The mechanisms and drivers of lithification in slag-dominated artificial ground

MacDonald, J. M. , Brolly, C. V., Slaymark, C., Spruzeniece, L., Wilson, C. and Hilderman, R. (2023) The mechanisms and drivers of lithification in slag-dominated artificial ground. Depositional Record, (doi: 10.1002/dep2.230) (Early Online Publication)

Abstract

Unconsolidated artificial ground is an ever-increasing feature on the Earth's surface but it poses various challenges such as pollutant release and ground instability. The process of lithification could be an important factor in changing the properties of artificial ground and ameliorating these challenges. In this study, a lithified deposit of a furnace slag associated with a former iron and steel works in Scotland was analysed to determine the mechanisms and drivers of lithification. Scanning electron microscope analysis showed that Ca leached from around the edges of clasts of slag through reaction of the chemically unstable slag with water from an adjacent water body. Dissolution of Ca (and OH−) from the slag caused the water in contact with the slag to become hyperalkaline, facilitating ingassing and hydroxylation of CO2 from the atmosphere (fingerprinted through carbon isotope analysis). Reaction of the dissolved Ca and CO2 led to precipitation of calcite. Scanning electron microscope analysis showed the calcite is distributed between slag clasts, forming rims around clasts and cementing clasts together into a solid rock-like mass. Understanding the mechanisms and drivers of lithification in artificial ground will be important, given its widespread nature particularly in urban areas where artificial ground is the substrate of most development.

• Item Type: Articles
• Additional Information: The analysis in this paper was partly funded by a Covid recovery grant from the University of Glasgow to JMM.
• Keywords: artificial ground, calcite, cementation, lithification, slag.
• Status: Early Online Publication
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hilderman, Miss Robin and Wilson, Dr Claire and Spruzeniece, Dr Liene and Brolly, Dr Connor and MacDonald, Dr John and Slaymark, Miss Charlotte
• Authors: MacDonald, J. M., Brolly, C. V., Slaymark, C., Spruzeniece, L., Wilson, C., and Hilderman, R.
• College/School: College of Science and Engineering > School of Chemistry; College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Depositional Record
• Publisher: Wiley
• ISSN: 2055-4877
• ISSN (Online): 2055-4877
• Published Online: 30 March 2023
• Copyright Holders: Copyright © 2023 The Authors
• First Published: First published in Depositional Record 2023
• Publisher Policy: Reproduced under a Creative Commons licence