The deaper you test using surface calibration, the bigger error on the readings(e.g. density going down with depth).
You have to calibrate every time your trench width and depth changes.
I think my question wasn't clear enough. I need your opinion on how to deal with "bleeding" through the gap between mold and base plate. Because of this "bleeding" pore water replaced by soil particles reducing moisture content and increasing density. That is why the curve goes up. Some labs...
Standard Proctor test for clean medium to coarse grained sand always creates a problem with bleeding and dry density going up, even after crossing ZAV line. Is there any method to determine optimum moisture content and maximum dry density using curve that goes only up?