United Kingdom Quality Ash AssociationPress Information
Exploding Foamed Concrete - November 2009 ongoing
During November 2009, an incident occurred where foamed concrete exploded due to a hydrogen gas build up. This explosion injured two workers. It is our understanding that this incident was a result of inclusions of elemental aluminium within the Incinerator Bottom Ash (IBA) being used as a coarse aggregate. These particles of elemental aluminium as we understand result from metal in the waste stream, such as aluminium foil, being intimately mixed with other wastes and the linear magnetic removal systems not being able to extract it prior to burning. The result is flecks of elemental aluminium are present in the IBA. The reaction in the foamed concrete of elemental aluminium and calcium hydroxide produced hydrogen gas, which is the same reaction as used in the manufacture of aerated concrete blocks – this reaction is nothing new.
In normal use the hydrogen gas with adequate ventilation will quickly disperse and pose no risk, however, if the hydrogen gas is trapped in a confined space in sufficient quantities it may result in an explosion taking place. Aerated concrete blocks production use this same effect to produce their cellular structure, here the elemental aluminium is added as a very fine powder. The resulting hydrogen gas produces the lightweight, cellular structure required for such blocks. Any residual hydrogen is removed during the autoclave process, so aerated blocks do not represent any risk to the user.
With regard to Pulverised Fuel Ash (PFA) and Furnace Bottom Ash (FBA) from the coal fired power stations, the UK power station operators do not generally burn wastes materials and never domestic waste, primarily because the stations are not registered as Waste Incinerators and the fuels that are used do not contain elemental aluminium. They burn coal and relatively small quantities of biomass and similar secondary fuels. Because of the nature of the fuels, there is zero risk of elemental aluminium being present in either the PFA or FBA. Also, with the combustion temperatures (>1,250 C) involved being relatively high in comparison with incinerators, any aluminium minerals are rapidly converted to the oxidised form, (Al2O3). In the oxidised form no deleterious reaction with any hydroxide will occur. In addition, most of the compounds in PFA and FBA are held in the glassy phase, so not readily available for such chemical reactions.
PFA has been used extensively as a filler aggregate for the production of foamed concrete for a number of years. Because its cohesive nature it leads to a stable air bubble structure in the final product; it’s readily available and is cost effective - hence why it is so widely used. FBA is generally not used, because it has traditionally all been sold to the block making industry, however, there is no technical reason why is couldn’t be used in foamed concrete as a coarse aggregate.
Both PFA and FBA do not contain elemental aluminium and therefore will not cause chemical reactions such as the production of hydrogen gas. They can be safely used in foamed concrete.
The UKQAA Business Plan for 2009-2010 - 2 June 2009
The UKQAA has produced a Business plan for 2009-2010. This document is a continually updated document that outlines the direction of the Association and aims for the immediate future.
The Quality Protocol and the regulatory position - 27 January 2009 (updated Feb. 2010)
For a number of years there have been differences in interpretation of the definition of waste between the Environment Agency and the UK Coal Fired Power Industry. However, after some years of work by the UKQAA, the Joint Environmental Programme (JEP) and the Association of Electricity Producers (AEP) in conjunction with WRAP and the Environment Agency (For England and Wales) , have finished working on a series of documents. These form a Quality Protocol (QP), a Technical Report and a Financial Impact Assessment. The Quality Protocol in conjunction with the other documents defines the criteria when coal fired ash products, PFA or fly ash and FBA, can be used without the necessity of obtaining waste exemptions and licences.
These documents have recently been through a public comment stage and will subsequently go to Europe for consideration. It is hoped the final version of the Quality Protocol for Bound and Grouts will be published late summer 2010. In the interim the Environment Agency has adopted a regulatory position which assists the fly ash industry in to continue to supply without having to apply for licences and exemptions. This document is called "The regulation of materials being considered under the Waste Protocols Project" and describes the position the Environment Agency (For England and Wales) will take during the interim period, the latest version is available from the Environment Agency's web site.
