The pressure distribution along stone columns in soft clay under consolidation and foundation loading

The mechanism whereby foundation loading is transmitted through the column has received little attention from researchers. This paper reports on some interesting findings obtained from a laboratory-based model study in respect of this issue. The model tests were carried out on samples of soft clay, 300 mm in diameter and 400 mm high. The samples were reinforced with fully penetrating stone columns, of three different diameters, made of crushed basalt. Four pressure cells were located along each stone column. The 60 mm diameter footing used in the model was supported on a clay bed reinforced with a stone column and subjected to foundation loading under drained conditions. The results show that the dissipation of excess pore water pressure developed during the initial application of total stresses, when the foundation was subjected to no loading, generated considerable stresses within the column, and that this was directly attributable to the development of negative skin friction. The pressure distributions in the column during foundation loading showed some complex behaviour.

Effects of seawater-neutralised bauxite refinery residue on properties of concrete

Various industrial by-products, such as fly ash, ground granulated blast-furnace slag and silica fume, have been used in concrete to improve its properties. This also enables any environmental issues associated with their disposal. Another material that is available in large quantities and requiring alternative methods of disposal is the Bauxite Refinery Reside (BRR) from the Bayer process used to extract alumina from bauxite. As this is highly caustic and causes many health hazards, Virotec International Ltd. developed a patented technology to convert this into a material that can be used commercially, known as Bauxsol™, for various environmental remediation applications. This use is limited to small quantities of seawater-neutralised BRR and hence an investigation was carried out to establish its potential utilisation as a sand replacement material in concrete. In addition to fresh properties of concrete containing seawater-neutralised BRR up to 20% by mass of Portland cement, mechanical and durability properties were determined. These properties indicated that seawater-neutralised BRR can be used to replace natural sand up to 10% by mass of cement to improve the durability properties of concrete without detrimentally affecting their physical properties. Combining these beneficial effects with environmental remediation applications, it can be concluded that there are specific applications where concretes containing seawater-neutralised BRR could be used.

‘Towards a Concrete Utopian Model of Green Political Economy’

Much of the thinking about the appropriate ‘political economy’ to underpin sustainable development has been either utopian (as in some ‘green’ political views) or ‘business as usual’ approaches. This article suggests that ‘ecological modernisation’ is the dominant conceptualisation of ‘sustainable development’ within the UK and other ‘developed’ Northern polities and most corporate/business interests, and illustrates this by looking at some key ‘sustainable development’ policy documents from the UK Government. While critical of the reformist ‘policy telos’ of ecological modernisation, supporters of a more radical version of sustainable development need to also be aware of the strategic opportunities of this policy discourse. In particular, the article suggests that the discourse of ‘economic security’, which can be attached to a radicalised notion of ecological modernisation, ought to be used as a way of articulating a radical, robust and principled understanding of sustainable development, which offers a normatively compelling and policy-relevant path to outlining aspects of a ‘green political economy’ to underpin sustainable development.