Issue link: http://digital.canadawide.com/i/178290
Versatile Material From ending traffic jams with a temporary flyover to boosting cladding esthetics and quality, precast provides solutions by Godfrey Budd W hen the City of Calgary needed a temporary ix for an annoying traf ic conundrum, the solution entailed precast concrete components for a lyover that could be rapidly constructed and then later disassembled. An intersection between one of the city's freeways – Glenmore Trail – and a regular city street was controlled by traf ic lights, and was a source of protracted traf ic delays, almost daily. Building a lyover/interchange seemed like a good solution – except it might have to be scrapped later to make way for a ring road, which would be owned by the province. The solution was a temporary two-lane bridge, about 44 metres long, over Glenmore Trail and somewhat east of the existing intersection. From design to completion – once plans were approved by the city – took only ive months, and construction of the superstructure was done in just 23 days. The overpass is designed to be disassembled and reused, and could serve as a detour once plans are inalized for the intersection. The overpass is supported by a foundation of spread footings that rest on mechanically stabilized earth (MSE) embankments, with use of a geo-grid mesh. The design team made use of some existing pre-stressed concrete girders and adapted the design accordingly. Precast concrete deck panels, 19.3 by 2.5 metres and 225 millimetres deep, were attached to the girders. The reusable lyover cuts commute times by an average of seven minutes and eliminates the associated emissions. Precast Concrete p.12-19Precast concrete.indd 13 Precast concrete is also playing a pivotal role in joint efforts involving more than 20 irms in developing netzero residential housing via a Habitat duplex project in Edmonton. Habitat for Humanity, Lafarge and Stantec Engineering are the three main partners, but a total of nearly two dozen irms are contributing materials, expertise and time – for free. "It's to learn what's the best way to construct a net-zero house or multi-residential buildings using precast concrete to achieve net zero. The RAIC is aiming for net zero," says Don Zakariasen, director of marketing at Lafarge Canada. The project is very much about developing a product to meet emerging and future demand, he says. "This is basically a learning tool. The biggest return we're looking for is in the knowledge base. We believe that this could be replicated in the more sustainable housing market." Some 22 design systems from precast panels to glazing and solar PV components support the construction of the Temporary two-way bridge over Glenmore Trail, Calgary, AB. Photos: Chris Bolin. duplex. "It's important to learn how you integrate everything in order to achieve net-zero. We won't learn unless we do it," says Zakariasen. The home's exterior insulated sandwich precast panels are R44 for walls and basement and R88 for the roof. The duplex also includes a six-inch-thick precast shear wall between the suites, 10-inch hollow core loor slabs, as well as precast stairs, steps, landings and balconies. Including panels, more than 80 precast components are to be assembled on site this spring. The duplex includes a geothermal heating and hot water system and solar PV panels. The precast elements for the net-zero duplex, which is targeting LEED Platinum certi ication, were made at Lafarge's Edmonton plant, and are expected to take just two days to assemble on site. The design team used Building Information APRIL 2012 /13 3/26/12 2:15:48 PM