Sources: National Concrete Masonry Association, Herndon, Va.; CP staff
NCMA staff will field questions and solicit input during an open webinar, October 14 at 1 p.m. (EDT), on a series of revisions it proposes for minimum web requirements in ASTM C 90–11 Standard Specification for Loadbearing Concrete Masonry Units.
Read MoreSource: National Concrete Masonry Association, Herndon, Va.
Preliminary results from NCMA Research and Development Laboratory tests on concrete masonry units and prism specimens indicate a one-to-one correlation in compressive strength at the 2,000-psi range. The measurement of 2,000-psi unit strength yielding 2,000-psi prism strength is one-third higher than widely referenced tables in current codes acknowledge.
Read MoreSource: National Concrete Masonry Association, Herndon, Va.
By Don Marsh
A change in ASTM C90-prescribed web configuration for concrete block has the potential to lower products’ material use and transportation costs; increase masons’ productivity through lighter units, while reducing fatigue and injury associated with heavier block handling; ease rebar congestion and grout placement in reinforced wall assemblies; and, boost R-values by a factor of 3 to 4, owing to improved thermal properties.
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