ASTM C78 uses a "third point" style bending fixture to perform flexure tests on concrete used in the construction of slabs and pavements.
ASTM C31 covers sampling and specimen preparation for fresh concrete in the field; ASTM C42 discusses specimens sawn from cured material;
and ASTM C192 covers laboratory prepared specimens. We recommend referring to the instructions in ASTM C78 for loading rates, proper specimen orientation,
and application of preload to ensure "no gap" contact between the specimen and the fixture.
A servo control system that allows the test to be performed automatically in a closed loop. We have found that operators prefer this type of system
to a manual control system because it allows for more consistent control of the loading rate and there is less risk of the specimen being impacted.
The desired result is for the modulus of rupture to be calculated and for the specimen to fail within the middle third of the tensile zone or the bottom
of the specimen span length. The partner software automatically calculates the modulus of rupture based on the maximum applied load and average
dimensional values of the specimen tested. If failure occurs outside the middle third of the specimen, but not more than 5% of the span length, a different formula
is used to calculate the modulus of rupture result. If failure occurs more than 5% outside the middle third of the tensile zone of the specimen, the result cannot be used.
We manufacture a variety of test systems suitable for meeting this specification, including the common industry standard "compression only" style systems for building testing.
We recommend reviewing the standard to fully understand the test setup, procedures and result requirements.
