The Mineralogical and Geochemical Processes involved in Rapid Natural Lithification of Artificial Ground

Artificial ground is a term used to describe parts of the land surface which have been modified by humans. This can include removing material from the natural land surface, such as quarrying, or depositing material on it, such as waste material from industrial processes. Around the world, almost three times as much material is moved by humans than by natural processes such as rivers. Artificial ground is typically in urban areas and so is favoured for building on, so-called 'brownfield land'. It can also enhance biodiversity, and may be used for carbon capture. However, it often contains pollutants, and is prone to landslides. Given these opportunities and challenges posed by artificial ground, it is important to understand natural processes which may act upon it.

When it is deposited by human activity, artificial ground is composed of loose material or sediment. This can become lithified, i.e. the loose sediment becomes fused together to become like a rock. With the ever-increasing volume of artificial ground being created, and the impacts lithification may have (such as immobilising pollutants and capturing carbon), it is important and timely to understand the causes of, and processes involved in, lithification of artificial ground.

This novel proposal will explore this frontier area of research by studying two UK case study sites where artificial ground has become lithified. Sample will be collected from legacy slag heaps (by-products from steelmaking) at sites in Scotland and NW England. Laboratory analysis of the samples will allow us to understand why artificial ground becomes lithified over very rapid timescales - much faster than natural sediments. This research will provide a fundamental understanding that will pave the way for further projects to understand more specific implications of lithification on practical aspects such as pollutant immobilisation, ground stability and carbon capture.