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6.4 Specimen Information
DROP-DOWN BOX - Select the specimen/test type to be run. This allows access to various specimen setup
input parameters. Care should be taken when entering the dimensions, as specimen stress is calculated from
this parameter. Care should also be taken when entering the following three important setup parameters:
• BREAK: Percentage threshold of the peak load used to detect a specimen break. For example, if the break
% is set at 70% and the system maximum load is 100,000lb, a drop to 70,000lb or less would trigger break
detection.
Care must be exercised if this setting is too high or too low. For example, if 95% was selected, the system
may stop the test when a chip breaks off a corner. Full breaking stress may never be reached. Alternatively,
if the percentage is too low, the system may never detect breakage, thus not stopping and retracting at the
end of a test. A break % from 50% to 70% is recommended for most applications.
• RAMP RATE: Ramp rate desired. This value should be set based on testing standards.
• PRELOAD: Load threshold in which to perform rapid advance before controlling at the desired ramp rate. This
value is the load before data collection begins. During preload, no break detection is applied. It is important
to select a preload value that is high enough, so that break detection is not activated prematurely. In most
applications, preload should not be set lower than 1% of a testing machine's capacity.
NOTE: ASTM C39 allows a fast advance up to 50% of the anticipated break strength before controlling at
35psi/sec.
6.5 Correction Factor
Per ASTM C39, only used for specimens that are not the standard 2:1 length to diameter ratio. When activated,
the correction factor is applied to displayed values. A value of 1 should be used when diameter vs. length does
not require applying a correction factor.
6.6 Break Type
Used to store the break type according to ASTM C39. When the checkbox "Ask for Break Type?" is selected, the
system will prompt the user to choose the break type at the end of each test (see Fig. 6d).
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Fig. 6c: Display Fields on Main Test / Run Screen
Automatic Concrete Compression Machine Manual
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