With some predictions estimating the global population will reach as high as 11 billion by 2050, it is crucial the design community plans infrastructure with sustainable and innovative practices in mind. As concrete is the most commonly used building material in the world—employed more than all other building materials combined—its ability to perform well has a direct impact on how sustainable the structure it supports is.
Pavement engineers, who deal with many of the same issues faced in the concrete-floor field, do not talk much about joint stability or differential movement. Instead, they talk about load-transfer efficiency—a related but distinct property. Whenever a load is applied to one side of a joint, it creates stress on the loaded side. Load transfer occurs when some of that stress gets transferred to the unloaded side. Load transfer efficiency (LTE) is a measure of how well the joint shifts stress to the unloaded side.
A stable joint—one that does not move excessively when a load is applied near it—is obviously better than an unstable one. However, the best methods to make joints stable are not always agreed upon. For example, one floor designer might call for stout, closely spaced dowels, while another also chooses dowels, but makes them thinner and spaces them farther apart.
While many concrete structures have a design life of 50 to 100 years, not all live up to expectations. Much of the concrete infrastructure currently in service across North America is badly in need of repair or replacement, and this premature deterioration is a large hidden cost to owners. What is causing this lack of durability?
Anyone involved with concrete finishing and protection—either through design, supply, or installation—is likely to have been affected by blistering and other moisture-related failures on floor finishes. A multi-million-dollar problem in North America, there are numerous reasons for such failures. However, a conversation being had more frequently today surrounds the relationship between alkali-silica reaction (ASR) and near-surface alkali reaction (NSAR) and finishing failures.
Canadian firms have been using tilt-up concrete for creative applications for many years, helping to push the construction method into new territory. Familiar as a building method for commercial and industrial facilities, tilt-up is increasingly being used in high-end buildings—and this turn of events is taking the material back to its starting point.
Constructing buildings requires the skills and knowledge to meet the demands of speed of construction, energy efficiency, resiliency to environmental conditions, cost efficiency, and long-term durability. The tilt-up concrete method, which speaks to all these attributes, has steadily grown since the 1940s due in large part to the development of the mobile crane and advancements in ready-mixed concrete.
Insulating concrete forms (ICFs) offered an energy-efficient mode of construction long before sustainability was widely pursued, or even understood, in the overall building industry. In the intervening years, competing building methods have seen improvements in thermal energy efficiency, but the properties of ICF have remained virtually constant, until recently.
In seemingly every sector, from government to real estate development to retail, project owners are looking to make their construction sites greener. The movement toward more sustainable construction practices is neither trend nor fad; it is a functional philosophy responding to both a heightened public consciousness of the impact of human activities on the planet and the added value of doing ‘the right thing.’