Some Aspects of the Surface Chemistry Involved in the Weathering of Building Limestone

Abstract

The surfaces of samples of two types of building limestone in pristine condition and weathered either in or out of direct rainfall have been studied using SEM, LAMMS and XPS. The surfaces of Portland and Monks Park limestones in pristine condition are shown to be composed essentially of Ca, C and O, as would be expected. Examination of weathered samples reveals significant levels of sulphur containing species due to atmospheric corrosion. The surfaces of sheltered samples appear to be composed entirely of CaS0₄ whilst exposed samples appear to have lower levels suggesting that S0₄ is leached from the sample surface by rainwater. Solubility data are presented to support this theory. SEM, LAMMS and XPS are shown to give useful informatiom about the surfaces of samples studied.