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Structural behaviour of highway structures subjected to alcali-aggregate-reaction - State-of-the-art report

Switzerland Flag
Complete with results
Geo-spatial type
Network corridors
Project website
Project Acronym
STRIA Roadmaps
Vehicle design and manufacturing (VDM)
Infrastructure (INF)
Transport mode
Road icon
Transport sectors
Passenger transport,
Freight transport


Background & Policy context

The alkali-aggregate reaction (AAR) leads to a volume expansion of the concrete with appropriate cracking. This has among other things a reduction in the mechanical properties of the concrete result. The AAR is a relatively slow process expiring; Damage to the building is visible only after decades.
While the AAR in different countries (eg. USA, Japan) is known for decades, the AAR in Switzerland is unique and has been only an issue in the field of concrete dams for several years. In the field of civil engineering structures, a few years ago an exponential increase in reported cases with damage caused by alkali-aggregate reaction (AZR) was recorded in Switzerland. The affected buildings have especially retaining walls and galleries, as well as bridges.

Due to the relatively small number of known damaged structures, the alcali-aggregate-reaction (AAR) did not yet receive a lot of attention by the profession. Anticipating an important increase in the number of structures with AAR damage, the knowledge should be improved and methods should be elaborated for an efficient evaluation and rehabilitation of reinforced concrete structures with AAR damage. This project will provide a state-of-the-art report from the viewpoint of structural engineering. Also, relevant research topics will be identified.


The objective of the project is to establish a state-of-the-art report on the theme of structural behaviour of reinforced concrete structures suffering from alcali-aggregate-reaction (AAR).


Previous research in the field of AAR were carried out mainly in the context of concrete dams. In this project, the research has focused on understanding the AAR at the (micro) level of the material concrete. Material laws were only sporadically derived, for example, to describe the loss of strength due to the AAR. The structural behaviour of the supporting elements or entire structures with AAR has been little studied.
The review of existing engineering structures consists essentially of three parts: (1) recording and interpretation of the structural state, (2) evidence of sufficient structural safety and (3) prediction of the state development. This also applies to reinforced concrete buildings with AAR.

To reach the project objectives, the following steps will take place:

  • Literature review
  • Survey of people in Switzerland and abroad with knowledge of reinforced concrete structures with AAR
  • Own rough analysis and reflections on possible resistance models for reinforced concrete with AAR


Parent Programmes
Institution Type
Public institution
Institution Name
Swiss Government: State Secretariat for Education and Research
Type of funding
Public (national/regional/local)


The objectives have been achieved by creating a progress report. Furthermore needs for further research were identified.

The research report includes the state of knowledge of engineering structures made of reinforced concrete with AAR (and less of the chemical-physical phenomenon of AAR) and the structural behaviour of components made of reinforced concrete prepare the topic for the civil engineer from the perspective of mechanical material properties.

The research report has shown a significant need for research, particularly as regards of the structural behaviour and assessing the structural safety of concrete structures with AAR. There is now a basis to define and edit further research targets.

The report also makes clear that today - even in Switzerland - the subject of the AAR should be made rapidly known in the professional world. There is a great need to inform the construction world over the damage from AAR to ensure that the phenomenon is also recognized in the state recording of concrete structures and conservation measures can be taken as early as possible.


Wälchli, Thomas; Brühwiler, Eugen:  Tragverhalten von Kunstbauten mit Alkali-Aggregat-Reaktion (AAR). Sachstandbericht ; Forschungsauftrag AGB 2002/030 auf Antrag der Arbeitsgruppe Brückenforschung -AGB-

Wälchli, T., Brühwiler, E.: Tragverhalten von Kunstbauten aus Stahlbeton mit Alkali-Aggregat-Reaktion (AAR) - Sachstandbericht. VSS-Bericht Nr. …, 2005.

Innovation aspects

The progress shown in the research report may be distributed on the basis of standard work, essays, as well as at conferences. The primary aim was to inform the world of work on the damage of concrete structures by AAR and their effects on the structural behaviour, the serviceability and the structural safety.


Lead Organisation
EU Contribution
Partner Organisations
EU Contribution


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