A mining company in the southwestern United States needed to test the fiber reinforced concrete (shotcrete) used to line the mine shaft of a new copper mine.
Flexural testing according to ASTM C1609-10 was essential to ensure that the concrete had the strength required to properly support the mine shaft.
The flexural specimens were made during the concrete construction process and had to be tested within 8-12 hours of construction, so a testing laboratory was not available.
The purpose of ASTM C1609-10 is to determine not only the peak strength of the concrete, but also the residual strength of the fiber after the first cracks appear.
Therefore, the test range extends far beyond the initial peak. The standard also states that the test must be performed under servo control at a very slow deflection rate,
with the servo feedback coming from the average of two deflection sensors placed on either side of the specimen. The initial crack in the specimen and the associated jump
in deflection (servo feedback) made the servo control very challenging.
lixian supplied a custom 300KN frame designed to perform ASTM C1609-10 testing and to test fiber reinforced concrete panels according to ASTM C1550-10a.
A standard third point bend fixture (W-6814) is available along with a custom sensor and mounting fixture for measuring average deflection.
