Observation of chemical hydration in inorganic mineral fibres

Abstract

An experimental study has been carried out and it was observed that inorganic mineral fibres of the slag wool and rock wool types exhibit a physical disintegration and morphological modifications on the fibre surface when these fibrous products have been exposed to water vapour or immersed in a liquid water medium under heating at temperatures up to 100° C for a period of several months. The physical disintegration transformed the fine and thread-like fibres into small segments and granules. Scanning electron microscopic examinations showed that a rough and eroded fibre surface was formed for those fibres which have been immersed in water and heated at temperatures below 60° C for about 3 months and that a reticular network structure or “honeycomb morphology” was developed on the Jibre surface for those fibres which have been immersed in water and heated at temperatures above 85° C and up to 100° C for about 4 weeks. Measurement of the pH value of the water solution and thermogravimetric analysis of the disintegrated fibres suggest that these modifications of the fibrous products are caused by two possible mechanisms: chemical leaching and chemical hydration. Thermal conductivity measurements showed that the disintegrated fibres have thermal insulating values about 15% lower than that of the normal and thread-like fibres.