Concrete scanning · Trois-Rivières
Concrete scanning and GPR in Trois-Rivières
In Trois-Rivières, concrete scanning with ground-penetrating radar (GPR) locates rebar, conduits and other embedded items before you core, drill or cut a slab, wall or column. The status of the opening gets settled before the visit, between declared work and work needing a permit.
Trois-Rivières
Working in Trois-Rivières
In Trois-Rivières, an opening in a slab may fall under a work declaration or a building permit depending on what is being done. Settling that question before the survey avoids tying a drilling date to an unfinished process. For the scan itself, indicate the intended position of each opening, what it has to cross and which face is reachable. An area cleared and marked on a plan shared with the contractor makes the sweep faster and the marking more reliable.
In Trois-Rivières, some light work does not require a building permit, yet a work declaration remains mandatory before starting. It is free of charge and can be filed by whoever carries out the work, with written authorization from the owner. Before coring or opening a slab, check which side your work falls on.
Preparing your project in Trois-Rivières
- Determine whether the opening falls under a work declaration or a building permit
- Obtain the owner’s written authorization if the filing is done by whoever carries out the work
- Mark the intended position of each opening on a plan shared with the contractor
What the Trois-Rivières building stock means for your concrete surveys
Founded in 1634, Trois-Rivières retains a heritage site declared in 1964, where the Ursuline monastery stands alongside middle-class and workers’ houses from the second half of the 19th century, boomtown-style houses and apartment buildings from the early 20th century. On June 22, 1908, a fire razed nearly 800 buildings. According to the City, the downtown area was rebuilt, its streets were widened, and the district still shows strong architectural consistency.
The forest shaped the riverbank. The Répertoire du patrimoine culturel du Québec places the city’s first sawmill in the mid-1850s, at the confluence of the Saint-Maurice River and the St. Lawrence. Around 1919, Canadian International Paper built a pulp and paper mill there that became, by the late 1920s, the largest newsprint mill in the world. Closed in 2000, the complex was demolished in 2001, except for the filtration plant, whose brick load-bearing walls support reinforced concrete beams and a concrete roof.
In the late 1960s, the city broadened its economic base toward college and university education, and the Université du Québec à Trois-Rivières was founded in 1969. The Laviolette Bridge, completed in 1967, is the only road link spanning the St. Lawrence between Montreal and Quebec City. From 2023 to 2025, the Government of Québec replaced the original deck of its central section using 680 precast panels.
In the downtown rebuilt after 1908, consistent facades say nothing about what has been poured inside since. A boomtown house or an early 20th-century apartment building may have received a basement slab, a retail floor or an elevator shaft long after it was built. Before opening, look for the date of these additions in permits or renovation drawings, because a recent slab and an original slab are not approached the same way.
In an industrial building with a mixed system, where brick load-bearing walls carry reinforced concrete beams, locate the beams and their bearings on a sketch before choosing where to place an opening.
How ground-penetrating radar works
Ground-penetrating radar (GPR) emits high-frequency electromagnetic waves and records their reflections at boundaries between materials with different properties, such as concrete and steel. The ASTM D6432 guide describes this investigation method.
GPR is also one of the non-destructive test methods for in-place concrete reviewed by the American Concrete Institute (report ACI 228.2R-13).
Method, preparation and GPR limitations
When to request a scan, how to prepare the survey, how to use the findings and what ground-penetrating radar cannot see are all covered on our concrete scanning in Quebec page. This page only covers what is specific to Trois-Rivières.
Frequently asked questions
Does concrete scanning damage the structure?
No. GPR is a non-destructive test method: the device moves over the concrete surface without drilling or coring it.
What can ground-penetrating radar detect?
Usually rebar, conduits and other embedded items whose electromagnetic properties differ from those of concrete. Readability depends in particular on depth and on the condition of the concrete.
Does the permit question have to be settled before a slab is scanned?
The two processes are independent, but running them out of order costs time. The survey can take place first, and its observations often help describe the intended work precisely. Check with the City which side your project falls on.
Who can file the work declaration?
The owner, or whoever carries out the work with the owner’s written authorization. Settle this before the visit, since it determines who deals with the City.
Sources
- ASTM D6432-19, Standard Guide for Using the Surface Ground Penetrating Radar Method for Subsurface Investigation
- American Concrete Institute, ACI 228.2R-13, Report on Nondestructive Test Methods for Evaluation of Concrete in Structures
- Ville de Trois-Rivières: Déclaration de travaux (in French)
- Répertoire du patrimoine culturel du Québec: Site patrimonial de Trois-Rivières (in French)
- Ville de Trois-Rivières: Histoire de Trois-Rivières (in French)
- Répertoire du patrimoine culturel du Québec: Usine de filtration de la CIP (in French)
- Government of Québec: Remplacement de la dalle centrale du pont Laviolette (in French)
- Auditor General of Québec, June 2022: Sels de voirie, chapter 4 (in French)
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