Q: Is using a RILEM tube test the best way to determine the water repellency of a concrete masonry structure?
-Water And Leakage Test
Dear WALT:
No. The short explanation is that a RILEM tube test measures the water repellency of a surface, making it suitable to evaluate the efficacy of non-water permeable coatings. While today it is generally used by the coatings industry, it originated as a way to provide the initial absorptive characteristics of stone masonry which could be correlated to deterioration rates. It evaluates an extremely small surface area with an extremely high pressure, making it suitable for coatings, but not for concrete. For water repellency in concrete masonry, we use an integral water-repellent admixture which repels water through the entire mass of the block and not just on the surface. It is important that this admixture also be included in the mortar.
To evaluate the water repellency of CMU, there are 3 industry recommended methods: the water droplet or water stream test which are quick field methods, a spray bar test which is effective in evaluating overall water repellency and a water uptake test which evaluates the capillary suction of CMU. More on these methods can be found in NCMA TEK 19-7.
Concrete masonry is allowed by ASTM C-90 to absorb a certain amount of water. This alone makes the RILEM an unsuitable test. Most concrete masonry systems are designed to have flashing and weeps so that if water does penetrate the face shells, it has a way to escape. For more on water penetration resistance in CMU structures, NCMA has several TEK which can be found on our website under RESOURCES. For more information on the RILEM test and concrete masonry go to NCMA FAQ 25-15.
Heidi Jandris grew up immersed in all things concrete block. As a kid she helped her dad build block walls and as an adult worked by his side as a welder. She received a Bachelor of Architecture degree from Pratt Institute and a Masters of Sustainable Building Systems degree from Northeastern University’s College of Engineering. She is part of the 3rd generation of her family’s business. She provides technical services to the design community while researching and implementing ways to improve the efficiency and lower the environmental impacts of their products.
