- 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.
 Find out more
 Related articles on Designing Buildings Wiki
Featured articles and news
A form of procurement where the contractor provides a single point of contact for a supply chain.
A month after the devastating fire, emergency reconstruction works are underway.
The London Build Expo is hosting a Diversity in Construction panel and networking session on October 24.
Analysis can help develop a specification, but must not lead to inappropriate specifications being accepted.
Dos and don'ts for creating a smart home.
New ICE publication recommends pay-as-you-go tax to fund roads and other financing options.
BSRIA launches a White Paper on wearable technology and wellbeing in buildings.
Have the pressures of the market shredded the core values of professionalism?
Lead times are a measure of the amount of time that elapses between initiating and completing a construction process.