Masonry Magazine September 1965 Page. 17
An Information series from National NCMA TEK 2 1968, NATIONAL CONCRETE MASONRY ASSOCIATION BLOCK Concrete Masonry Association Sizes and shapes of Concrete Masonry Units
The shapes and sizes of Q BLOCK masonry units are available in such variety as to accommodate the needs of modern masonry construction regardless of the style or the location of the building.
Q BLOCK standards
Concrete masonry designated Q BLOCK units by their manufacturers are made under a quality control program of the National Concrete Masonry Association. Leading producers in the United States and Canada now manufacture to Q BLOCK standards. In order to receive Q BLOCK certification the manufacturer must demonstrate that his products comply by submitting periodic laboratory tests. The Q BLOCK designation includes three load bearing specifications for concrete masonry units. Qualified manufacturers receive a "Certificate of Quality" (reproduced to the right) which is valid for three months. Then the certification process is repeated quarterly.
15
16
masonry units made, such as solar screens, ornamental block, etc., to which these references do not apply. Dated Q BLOCK Certificate Assures Quality Products
LOAD BEARING SPECIFICATIONS AND USE OF 3 TYPES OF Q BLOCK UNITS
ASTM C90-64T Concrete Black Hollow Load-Bearing
ASTM C145-64T Concrete Block Solid Load-Bearing
ASTM C55-64T Concrete Building Brick
Grade
Use
Use
sizes
The concrete masonry industry has converted to modular units. The units used normally in modern building construction are solid or hollow rectangular prisms nominally (this designation means the dimension includes the mortar joint of ") 8 high, 16" long and 4, 6, 8, 10 or 12" wide. In addition to the 16" length, units are also commonly produced in half-length or 8" long.
The nominal dimensions of these standard units provide that with the " mortar joint, wall lengths and heights of modular standards can be obtained. The illustration at the top of this page shows the difference between actual and nominal dimensions using an 8"x8"x16" block as an example. There are, of course, special concrete
U-I, U-II
For use in unprotected exterior walls below grade and also for unprotected exterior walls above grade that may be exposed to frost action
P-I, P-II
For use in protected exterior walls below grade and also for protected exterior walls above grade that may be exposed to frost action
G-I, G-II
For general use above grade in walls not subject to frost action or where protected from weather
"Designations as to grade are ASTM tentatives.
For architectural veneer and facing units in exterior walls and where high strength and/or resistance severe frost action is desired
For general use where moderate strength and resistance to frost action and moisture penetration are required
For use in backup or interior masonry or where effectively protected against moisture penetration