Gyratory compaction involves metal-to-metal interactions. These interfaces need proper lubrication to function as intended and produce consistent specimens over an extended period of time.
An incorrect amount lubrication can negatively impact the performance of your machine, which could affect specimen density.
- Too little grease causes energy to be consumed at the metal-to-metal interface instead of transferring to the material being compacted. Less compactive energy reaching the asphalt mixture leads to a specimen of lower density.
- Too much grease can cause the gyratory system to perform poorly as well. For example, too much lubricant between the ram foot and the bottom plate of the mold assembly may lift the plate thus imparting an angle in the plate that is designed to be flat. Higher angles of gyration than intended lead to higher specimen density.
Lubricate your machine according to the guidelines provided in the Operation Manual.