Expansibility of some vermiculites

Abstract

The thermal expansion of four samples of >vermiculite>, one sample containing both vermiculite and mica and one sample containing vermiculite and mica/vermiculite interstratification from various geological origins have been studied. All samples yield good pyro-expanded products. However, minerals containing mica or mica/vermiculite interstratification have the highest expansibilities. It is suggested that the sudden release of interlayer water is not the only factor influencing the thermal expansion of these samples, e.g. the presence of relicts of altered mica, loss of OH groups or chemical composition.