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2017WinterShotcreteEMag

2016 Outstanding Infrastructure Project Bordeaux Prison: Rehabilitation and Repair of the Perimeter Walls By Kevin Robertson and Pierre Brassard In 1891, the city of Montreal, QC, Canada, purchased land in Bordeaux (now the borough of Ahuntsic- Cartierville) for construction of a new prison to replace the outdated 1820s Pied-du-Courant prison, located in the Ville-Marie borough. The prison, one of the few Pennsylvanian-styled prisons in Canada, was designed by Jean-Omer Marchand and R.A. Brassard, and built between 1908 and 1912 at a cost of $2.5 million, an astronomical amount in 1912. On November 18, 1912, Bordeaux Prison opened its doors for the first time to 100 prisoners. It was then, as it is now, the largest provincial prison in Quebec; it was built to hold 500 prisoners but now has a capacity of 1189 inmates. The star-shaped building consists of a central 12-sided domed hub from which spring six cellblock wings that feature large outside cells ranged along the exterior walls. The new jail included state-of-the-art workshops placed at the heart of the prison, in front of the cellblock, and on both sides of the administration building. The whole complex stands within a five-sided compound surrounded by a double wall. Today, Bordeaux Prison is the largest and most important prison in the province of Quebec. It is owned and operated by Société québécoise des infrastructures (SQI). The prison is protected by two peripheral concrete walls separated by an interior path. The heights of the inside and outside walls are 25 and 14 ft (7.4 and 4.4 m) and approximately 30 ft (9.1 m) wide, respectively. Exposure to over 100 years of the freezing-and-thawing cycles experienced during Montreal winters resulted in significant deterioration throughout the concrete walls. Core samples revealed that concrete deterioration ranged from 2.5 to 4 in. (65 to 100 mm) in depth. This contract was the fourth phase of the entire restoration project. The first two phases called for a removal of the deteriorated concrete. Lightweight precast panels were installed using a steel stud hanger system to protect the walls from any further deterioration. Phase three called for removal of the deteriorated concrete and replacement using the form-and-pour method. Upon evaluation, however, it was evident this method was more costly and created longer delays. The section of walls that were to be repaired using the form-and-pour method required construction of a temporary wall in front of the existing wall to prevent inmates from climbing the wall formwork and escaping. The formwork had to be fireproof and thicker to provide room for the concrete to be placed within the form. The entire work area required an around-the-clock security patrol to prevent escape attempts. Phase four of the project was released for tender in late 2014 and was awarded in 2015 to General Contractor Construction Jessiko Inc. Shotcrete-related work was a large portion of the project and included surface preparation, shotcrete placement, and curing. Jessiko chose Groupe Lefebvre M.R.P., an experienced and well-known concrete repair, waterproofing, and shotcrete contractor from the greater Montreal region for that portion of the contract. SIGNIFICANCE OF SHOTCRETE For phase four, the structural engineering firm Geniex investigated the use of shotcrete to place the significant amount of concrete that would be required to replace the removed deteriorated concrete. Although they had never before specified shotcrete as a concrete placement method, the engineers conducted considerable research into the benefits of the shotcrete process and eventually determined that the dry-mix shotcrete process would provide the best option. The main benefit offered by the shotcrete process was the speed of repairs (extremely important because the courtyard could not be shut down for long periods of time unless a new, temporary wall was constructed in front (as was the case using the form-andpour method). A long-term durable concrete repair was also critical to ensure overall performance. The engineer specified the use of King MS-D1 SY, a silica-fume-enhanced, prepackaged shotcrete material for dry-process applications. Among the important factors in selecting this product was the fact it was air-entrained. Although some believed that achieving consistent air content in dry-mix shotcrete was impossible, test data from 22 Shotcrete | Winter 2017 www.shotcrete.org


2017WinterShotcreteEMag
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