Tag Archives: 07 19 00?Water Repellents

Durable Waterproofing for Concrete Masonry Walls: Redundancy Required

A single-wythe concrete masonry wall may be a cost-effective structural element, but it can present challenges for waterproofing. The National Concrete Masonry Association (NCMA) recommends redundancy to keep concrete masonry walls dry through techniques at the surface of the wall, within the wall, and through adequate drainage systems. Unfortunately, many concrete masonry wall designs rely solely on admixtures in the concrete masonry units (CMUs) and mortar and surface-applied water repellents. However, low absorption values do not guarantee water penetration resistance; this disconnect in the industry is a leading reason for leakage in single-wythe concrete masonry walls.

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Testing the Test: Water Repellents

Water repellents can be confusing, from the imprecise terminology (i.e. sealers versus coatings versus sealants) to the wide variety of chemistries available. There can also be a stigma associated with repellents—many consultants are concerned about negative side effects from applying a material to the outside of a porous material, potentially impeding vapor drive from the interior.

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Testing the Test: Water Absorption with RILEM Tubes

RILEM tubes can be used to assess a substrate’s resistance to water absorption, to compare the absorption before and after treatment with a water repellent, and to evaluate the durability of a repellent by periodically measuring absorption. Although widely used by the construction industry, there is currently no industry standard available describing exactly how to perform the test. Small changes in the testing procedure may lead to different results, including how to attach the tube, how to fill it, and at which intervals to perform the readings. Standardization would improve the uniform interpretation of results.

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