Corrosion mapping · Saguenay
Corrosion mapping in Saguenay
Corrosion mapping locates the zones where reinforcing steel is likely corroding in a concrete slab or wall, so that repairs can be targeted in Saguenay. Covering a surface by sector, to follow a change rather than record it once.
Saguenay
Working in Saguenay
A corrosion map makes sense when it can be repeated later on the same division. In Saguenay, on a structure in use, that means fixing the sectors, their naming and the drawing format from the first pass. Indicate the areas already repaired, those in doubt and the use that will be made of the result. A survey whose division changes at every pass compares poorly with itself.
Saguenay directs permit requests to two separate counters, Info-permis résidentiel and Info-permis commercial. A survey that supports work in a commercial or institutional building is therefore not prepared in the same place as a residential project. Identifying the right counter before planning avoids a round trip when the application is filed.
Preparing your project in Saguenay
- Fix the division into sectors and their naming from the first pass
- Locate the areas already repaired and those in doubt
- Agree on the drawing format that later passes will reuse
Saguenay, a city of aluminium and wood, seen from the concrete
Saguenay produces one third of all the aluminium made in Canada, according to Promotion Saguenay, which also describes the forest industry as inseparable from the regional economy. Port de Saguenay notes that the Chicoutimi pulp mill was, in the early 20th century, the largest mechanical pulp mill in the world, and that aluminium smelters developed from the 1920s onward thanks to the hydroelectric potential and the possibility of building a deep-water port. Opened in 1985, the Grande-Anse marine terminal handles, among other goods, lumber, pulp and paper, industrial salt and coal.
In the Jonquière borough, the Arvida heritage site covers 178 hectares and includes more than 800 buildings, mostly detached single-family houses built between 1926 and 1950. The Répertoire du patrimoine culturel du Québec describes series construction: in 1926, Arvida Works started 270 houses and finished them in 135 days, notably by reusing four forms to pour the foundations, and the houses were built from 34 standard plans. Brick dominates in institutional and commercial buildings.
Nearby, the Arvida aluminium bridge, built in 1949 and 1950, is the first bridge in the world made entirely of aluminium. It links the former town of Arvida to the Shipshaw II generating station, its deck includes concrete, an aluminium alloy forms the layer separating the aluminium from the concrete, and the structure was restored in 1995 and in 2013.
The Arvida bridge illustrates a common case in an industrial city: metals other than the reinforcement in contact with the concrete or embedded in it. Flag these elements (anchors, rails, plates, aluminium structures), since the interpretation of half-cell potentials takes into account what is electrically connected to the reinforcement.
In an industrial or port area where salt is stored or handled, mention it in the request, along with washed areas and places where water pools. The presence of chlorides guides the choice of sectors to map.
Measuring corrosion activity
The ASTM C876 test method covers the estimation of the corrosion potential of uncoated reinforcing steel in concrete, for the purpose of determining its corrosion activity. Taken on a grid, these measurements produce a map of the surveyed surface.
Exposed slabs and parking garages
Parking garages are subject to specific obligations in Quebec: an annual visual verification and an in-depth verification report by an engineer every five years, according to the Régie du bâtiment du Québec. A corrosion map helps locate the zones to watch between these verifications.
- On a cracked or spalled parking slab
- Before planning concrete repairs
- To monitor an area that has already been repaired
Mapping method, process and limitations
How potential measurements work, how the survey runs, how to read the maps and their limitations are covered on our corrosion mapping in Quebec page. This page only covers what is specific to Saguenay.
Frequently asked questions
Does corrosion mapping indicate the strength of the structure?
Not directly. It provides information on the corrosion activity of the rebar; assessing structural capacity is an engineer’s responsibility.
Why combine it with a concrete scan?
Ground-penetrating radar locates the rebar and estimates its depth, which helps position corrosion measurements on the steel.
Why fix the division at the first survey?
Because a comparison only means something on the same division. Changing sectors between passes makes it impossible to say whether an area changed or only the way it was outlined.
Can the result support a call for tenders?
It can document the extent to consider, provided the report states the method, the areas covered and the limits. The expected content is settled when the request is made.
Sources
- ASTM C876-22b, Standard Test Method for Corrosion Potentials of Uncoated Reinforcing Steel in Concrete
- Régie du bâtiment du Québec: Parking garages, maintenance and inspection
- Ville de Saguenay: Construire et rénover (in French)
- Promotion Saguenay: Key sectors
- Port de Saguenay: Historique (in French)
- Répertoire du patrimoine culturel du Québec: Site patrimonial d’Arvida (in French)
- Répertoire du patrimoine culturel du Québec: Pont d’aluminium d’Arvida (in French)
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