SYMPOSIA PAPER Published: 01 January 1999

A New Concept in Preventing Water Leakage Through Single-Wythe Concrete Masonry Walls


In this paper, the details of a unique patented, water-repellent concrete block design that prevents moisture that enters the core area from reaching interior surfaces are presented. The subject water leakage-controlling concrete masonry unit (WLC CMU) employs a three stage water leakage prevention process, as follows: 1) the use of water- repellent admixtures and performance-optimized mix designs to resist the passage of wind- driven rain through the block and mortar itself; 2) a horizontal beveled edge, and chamfered vertical sides of the block's face shell that provide improved access for proper joint tooling and facilitates water drainage away from bed joint areas; and, 3) a series of grooves and channels that prevent moisture migration across the block web surfaces, and directs it to the flashed courses where it can be effectively drained from the building envelope. Wind- driven rain tests performed by the National Concrete Masonry Association (NCMA) clearly showed the benefits of WLC CMU technology. Using identical materials, mix design, and block manufacturing equipment, a 99% reduction of moisture penetration to the core area was witnessed twice after 72 hours of ASTM E 514 testing.

Author Information

Sauve, D
NewBlock Corporation, Belle River, Ontario, Canada
Sroka, K
Master Builders, Inc., Cleveland, OH
Nmai, C
Master Builders, Inc., Cleveland, OH
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Developed by Committee: E06
Pages: 173–198
DOI: 10.1520/STP13337S
ISBN-EB: 978-0-8031-5401-8
ISBN-13: 978-0-8031-2607-7