Scope:

ASTM D4501 specifies a standard test procedure and fixture for the characterization of block-shear strength for adhesives. Rigid adherend blocks, plates, or disks are bonded together using adhesive and the shear force needed to break the bond is measured. The ASTM D4501 test is applicable when the shear moduli of the adherends exceed the shear modulus of the adhesive. The ASTM D4501 test can be performed on any machinable or non-machinable substrate materials that can be adhesively bonded, such as ceramics, wood, glass, magnet moldings, and plastics.

Procedure:

The ASTM D4501 test is conducted on a specimen formed by adhesively bonding a small piece of the substrate to a larger piece. The specimen is then placed inside a shearing fixture, which comprises a holding block to clamp the larger piece and a shearing tool to shear off the smaller piece. The size of the holding block limits the maximum substrate size to 80 mm × 80 mm × 13 mm (3 in. × 3 in. × ½ in.). The maximum size of the smaller piece is limited by the shearing blade to 30 mm × 30 mm × 13 mm (1½ in. × 1 ½ in. × ½ in.). The ASTM D4501 fixture is attached to any universal testing machine capable of applying a force not less than 44 kN. The shearing tool is a movable blade that is in contact with the smaller piece and when pulled from the testing machine, it shears off the smaller piece at a sufficient applied force. The maximum force to shear apart the smaller piece from the larger piece gives the block-shear strength of the adhesive.

Video 01: ASTM D4501 Block shear fixture

Specimen size:

The size and shape of the larger and smaller substrate pieces can vary within the overall size limitation of the ASTM D4501 fixture. Suggested sizes for the smaller piece are 25 mm × 25 mm × 13 mm (1 in. × 1 in. × ½ in.) for non-metallic blocks and 25 mm × 25 mm × 6 mm (1 in. × 1 in. × 1/4 in.) for metal blocks.

Result:

The ASTM D4510 adhesive shear strength is reported in megapascals.

Conclusion:

ASTM D4501 specifies a standard test procedure and fixture for the characterization of block-shear strength for adhesives.