Manufactured Masonry Units
Masonry – the art and science of building structures with individual units held together by mortar - has been responsible for some of the most celebrated structures in existence, including the Egyptian pyramids, the Taj Mahal and the Great Wall of China. Masonry continues to play an important role in the modern construction industry throughout the world, largely due to the standardization efforts of ASTM International Committee C15 on Manufactured Masonry Units, which is celebrating its 75th anniversary this year.
Committee C15 was formed in 1937 through the merging of two former ASTM committees, C03 on Brick and C10 on Hollow Masonry Building Units. The first C15 meeting was held on June 30, 1937, in New York, N.Y. C15 members will celebrate the ongoing legacy and positive influence of the committee on the construction industry and beyond during an anniversary dinner in Atlanta on Dec. 5.
James Tann, chairman of C15, and president of the mid-east region of the Brick Institute of America, makes a succinct case for the overall importance of the committee: "Simply, C15 has set the standards for compliance with building codes and project specifications. Building codes reference C15 standards, so if I want to comply with building codes, I have to abide by C15 standards. Likewise, when a construction project is being designed and the project's specifications are authored, those specifications would also cite C15 standards related to brick and block."
C15 maintains jurisdiction over 60 ASTM test methods, practices, guides, specifications and terminologies developed and maintained by the following subcommittees:
"The masonry industry refers to hand-placed units, laid in mortar," says Richard Klingner, Ph.D., the L.P. Gilvin Centennial Professor in Civil Engineering at the University of Texas at Austin, and a C15 member. "The units could be concrete masonry units, fired clay masonry units, autoclaved aerated concrete masonry units and other types of units."
Klingner says that one of the most attractive characteristics of masonry products is their hand-placed appearance and the variations that accompany it. "Use of C15 standards ensures uniform quality across a wide range of products and in the context of those inherent variations. The standards are so widely used in the masonry industry because they are an excellent way for users to obtain the appearance, strength and durability that they want\; designers can produce masonry elements with the necessary strength and other qualities, and manufacturers can produce units with the required characteristics in a cost-effective manner."
Klingner says that the overall effect of C15 on the masonry industry has been to ensure uniform quality and dependability across a wide range of materials, shapes, sizes and architectural appearances.
Two of the most important C15 standards are ASTM C90, Specification for Loadbearing Concrete Masonry Units, and ASTM C216, Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale). C90 covers hollow and solid concrete masonry units made from hydraulic cement, water and mineral aggregates. C216 covers brick made by firing clay and shale materials, intended for use in masonry and supplying structural or facing components, or both, to a structure. Both standards are used extensively around the world.
Other key C15 standards include C62, Specification for Building Brick (Solid Masonry Units Made from Clay or Shale)\; C652, Specification for Hollow Brick (Hollow Masonry Units Made from Clay or Shale)\; and C1692, Practice for Construction and Testing of Autoclaved Aerated Concrete Masonry. According to Klingner, each of these standards is the fundamental document for the materials that it covers.
Klingner says other industries have been positively impacted by the work of C15. These include the cement industry and others involved in the production of mortar and grout for unit masonry\; the work of other structural materials with which masonry units are used (for example, concrete and steel)\; and the work of other nonstructural materials with which masonry units are used (for example, insulation and air barriers).
Lynn Lauersdorf, a C15 member since 1969, is a masonry specialist who worked for the Wisconsin state government for more than 40 years. Lauersdorf served as chairman of ASTM Committee C12 on Mortar and Grouts for Unit Masonry for six years and notes the special relationship that the two committees have.
"Neither one can live without the other," says Lauersdorf of C12 and C15. "You have to have the mortar and you have to have the units. Put them together and you have masonry. It's a matter of knowing what units you're working, as well as what mortar should be used with that type of unit for whatever the circumstances would be."
Lauersdorf says that C15 has adapted to changing times by incorporating what were once new materials such as imitation stone into their standards. He feels that, in the future, the committee will be taking on sustainability and workmanship issues with masonry, mortar and units. These concerns may eventually result in standards that address such topics as masonry units formed from recycled materials, lower energy for manufacturing and job site inspection.
Research has always played a large role in the work of C15. Subcommittee C15.04 on Research continually examines C15 methods to obtain better information for ongoing revisions to the standards. Likewise, the results of research done within companies in the brick, concrete block and mortar industries are often disseminated through C15 symposia and other ASTM-related activities. Recent innovative ideas discussed at symposia include masonry wall systems with high energy efficiency, thermal resistance and modern ways to select the best materials for restoring and maintaining historic masonry.
Regarding C15's future, Tann says, "We're going to be looking at newer units, whether brick or concrete block, newer configurations of units, in an attempt to address manpower issues in the field - bigger units, maybe interlocking units to be used in building construction. Sustainability issues will lead toward looking for different formulations, including more use of recycled content in both brick and block."
To sum up, Klingner notes, "Committee C15 develops standards for manufactured masonry units and assemblies of those units that are absolutely necessary for reliable performance and stable, consistent production. The work of thousands of volunteers, within a framework carefully maintained by ASTM staff, has proven to be an effective way to standardize an incredibly heterogeneous industry."