Building envelope and infrastructure research, environmental stewardship, education and certification programs enhance industry quality and create opportunities
Canadian Design and Construction Report special feature
Precast prestressed concrete has a diversity of applications and enhancements, making it an ideal construction material for many types of buildings. Here are some observations provided by the Canadian Precast/Prestressed Concrete Institute (CPCI).
High-performance enclosures perform above normal levels, specifically in owner-specified areas such as rain penetration resistance, air tightness, energy performance, or durability. Architectural precast concrete wall systems can be an excellent choice for high-performance building enclosures. To achieve the best control of rain penetration, precast concrete wall designs should employ a perfect barrier-drained joint system. They should use a drained, two-stage joint between the concrete barrier elements at all penetrations.
This approach is theoretically sound, supported by decades of real-life experience, and allows for other high-performance attributes such as excellent air tightness and high thermal resistance.
Some designers choose to ignore the unique properties of precast concrete, and design precast systems that attempt to mimic the drained rain control approach of brick, stone, or stucco veneers. As it is well established that precast concrete panels themselves do not allow rainwater to penetrate, the rain control performance of precast is not improved by draining behind the panels. In fact, there are numerous increased risks that are created by using the drained approach if normal construction sequences are used (Straube 2012).
Infrastructure for life
CPCI is promoting a new way of doing business, in an attempt to address two problems associated with current infrastructure construction methods. First, Canada’s infrastructure is aging. Much of the highway and water and sewer systems were built in the 1950s and 1960s. Some have already failed or are in great need of rehabilitation or replacement.
Precast concrete elements have generally performed well and can be easily repaired to prolong their service life. Secondly, traffic demand has grown tremendously without a corresponding increase in highway capacity. The result is an increasingly high level of congestion. Large building construction projects simply compound traffic problems during lengthy construction periods. The traveling public demands high quality, longer-lasting highways, bridges and structures but they want any construction-related activity completed quickly. In order to address this problem, public and private authorities need to adopt a new philosophy of “Get in. Get out. Stay out.”
Accelerated construction is a means to achieve the reconstruction and new construction of major projects while minimizing delay and community disruption. However, accelerated construction is not simply “building things faster.” Rather, it includes a range of techniques, processes, and technologies to achieve the desired result of reducing congestion due to construction while improving quality and life.
The Infrastructure for LIFE program advances longer-lasting infrastructure using innovative technologies and practices. It can provide the financial incentives to clients while demonstrating and promoting the state-of-the-art technologies, elevated performance standards, and new business practices in the construction process that results in improved safety, faster construction, reduced congestion from construction, and improved quality and user satisfaction.
- Regulatory authorities are realizing that precast concrete components can be used to minimize interference to the public during municipal construction projects. Traffic holdups also have an adverse impact on the environment. The use of precast concrete components for many new or replacement bridge and/or water and sewer projects have demonstrated significant reductions in construction time, reduced impacts on traffic flow and the environment, as well as long life performance.
- Precast infrastructure components include conventionally reinforced and pre-tensioned or post tensioned structural elements such as beams, I-girders, bulb tees, double tees, stemmed members, box girders, solid slabs, full or partial depth bridge deck slabs, conventional and integrally insulated wall panels, hollowcore slabs, joists, stairs, seating members, railroad ties, piling, sheet piling, piling caps, retaining wall elements, median barriers, parapet walls, sound barriers, vaults, box culverts, pipe and manholes.
In 2007, the CPCI established an enhanced on-going quality assurance program available to CPCI member and non-member companies to improve the overall quality and consistency of precast concrete products. The CPCI precast concrete certification program for structural, architectural and specialty precast concrete products and systems confirms that the precast manufacturer has an ongoing quality assurance system. The CPCI program is recognized for the thoroughness and frequency of audits, the stringency in attaining first certification, the strict requirements to maintain certification, as well as for adding new product groups, and many other program principles such as compliance with the more stringent requirements of either CSA A23.4 or PCI MNL 116 and 117.
Audits examine all aspects of the plant operation including engineering practices, production methods, construction methods, controls and management commitment. The numerically-graded audit report is uniform coast-to-coast from large plants to small. Independent engineers make the two-day appraisal twice annually. Grades are non-negotiable with an 80 per cent passing requirement. A failed grade requires a thorough review of improvements with an extra audit within 60 days, and special audits are required when substantiated complaints are received from owners or owner’s representatives. The total process for initial certification takes a minimum of 90 days to attain plant certification, but it is this level of scrutiny that enables a higher level of assurance for building departments and owners.
Canadian precast concrete sustainable plant program
CPCI officially launched the new sustainable plant program in 2012. This program aims to reduce the environmental impact at the manufacturing level while creating a culture of sustainability within the industry. The benefits of sustainable business practices are well documented. As the leading technical resource for the precast concrete industry in Canada, CPCI is providing the tools for its member plants to measure and implement changes that will have a measurable improvement in their environmental and economic performance using a web-based software tracking program.
The CPCI sustainable plant program encourages continuous improvement and compliance to environmental and sustainability regulations and standards. Environmental performance will be determined based on the intents of all applicable government environmental policies.
Sustainability performance builds on the CPCI’s Canadian precast concrete life-cycle assessment (LCA) research. The program is not intended to replace municipal, provincial or federal environmental acts and their requirements. Instead, it is a program designed to track the improvements implemented by manufacturers and it is their responsibility to comply with applicable government regulations.
As part of this program, facilities will be required to submit confidential benchmark reports on a semi-annual basis. The aggregated results of the program will be communicated to the public every two years through the CPCI sustainability report.