ASTM C67
Flexure and Compression Testing Brick and Clay Tile
Theory:
ASTM C67 covers a standard specification for flexure and compression testing brick and structural clay tile used as building materials. There are three tests under this standard which relate to universal testing machines. They are the flexure test (MOR), the compression test, and the breaking load test. Both the flexure and the breaking load test can use the same 3 point bend fixture.
Geometry:
The compression test requires a spherically seated block or platen which covers the entire area of the brick.
Sample Sizes for this test are according to the manufacturer. Whole bricks and tiles are used.
The 3 point bend fixture uses articulating supports which can rotate freely in the perpendicular direction to the length of the brick sample. This articulating supports allow for a perfect axial force with no forces from the transverse direction.
The 3rd point loading nose is a steel rectangular plate which is 1/4" thick, 1.5" wide, and 4" long.
Solution:
The exact fixture needed varies between the three tests.
Spherically Seated Platens are used for the compression test. In this case, 1 platen is fixed and the other is allowed to articulate on a spherically seated joint. The platens must cover the entire surface of the sample. A rectangular plate can also be used.
The 10,000 lb. 3 point bend fixture can be used for this test. The support points for the MOR test are modified to articulate according to the standard. The 3rd point bending nose is a steel rectangular plate. The standard design of this fixture can test standard brick sizes which are 3.625"x2.25"x"8" (DxHxL). Where depth corresponds to the width of the rollers. Standard rollers of 4" width are available as well as custom specific sizes.
The Breaking Load test requires the same 3rd point loading nose but the support points are more basic. Fixed rollers with 1" in diameter are suitable for this test.
Universal Grip offers both fixtures and full testing systems for performing ASTM C67. Galdabini Universal Testing Machines can be pre-programmed and ready to test according to any global standard. Galdabini machines are highly flexible and easy to use because they are designed for the global market.
Analysis:
Compression Strength is the maximum load the brick can withstand before rupturing and failing. Once the brick cracks, it loses its structural integrity.
The Modulus of Rupture is for the 3 point flexure test. The MOR is derived from the max load recorded before the brick cracks. The exact equation can be found in the ASTM standard. The brick usually breaks in the middle.
The Breaking Load is just the maximum load. The breaking load can also be expressed as the breaking load per unit width. Averages per lot can be calculated with the Galdabini machine.
