“The density of my compacted specimens are low. What causes this problem?”
A Potential Solution
Check the specimen diameter setting on your machine if you are using a Pine AFGC125X, AFG1, or an AFG2. The AFGC125X can be set at 150 mm or 100 mm. The AFG1 and the AFG2 allow for 150 mm, 100 mm, and 4 inch diameter molds. Make sure it is set to the size specimen being compacted.
“No way! I wouldn’t make that mistake.” you say.
You might be surprised how often this solves the problem. It happens. It’s okay.
The Solution Explained
Pine’s gyratory compactors apply a force to achieve the 600 kPa of pressure required by AASHTO T312 based on the specimen diameter. A 100-mm specimen requires the application of 4,712.4 N of force to achieve 600 kPa of pressure. A 150-mm specimen needs 10,602.9 N. If one is compacting a 150-mm specimen but has the specimen diameter set to 100 mm in the control system, the machine applies a force of 4,712.4 N generating a pressure applied to the specimen of 266.7 kPa, only 44% of the required pressure. This will always lead to an under-compacted specimen.
What Does Pine Recommend?
- Check the control settings in your gyratory compactor. Make sure they are correct.
- Contact Technical Support at 724-458-6393 or firstname.lastname@example.org if the problem persists.
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