the effects of grinding on the physical properties of clay
TRANSCRIPT
Scholars' Mine Scholars' Mine
Masters Theses Student Theses and Dissertations
1968
The effects of grinding on the physical properties of clay soils The effects of grinding on the physical properties of clay soils
Thomas Michael McMillen
Follow this and additional works at: https://scholarsmine.mst.edu/masters_theses
Part of the Civil Engineering Commons
Department: Department:
Recommended Citation Recommended Citation McMillen, Thomas Michael, "The effects of grinding on the physical properties of clay soils" (1968). Masters Theses. 5178. https://scholarsmine.mst.edu/masters_theses/5178
This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected].
I _,.1 fT C./ '11f
'!HE EFFECTS OF GRINDIHG ON THE PHYSICAL PROPER~ES OF CLAY OOILS
'"' iD '~ BY . """'-"'
THOMAS :MICHAEL McMilLEN , J 'lt.fif'
A
submi. tted to the f'acul ty' o:f
THE UNIVERSITY OF MISSOURI - ROLLA
in partial f'ul..f"illment o:f the requirements :for tbi
Pegrea o:f
MASTER OF SCIENCE IN CIVIL ENGINEERING
Rolla, Missouri
1968
Approved by
... "5._,....,1:1 1.4:; • .. •0'
St.udies o:f t.he e.f'feet of grinding on clay soils are ~ised ..
Fundamental aspects o:t tbixot.ropic pben.omena are also explored.
Vetters clay and Lebanon sUt loam are used as test soils. TheM
soils are ground to varying degrees and the devia:tions in pi:o>"sieal
properties are determined. A.tterberg Limits, specific gravi:t.y,
grain size, X-ray di:ttraction, and D.T.A. tests are run on e.a.ch soll
batch (ground :for 0 minutes, 30 minutes, 60 minutes, and 120 minutes).
ii
A thixotropic study, consisting of uncontined ccapres8ion and labora:tor.y
vane shear tests, o:f each soil batch is ade.
The results of the teste are analyzed, compared, and Ta:riatiorus
are explained.
The writer would like to express his gratitude to his advisor,
Dr. James C. Armstrong, tor his guidance during tbe conception and
preparation o:r this thesis.
iii
The writer would also like to thank Dr. Day o:r the Ceramic
l!hgineering Depa.rtment, University of Missouri at Rolla, tor assistance
with the X-ray diffraction aDd D.!' .A. curves, and Professor J. B.
Heagler for valuable guidance and snggesM.ons.
Special acknowledgeaent is due Mr. Riehard Franke, Hr. BUl Gra.ba.,
Mr. Christopher Oro'V8s, Hr. Sid Asaad, and Mr-. AJ.an Lawai for assist.mce
during the stud;y", espeoiall.y tbe preparation of samples.
The writer is also gra~ to Mrs. Sherrill Rwssell tor t;Jping
both earlY" drafts and t:be :tiDal 81lusoript.
The writer also thanks tbe University ot Missouri At Rolla for
providing f"inancial help t.hrough a Baaea.rch Assistantship during a
portion of this investigation.
Finally', the writer wishes to express his deep thanks to his vUe,
Ma.ril.yn, for her never ending assistance, enthusiasm, and encourage
ment.
.ABSTRACT •••••• ACKNOWIEDGEHENre • • LIST OF FIGURES. • • LIST OF TABLES • • .. LIS'! W S!MB)LS. • •
• • • • • • • • • • • • • • . . . . . ,. . . . . . . . . • • • • • • •
• • • • • • • . . - . ~ . . • • • • • • • • • • • • • • • • • • • • •
I. m'IRODUCTION. • • .. .-. -. • • • ., ,. • • •
REVIEW OF LITERA.~ • • • • • • • • •
A. E.ffec1i of GriDding .. • • • • • • . • B. Historic Thixotropic Studies. • G. TIWI:otro.pie Hit.,t.er;}..als .• ... • • . • D. Thixot-ropy in Ola:y-Water SysteiiS. . E. Ob&e.rTed Bdxotrop,- iJl SoU&. • • •
III. RESEARCH PROGRAM. . . . . • • • • • • •
• . • • • • • . • • . . • . • • . • • • • • • • • . • • • . • • . . • • • • • • .. • . • •
• • • • • • •
• • • • • • • • •
.. • • . • • • • • • . • . • • • • . • • • • • • . • • • • . . • • • • • • •
. . . . . • • • •
A. B. c. D.
Research Procedure. • .. • The isaeeroa HatariaJJAJ .. ~~.
