A breakdown of new codes and standards that affect the precast industry.
By Eric Carleton, P.E.
The use of codes and standards is vital to the design and construction process. The intent of these material standards is to provide a minimum level of uniformity
for the quality and performance of materials and products used.
In the United States, the most commonly referenced material standards for the precast concrete industry are from ASTM International for municipal and private sector work, and the American Association of State Highway and Transportation Officials for public sector transportation projects. Canadian provinces reference products in accordance with CSA Group in addition to ASTM standards, which are not covered by CSA.
The design and fabrication practices for concrete are most notably recognized and developed within the codes and standards from the American Concrete Institute. In some cases, the standards and codes of each are intertwined. For example, ASTM C478, “Standard Specification for Circular Precast Manhole Sections,” references the “appropriate sections of the latest edition of ACI 318 ” when acceptance is based on rational design.
Each standard-making body is made up of interested regulators, government engineers and officials, design engineers, contractors, members of academia and industry experts. These individuals establish rules and bylaws to ensure uniform evaluation of proposed revisions to existing standards or development of new documents. Most material standards organizations, such as ASTM and AASHTO, have a minimum of one annual meeting where new standards or revisions can be proposed and enacted following ballot processes. Major ACI design or building codes are typically referenced in municipal and state ordinances and, consequently, revisions of these important documents tend to occur on regular specified cycles – typically three or five years. These extended code cycles provide ample time for any proposed revisions to have adequate public review, discussion and debate before adoption or denial.
ASTM International is comprised of many technical committees, but there are three of specific interest to the precast concrete industry: Committee C27 on Precast Concrete Products, Committee C13 on Concrete Pipe and Committee C09 on Concrete and Concrete Aggregates.
These committees are very active and many new standards have been developed in the past year. In addition, these committees have a number of work items, which may lead to new standards.
AASHTO material and testing standards are developed by the Subcommittee on Materials. This committee consists of appointed state department material engineers who serve on a variety of specific technical sections that are responsible for products used on department of transportation projects. Specific technical sections that have material and test standards of interest to the precast concrete industry are 3b – Concrete Materials and Fresh Concrete Properties, 3c – Hardened Concrete Properties and 4a – Rigid Pipe.
The 4a Task Group recently published a document for the precast industry titled R-73-16, “Standard Practice for Evaluation of Precast Concrete Drainage Products.” This is intended to be a guide document for DOT plant and field inspectors. It describes the evaluation of precast concrete pipe, box culverts, manholes, and drainage inlets and gives criteria for acceptable products and repairable products, as well as the rejection of defective products.
ACI is comprised of seven primary committee groups of interest to the precast industry: 100 General, 200 Materials and Properties of Concrete, 300 Design and Construction, 400 Concrete Reinforcement and Structural Analysis, 500 Specialized Applications and Repair, 600 Certification and 700 Education.
The primary concrete structure design code, ACI 318, which falls under Committee 300 Design and Construction, had a major update and rewrite published in 2014 and was introduced to the public in 2015. Last year, another critical code, ACI 301, “Specifications for Structural Concrete,” went through its code cycle with the document being published and introduced to the public.
Current ACI Committee 301 Chair Michelle L. Wilson said a new provision, which will affect precast aggregate suppliers, can be found in section 18.104.22.168, “Resistance to Alkali-Silica Reaction.” It states, “unless otherwise specified or unless (structural) members are assigned to Exposure Class C0, use one of the three options below for qualifying concrete mixtures to reduce the potential of alkali-silica reaction.”
This means that unless specified to not be tested for ASR, any concrete exposed to a wet condition must have the aggregates tested for ASR and comply with the required limits. Wilson also said personnel who post-tension precast components have additional certification requirements.
In addition, ACI 350, “Code Requirements for Environmental Engineering Concrete Structures,” is undergoing its review and an update may be published in 2017. Lastly, Committee 600 is reviewing criteria and requirements to develop a special field certification for self-consolidating concrete.
Standards and codes used in construction are constantly under review as technology and materials continue to change. It is important for precast concrete manufacturers to stay abreast of any major changes to material standards or design codes that affect the products they manufacture. The most direct way to stay informed is to join the respective standard-making associations and become involved in the process. In addition, NPCA technical services engineers will continue to participate on these and other important codes and standards bodies.
Eric Carleton, P.E., is NPCA’s director of codes and standards. He is also an ASTM Award Merit recipient and currently serves as vice-chairman of ASTM C13, Concrete Pipe.