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Alkali Aggregate Reactions in Finland 2011 - 2013

 

Alkali Aggregate Reactions in Finland

Alkali-aggregate reaction (AAR) in concrete is one of the least dealt with concrete degradation mechanism in Finland. Historically, is has been taught in Finnish building technology education and material science that alkali-aggregate reactions are not a concern. It is a common belief that there is no AAR due to the exceptional quality of Finnish rock. Finnish aggregate and concrete durability guidelines even state that “According to common belief AAR is not a problem when using Finnish aggregates.” (BY43, 2008). However, several cases of AAR in concrete structures have been identified in recent disclaiming this common assumption and raising concern about the occurrence and extent of AAR in Finland. With the ageing of Finnish infrastructure condition assessments are becoming more common and now signs of AAR are more apparent.

As early as 1992, Hannu Pyy (Vahanen Group) identified in a presentation at a Nordic mini-seminar on AAR in Stockholm that “so far AAR has not been reported in Finland [*]. This is a wonder when considering the composition of Finnish bedrock and the fact that AAR has been reported in countries around us. How could it (Finland) be a white spot on the map?”. This was also reinforced by Jouni Punkki (Consolis) and Veli Suominen (GTK) in their 1994 Betoni lehti article entitled “Alkalikiviainesreaktio Norjassa – ja Suomessa?” (AAR in Norway – and Finland?) where they questioned why Finland would be immune to AAR risks [*]. Further details about Finland’s AAR risks are documented in recent articles [*].

VTT performed the first study on the topic of AAR in Finland [*], funded by The Finnish Transport Agency. The study documented more than 50 cases of obvious AAR damage in Finnish concrete structures that have been investigated over the past 15 years. An obvious AAR case meant that gel could be detected in the cracks and/or aggregates. The study clearly showed that AAR exists in Finland and the need for this topic to be addressed seriously.

[*] see publications