• • • • • • • • • • • • • • " .. • :4111 ...... • • • • •
• • . . DISOOSBIOX OF TEST R$SULTS. - . . . ~ . . . . . ~ . • ••
iv
Page ii iii
v vii
viii
1
2
2 6 1 9
15
20
20 20 22 27
32
-'· M._'ber~t UJa1 te,. G:ra.in, ~, . .Bpeei.fio Gravitq.. • • • 32 B. X-Raf" Dii'f'raetioP, D;lf't"tweatial, bl1El .Anal:y'sis. • • » G. Thixotropic ~lea • • • • • • • • • • • • • • • • • 42 D. V'atle Bheu'• Uneontiluui ·~IL. .. • • • • • • • • S!>
v. • • • • • • • • • • • • • • • • • 67
VI. SUGGESTIONS . . . . . . . . . . . . . • • • • • • • • • •
VII. APPENDIX A - TEST RESULTS . . . . • • . . . . . • • • • • 71
VIII. BIBLIOGRAPHY. .. . .. • • • • • . . . . . • . . . . . . . . 80
IX. VITA .. . . . . . . . . . • • • • • • • . . . . . . • • • • 83
,!/
LIST OF I'IGURES
Figures
1. Particle size relationships tar a. 0 hours, b. 12 boars, c. 96 hours, d. 288 bours, e. 576 hours, and t. 1000 hours
2. Relationship o:t a. deaaiv in carb<m 'tevachloride a.tter acid extraction and b. density" in carbon tetrachloride
v
Page
• • 4
before acid extractiOD and. t.t.e o1 grinding. • • • • • • • • • 4
3. 'fbermog:raviaet.ric analysis of gro\lld. kaolinite :tor a. 0 hour~! b. 12 hours, o. 96 hours, d. 192 hours, e. 288 hours, t. 304 hours, g. 576 hours 1 aBd h. 1000 hours. • • • • • • • • 5
4. Strength regain in a tbixotropic uter:ial •••••
5. Energy-distance curves for dilute euspeasims of dispersed, flocculated, and thixotropic JB&terials.
• • • • • •
• • • • • •
8
10
6. Sediment structures. • • • • • • • • • • • • • • • • • • • • • 12
' ••• r14 7. Jnerra-distance curves tor a tldxotropie aoll. • • • • •
8. Tbixotropi.c strength ratio for silty ela7 as a .ftm.ction of :molding water ccmtent tor a. e • 1%, b. e • ~ .. c. e • 5%, and a. e - 1~ •••••••••••••••••••••• • • 17
9. Thixo'tr()Jd.c strength ratios tor ditferent values of a:xial. strain: a. 1!C, b. 2\.i, c. 5%, aDd d. 1~. • • • • • • • • • • 18
10. • • •
11. Schematic of extruders vacuua chaaber with a. original. design and b. m.odified design. • • • • • • • • • • • • • • • • 26
12 • Casagrande 1 s PJ.astici ty Chart. • • • • • • • • • • • • • • • • .3S
13. Grain size analysis tor high plastic &oil. • • • • • • • • • • 31
14. Grain size analysis tor Jl8diua plastic eoil.. • • • • • • • • •
15. Typieal. X-ra:r dif'.traction pattern tor ·high plas14c elq ( 0 minutes grinding tiJae) • • • • • • • • • • • • • • • • • • •
16. Typical X-ra;y diffraction pattern tor mediua plastic cla7 (0 minutes grinding time) •••••••••••••••••
17. !ypieal. D.'.f .A. pa.ttems, a. High plastic-natural, b. Medium plastic--natural. • • • • • • • • • • • • • • •
18. Uncontined coapressioa 'test. reeul~ o. JdP planie 8Cid1. ground ror o minutes (natlD"al). a:f'hr various qing periods in dllTS• •••••••••••••••••.••••••••
• •
• •
• •
40
41
47
19.. Unconi'ined compression test results on high plastic soU ground for 30 minutes ai't.er various aging periods in days.
20. Unconfined compression test results on high plastic soil gromd for 60 minutes after various agiug periods in days.
21 • Unconfined compression test results on high pla.stic soil
22.
gromd for 120 minutes after various aging periods in days
Unconfined caapression test results on medium plastic soil ground for 0 minutes (natural) after various aging periods in days. • • • • • • • •. • • • • • • • • • • • • • • • • •
23. Unconfined compression test results on medium. plastic soil grotmd for 30 minutes after various agiBg periods in days.
