By Sue McCraven
Editor’s Note: Work in the precast industry inevitably involves a requirement or specification established by one of many associations with acronyms such as ASTM, ACI and CSA. This series introduces you to these associations and their histories and a perspective on why they matter to precasters. This article takes a close look at the American Concrete Institute.
For the past 70 years, before the development of precast or prestressed concrete, the vast majority of structures made with cement, stone and water were cast-in-place concrete. Concrete was poured on site into wooden forms to build bridges and other structures. America’s first concrete roadways were tamped (pounded) laboriously by hand. Masons troweled mortar, made with cement, to erect brick and concrete blocks into homes and buildings. With a lot of manual labor and sweat, reinforced concrete played a major role in building our infrastructure. It was understandable, therefore, that the prevailing building codes were written only for cast-in-place construction.
When the Walnut Lane Memorial Bridge (the first major precast/prestressed concrete bridge made in the United States) was built in Philadelphia in the 1950s, there were no applicable U.S. codes for precast concrete. The design, technology and specifications for this bridge were imported from Europe. The successful completion of the Walnut Lane Bridge was the inspiration for more than 200 precast concrete plants being established in North America during the ’50s and ’60s.
Strength through consensus: ACI 318
With its foundation in 1904, the American Concrete Institute (ACI) has been the pre-eminent authority on concrete technology for more than a century. A nonprofit technical and educational society, ACI holds national conventions where technical committees meet to discuss issues relating to concrete technology and structures. Through committee member debate and consensus, sound guidelines for concrete construction are formulated. Over the years, ACI has established itself as a powerful advocate for the growth and development of reinforced concrete.
One prominent committee is familiarly called ACI 318. Through the volunteer efforts of dedicated professionals in many fields over the years, ACI produced what is known in common vernacular as “The Code,” essentially the technical backbone for all reinforced concrete construction (see the sidebar “ACI 318: Code or Standard?”). Formally, this lengthy document is entitled “Building Code Requirements for Structural Concrete (ACI 318) and Commentary.” If you are a structural engineer, ACI 318 is almost like a professional bible. With the validity of its scientific and engineering principles, ACI’s consensus-built documents are the foundation for the best design and construction practice for anything built of concrete, anywhere. Simply put, whenever an engineer anywhere in the world needs to build a basic floor slab or plan a sophisticated nuclear power plant, ACI is the first informed stop in the design process.
When did ACI first acknowledge precast concrete?
Even without its own national code of practice, precast concrete construction grew steadily.
In 1963, ACI’s building code (ACI 318-63) contained its first provisions for prestressed concrete. This was a document based on committee recommendations that were augmented by manufacturers and specialists knowledgeable in precast. For the first time, ACI 318, in the 2002 edition, included design provisions for precast/prestressed concrete structures in seismic areas.
ACI’s contributions to the industry
ACI has nearly 20,000 members worldwide, ranging from engineers and architects to students, business people, contractors and academia. One of the established purposes of ACI is to disseminate and advance documents relating to all aspects of reinforced concrete, not only through ACI 318, but also with its many specifications, guides and reports.
ACI is known around the world for its respected publications, including Concrete International magazine and two technical, peer-reviewed, bimonthly journals, “ACI Materials Journal” and “ACI Structural Journal”). For information on ACI’s programs, conventions, membership and publications, visit www.concrete.org.
In addition to its two annual conventions, ACI also conducts seminars around the world that are designed to keep the construction industry up to date on emerging technology. ACI is well known for its personnel certification programs that provide credentials to individuals from laborers to construction supervisors. Local ACI chapters are open to everyone from students to engineers, and their regional meetings offer informative presentations. Scholarships and fellowships are available to outstanding students at the undergraduate and graduate level studying fields related to concrete.
Concrete canoes, consultants and contractors
Student competitions (including handmade, lightweight concrete canoes that not only float but are actually raced) sponsored by ACI are great fun and excellent practical learning experiences. For academia, ACI includes faculty networks and opportunities to submit research manuscripts to either of two peer-reviewed publications, the ACI Materials Journal or the ACI Structural Journal.
The ACI Board of Directors includes university professors and researchers, structural engineers, private consultants, designers and architects, construction business owners and concrete support industry representatives, and contractors.
“As concrete design and construction continues to evolve, the American Concrete Institute is committed to staying at the forefront of the industry’s technology and innovation,” said Ron Burg, ACI’s executive vice president. “In accordance with ACI’s vision of being recognized as a prime source of knowledge, insight and influence regarding concrete and its application, this year the industry will be seeing a plethora of new information and resources coming from the Institute, including: ACI Committee 318’s updated Building Code Requirements; a new partnership with the Concrete Reinforcing Steel Institute to certify concrete adhesive anchor installers; the launch of ACI’s sustainability-focused online learning; the population of our Online Research and Information Portal with resources from our International Partners; and updates to many ACI documents.”
The concrete industry, whether cast-in-place or precast, owes much of its progress to ACI and to the highly qualified professionals who have volunteered their time and talent for more than a century.
ACI 318: Code or Standard?
A question often arises as to whether ACI 318 describes a standard or, rather, a code that is a legally enforced document.
“Legality of Codes: It may not be widely understood that the ACI 318 Building Code Requirements for Structural Concrete, despite its title, is a standard and not a code. A standard, unlike a code, is not a legal document. A standard acquires legal authority usually by a two-step adoption process. The first step is adoption of the standard by a model code. The second step is adoption of that model code by the legal code of a local jurisdiction (city, county or state). For instance, ACI 318-95 is currently law within the state of California, because the 2001 California Building Code has adopted the 1997 Uniform Building Code (UBC), which in turn has adopted ACI 318-95.”