Sep 25, 2023
How to Perform I-FIT
Of the cracking tests gaining popularity for their correlation to field results, the Illinois Flexibility Index Test (I-FIT) scores near the top of the class. If your department of transportation (DOT) requires you perform this test on your balanced mix designs (BMD) or other mixes, here’s how to do it.
In simplest terms, you make a specimen in a gyratory compactor (SGC) and then test the specimen in a bending test fixture. Of course, the devil is in the details.
Step 1. In the SGC, compact the specimen to a height of 160 mm.
Step 2. Trim the specimen to get two semi-circular specimens.
Step 3. Cut a 15-mm deep notch, 1.5-mm wide in each specimen base perpendicular to the loading axis.
Step 4. Take measurements of the specimens for the second phase of the test.
Step 5. Submerge both specimens in a water bath for two hours at 25 degrees C.
Step 6. Double-check ethernet connection, warm up the bending test fixture, and launch the app.
Step 7. Place and align the specimen in the bending test fixture so that the load presses against the top of the semicircular curve.
Step 8. As the SCB fractures, a smooth load displacement curve will be recorded. This is used for analyzing the test results.
Step 9. To calculate the Flexibility Index (FI), you post-analyze the data.