“Sustainable development-a philosophy that focuses on meeting our construction needs today without depleting future resources.” - Portland Cement Association, Concrete Thinker.

In construction, the “green” building movement and “sustainability” are now familiar topics and hotly discussed. Contributing to this discussion is concrete masonry - a structural concrete wall system. In this discussion, I won’t attempt to address all of the environmental benefits attained during construction as well as for the life of the building. After analysis, however, concrete masonry systems are very often the solution to the quest for green construction.

Why is concrete masonry? The main reasons involve minimal maintenance, long life and resistance to damage from moisture, weathering, and vandalism, resistance to earthquake, wind, and fire, economical installation, sound attenuation, and last, but not least, energy savings due primarily to thermal mass effects.

In addition, structural-grade lightweight concrete masonry units, using lightweight aggregates, are up to 25% lighter than traditional masonry units. Lightweight CMU can speed installation by substantially increasing the number of units per hour that a mason can lay.^{1, 2, 3}

Promoters of wall systems today offer plenty of information as to why their systems are sustainable or green. Please feel free to comment as to how the concrete masonry wall system can facilitate the development of LEED points for your project. But just for thought, consider the interesting and concise definition of sustainability offered at the beginning of this article.

The masonry contractor, the hands-on professional who delivers the masonry wall system, is most assuredly today’s “construction need”. Few doubt the importance of masonry contractors - but many do not think about the potential for future depletion of this human resource. No, you won’t get LEED points for decisions that directly affect these men and women. Whether or not you are the purchasing agent, specifier or estimator (usually persons who do not actually perform the work of building the wall), you can help ensure the healthy longevity they richly deserve, and we need, as the “deliverer”.

Statistics show that where masons can get lightweight concrete masonry units - as defined by ASTM C 90 - they prefer to use them. As a recent paper acknowledged, “masons and contractors widely seem to prefer lightweight blocks”.⁴ No worry here since structural lightweight CMU, at equal compressive strengths, has greater strain capacity than the heavyweight units.⁵ If you would like more information on lightweight block made with structural-grade expanded shale and clay lightweight aggregate, contact me.

In these innovative times, new block wall systems offer higher R-values, high heat capacity (thermal mass), internal continuous membrane water and air barriers and enhanced impact resistance to name a few recent improvements. They can be designed for up to 200 mph hurricane force winds. The industry is responding like never before.

As a closing thought on sustainability, think about better thermal performance of the masonry wall. Also, consider how more lightweight aggregate is delivered per gallon of fuel to the block producer than heavyweight aggregate. And talk to your block manufacturer regarding how many additional blocks they can deliver per gallon of diesel to your next project, as opposed to the heavyweight units. The list of considerations goes on.

Stephen Stange
Sr. Sales Representative

Stephen Stange works for Texas Industries, Inc. (TXI) as a Senior Sales Representative in the Expanded Shale and Clay Lightweight Aggregate product group based in Houston, TX. Stephen has been a construction professional for the past 35 years, involved in real estate development, construction management, and the specification development process. He is certified by the National Concrete Masonry Association as a Certified Consultant of Concrete Masonry (CCCM) and is certified by CSI as a Construction Documents Technologist (CDT).

¹ PCA, Concrete Thinker webpage, 2008

² “Research Investigation of Masonry Productivity”, NCMA R&D Laboratory, reprint permission of MCAA

³ Rynold Kolkaski, Masonry Estimating, 1988

⁴ Rosecrance, J.C, “Effect of concrete block weight and wall height on electromyographic activity and heart rate of masons”, 2005 (Ergonomics magazine)

⁵ T.A. Holm, Block Concrete Is a Structural Material, Journal of Testing and Evaluation, July 1976