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This paper describes an objective means of assessing the amount of voidage found within the curved surface of concrete core samples that has been developed by mechanically rolling core samples above a modified flatbed desktop scanner so as to align with the scanning charged coupled device illuminated cross-head. A freely distributed software program was used to process all images to determine percentage voidage and voidage size distribution among other attributes. This work shows that the size, shape and distribution of air voids and aggregate characteristics can be determined using core samples scanned over modified flatbed desktop scanners. A proprietary office desktop scanner with a resolution of 1200 dpi was used.

A B S T R A C TThe UK has a long history of the use of coal fired power station ash products in a range of applications in construction. These range from use in concrete as a cementitious material through to its use as a fill material in embankments. While there have been no environmental problems associated with these uses, environmental regulations emanating from the European Union (EU) are increasingly impacting on the use of these materials. Unfortunately it is not a single set of regulations that are being applied, but three separate and apparently disconnected initiatives; these are Registration, Evaluation and Authorisation of Chemicals (REACH), Essential Requirement 3 (ER3) and the Waste Framework Directive (WFD).Coal fired ash products such as fly ash (FA) and furnace bottom ash (FBA) are treated by the Environment Agency (EA) for England and Wales as waste materials falling under the Waste Framework Directive (WFD). Being classified as a waste theoretically leads to a series of exemptions and licences being required before use of these materials in construction applications, involving the contractor in expense and time. In practice the EA have taken a reasonably pragmatic approach in the majority of cases, but the WFD has clearly had a negative impact on ash sales. In order to alleviate this bureaucracy the principle of defining 'end of waste' criteria was created using a document called a 'Quality Protocol' (QP) for FA and FBA. This, after many years of work, is due to be published in 2010.While the requirements of the QP protect the environment from any perceived threat from FA and FBA, a separate regulation, REACH, was imposed against industry for all chemical products placed on the market. As the QP defined when FA and FBA cease to be wastes, they are thereafter products which have to be registered under REACH. If the QP and REACH were not sufficient protection to the environment, ER3 is being implemented through product standards, which places limit values on potentially polluting toxic compounds. Of course, the testing standards being applied for these three initiatives are potentially all very different.The result of this tri-regulation approach within the EU is duplication and excessive bureaucracy on products that have a proven track record. While the UK government's and EU's stated aim is to encourage recycling, these various regulations will have the opposite effect. This paper will outline the requirements of these regulations and detail some of the problems associated with compliance and the production and supply of power station ash products in the UK.

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