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2014SumShotcreteEMag

Sustainability Article reprinted from the Fall 2006 issue of Shotcrete magazine 2005 Outstanding Repair and Rehabilitation Project: Pointe de la Prairie Lighthouse By Patrick Giroux and Simon Reny TIsland across from Baie-Saint-Paul in the against impact from ice flows. In several areas,(6 mm) thick steel plate surrounding the concretebase was designed to provide added protectionhe Pointe de la Prairie Lighthouse is locatedon the north shore of the Île-aux-Coudres St. Lawrence River. Since its construction in 1972, these plates were completely destroyed. The the lighthouse has been exposed to extremely extent of the concrete deterioration behind these severe environmental conditions. Exposure to salt plates was so severe that in some areas it reached water, continuous freezing-and-thawing cycles, nearly 3 ft (915 mm) in depth. and impact from ice flows have contributed over In the summer of 2004, Public Works and the years to severe deterioration of the concrete Government Services Canada elected to tender a that makes up the base of the lighthouse. A 1/4 in. project to conduct a much needed, major reha- bilitation of the lighthouse. The consulting engi- neers at BPR Inc. recognized the need to come up with a system that would meet the challenges associated with the difficult access while pro- viding protection against the severe environ- mental conditions. Working with engineers from King Packaged Materials Company, BPR Inc. specified a dry-mix shotcrete mixture containing silica fume, steel fibers, a granite-based coarse aggregate, air- entraining admixture, and a set accelerator. The air-entraining admixture was specified to provide improved durability, the steel fiber and granite stone were incorporated to provide resistance to impact and abrasion from ice, and the set accel- erator and the silica fume were specified to reduce Pointe de la Prairie Lighthouse before reconstruction the risk of washout created by the rapidly moving tides and waves. The new structural design of the base of the lighthouse did not include the use of steel plate to guard against impact and abrasion damage. It was agreed that this protection would be offered by the impact and abrasion-resistance properties of the shotcrete. In July of 2004, Public Works and Government Services Canada awarded the contract to complete the rehabilitation of the lighthouse to Yves Germain Construction of Québec City, QC, Canada, and the shotcrete portion of the contract was sub-con- tracted to Cimota Inc., also of Quebec City. Cimota elected to have the preblended shotcrete mixture supplied in 2200 lb (1000 kg) reusable bulk bags and worked with personnel from Yves Germain Construction to schedule the shipment of the mate- Nozzlemen shooting the base of the lighthouse rial to the work site by barge. As in all dry-mix 48 Shotcrete • Summer 2014


2014SumShotcreteEMag
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