Masonry |
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Stone walls suffer greatly from exposure to the elements over time, and small cracks grow quickly when subjected to the extreme kinds of freeze-thaw cycles experienced in Ottawa. Water seeps in and freezes, forcing the cracks wider, then thaws, washing out the debris. Airborne pollutants also play a part: mixing with rainwater they chemically alter the mortar between the stones, weakening it and wearing it out; they also coat the stones, preventing the natural flow of moisture into and out of the stones with the seasons.
Accumulation of airborne pollutants
on stone. July 25, 2001
The Library renewal project team knew that the building's stonework was in dire need of repair, yet the extent of that need was surprising once previously hidden areas (like those around windows and eaves) were uncovered. As well, the rubble core structure within the Library's inner and outer stone walls was found to have disintegrated or washed away in several areas.
Grout tubes inserted in stone. February 5, 2003
To minimize the intervention while addressing all the problems that existed, the renewal project team carefully assessed every stone and determined its need for cleaning or repair. New fill (called grout) was added within the walls, and new mortar was inserted between the stones—preserving the original stately character of the Library while ensuring its ability to endure many more decades of use.
New and restored stone. January 13, 2006 (Roy Grogan)
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