The standard “ASTM C557-03 Standard Specification for Adhesives for Fastening Drywall to Wood Framing” published by the American Society for Testing and Materials (ASTM) describes the properties and minimum performance standards of adhesives used to bond drywall backing paper to wood framing members.
For the purposes of this standard, the terms and definitions given in the "ASTM D907-12 Standard Terminology for Adhesives" standard are valid.
This standard applies to adhesives for bonding drywall backing paper of any thickness to wood framing members. This standard provides a basis for ensuring the quality of adhesives. While the bonds provided by these adhesives have sufficient strength on their own to maintain the bond between the adherends, they are not intended to replace the common practice of using mechanical fasteners to maximize the integrity of drywall-wood framing structures.
The tests are suitable for product performance certification and quality control programs and can be useful to the general public, adhesive manufacturers, distributors, specifiers, architects, contractors, testing laboratories and other businesses and professionals.
The results do not include all possible conditions that may occur during final assembly, but do show a range of performance characteristics for laboratory-controlled bonding variables.
Adhesives shall be homogeneous, uniform mixtures of elastomeric polymers or viscoelastic resins, or both, free from lumps or foreign matter. The physical property requirements for adhesives are specified in this standard as follows:
Adhesive performance must comply with the requirements outlined in the table titled “Adhesive properties and performance requirements” provided in the standard.
A sample size of approximately 1 L of test adhesive is the minimum amount required to complete a full test series. The sample should be processed and stored according to the manufacturer's recommendations. For qualification testing, the sample should be representative of the final product for which recognition is desired.
When determining the shear strength (shear strength development rate), each laminate is constructed by bonding a 102 mm x 89 mm x 12,7 mm thick drywall face paper sheet to a 15,9 mm or 15,1 mm plywood block of the same dimensions with a commercially available PVA adhesive. The plywood reinforces the drywall to prevent fracture before the ultimate shear load is achieved. The grain of the drywall back paper is parallel to the 89 mm direction.
When determining shear strength, test specimens are prepared by bonding a 102 mm x 89 mm piece of plywood to a previously prepared drywall-plywood laminate as follows: The test adhesive is spread onto the plywood bonding surface with a trowel having 4,8 mm deep V-notch grooves with the adhesive backing parallel to the wood grain. During application, the trowel is held at an approximately 90 degree angle to the receiving surface. An open time of 30 seconds plus/minus 5 seconds is allowed after spreading is complete. The drywall-plywood laminate backing paper is placed squarely on the adhesive-coated plywood with an overlap of 63,5 plus/minus 1,6 mm, thus creating a bonding area of 64,5 cm2. Six No. 51,0 wire spacers, at least 20 mm long, are placed at the 25,4 mm plus/minus 1,6 mm joint. The spacers are placed so that one is on the centerline of the bonded area (perpendicular to the ridges) and the others are 25,4 mm away from and parallel to the center spacers. Immediately after assembly, each test specimen is compressed under a uniformly distributed load of 3 N for 3,5 to 67 minutes. After a period of 3 to 3,5 minutes, the load is removed, excess adhesive from the bonded edges is wiped off with a square-edged spatula, and the spacers are withdrawn, taking care not to disturb the alignment of the bonded parts.
In determining shear strength, after proper conditioning, the specimen is tested in a shear test using a compression-shear test mixture. The lower edge of the drywall-plywood laminate bears on the self-aligning slot when the test load is simultaneously applied to the upper edge of the single plywood. The applied stress is distributed parallel and uniform to the bond line shear plane and requires careful orientation using wedges and self-aligning fixtures as necessary. Shear strength is determined at a crosshead speed of 12,7 mm/min. Observations are made during the stress application to ensure that the test fixture maintains proper alignment and that the mixture operates without binding or rubbing throughout the test. Record the maximum shear strength and the average shear strength for the 24-hour, 14-day cycling exposure and static load test conditions.
When determining the shear strength after 24 hours, five shear test specimens are prepared using the procedure described above. After the shear test specimens have cured for 24 hours plus/minus 1 hour under standard conditions, the shear strength is determined.
When determining the shear strength after 14 days, five shear test specimens are prepared using the procedure described above. After conditioning the specimens for 14 days under standard conditions, the shear strength is determined.
When determining the shear strength after cyclic exposure, five shear test specimens are prepared using the procedure described above. After conditioning the shear test specimens at standard conditions for 14 days, the shear test specimens are processed for four complete cycles. The shear test specimens are stored at standard conditions for 24 hours after each cycle. At the end of the cycle, the shear strength is determined.
When determining the shear strength for static load, ten shear test specimens are prepared using the procedure described above.
Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "ASTM C557-03 Standard specification for adhesives for fixing drywall to wooden frame" standard are also provided to businesses.
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