Maclean's - Montreal is falling down

When a grapefruit-sized chunk of concrete smashed through the windshield of a 29-year-old man’s car in Montreal last Thursday, city officials quickly scrambled to the scene. Like most Montrealers, they assumed the worst—that it was yet another in a series of mishaps involving the city’s crumbling infrastructure.

All evidence to the contrary, just why is Montreal falling apart? “Our problem is we built most of the facilities in the ’60s and ’70s, built them in a hurry,” says McGill University’s Saeed Mirza, an expert on concrete infrastructure. “The result is that the quality control was not there.”

The problem boils down to the ill-advised design choices and poor-quality concrete that were used in the rush to build up Montreal ahead of Expo ’67 and the 1976 Olympics, he says. “Our concrete is permeable and we didn’t design the drainage on our overpasses and bridges properly. The lack of drainage and the permeability of the concrete enabled the chlorides to get in from the de-icing salts. That, of course, led to the corrosion of the steel reinforcements. When steel corrodes, it expands. That pressure causes the weakest link to fail.”

The result is a familiar sight to most Montrealers: cracked and crumbling concrete barely hiding the disintegrating steel bars inside.