24. Unconfined compression test results on m.edium plastic soil ground for 60 minutes after various aging periods in days.
25. Unconfined compression test results on :raedi'Ulll plastic soil
vi
• • 48
. ' 49
• • 50
• •
• •
• •
ground for 120 minutes atter various aging periods in days • 54
26.
27.
28.
29.
30.
Comparison of shear strength values determined by the unconfined c011pression and vane shear tests for the high plast.ic soil ground for 0 minutes (natural) ••••••• • • •
Comparison of shear strength values determined by the unconfined compression and vane shear tests for the high plastic soil ground for 30 minutes • • • • • • • • • • • • • •
Comparison of shear strength values determined by the unconfined compression and vane shear tests for the high plastic soU ground for 60 minutes • • • • • • • • • • • • • •
Comparison of shear strength values determined by the unconfined compression and vane shear tests for the high plastic soil ground for 120 minutes ••••••••••••
Comparison of shear strength values dete:ndned by the unconfined compression and vane shear tests for the medium plastic soU ground for 0 minutes (natural) ........ .
• •
• •
31. Comparison of shear strength values determined by the unconfined compression and vane shear tests for the :medium plastic soil ground for 30 minutes • • • • • • • • • • • • • •
32.
33.
Comparison of shear strength values determined by the unconfined compression and vane shear tests £or the medium plastic soil ground for 60 minutes • • • • • • • • • • • •
Comparison of shear strength values determined by the unconfined compression and vane shear tests for the medium plastic soil ground for 120 minutes. • • • • • • • • • • •
• •
• •
51
59
60
61
63
vii
LIST OF TABLES
Tables Page
I. PHYSICAL HWPERTIES OF HIGH PLASTIC son.. • • . • . • • • • .33
II. PHYSICAL HWPERTIES OF MEDIUM PLASTIC OOIL •••
III. DEGREE OF SATURATION AND VOID RATIO FOR
• • • • • •
IV.
RANDOM SAMPLES--HIGH PLASTIC CLAY ••••
DEGREE OF SATURATION AND VOID RATIO FOR RAND<M SAMPLES--MEDIUM PLASTIC CLA.Y • • •
• • • • • • • • •
• • • • • • • • •
V. COMPARISON OF THIXOTROPIC STRENG'l'H RATIOS •• • • • • • • •
.34
45
46
65
c
ce
g
mm
PI
Qu
t
tsf'
u
v.s.
w.c.
LIST OF SYMBOLS
cohesion
cubic centimeters
millimeters
plastic index
shear strength as determined by tbe unconfined compression test
time
tons per square foot
micron, .001 millimeters
shear strength as determined by the vane shear test
water content
viii
1
I. IftRODUCTION
Qeneral
The data obtained by difi'erent researchers .from similar clay-water
qst.em.s bas not always agreed. It is believed that one of the causes
:!Glr such discrepancy is va.ry:f.ng the method of preparing ·specimens for
testing.
In this thesis, the writer has attempted to analyze the results ot
grinding on two soils, one a higbl y plastic soU and the other a medi1l11l
plastic soU. It is believed that this analysis . wUl increase present
knowledge on tlle subjects of sample preparatiOD and thixotropj.c strength
time studies.
II. REVIEW OF LITERUURE
A. Et.feet o.f Grindil!g
Previous in.formation on the direct effects o.f grinding on a clay
soil is very limited in scope. Gregg, et. al. (11 1 12)* ground a
kaolin lll&terial. .for various tim.e periods up to 1,000 hours in an
attempt to determine the effect on various pbTsical. properties.
Gregg concluded that:
1 • The X-ray powder anal,ysis shared that t.he original.
material was a veil-ordered kaolinite vit.h sc.me llica.
However, during grinding tbe lilles beeame progressively
broader and weaker until, at 1 1 000 hours, no pattern
vas discerna.ble. Uter acid treatment,. kaolin could
be identified in all suplee up to S76 hours grinding
tiae, but not bqoad. Ho indication of a new ·
deeCDpOsition product with its OlfD distinct structure
was given.
2. The specific surface (inverse to grain size determi
nations) vas seen to increase greatl.)" wit.h grindiRg
time up to about Soo hours and then decrease
gradually. This great increase shaled a .fracture
o.f the particles by shearing parallel to the
cleavage plane 1 as well as across the plates. The
decrease after about S00 hours vas attriButed . to a
*The nUIIbers in parenthesi.s refer to the like-nllllbered references to this paper.
