S. Brand. His research interests are in cement chemistry and nanoscale interfacial characterization using electron microscopy.