In regard to unbound materials, these have proceeded to a sampling sub-group, which shall review the chemistry and leachates of PFA in embankments applications. This will eventually set limiting criteria for PFA in such applications and form the basis of another Quality Protocol. This work is expected to complete in mid 2011, with a revised Quality Protocol being available some 6 months afterwards. In the interim period, the Environment Agency regulatory position will be updated accordingly to continue to allow the use of PFA in embankments, fills, etc even after the change in exemptions to permits, which occurs in April 2010. As the regulatory position is constantly being revised, please find and download it from the Environment Agency's web site.
NB: Please ensure you have the latest information on the WFD and QP by visiting the Environment Agency's web site - see http://www.environment-agency.gov.uk/ and carrying out a search for Quality Protocol and/or PFA. The UKQAA cannot accept any liability for any changes that may occur in the regulatory position taken by the Environment Agency - it is up to the user to ensure they have the latest information on the issue.
WRAP/Environment Agency Quality Protocol - 8 September 2008
After a number of years of work by the UKQAA, the Joint Environmental Programme (JEP) and the Association of Electricity Producers (AEP) in conjunction with WRAP and the Environment Agency, have finished working on a series of documents. These are a draft Quality Protocol, a Technical Report and a Financial Impact Assessment which have now all been made available for public comment. The Quality Protocol in conjunction with the other documents defines the criteria when coal fired ash products, PFA or fly ash and FBA, can be used without the necessity of obtaining waste exemptions and licences. These documents are available on the Environment Agency's web site and also on the Dialogue by Design web site where comments can also be registered via the internet. Comments have to be submitted before 1 December 2008.
The power generation industry see the Quality Protocol as a method of removing the stigma associated with the 'waste' terminology and will hopefully encourage the construction industry to use these products beneficially to reduce environmental impacts. These materials have been used since the 1950's without problems, but the classification as 'waste' implied by the EU Waste Framework Directive has resulted in a reduction in utilisation. It is hoped the Quality Protocol will remove this blight and allow the use in suitable locations to develop to their full potential.
The industry position regarding the definition of waste is outlined in the following UKQAA Position Paper. This issue has been plaguing the industry for some 8 years. Click here to download Position Paper 2c - July 2007. This position still stands in that the industry has never accepted that ash products destined to be sold for beneficial use were ever classified as waste. This was opposite to the Environment Agency's view of the legal situation. However, the publication of the Quality Protocol is seen as a pragmatic solution to this issue, presuming it proves acceptable to all sides.
Responsibly Sourced Materials - 4 August 2008
The Concrete Centre, The British Cement Association and the British Precast Concrete Federation has been developing a Responsibly Sourced Materials scheme. The UKQAA has, like other material suppliers, agreed to work alongside the various concrete schemes being developed as well as develop its own scheme for the ash supply industry. While there are some aspects the commitments we were unable to agree originally, these were subsequently altered and the UKQAA was able to sign up to the initiative. See: Press Release Responsibly Sourced Materials 04-08-08.pdf
Waste Framework Directive and ash as waste
The UKQAA Position Paper outlines the power industry's position over the definition of waste, which has been plaguing the industry for some 7 years. This position paper has been updated to encompass recent court decisions and the draft revision to the Waste Framework Directive currently before the Council of Europe. Click here to download Position Paper 2c - July 2007
Coal Fired Power Station Products and the classification as wastes
The UKQAA, in conjunction with the Association of Electricity Producers(AEP) and the Joint Environmental Programme (JEP) has for a number of years been disputing the Environment Agency's decision to classify many coal fired power station products as 'wastes'. For some applications, this classification results in a massive increase in costs to the contractor and client as well as increased bureaucracy and delays. The UKQAA Position Paper No 2 - Waste Regulations details the positions of both the power industry and that of the Environment Agency. In addition the UKQAA did publish a series of specific newsletter on the issue during 2003 and 2004. They are;
The impasse continues to this date (2010).
Coal Fired Power Station Products and Dioxins
Dioxins are compounds formed during incomplete combustion. Following a TV programme regarding incinerator bottom ash and its use in building blocks, coal fired power station ash products were drawn into the debate and suspicion was cast over our materials. A press release was issued in July 2001 and subsequently updated in February 2002;
Statement on Dioxins - February 2002Subsequent research carried out by The University of Dundee into dioxins in a wide range of building products found no detectable levels of dioxins in both old and new building products.
