ASTM C557 – Standard Specification for Adhesives for Fastening Gypsum Wallboard to Wood Framing

ASTM C557  covers the minimum performance standards for and properties of adhesives intended to bond the back surface paper of gypsum wallboard to wood

framing members.

Test requirements and test methods for the adhesive used for the application of all thicknesses of gypsum wallboard are also covered.

The specification provides a basis for ensuring the quality of adhesives.

Compression shear test, tensile test, gap filling or bridging characteristics test, freeze-thaw stability test, and accelerated adhesive aging shall be performed on the adhesive.

The tests are suitable for products performance certification and quality control programs and can be useful the general public, adhesive manufacturers,

distributors, specifiers, architects, contractors, testing laboratories and other businesses and professionals.

*** There are two main tests described in C557.

The first and most widely used is the shear test which uses a balanced guillotine style shear fixture.

The second is a tensile test which uses a specialized fixture to pull a rectangular piece of wood off of the drywall.

ASTM C557 / Geometry

The shear strength test requires a shear fixture built similar to the one used for ASTM D905.

The fixture window is enlarged to accomodate for the 102 x 89 mm (WxH) prepared sample size.

There is also an adjustable sample shelf on the fixture which can accomodate samples 0-32mm in total thickness.

The tensile test fixture is 5″ x 5″ square which can hold the 4 x 4 x 5″ sample. The sample is held on the edges, which allows the test operator to glue the square

wooden specimen to the gypsum drywall.

*** Before conducting ASTM C557 , it is important to read the entire specification. Standards can be obtained from appropriate standard authorities.