Concrete Cancer Scare - High Alkali Cement from Westbury Works

Published February 2005

The construction industry is at risk of substantial claims for damage to buildings caused by the use of concrete containing high alkali cement.

Last month Lafarge Cement UK announced that the alkali content of cement produced at its Westbury plant in Wiltshire during the period September 2002 to December 2004 was higher than the mean alkali value that it had declared. Instead of being classified as "high alkali" cement it was misrepresented as "moderate alkali" cement.

Reports indicate that several ready-mixed concrete companies in the south and south-west of England including Hanson, RMC and Tarmac have supplied contractors with concrete that does not conform to specification. There is a risk that in certain circumstances concrete made with this cement could develop alkali silica reaction (ASR), commonly known as "concrete cancer", leading to structural damage. According to the British Cement Association's web-site (www.cementindustry.co.uk):

Assessing the risk posed by this high alkali cement is not straightforward.

Lafarge has sought expert advice from Professor Les Clark of Birmingham University on the level of alkali content likely to cause damaging ASR. He has given generic advice on the level of risk of damaging ASR developing in concrete with varying levels of alkali content.

However, for ASR to cause damage to structures a number of other contributory factors must be present in addition to high levels of alkalis, in particular a reactive aggregate and a source of moisture. Even then the nature of the construction, for example the reinforcement design, will play a part in determining whether damage is likely to be caused. It can also take anything from two to fifteen years for damage to materialise.

Employers, owners and/or contractors should carry out their own risk assessments now rather than wait what could be many years for damage to occur. This will entail asking ready-mixed concrete suppliers to identify and give details of any loads of concrete supplied to a particular site with a higher than specified alkali content. Independent expert advice will then be required to assess the level of risk of damaging ASR developing in the structure taking into account other site specific matters such as the site environment, the reinforcement detailing and the consequence of failure. It should then be possible to determine whether testing and/or remedial works are required.

A number of difficult legal issues will arise in relation to any project where high alkali cement has been used, for example:

• Has there been a breach of the express and/or implied terms of the building contract (and/or of any warranties) by the contractor in using concrete supplied with a higher than specified alkali content? Are contractors also liable in tort for negligence?
• Is the employer or building owner entitled to redress irrespective of the risk of damaging ASR occurring?
• Is the contractor under a legal duty to warn the employer or owner of the risk?
• Even if there is no such legal duty, are there good reasons for the contractor to give a warning? Issuing a warning may for example serve to increase the burden on the employer or owner to mitigate their losses. On the other hand, care needs to be taken by the contractor to avoid the risk of attracting additional liability for negligent advice.
• What is the limitation period for the employer or owner to bring a claim against the contractor? Is the limitation period the same for the contractor to pass on those claims to the concrete supplier? Is this a latent defect covered by special rules extending the limitation period? What is the limitation period once the risk of damage has been disclosed?
• What guarantees or warranties have been given/should be given by the concrete supplier? How long do they remain enforceable? Should immediate steps be taken to seek appropriate indemnities from the concrete supplier?
• Are there likely to be exclusion and/or limitation clauses in concrete supply contracts so that the contractor is left exposed? Can the validity of any such clauses be challenged?
• What is the position if the concrete was supplied to sub-contractors instead?
• Do employers, building owners and/or contractors have the right to take direct action against the cement producer given that (according to the British Cement Association web-site) the alkali test data was deliberately misreported?
• Are there any insurance issues, for example should contractors notify their CAR, Public Liability or Project insurers?

To summarise, appropriate risk assessments should be carried out by employers, building owners and contractors. If you are a contractor the steps you should take include the following:

1. Ask all your ready-mixed concrete suppliers (not just Hanson, RMC and Tarmac) whether any of their cement was sourced from Lafarge's Westbury works.
2. If so, seek confirmation from the suppliers that the alkali content of all such cement matches that specified.
3. If the alkali content of any concrete supplied is higher than that specified:

• obtain full details of the loads in question
• take independent expert and legal advice check the terms of any relevant insurance policies and notify insurers
• request that the supplier and/or the producer give an indemnity against any costs that you incur in investigating the technical and legal consequences, including in respect of claims that may be made against you by employers or building owners
• consider passing relevant details to the employers or building owners in order that they may seek appropriate advice, carry out any necessary testing and/or put in place a suitable inspection regime.

Pinsent Masons is advising a number of contractors on this matter and will be preparing a report on the various legal issues raised. If your company would be interested in obtaining a copy of our report please let your usual contact know.