According to a report in the UK press Lafarge workers falsified data on cement supplied to its ready mixed concrete customers Lafarge has been selling its ready mixed concrete customers cement containing excessive levels of alkali High-alkalinity cement has been linked to the development of concrete cancer - alkali silica reaction - which can weaken and damage structures, says Construction News. Now hundreds of contractors are frantically carrying out audits to see if they have used the affected material on site.
The scandal centres on Lafarge’s Westbury cement production plant in Wiltshire where employees deliberately falsified test data between September 2002 and December 2004 by claiming material had a lower alkali level than it actually had. Because of this ready mixed concrete plants in Avon, Berkshire, Devon, Dorset, Gloucestershire, Hampshire, Oxfordshire, Somerset and Wiltshire have inadvertently supplied concrete that does not conform to clients’ specifications. Local ready mixed concrete suppliers have been affected alongside national organisations including Hanson, RMC and Tarmac.
Lafarge has notified its customers and now the ready mix companies are liaising with clients who may have been supplied with hundreds of thousands of cubic metres of substandard concrete. Lafarge claimed that despite the Westbury plant producing more than a million tonnes of cement over the period less than 1,000 cu m of concrete was at high risk a spokesman said: "At least half the cement from Westbury is used in concrete that includes slag or ash.These additions act to reduce the alkali level and so these mixes would not be affected. Also for concrete to be at risk of developing alkali silica reaction it needs to be combined with highly reactive aggregates and moisture."