ABSTRACT

The term 'delayed ettringite formation' is widely accepted, but other terms, such as secondary or late ettringite formation, are also in use. The adjective 'secondary' is ill chosen, as it has an established meaning in petrology, denoting material that has formed by recrystallization. Some of the delayed ettringite that forms after curing at an elevated temperature is almost certainly a product

of recrystallization, and thus also secondary, but secondary ettringite may originate in other ways. DEF has been defined as the formation of ettringite in a material that has been subjected to a temperature sufficient to destroy any that was previously present [1]. This definition is unsatisfactory, as ettringite is sometimes present at the end of the heat treatment.