Influence of polluted urban atmosphere on the weathering of low durability glasses

Author： Munier I. Lefèvre R. Geotti-Bianchini F. Verità M.

ISSN： 0017-1050

Source： Glass Technology - European Journal of Glass Science and Technology Part A, Vol.43, Iss.6, 2002-12, pp. : 225-237

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

The weathering of glass exposed to an urban atmosphere was studied through an in-field experiment using two low durability alkali rich glasses. The glasses were exposed according to two modes: sheltered or unsheltered from direct rain, and during two exposure periods: from November 1997 (over one year) and from May 1998 (over three months). Infrared spectroscopy, analytical scanning electron microscopy, electron probe microanalysis and secondary ion mass spectrometry allowed the authors to characterise the formation of a leached hydrated layer in the surface of the samples. This layer developed whatever the season and exposure mode. This underlines the role played by all water suppliers: rain, but also humidity.The action of the latter is not negligible. The weathering is more pronounced in winter when rain and humidity are high. The sheltered samples also underwent another type of weathering process (characterised by a gain of weight): the development of neocrystallisations on the glass surface. These neocrystallisations mainly consist of sulphated salts. Their cationic composition depends on the chemical composition of the underlying glass. The sulphate formation is essentially favoured by high sulphur dioxide atmospheric content and, to a smaller extent, by the presence of water.