Sustainable medium-strength concrete (CS-Concrete) from colliery spoil in South Wales UK

Abstract

Colliery Spoil (CS) (minestone), a by-product of coal mining. Albeit its abundance in most parts of the world, its potential as a construction material has not been fully realized. The major problems identified in attempts to utilize CS in construction include excessive wear, expansive behaviour, leaching and radioactivity. Thus, to date, the bulk of the CS utilization is limited to isolated cases of highway embankments, backfilling of mines, quarries and other surface tips, or in extreme cases subjected to marine and other disposal This paper reports on the scope of technological benefits of utilizing colliery spoil (CS) in low to medium strength concrete. There has been intermittent pursuance of the benefits of utilizing colliery spoil in the United Kingdom. However, there is still no well-accepted and/or positive feedback on any collierybased technology and/or construction material, apart from that relating its use for bulk fill. This research was triggered by proximity of large supplies of both CS and slag in South Wales, UK, as well as the authors’ interest in advances in sustainable construction. Two fractions of colliery spoil were mixed in equal proportions and used for concrete where the binder was PC, or novel binders comprising of either Wastepaper Sludge Ash (WSA) or WSA combined in equal proportions with Ground Granulated Blastfurnace Slag (GGBS), themselves industrial wastes or by-product materials. Compressive strength of compacted cube specimens was monitored for a period of up to 56 days of curing. Results indicate that the performance of systems incorporating CS and WSA were of very poor workability, but the resultant strength was within the low-to medium category usable for blinding concrete and or for use in bound granular fill or foundations.