Acrylic Foam Structural Glazing Tape: A New Bonding Alternative

A durable, high-performance glazing option for curtain wall construction
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Iguatemi Corporate office building, Porto Alegre, Brazil . The curtain wall is bonded with acrylic foam structural glazing tape.
Courtesy of 3M

When reviewing global product applications, it is useful to review the local building construction practices such as whether building codes apply, and how they impact the introduction of new products and construction installation methods. In many regions of the world it is common practice to do a mock-up testing of the building facade before construction. A two or three-story high mock-up is built according to the specifications of the project and then tested for wind load, structural performance and other conditions. In Singapore, mock-up testing is mandatory.

In India, where over 200 projects with acrylic foam structural glazing tape have been completed since 1995, there are no building codes for glazing and mock-ups are uncommon. Builders generally follow established practices and, once drawings and specifications are approved, begin construction. The introduction of acrylic foam structural glazing tape for structural glazing, therefore, required a cautious approach. In some cases, a manufacturer may set up a local laboratory facility to study and test performance and safety before product fabrication.

2005 ASTM Structural Performance Tests for Structural Glazing (Winwall Technology Pte Ltd − Singapore)

Third Party Testing Data. Acrylic foam structural glazing tape has undergone a number of key ASTM construction related tests, plus structural performance tests in Brazil in 1998, the country which had the first and subsequently the majority of applications of tape used for structural glazing. The most significant test in terms of informing architects and curtain wall fabricators in the U.S. are the 2005 ASTM Structural Performance Tests for Structural Glazing. This included testing according to ASTM E283, ASTM E331, ASTM E330 and additional temperature cycling from -13°F to 158°F. They were undertaken at Winwall Technology Pte Ltd, in Singapore, an independent accredited 3rd party test facility specializing in the testing of curtain wall mock-ups in South-east Asia. This testing was also observed by Dr. E. C. C. Choi, Ph.D., C.Eng., FIC (UK), MASCE (USA), MHKIE (Hong Kong), MIE and CPEng. (Australia), civil engineering and curtain wall consultant, professor, School of Civil & Environmental Engineering, Nanyang Technological University, Singapore, and specialist in wind characteristics, wind loading, weather tightness, curtain wall, and building envelope technology.

Performance. The objective of the test was to compare the performance of panels mounted using acrylic foam structural glazing tape with those mounted using structural silicone sealants. The glazed panels submitted for the tests were built at a leading manufacturer of architectural curtain wall panel systems using designs, materials, assembly procedures and factory conditions typical of the construction industry.

The first sequence of test panels consisted of laminated glass bonded with acrylic foam structural glazing tape, a double glazed unit (DGU-insulated glass) bonded with acrylic foam structural glazing tape, and a DGU bonded with a one-part structural silicone sealant. The three panels in the second test sequence consisted of a single pane tempered glass bonded to acrylic foam structural glazing tape, a single pane tempered glass bonded with a one-part structural silicone sealant and a DGU bonded with acrylic foam structural glazing tape. (The DGU bonded with acrylic foam structural glazing tape was subjected to the complete testing protocol twice).

Overall, the test result showed that the performance of the panels mounted using acrylic foam structural glazing tape was as good as the panels mounted using the conventional structural silicone sealant. All the panels performed satisfactorily; there was no measurable air infiltration, no water penetration was observed, and the panels withstood pressures up to the design pressure of 60 psf (2.9 kPa) even after the panels had gone through twenty cycles of extreme temperature cycling of -13°F to 158°F (The pascal (Pa) is the System International (SI) unit of pressure or stress). The pressure cycling was conducted first at ambient temperature conditions of 90°F according to ASTM E330. Upon passing of all panels at this temperature, the pressure cycling was then repeated up to 60 psf at -13F and then again at 158°F. All panels passed this additional pressure cycling demonstrating the capability of the acrylic foam structural glazing tape to withstand high windloads in hot and cold environments. Once this was completed the integrity of the air seal was again measured with no leakage observed with any of the glazed panels. The windload pressure cycling was then repeated up to more than twice the design pressure without showing any sign of delamination or damage, The panels in the second test sequence sustained a peak load of 210 psf (10 kPa) without failure. It should be noted that the DGU bonded with acrylic foam structural glazing tape was subjected to the entire test sequence twice. In the first test sequence, the laminated glass panel fractured at a negative pressure of 175 psf (8.4kPa). On inspection, it was observed that along the four edges of the glass panel where the acrylic foam structural glazing tape glazed the panel, the broken glass remained adhered to the frame. This demonstrated that the tape mounting was stronger than the glass panel.

PHYSICAL PROPERTIES AND PERFORMANCE CHARACTERISTICS
Peel Adhesion:
(stainless steel, ASTM D 3330)

20 lb/in width (350 N/100 mm)
Normal Tensile:
(aluminum T-block, ASTM D 897

70 lb/sq in (480kPa)
Dynamic Overlap Shear:
(stainless steel, ASTM D 1002)

65 lb/sq in (450 kPa)
Static Shear:
(stainless steel, 72ºF (22ºC)
ASTM D 3654) 150ºF (66ºC)
200ºF (93ºC)

1000 g/0.5 sq.in (holds 10,000 min.)
500 g/0.5 sq in (holds 10,000 min.)
500 g/0.5 sq in (holds 10,000 min.)
Solvent Resistance: Excellent
UV Resistance: Excellent
Temperature Resistance:
Short Term: (minutes, hours)
Long Term: (days, weeks)

Acrylic foam structural glazing tape: typical physical properties and performance characteristics. Note: This technical information and data should be considered representative or typical only and should not be used for specification purposes.

For the structural performance tests, slightly higher deflection values were recorded for the tape-mounted panels when compared to the panels bonded with the structural silicone sealant. Deflection values at the glass edge were approximately 2 percent − 11 percent greater than the equivalent panels bonded with structural silicone. This was possibly due to the compressibility of the acrylic foam structural glazing tape. These values were for the tests carried out under the design pressure of 60 psf at the three different temperatures. The increased deflection values are still considered low and acceptable and were not of concern.

 

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Originally published in May 2007

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