Concrete Repairs and Cleaning at the Canadian Centre for Architecture Sculpture Garden

The Canadian Centre for Architecture is a Montreal-based research institution and museum with the “specific aim of increasing public awareness of the role of architecture in contemporary society and promoting research in the field”. The CCA regards its campus as a key feature of its collection. Although only the 1874 Shaughnessy House is currently recognized by the three levels of government, its 1988-89 contemporary addition and adjoining sculpture garden meet most requirements to become eligible for recognition.
The 1988 Ernest-Cormier Esplanade (sculpture garden) was designed as a coherent ensemble of concrete artworks by the late architect Melvin Charney. It is comprised of 10 allegorical columns and a sculptural façade.
The presentation will focus on the recent rehabilitation of the concrete sculptural façade. It will examine the project through the lens of the close collaboration between the preservation architect, masonry conservator, concrete testing laboratory and contractor spanning from surveys and cleaning mock-ups to the completion of construction. This process allowed for early assessment of compatible and workable repair material and cleaning techniques as well on site adjustments of the selected strategies during construction. The choice to involve a mason specialized in heritage masonry to address a contemporary concrete structure will also be discussed to highlight the relevancy of traditional approaches to modern materials. Maintaining balance between the integrity and authenticity of the work was key in the decision making process.
Cleaning approach: Various mock-ups to remove calthemic deposits, level of clean, advantages and limitations of selected micro-abrasive cleaning, monitoring the evolution of remaining deposits one year after work completion.
Repair approach: limited historical data, original concrete characterization (discrete destructive testing on a sculpture), development of a mixture of repair material compatible with the concrete in place, preparing in-shop concrete samples for a color and aggregate repartition match, assessing the impact of concrete cleaning on the previously planned repair strategy, and (finally) implementing the repairs while ensuring visual compatibility with the uneven appearance of the original concrete:
Next steps: monitoring repairs; and repairs options for the allegorical columns based on concrete testing (if time allows).