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Consolidating previous research on the development of novel microcapsules for self-healing in cementitious systems, this work forms a base for developing an implementation strategy and guidance for microcapsule-based self-healing technology. The study presents details of the first commercial deployment of this technology, as a ready-mix self-healing additive for commercial application. This involved the on-site construction of two slabs in a new development at the University of Cambridge. This paper describes the optimization of the mix, the structural concept and design, and processing and casting procedures. Prior to application, the compliance and compatibility of the healing additive with the concrete according to specifications and requirements of the design were investigated, validating the use of the developed system. These were complemented by large-scale laboratory testing of the healing efficiency under damage scenarios identified as critical for the on-site application. The performance of the site installation was monitored over 12 months through a combination of nondestructive testing methods. Results are presented with durability indicators confirming the in situ enhanced performance of the proposed self-healing system. [ABSTRACT FROM AUTHOR]

This paper reviews one way in which colliery spoil can be utilized in low-strength concrete. Colliery Spoil (CS) (minestone), a by-product of coal mining, is abundant in most parts of the world. It has potential as a construction material but it has not been fully appreciated. This is partly because colliery spoil is not easy to utilize, due a number of drawbacks. The major problems identified in attempts to utilize CS in construction include excessive wear, expansive behaviour, leaching of heavy metals and even 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 colliery-based 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. [ABSTRACT FROM AUTHOR]