c. Remove excess soil from outside of tube.
d. Transfer the soil from the tube to the oven or microwave safe container.
NOTE:
If samples must be stored prior to weighing, seal the container with tape or inside
a plastic bag to prevent water loss and store away from direct sunlight.
e. Weigh the container holding the wet soil, and subtract the container weight from this
value to get the wet soil mass.
f. Record the wet soil mass.
g. Remove water from the sample by heating using an oven or microwave. Oven drying
requires 24 hours at 105 °C. Microwave drying typically takes 20 minutes depending
on microwave power and sample water content. ASTM Method D4643-93 requires
heating in microwave for 3 minutes, cooling in desiccator then weighing and
repeating this process until mass is constant.
h. Weigh the container holding the dry soil, and subtract the container weight from this
value to get the dry soil mass.
i. Record the dry soil mass.
j. Repeat process to take replicate samples. Three carefully handled samples provide
good results.
9. Calculate gravimetric water content from wet mass of sample (m
wet
) and dry mass of
sample (m
dry
):
For the bulk density,
the dry mass of the sample is divided by the sample tube volume.
The volumetric water content is the product of the gravimetric water content and the bulk
density
The average water content for the replicates and the recorded CS650 period are one
datum pair to be used for the calibration curve fit.
CS650 and CS655 Water Content Reflectometers
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