2
phenomena simil.ar to cleaved mica, in that it will
readily stick to itself it lightl7 pressed together.
Apparentl7 soae re-aggregation oocurred when the
sheared fragments slid relative to one anot.h.er,
resulting in the decrease. Figure 1 shows the
results of grinding on the kaolinite.
3. Densi t7 studies showed an apparent decrease in
density in carbon tetrachloride with grinding time,
amounting to about 14%. Figure 2 shows these
results.
4. The thermogravimetric study showed that there was no
deviation in total loss of water between 1 OOOC and
1 , 000°C. It is concluded that the broadening of
peaks of weight change/time change versus time and
its slight :movement towards lower temperatures
shows that an increasing proportion of the :material
is having i'tis lattice strained or distorted. Thus,
decomposing or driving off of the structural water
occurs at a lower temperature. Also, a high degree
of disorder is denoted b7 the rather inde.tinite
peaks. Thus, by grinding, increasing proportions
of kaolinite are converted into a modi:f'ication w1 th
'the same chemical composition as the original
kaolinite, but with a largely disordered lattice.
Figure 3 shows the results of t.be thermogravimetric
anal;rsis.
3
~ ~ ~
tl (I) 0
~ p...
4
100
80
60
40
20
0 1000 100 1 .. 1
Fqui valent Stokes' Diameter, 4{
(After Or egg) Figure 1.. Particle size relationships for a .. 0 hours, b. 12 hours,
c. 96 hours, 288 hours, e. 576 hours, and f .. 1000 hourte~ ..
2 .. 6
2.4
0 1000 Time of grinding, hours
(Uter Gregg) Figure 2.. R•la.tionebip . of a. density in carbon tetrachloride a.f'ter
ac:td extracti an am b. density m carbon tetrachloride before acid e:x:t.raction and time of grinding.
, , , I
Fisure 3. ~ .;. ~ ' .
"'(.A.ftF Gl:egg) ThermograTimatrio anal:yeis ~ ground kaolinite tor ~'~, 0 lu:Mar81 S-'_.£'1t:~'.heva,,,c~·,96,~e, d-. 192 hours, e. 288 hours, t. 384 hours, g. S76 hours, and h. 1000 Ja.our4!1. ,~::r .: . , ,
In summary it was decided that grinding probably breaks up the
particl.es and distorts, but does not destroy the crystalline structure
of the kaolinite lattice.
B. Historic Thixotropic Studies
6
In the early twenties, a decrease in strength o:f some clays with
remolding at an unaltered water content was noted by investigators :for
the Siiedish Geotechnical Commission during the stud7 of landslides.
Subsequently, A. Casagrande ( 8) observed deviations in the consolidation
characteristics of natural and remolded samples. He proposed the theo:r:y
that the clay particles settle during the process of sedimentation into
a definite arrangement which he termed the "clay- structure." Casagrande
goes on to state that this structure, consisting o:f a coarse-grained
skeleton cemented together by highly compressed clay whose interstices
are .filled with so.ft clays, "is chie:f'ly dependent on the exeeedingly
slow process of natural sedimentation and consolidation. '3 He presumed
that the remolding destroyed the connecting links between the soil
grains and replaced these links with a soft clay. Thus, Casagrande
concluded that nif we destroy the structure that nature has taken many
centuries to build up, we cannot restore it. rr
In 1941, Terzaghi (31) offered a :t."tm.dam.en'tall.y different explana
tion of the manner in wbi.cb undisturbed clays acquire their strength
and rigidity. According to Terza.gld, the streDgtb and rigidity is
acquired primarily by "slow phy'sico-chemical processes" which are
related to the surface activity of the individual grains. Each clay
particle is surrounded by a shell of abs'Orbed water, which can be con
sidered solid at the particle Sllrfaee and somewhat viscous SJil&y from
the particle surface. Terzaghi explains that upon sedimentation and
further consolidation, the soU particles and their water shell are
pushed closer together and may merge at a number of points in the clq
mass resulting in increased sti.f.fness. The reverse of this takes place
in remolding and the clay becomes pl.astic.
More recent laboratory studies and .field evidences have been
advanced in support of both concepts.
