- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 22 Jun 2018
Alkali-aggregate reaction (AAR)
However, the material had a 'guilty secret' that was only revealed by research in the USA during the 1930s. In some circumstances, an expansive reaction can gradually occur between aggregate constituents and alkaline hydroxides from the cement, causing damage to the hardened concrete within structures.
This has become known as 'alkali-aggregate reaction' (AAR), or most commonly and more specifically, 'alkali-silica reaction' (ASR). This AAR family of mechanisms is by no means the most frequently encountered threat to concrete durability or the serviceability of structures, but it can be a serious issue when it occurs.
 Getting to grips with AAR
Over more than 40 years, I have been privileged to witness practising engineers and applied scientists getting to grips with AAR worldwide. I believe we now understand the several reactions, including how to recognise them in existing structures and manage the situation, but crucially also including how to determine any possible AAR potential in new works and take effective precautionary measures.
However, challenges remain, especially as appreciation of the potential threat from AAR is not universally or equally appreciated everywhere in the world, and we are still finding types of structure that behave exceptionally. Overall, the prospects are encouraging for both a declining incidence of AAR damage and successful approaches to management and/or repair of affected cases.
This article was originally published by ICE on 30 June 2016. It was written by Simon Fullalove. You can see the original article here.
 Related articles on Designing Buildings Wiki
Featured articles and news
A survey of Leicester’s historic buildings resulted in local listing being taken more seriously.
Demolition is the most high risk activity in the construction sector. Read our introductory article here.
BSRIA report on the domestic boiler market, with China recording the most 'dynamic market uptake'.
Do we really know everything important about the impacts of our infrastructure projects? And if we don’t, does it matter?
Former Chief executive Richard Howson blames government for being 'poor payers'.
An environmental plan is an essential tool for setting and managing environmental objectives for a project.
CLC call for an 'outcome-based, transparent and efficient' industry with new report.
The first NIC assessment suggests there is a golden opportunity to provide low-carbon energy.
It's featured prominently as the backdrop to the World Cup coverage - read about the most iconic building in Russia.
Report highlights growing need for soft skills and digital skills among civil engineers.