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Technical Note (National Research Council of Canada. Division of Building Research), 1957-01-01
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Firth River Soil Test Results
Pihlainen, J. A.
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DIVISION OF BUILDING RESEARCH
NATIONAL RESEARCH COUNCIL OF CANADA
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JH[
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AIL
NOT FOR PUBLICATION
No.
216
NOTlE
FOR INTERNAL USE
PREPARED BY J.A .Pihlainen CHECKED BY APPROVED BY R.F.L.
PREPARED FORDr .. R.. S. MacNeish
National Museum of Canada SUBJECT
Firth River Soil Test Results
January,
195?
The soil test results reported in this Technical Note were requested
by Dr. R. S. MacNeish, National Museum of Canada. The tests were
conduc-ted on samples which he obtained at an archeological site on the Firth
River,
Y.
T. during the summer of1956.
The testing was prompted by thethought that routine en ineering soil classification tests might show some similarities among the samples and, in addition, might answer some
ques-tions on the origin of the soils. Before commenting on the soil test
results, a brief word about the tests appeared to be in order. 1. Plasticity
The physical properties of clays differ greatly at dirferent water
contents. Any clay may act almost like a liquid; it may show plastic
behaviour, or it may be stiff, dependin only on how much water it
contains. up. asticityt1, which is a property of outstanding importance
in fine-grained ｳｯｴｬｳｾ may be defined as the ability to undergo changes
of shape without rupture.
Standardized tests are carried out to determine these properties. These properties define the water content ranges in the plastic and liquid states, i.e. the liquid limit, whicti is the water content of the clay when the solI has properties at the boundary of the liquid and plastic states and, the plastic limit, which is the water content of the clay when the soil has properties at the boundary of the plastic
and the semi-solid states. The plasticity index is the difference of the
liquid limit and the plastic limit or the water content range in which
the clay exhibits plastic properties. The tests are somewhat emphirieal
but are valuable in the investi ation of any given clay and also in comparison of clays.
Inspection of the plasticity results shows that if any grouping
of the soils does exist, two subdivisions are probable. The first
group, comprised of samples
25, 31
and52,
has a combined average liquidlimit of
34.5%
and a plasticity index of15.6%.
These values aregenerally characteristic of inorganic clays of intermediate
compressi-bility. The second group of samples ｣ｯｭｰｾｬｳ･､ of samples
32, 33
and51,
has a combined average liquid limit of
35.2%
and a plasticity index of906%. These va ues are characteristic of organic soils and inorganic
silts of low and intermediate compressibility. Sample
30,
appeared tobe plastic but repeated testing gave erratic results. It is thought
2
-that the apparent plasticity is the result of contained organic matter. 2. Grain_Size
The hydrometer method was used to determine the grain-size
distribu-tion of the samples. In engineering soil ､･ｳ｣ｲｩｰｴｩｯｮｳｾ the following
grain-size limits are in most common use: Clay - particles less than 0.002 rom.
Silt - particles greater than 00002 rom. but less than 0.06 rom.
Sand - particles greater than 0.06 rom. but less than 2 mID.
Gravel - particles greater than 2 rom.
The two groupings of the Firth River soil samples suggested by the plasticity tests are supported although not completely verified
by the grain-size distribution. The group of samples numbered 25, Ｓｬｾ
and 52 have clay-size fractions greater than 30% while the second group
(numbered ＳＲｾ 33 and 51) have clay-sized fractions less than 30%.
3. Activity
The activity value refers to the plasticity index divided by the
clay-size fraction. It has been found that there is some degree of
correlation between activity, the mineralogy and the geological history
of a Clay.
The ninactive" clays (activity less than 0.75) seem to possess one or more of the following characteristics:
(a)
(b)
(c)
clay fraction either consisting predominantly of kaolinite or containing little true clay mineral;
deposition in fresh water;
deposition in salt water but subsequently leached by percolation of fresh water.
less than
No
25 and 51 Clays combining the characteristics (a) and (b) or (a) and (c) form the
least active group (ioeo less than 0.5)0 Apart from kaolinp the typical
members of this group are late glacial clays derived largely by mechani-cal erosion of non-argillaceous rocks by ice sheets, and deposited in ice-dammed lakes; and post-glacial marine or lacustrine clays which have been subsequently leached by fresh water, usually following isostatic uplift.
The activity values of the Firth River soil samples are 0.5 and the preceding explanation (of Skempton) is in order. grouping of the activity values is apparent although samples have smaller than average activity values.
Table I presents a summary of test results of the seven Firth River soil samples.
,
3 -TABLE I
FIRTH RIVER SOIL SAMPLES SOIL TESTS RESULT SUMMARY
Plasticity Grain Size % ｾ
Sample Liquid Plastic Plasticity Clay Silt Sand Activity
Number Limit Limit Index
10002 rnrn.. .002-.06rnrn..
less than Value.06mrn..
25
34.7
20 .. 7
14.. 0
38
42
20
0.368
30*
-
-
-
20
33
47
-31
36.7
18.3
18.4
32
34
34
0.575
32
3207
22 .. 3
10 ..4
23
25
42
0.453
33
35.4
26 .. 3
9..
120
42
38
0.455
51
37 .. 5
28.3
9.2
30
33
34
0.306
52
32.1
17.6
14.5
36
40
24
0.405
*
Although apparently plastics repeated test results very erratic.National Research Council Division of Building Research
Appendix A
Technical Note
WOe
216UFirth River Soil Test Resultslt
Six additional soil samples from the Firth River, YeT. were tested at the Building Research Centre during January
1957. The results of these tests are shown in the following
table.
Table lA
Firth River Soil Samples
Additional Soil Test Result Summary
Plasticity Grain Size
%
Sample Liquid Plastic P1asticit;y , Clay Silt Sand ｾ｣ｴｩｶｩｴｹ
ｾｵｭ｢･ｲ Limit Limit Index .002 rom. •002-.06 JDDl. 0.06 mm • Value
7 Non-Plastic 19 25 56
-26 22.3 15.4 6.9 18 32 50 0.38 29 2607 2104 5.3 20 30 50 0.26 34 45.7 32.5 13.2 32 44 24 0.41 49 4905 4101 8,4 26 56 18 0.32 50 Non-Plastic 4 13 20%Graval
