Humboldt H-3750.5F Relative Density Apparatus - Manual (Page 5)

2 Assemble the guide sleeve on top of the mold and tighten the clamp
assemblies so that the inner wall of the sleeve is in line with the inner wall
of the mold. Tighten the lock nuts on the two set screws equipped with lock
nuts. Loosen the clamp assembly having no lock nuts. Remove the guide
sleeve. Weigh the empty mold and record the weight.
3 Fill the mold with soil by the procedure specified in b) or c). Min. Den. Proc.
4 Attach the guide sleeve to the mold and place the surcharge base plate on
the soil surface. Lower the surcharge base plate, using a hoist in the case of
the 0.5 cu ft mold.
5 Set the vibrator control at maximum amplitude and vibrate the loaded
specimen for 8 minutes. Remove the surcharge weight and guide sleeve
from the mold. Obtain and record dial indicator gage readings on two
opposite sides of the surcharge base plate, average, and record the average.
Weigh the mold and soil, if this has not been done in the minimum density
determination or if an appreciable amount of fines has been lost during
vibration. Record the weight.
b) Wet Method:
1 The wet method may be conducted on oven dried soil to which sufficient
water is added or, if preferred, on wet soil from the field. If water is added to
dry soil, allow a minimum soaking period of ½ hour.
2 Fill the mold with wet soil by means of a scoop or shovel. Add sufficient
water to the soil to allow a small amount of free water to accumulate on
the surface of the soil during filling. The correct amount of water can be
estimated by a computation of the void ratio at expected maximum density
or by experimentation with the soil. During and just after filling the mold,
vibrate the soil for a total of 6 minutes. During this period, reduce the
amplitude of the vibrator as much as necessary to avoid excessive boiling
and fluffing of the soil, which may occur in some soils. During the final
minutes of vibration, remove any water appearing above the surface of the
soil.
3 Assemble the guide sleeve, surcharge base plate, and surcharge weight as
described in Paragraph a) 4).
4 Vibrate the specimen and surcharge weight for 8 minutes. After the vibration
period, remove the surcharge weight and guide sleeve from the mold.
Obtain and record dial indicator gage readings on two opposite sides of the
surcharge base place. Carefully remove the entire wet specimen from the
mold and dry to constant weight. Weigh dry specimen and record.