Joint Geometry

When this paper was initially conceived, it was felt that joint geometry should be discussed. Why? With a pressure-constant strain device, the joint geometry is easily visualized because the strain on the sealant does not fluctuate by any action of the tester meaning that when the sealant thins, the probe goes deeper into the joint, and when the sealant thickens, the probe stays closer to the surface of the joint. This observation has been demonstrated with sealant manufacturers representatives present during the testing process. To verify what was visually discernable on the surface during the test, locations with what appeared to be radical deviations were marked, cut into, and examined by the sealant manufacturer’s representatives. In nearly every case, the anticipated geometry was confirmed.

However, assuming no failure in adhesion had yet occurred at the location, the information was noted as verification that the pressure-constant device is able to provide that kind of information, not as a pass/fail criterion for the test. At no time was this information reported upon. Before that type of infor­mation is deemed necessary to collect and report, sealant manufacturers must define the pass/fail criterion. Put another way, it is the opinion of the author that the purpose of sealant testing in a nondestructive testing system should primarily be focused on finding adhesion failures, the main purpose of this discus­sion as stated in the Introduction, and additional information derived from testing may or may not be relevant.

Conclusions

Nondestructive field testing of installed weatherproofing sealant joints using a pressure-controlled, con­stant, and calibrated testing device provides valuable information. Much attention has been paid in devel­opment to make the device independent of the user to regulate and maintain the contact probe pressure. The calibration of the device to the property of various sealants allows the user to refer to a calibration chart, dial up the correct pressure, and let the device do the rest. This means that no matter the user, when identical pressures are dialed into the test device system, the pressures applied to the test specimens are consistent. Our initial studies indicate that this approach provides a reproducibility potential that may not be available from less controlled or uncontrolled test devices. However, other devices can provide infor­mation, too. For example, one may use a three pronged roller assembly known as an “adjustable backer rod placement device” which offers limited pressure control potential to the center roller from the side by side rollers moving over adjacent surfaces. Also, a window “screen roller” where pressure is uncontrolled, or rather is controlled by the arm of the person using the device, may be used. Additional research in comparing various devices to determine significant differences affecting outcome is under way. In the meantime, no matter what device is used, the author would suggest that the focus of any testing should be directed toward uncovering adhesive sealant failures with the intent to tag and fix the failures. This is because even a very small failure rate (defined in the Introduction as “loss of sealant adhesion”) in terms of total installation of sealant can pose substantial problems for the building. Figure 5 illustrates the “tag and fix” approach to sealant testing. Since in the example shown the sealant was silicone, the documenting consultant used survey ribbon and a construction grade stapler to fix the “flags” into the sealant bead at the failure locations making it easy for the sealant installer to make repairs.

The Future of Sealants in Barrier Wall (Face Sealed) Construction

An associate of the author made the following comment when presented with the data included in this paper [3]: “Even with above average workmanship, there will always be a failure rate. Even if sealant joints on any given project are as good as 99.5 % successful (an extraordinary achievement in any human endeavor), the remaining 0.5 % can cause significant damage. Submarines have bilge pumps to catch the leaks from the 0.5 %. There needs to be a second line of defense. Nothing we do is perfect enough to rely on a sealant joint 100 % of the time, and in my opinion, this is a foolhardy approach to building design.”

The problem is that the majority of constructed buildings in the United States and throughout much of the globe rely on face sealed technology. Due to the high cost of rain screen technology, this situation will likely remain unchanged in the immediate future.

In the meantime, water is promiscuous and has all the time in the world. How long does the industry have to take appropriate action to address the problem of less than adequate building seals? When does “zero tolerance” start to enter our mentality?

Ultimately, will sealants be relegated to a position of irrelevance in exterior building construction? Will barrier wall systems (face-sealed) disappear? In the opinion of the author, despite the cost, the rain screen wall system may well become the gold standard unless enhanced field testing of sealants is adopted by the industry as a recommended and encouraged activity.

