{"id":3558,"date":"2013-08-09T15:15:19","date_gmt":"2013-08-09T19:15:19","guid":{"rendered":"http:\/\/www.constructionspecifier.com\/?p=3558"},"modified":"2017-01-20T10:40:18","modified_gmt":"2017-01-20T15:40:18","slug":"testing-the-test-water-absorption-with-rilem-tubes","status":"publish","type":"post","link":"https:\/\/www.constructionspecifier.com\/testing-the-test-water-absorption-with-rilem-tubes\/","title":{"rendered":"Testing the Test: Water absorption with RILEM tubes"},"content":{"rendered":"
\"All<\/a>
All images courtesy Building Diagnostics Inc.<\/em><\/figcaption><\/figure>\n

by Adrian Gerard Saldanha and Doris E. Eichburg<\/strong>
\nWater repellents are often applied to exterior walls to reduce absorption. A common question from building owners is, \u201cWhen does the repellent need to be re-applied?\u201d Since water repellents are clear, visual inspections are not useful to evaluate their durability. A simple field test frequently used to measure the effectiveness of water repellents is the RILEM tube. But is this widely used test reliable?1<\/sup><\/a><\/p>\n

The RILEM tube test was adopted in the United States in the early 1980s by the water repellent manufacturing industry to assess water absorption properties of walls and other substrates, with or without treatment. Simply put, the test measures the quantity of water absorbed by a particular substrate over a given time through an uptake tube. The uptake tube is sealed to the substrate with putty (Figure 1).<\/p>\n

RILEM was an acronym for the original French name of a European organization founded in 1947 to promote scientific co-operation in the area of construction materials <\/a>and structures. A RILEM technical committee developed \u201cTest No. II.4 Water Absorption Under Low Pressure (Pipe Method)\u201d\u2014now commonly known as the RILEM tube test\u2014and explained its uses in a 1980 report.2<\/sup><\/a><\/p>\n

\"RILEM<\/a>
RILEM uptake tube attached to substrate with putty, graduated from 0 to 5 ml<\/span>.<\/figcaption><\/figure>\n

The hydrostatic head developed by the column of water in the tube can be correlated with wind-driven rain of a certain speed. This relationship is not linear; pressure is proportional to the square of velocity, so the wind speed per 1 ml (0.04 oz) of water at the bottom of the tube is about twice that at the top of the tube.<\/p>\n

The tubes described by RILEM in its 1980 report were shorter (98 mm [3.9 in.] from the center of the round cylinder to the top reading mark, labeled \u20180\u2019), and were graduated from 0 to 4 cc (about 0.14 oz). The tubes readily available today are longer (about 120 mm [4.72 in.]) and graduated from 0 to 5 ml (about 0.17 oz). The 0-ml line (top of tube) correlates to 158 km\/h (98 mph) and the 5-ml mark (near the bottom of the tube) correlates to 72 km\/h (45 mph). Tubes have also been produced with graduations in wind speed.<\/p>\n

Testing the test<\/strong>
\n<\/a>Although widely used, there is currently no industry standard on how to perform a RILEM test. ASTM International has reported plans to develop an uptake tube test method for water repellents, but that standard is years away.3<\/sup><\/a><\/p>\n

The authors found manufacturers use different time intervals for their readings, different amounts and types of putty to attach the tubes, and different initial water fill levels. Therefore, RILEM tests were performed in a laboratory setting to assess whether those differences matter\u2014essentially, \u2018testing the test.\u2019 The parameters included:<\/p>\n