C. Thixotropic Materials
7
The term thb:otropy is derived .froa thi:xis, meaning to touch or
strike, and trepo, meaning to turn or change. Thus, thixotropy means
literally to change by touch. In 1927, A. F. Peter.fi (23) introduced
the term.. Later Freundlich ( 1 0) used the term to describe the
phenomenon of isothermal, reversible gel-sol trans.formation in colloidal
suspensions. It has more recently been referred to ( 6) as a process
o.f softening caused by manipulation or working .followed by a gradual
return to the original strength when tbe material is a.llowe4 to rest.
Figure 4, .from. Skempton and Northey (30), shows this characteristic
strength regain o.f a tbixotropic material.
The term, thixotropy itsel.f, :m.ea.n.s different things to :men in
dif'.ferent .fields of endeavor. The colloid chemist is concerned with
strength gain and gel-setting ti:mes o.f a .few lldnutes or perhaps seconds.
'!'be soils or design engineer is more concerned, however, with strength
gain over a longer period of' time. He is also m.ore generally" concerned
with :moisture contents between the plastic and liquid li:mits, as
generally . .found in nature. A separate term., age hardening, has been
proposed for use by the engineer, but accordi.Dg to definition, the
8
I.
''
;, ., ' ' i
• ~.t.
' ' tf. -. --t--:--.....-T :J ' i ~ '.
E-t g.
.' ~ 1 {
·~,
~ ..., tl
.::1 a Ill
• 't""" l :S i
I I' ~ • ..::t
:: ~ f!&t
9
strength regain in a clay--water system is as much thixotropy as strength
gain in a dilute suspension. The ditference being one of degree and not
fundamental behavior. ..U though suspensions bear little resemblance 'to
clay soils physically, it is not unreasonable to suppose that some inter
particle farces., as well as principles of flocculation and dispersion,
are the same as in more concentrated clay-water STStem.s.
D. Thixotropy in Clay-Water Systems
In his early work., Freundlich (10) shows tbat thixotropic behavior
depends on the balance of forces acting between particles. A. tendency
for particles of the same substance 1;o adhere upon contact may be
important in thixotropy. .An unbalance of surface forces exists on all
particles of finely-divided :matter, and these electrica.l .forces result
from. discontinuities and atomic substitutions in the la'ttice o:t the clay
mineral. Since these forces are concentrated on the suri"aee of the
particles, they becOl'l.e quite large when the ratio of sur.tace area to
mass increases rapidl.y. Such is the case with clay--sized particles
wldch usual.ly :tal.l vi t.hin the range o.t a colloid, one micron to one
milli-micron in diameter. These unsatis:tied forces can be satisfied
either by contact with particles of the sam.e substance or by absorption
of ions .from the adjacent phase. Solidification of t.he suspension may
actually occur when particles as a result o.f thermal :motion may adhere.
The explanation o.t t.hixotropy on the basis o.f attraction-repulsion
force-balance has received support by many investigators including
Marshall (17), Verwey and OVerbeek (33), and Lambe (15}.
The concept o.f .force-balance is shown in Figure 5, where the
·P.
'· '
10
Olose pal.11ele approaeb pnven"Md by ecergy barrier--particles disperse.
'· .
Curve tar tb:lxot.ropic tllata1"1t.l ...... sp•~·. at. particles at reet-raaoldlna ••• par\iclee •&J traa a1n1-.... ... iaOrea.M S. .... ., O&UMS d.acl"ease 1n strength.
~,~. · ·De:tg .. diatanoe ~e 1'o:r dJ.lute suepenaicae ot dispersed, nocoulated, and th:b:otrop1c uteriale.
''·
!'
11
ordinates to the curves represent the energy (positive if repulsion and
aegative if attraction) necessary to bring the particles :tram an
!nf'inite spacing to any given spacing along the abcissa. Curve A repre
sents a s'tiable suspension which exhibits neither flocculation nor
thixotropy because of the energy barrier preventing close approach of
particles. Curve B represents a condition where particles will
spontaneously agglomerate and settle out. The energy minimum indicated
bn curve C represents the position of particles in thixotropic gel.
Any movement (such as caused by shaking or shearing strains) which
tends to change the particles spacing causes an increase in energy of
repulsion leading to a more fluid condition.
This curve is derived on the untrue but simpl.i.fying ass'lDilption of
parallel plate-shaped particles charged only on their surface, sitting
at some distance :tram each other in a near-parallel array. Investiga
tors (32, 14) have shown that these curves must be considered to be
approximate because clay particles deviate quite appreciably from t.his
assumption in that they have charges on their broken edges. According
to Van Olphen particles in the gelled state are linked in a random
array.