[1] Anonymous, Real time World Statistics, online at: http://www. worldometers. info/ world-population/

[2] Anonymous, Key World Energy Statistics 2011, International Energy Agency (IEA), Paris, 2011, available for download at: http://www. iea. org/textbase/nppdf/free/2011/ key_world_energy_stats. pdf

[3] Anonymous, BP Statistical Review of World Energy, 2011, available for download at: http://www. bp. com/assets/bp_internet/globalbp/globalbp_uk_english/reports_and_ publications/statistical_energy_review_2011/STAGING/local_assets/pdf/statistical_ review_of_world_energy_full_report_2011.pdf

[4] Anonymous, The Little Green Data Book, The World Bank, Washington, D. C., 2011, online at: http://data. worldbank. org/products/data-books/little-data-book/little-green- data-book

[5] Anonymous, Energy Efficiency Trends in Residential and Commercial Buildings, U. S. Department of Energy, 2008, available for download at: http://apps1.eere. energy. gov/buildings/publications/pdfs/corporate/bt_stateindustry. pdf

[6] Schattenberg, P., “Ancient Algae: Genetically Engineering a Path to New Energy Sources?”, ScienceDaily, July 11, 2011, online at: http://www. sciencedaily. com/releases/ 2011/07/110711164533.htm

[7] Jess, A., Kaiser, P., Kern, C., Unde, R. B., von Olshausen, C., “Considerations Concern­ing the Energy Demand and Energy Mix for Global Welfare and Stable Ecosystems”, Chemie Ingenieur Technik, Vol. 83, No. 11, 2011, pp. 1777-1791.

[8] Anonymous, Estimating the Amount of CO2 Emissions that the Construction Indus­try can Influence – Supporting material for the Low Carbon Construction IGT Report, Ministerial Correspondence Unit, Department for Business, Innovation & Skills, Lon­don, United Kingdom, 2010, available for download at: http://www. bis. gov. uk/assets/ biscore/business-sectors/docs/e/10-1316-estimating-co2-emissions-supporting-low- carbon-igt-report

[9] Cole, R. and Kernan, P. “Life-cycle Energy Use in Buildings”, Building & Environ­ment, Vol. 31, No. 4, 1996, pp. 307-317.

[10] Reppe, P. and Blanchard, S., Life Cycle Analysis of a Residential Home, Report 1998­5, Center for Sustainable Systems, University of Michigan, 1998, available for down­load: http://www. umich. edu/~nppcpub/research/lcahome/homelca. PDF

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[12] Anonymous, Buildings and their Impact on the Environment: A Statistical Sum­mary, Revised April 22, 2009, U. S. Environmental Protection Agency, Green Build­ing Workgroup, available for download at: http://www. epa. gov/greenbuilding/pubs/ gbstats. pdf

[13] Wolf, A. T., “Sustainability Driven Trends and Innovation in Glass and Glazing”, 2009, available for download at: http://www. dowcorning. com/content/publishedlit/ sustainability_driven_trends_and_innovation_in_glass_and_glazing. pdf

[14] Anonymous, “Attaching Hard-to-bond Construction Materials for Innovative Per­formance”, online at: http://www. specialchem4adhesives. com/home/editorial. aspx? id= 5505&lr=mas12184&li=10020918

[15] Knight, A., “The New Frontier in Sustainability – The Business Opportunity in Tackling Sustainable Consumption”, BSR, San Francisco, USA, July 2010, available for download at: http://www. bsr. org/reports/BSR_New_Frontier_Sustainability. pdf

[16] Guy, B. and Shell, S., Design for Deconstruction and Materials Reuse, available for download at: http://www. recyclecddebris. com/rCDd/Resources/Documents/CSNDesign Deconstruction. pdf

[17] Steward, W. C. and Baum-Kuska, S. S., “Structuring Research for ‘Design for Decon­struction’”, Deconstruction and Building Materials Reuse Conference, 2004, available for download at: http://citeseerx. ist. psu. edu/viewdoc/download? doi=10.1.1.195.573&r ep=rep1&type=pdf

[18] Jacobsson, D., “Strong Adhesion to Fragile Surfaces – Debonding on Demand”, online at: http://www. adhesivesmag. com/Articles/Green_Recycling/BNP_GUID_9-5- 2006_A_10000000000000679822

[19] Manfre, G. and Bain, P. S., “Debonding TEM technology for reuse and recycling auto­motive glazing”, Glass Performance Days, 2007, pp. 791-796, available for download at: http://www. glassfiles. com/library/3/article1162.htm

[20] Anonymous, “Reversible glue ‘de-bonds’ at the touch of a button”, Royal Society of Chemistry (RSC), 2006, online at: http://www. rsc. org/chemistryworld/News/2006/ July/26070601.asp

[21] Watson, D. E., Is Homo sapiens sapiens a Wise Species?, online at: http://www. enformy. com/$homosap. html

[22] Projects with bonded glass frames have been erected before by Tim Mcfarlane [6] [9]. Nevertheless, this concept was not pursued.

