AASHTO PP 92:19(2020) Standard Practice for Preparation of Test Specimens Using the Plastic Mold Compaction Device.
6.2. Form a specimen by compacting the sampled material into the plastic mold assembly in three approximately equal layers. Compact each layer with a prescribed number of uniformly distributed blows from the 4.54-kg (lO-ib) rammer dropping free from a height of 457-mm (18-in.) above the elevation of the stabilized soil. A minimum of 4 blows are to be applied to each layer, but more blows may be used to achieve desired specimen density. The number of blows shall be the same for each layer. Use a scarifying tool to scarify the top surface of layers before compacting subsequent layers to prevent compaction planes within the specimen. After compaction approximately 6.4-mm (0.25-in.) of compacted material should extend above the top of the plastic mold. Record the time of compaction completion to the nearest minute.
Note 4—Compaction approach presented is intended to produce test specimens with an appropriate specimen density. Appendix X2 provides a procedure to determine the number of blows per layer to achieve a desired specimen density.
6.3. Remove the collar and plastic mold from the PM device. Carefully trim the compacted specimen even with the top of the plastic mold by means of a straight edge. Immediately place the plastic lid on top of the specimen.
6.4. Label specimens with appropriate information and allow to cure inside the plastic mold for at least
24 h before extruding the test specimen. To extract the specimen from the plastic mold assembly, remove the plastic plug and use a sample extruder. The jack should press against aluminum plate during extraction to prevent specimen damage. Curing conditions should be reported (e.g. on lab bench at room temperature. at project site, etc.).
6.5. Once extruded, remove the aluminum plate from the bottom of the specimen. Measure specimen mass with a balance and specimen volume with calipers. Measured moisture content can be used to calculate dry density. The specimen is now ready for additional curing and/or mechanical property testing.
Note 5 —Guidance on expected specimen dimensions is given in Appendix Xl.AASHTO PP 92 pdf download.