CE 327L: Sieve Analysis, an overview The purpose of the Sieve analysis is to determine
the grain size distribution of your soil for the purpose of soil classification.
The result of this test is a Grain Size Distribution Curve.
This curve is a plot of soil particle diameter vs. the percentage of the dry sample by weight
that is smaller than that diameter.
Most natural soils contain a variety of particle sizes mixed together.
There are three general classifications of soil by size: fines, sands, and gravels.
Fines are any soil passing the #200 sieve and consist of clays and silts.
Gravels are any soil retained by the #4 sieve, and sands fall in the area in between.
The particle diameters that correspond to certain percent-passing values for a given
soil are know as D-Sizes.
For example D10 is the grain size that corresponds to 10 percent passing.
Two additional parameter, the coefficient of uniformity, C-sub-u, and the coefficient
of curvature, Cv, are based on D-sizes.
According to ASTM standards D422, the test consists of preparing a soil sample with known
weight of solids, Ws, and passing it through the sieves.
It's very important to select a representative sample of your soil.
Depending on the diameter of your maximum particle size your sample can be as small
as 500g or as large as 4000g.
Follow the table shown in the lab manual to determine your representative sample size.
The sample used for the analysis must be representative of the original sample.
It is important not to allow segregation to occur when selecting the sample.
If a mechanical sample splitter is available it can be used to divide a large sample into
smaller samples.
If a sample splitter is not available the sample may be divided by quartering the sample.
Place the bulk sample in the center of a plastic sheet and divide the sample into quarters.
Retain one quarter of the bulk sample, if the remaining quarter sample is still too
large quarter the sample until you retrieve your representative sample size.
Weigh the sample and take a separate sample of the same material to determine the moisture
content for the purposes of calculating the weight of the solids in the sample.
Use standard moisture content test procedure The first step after weighing your sample
is to remove the portion of the sample that is finer than the # 200 sieve by wet washing.
We want to remove this portion of the sample to prevent the remainder of the sample from
forming clumps, and thus being caught on the wrong sieve.
However the portion of the soil that is washed it is a representative part of the sample
and must be accounted for.
We will account for this portion of the sample by computing the weight lost during wet washing.
Therefore it is very important not to lose any of the sample except that portion that
is actually washed through the #200 sieve.
Wet-wash the sample in the sink using a deep dish #200 sieve.
Carefully wash the entire sample until your left with only the portion larger than #200
seive..
Using a water bottle, carefully transfer the soil into a large ceramic evaporating dish.
Place the evaporating dish and soil into the microwave oven.
Heat it until the soil is dry using periods no longer than 2 minutes.
At the end of each two minute period carefully stir the soil with a clean spatula to allow
water vapor to escape.
Once this portion of the sample is dry, you are ready to sieve the sample.
To sieve the soil you must create a sieve stack.
The sieves are arranged in order with the coarsest one on top and the finer sieves below.
The last item in the stack is the pan.
A standard sieve stack is shown (lid, 3", 1 1/2", �", 3/8", #4, #8, #16, #30, #50,
#100, #200, Pan).
You may not need all the sieves shown in this stack.
The exact arrangement of sieves will depend on nature of the sample you are testing.
Once you have determined the sieves that will be in your sieve stack, clean each sieve to
remove any loose soil in the sieve and measure the empty weight of each sieve.
Once the sieves have been weighted empty, assemble your sieve stack and pour the soil
through the top of the sieve stack.
As the soil passes through the sieve stack, the soil in retained on the various sieves
depending on particle sizes.
Use the mechanical shaker to aid in sieving the soil.
Do not use this device until you have received instruction on its proper operation.
After sieving, carefully remove each sieve from the stack.
Use a screw driver to screw driver to pry the sieve apart to prevent spilling any of
the sample.
Then determine the weight of each sieve with its retained soil.
Reduce your data using the data sheet provided and following the procedures in the lab manual.
Plot you grain size distribution curve, compute the coefficient of uniformity and the coefficient
of curvature and classify the soil.