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The expansion of concrete caused by alkali-aggregate
reaction (AAR) causes significant deformation at the Mactaquac
Generating Station. In 1988, remedial measures began to relieve the
stress caused by AAR and these activities continue such as diamond
wire saw cutting that is used to make 15 millimeter slot cuts in the
powerhouse and the water retaining structures. Before cutting,
multi-strand tendons and anchors were installed on the downstream face
of the intake to provide extra strength to the structure. To date,
there have been 28 different areas cut with 15 of these requiring
regular re-cutting due to the high AAR growth rate.
On August 25,
2011 a new slot cut was made nearby the West End Pier (WEP) of the
main intake. A sudden along-track displacement of 4 mm was detected by multiple filters inside of the GNT’s mmVu®
deformation monitoring software. |
