• Grade SW—Brick intended for exposures below freezingin the presence of moisture. Minimum compressivestrength requirements are 4,500 psi (31 MPa) for an individualunit and 5,500 psi (37.9 MPa) for an average ofthree units, based on average gross area. The maximumwater absorption is 15 lb/ft 3 (240 kg/m 3 ).• Grade MW—Brick intended for exposure <strong>to</strong> temperaturesbelow freezing, but unlikely <strong>to</strong> be saturated withwater. Minimum compressive strength requirements are3,000 psi (20.7 MPa) for an individual unit and 3,500psi (24.1 MPa) for an average of three units, based onaverage gross area. The maximum water absorption is18 lb/ft 3 (288 kg/m 3 ).PREFACED CONCRETE AND CALCIUM SILICATEMASONRY UNiTS—ASTM C744ASTM C744 (ref. 13) establishes requirements forthe facing materials applied <strong>to</strong> masonry unit surfaces. Forthe units on<strong>to</strong> which the surface is molded, C744 requirescompliance with the requirements contained in ASTM C55,C90 or C129, as appropriate. Facing requirements in C744include: resistance <strong>to</strong> crazing, surface burning characteristics,adhesion, color permanence, chemical resistance,cleansability, abrasion, and dimensional <strong>to</strong>lerances.CONCRETE MASONRY UNiTS FOR CATCH BA-SiNS AND MANHOLES—ASTM C139ASTM C139 (ref. 14) covers solid precast segmentalunits intended for use in catch basins and manholes. Unitsare required <strong>to</strong> be at least 5 in. (127 mm) thick, with aminimum gross area compressive strength of 2,500 psi(17 MPa) (average of 3 units) or 2,000 psi (13 MPa) for anindividual unit, and a maximum water absorption of 10 pcf(16 kg/m³) (average of 3 units). The overall unit dimensionsmust be within ± 3% of the specified dimensions.REFERENCES1. International Building Code. International Code Council, 2006, 2009, 2012.2. Specification for <strong>Masonry</strong> Structures, TMS 602-11/ACI 530.1-11/ASCE 6-11. Reported by the <strong>Masonry</strong> Standards JointCommittee, 2011.3. Standard Specification for Loadbearing Concrete <strong>Masonry</strong> Units, ASTM C90-11b. ASTM International, 2011.4. Standard Test Methods for Sampling and Testing Concrete <strong>Masonry</strong> Units and Related Units, ASTM C140-11b. ASTMInternational, 2011.5. Control Joints for Concrete <strong>Masonry</strong> Walls—Empirical Method, TEK 10-2C. National Concrete <strong>Masonry</strong> Association, 2010.6. Control Joints for Concrete <strong>Masonry</strong> Walls—Alternative Engineered Method. TEK 10-3. National Concrete <strong>Masonry</strong> Association,2003.7. Design and Construction of Dry-Stack <strong>Masonry</strong> Walls, TEK 14-22. National Concrete <strong>Masonry</strong> Association, 2003.8. Standard Test Method for Linear Drying Shrinkage of Concrete <strong>Masonry</strong> Units, ASTM C426-10. ASTM International, 2010.9. Standard Specification for Concrete Brick, ASTM C55.9a. ASTM C55-03, ASTM International, 2003.9b. ASTM C55-11, ASTM International, 2011.10. Standard Specification for Concrete Facing Brick, ASTM C1634-11. ASTM International, 2011.11. Standard Specification for Nonloadbearing Concrete <strong>Masonry</strong> Units, ASTM C129-11. ASTM International, 2011.12. Standard Specification for Calcium Silicate Brick (Sand-Lime Brick), ASTM C73-10. ASTM International, 2010.13. Standard Specification for Prefaced Concrete and Calcium Silicate <strong>Masonry</strong> Units, ASTM C744-11. ASTM International, 2011.14. Standard Specification for Concrete <strong>Masonry</strong> Units for Construction of Catch Basins and Manholes, ASTM C139-11. ASTMInternational, 2011.NCMA and the companies disseminating this technical information disclaim any and all responsibility and liability for theaccuracy and the application of the information contained in this publication.NATIONAL CONCRETE MASONRY ASSOCIATION13750 Sunrise Valley Drive, Herndon, Virginia 20171www.ncma.orgTo order a complete TEK Manual or TEK Index, contact NCMA Publications (703) 713-19004 NCMA TEK 1-1F
March 1 -3, 2012NCMA Annual Convention • February 29-March 3, 2012SpECIAL ThANkS TO Our INduSTry pArTNErS
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