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  British Cement Association | information | key issues | Alkali Incident
 

Special Section: South West Alkali Incident

This is a special section of the British Cement Association's website.  It has been set up to help anyone who received concrete made with cement from Lafarge Cement UK's Westbury Works in Wiltshire between September 2002 and December 2004 and is concerned that it needs checking.
 
What happened?
Lafarge has discovered that the alkali levels in its cement during this period were  higher than the declared mean alkali levels used by concrete producers in creating their mix designs. As a result a number of ready-mixed concrete producers inadvertently supplied non-conforming concrete to customers in the South West of England.
 
After completing a detailed investigation to identify what happened, Lafarge has confirmed that this incident was isolated to Westbury Works and solely related to the reporting of alkali levels. Quality reporting and cross-checking systems were strengthened in all plants to ensure that such an incident cannot happen again.  
 
The true alkali data for the period was documented and has been made available.  The company has been working with the ready-mixed concrete producers to whom it supplied Westbury cement during the period, sharing all technical data and meeting its responsibilities in dealing with the problem.
 
Read the press release
 
What problems could high alkali cement cause?
Concrete is inherently alkaline.  However, in certain conditions, high levels of alkali have been linked to the development of damaging alkali silica reaction (ASR) to an extent that it causes the concrete to expand and crack.  For damaging ASR to occur, all of the following factors must be present: high levels of alkali in the concrete; reactive aggregates; and the presence of moisture.
Further information on ASR.
 
BCA information sheet on ASR.
 
 
How will I find out if it may affect my structures?
The producers' analysis of ready-mixed concrete mix designs over the two-year period has identified a very small proportion of concrete supplied in the South West that is of concern and may require monitoring for the potential development of damaging ASR.  All purchasers of concrete that could be affected have been informed.
 
Lafarge further actions
Lafarge continues to work with specialist engineering companies Arup and Halcrow to provide customers who have structures with a high or medium risk of developing a reaction with independent assessment of the structure and advice on how it should be managed.
 
Lafarge is a responsible producer and is standing by its product; any problems resulting from the use of the product are assessed on a case-by-case basis. Where necessary steps are being taken to manage the possibility that an adverse reaction might occur. These include: (a)encapsulating the affected concrete in a further concrete 'skin' and (b) sealing it inside a waterproof membrane.
 
Further information: Lafarge Cement UK's Help Desk, Tel: 0870 6090011
 
updated 04 January 2006
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