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Calcium loading of quartz sandstones during construction: implications for future decay
Author(s) -
Smith B. J.,
Turkington A. V.,
Curran J. M.
Publication year - 2001
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.233
Subject(s) - gypsum , geology , calcium , lime , quartz , mortar , permeability (electromagnetism) , permeameter , geotechnical engineering , mineralogy , geochemistry , materials science , soil science , chemistry , metallurgy , paleontology , biochemistry , oceanography , hydraulic conductivity , membrane , soil water
Damage to quartz sandstones in polluted urban environments is frequently associated with the presence of calcium salts, especially gypsum. For this association to occur it is necessary to identify external sources of calcium. This paper describes an experiment in which the demolition of two sandstone test walls (Dumfries and Dunhouse sandstones) built with a lime mortar demonstrates the loading of the outer 1–2 cm of blocks with calcium. Although this calcium may eventually be mobilized into the interior of blocks, a significant initial effect is a marked reduction in permeability (identified by before and after measurement using a gas permeameter). It is suggested that this sealing effect helps to constrain moisture and possibly salt cycling through the outer, exposed surface of blocks. Eventually this may contribute to the rapid, catastrophic decay of individual blocks, and is a factor that must be built into any future modelling of this decay process. Copyright © 2001 John Wiley & Sons, Ltd.