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[23]Energy regulations pay special attention to the summer overheating protection. If neces­sary, measures—for example, controlled ventilation, sun protection glazing, or external solar shading—are to be taken to ensure the verification of the summer overheating protection.

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[24]ANSYS release 12.1: ANSYS, Inc., Southpointe 275 Technology Dr., Canonsburg, PA 15317.

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[25]Tantec A/S, Indusrivej 6 6640 Lundrskov, Denmark.

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[26]The Aerogen Company Ltd., Unit 3, Alton Business Centre, Omega Park, Alton, Hamp­shire GU34 2YU, UK.

[27] Arcotec GmbH, Rotweg 24, 71297 Monsheim, Germany.

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[28] VG Scientific Factory, East Grinstead, West Sussex RH19 1UB, UK.

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[29] “Seal continuity" as a concept, throughout this paper, refers to fully functioning weath – erseals; if the sealant is not fully adhered, the weatherseal is not continuous and fails to perform. Therefore, although ASTM C 1736 is primarily a test for adhesion, as defined by its title, the intended result of the standard practice is seal continuity.

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[30]ASTMC 1521-09e: “7.4.1 The frequency of the testing depends upon the reasons for per­forming the test procedures; 7.4.4 Destructive Procedure—For each area to be inspected, perform procedure every 100 linear ft. in the first 1,000 linear ft. of joint. If no test failure is observed in the first 1,000 ft. of joint, perform procedure every 1,000 linear ft. thereafter or approximately once per floor per elevation."

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[31] ASTM C 1521 contains non-destructive procedures; however, the practice is designed to evaluate sealant performance at discrete locations, whereas ASTM C 1736 can be used to facilitate joint seal continuity up to 100 %.

[32] David Nicastro, Engineering Diagnostics, Inc., Austin, TX; Patrick Gorman, Gorman Moisture Protection, El Paso, TX; and Jerome Klosowski, Klosowski Scientific, Bay City, MI.

[33] The force load in the system is equal to the cylinder bore area multiplied by a given air pressure. For example, a cylinder with a bore area of 0.44 in.2 (11 mm2 ) at 20-PSI (0.13 MPa) delivers 8.8 force pounds (39 N).

[34] An “adhesion in peel" test procedure requires force to destruction and a peel angle of 180° (ASTM C794 [9]).

[35]ASTM C 1736 dictates that the wheel is to be at minimum 1/8 in. (3 mm) narrower than the joint under test. If the wheel does not have adequate clearance, the sealant bead might come into shear.

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[36] A 2-to-1 width-to-depth ratio is the industry average “ideal" joint configuration in stand­ard practice. Specific configuration designs may vary, as should test force calibration to “an appropriate bond line stress."

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[37] See ASTMC 1736 at Section 6 and note 3.

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[38]

2Anton Paar GmbH, 73760 Ostfildern, Germany, http://www. anton-paar. com/

[40] corporate en

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[42]WUFI is a transient, one-dimensional hygrothermal model that includes moisture absorption and desorption in component materials and solar radiation and wind driven rain exposure.

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aStandardized default strain rate of 2 in./min (50.8 mm/min) used in Cl 135 test method, ^percent change from standardized default strain rate.

[44]t>ow Corning Corporation, West Salzburg Road, Midland, MI 48686.

[45]auaqus™ Software, HKS Michigan, І4500 Sheldon Road, Suite 160, Plymouth, Ml 48170-2408.

[46]ЛЛМЛ—American Architectural Windows Manufacturers Association, 1827 Walden Office Square, Suite 550, Schaumburg, 1L 60173-4268.

[47]Hydrostatic pressure on a below-grade structure increases with the depth below the groundwater level. The hydrostatic pressure of freshwater increases at 9.79 MPaX lU-?/m (0.433 psi/ft).

Manuscript received November 21. 2004; accepted for publication October 27. 2005; published online February 2007. Presented at ASTM Symposium on Durability of Building and Construction Sealants and Adhesives, Second Symposium on 15-16 June 2005 in Reno, NV; A. T. Wolf, Guest Editor.

[49] Research Associate and Professor, respectively, Structural Engineering Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama. 226-8503, Japan.

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