Two types of flocculation, salt type with an orientation approach
ing parall.elism, and a non-salt type with an orientation approaching a
perpendicular array, can exist. These orientations and a dispersed
orientation are illustrated in Figure 6. Regardless of the type of
particle association, it seems that thixotropic behavior is associated
with a tendency for particles to flocculate, as long as they are :tree
to choose their positions.
12
a... Salt flocculation
• Noo-salt fiooculation
o.. Dispersion
... (A.tter Lad>e)
F~ 6 .• ~ent ~tructures.
13
Kruyt ( 13) points out that the thixotropic phenomena is enhanced in
systems of elongated particles, such as clay. One explanation of this
is the large surface area to mass ratio of the clay particle. Further
support of this concept is the .fact that kaolin shON"s a much lesser
degree of thixotropy than illite which, in turn, shows a much lesser
degree of thixotropy than bentonite.
1n an undisturbed thixotropic qstem, a state o.f equilibrium
occurs. In other words, the forces o.f attraction are balanced by the
forces of repW.sion. Fi.gure 7 shows typical energy-distance curves for
a thixotropic soil. In the first sketch, a line is drawn ind.icating an
additional energy of repUlsion introduced by externally applied shearing
strains. This, when added to the double layer repulsion, acts to
f'urt.her disperse the system and resist .flocculation. That is, a :more
or less parallel arrangement of the particles in the shear zone is
forced on the material. When the shearing or remolding ceases, the
externa.ll.y applied energy is reduced to z.ero. Therefore, the net
repulsive force diminishes and eventual.l.y eliminates the energy barrier.
The result is a tendency tON"ard .flocculation.
Most soils have been found to have a balance of inter-particle
forces leading to a structure somewhere between complete dispersion and
complete .flocculation. Based on this observation and the fact that a
given soil exhibits different thixotropic behavior at different water
contents, a soil should meet the following conditions in order to
exhibit thixotropy:
1 • The net interparticle .force-balance is such that the
soil will fiocculate if given a chance.
Double layer repulsion
Total energy of intera.ction
Energy barrier preventing flocculation
Extern.ally apFlied energy (repulsion)
Distance between part.ioles
Attr-ction
a. Energy-distance curves for a thixotropic soU durin& re11tt0l~--Repulsive energy barrier prevents flocculation.
Attraction Total energy of interaction
14
b. Energy-distance orirves f'o!' a thb:.:otropic soil at rest--Attraction exceeds repulsion, particles tey to flocculate •
(After Mitchell)
Figure 7. Energy-distance curves :for a t.b.ixotropic soU ..
2. The flocculation tendency is not so strong that it
cannot be overcome by mechanical actions such as
shearing.
15
In summary, thixotropic behavior is the natural response o:r a soil
structure to a change in ambient conditions. The structure created by
remolding or compaction must be compatible with the externally applied
shearing stresses. When shearing stops, the excess internal energy
within the soil is dissipated by :means o:t small particle movements and
water redistribution until a structure in equilibrium with the "at
rest" :forces is created.
E. Observed Thixotropy in Soils
Seed and Chan (26) suggest, and others (21) support, the use of a
thixotropic strength ratio rather than the absolute strength gain o£
the material. 'rhe thixotropic strength ratio, strength at any time, t,
to the strength at time zero, permits direct comparison ammg batches of
different soils or the same soil at dif.ferent water contents. They go
on to state that the thixotropic strength ratio is the important thing
to observe, because it is more important for a soil of low initial
strength to double its strength than for a soil with a reasonably high
initial strength to increase its strength slightly, even though the
actual. amount o.f increase might be the same.
The effect o.f initial structure is obvious, because thixotropic
effects are caused by dispersion-flocculation phenomena. For example,
when the interparticle forces are such that particles are strongly
flocculated and remain flocculated despite the application o.f external
strains, thixotropy is negligible. This is to be expected because the
16
soil mass is in a state of near equilibrium from the beginning.
Figure 8 shows the results of tests by Seed and Chan on a compacted
silty clay with an aging period of one week, in which thixotropic
strength ratio :is plotted as a function of water content. This curve
indicates strong flocculation at low water contents, dispersion at high
water contents, and a weak state of flocculation susceptible to exter
nal shearing forces at intermediate water contents. From Figure 81 it
can be seen that thixotropic effects are greatest at some intei'IIlediate
water content. In this stud;y, optimum moisture content was 17.5% for
a kneading com.pa.cti.on procedure. Apparently a :f'loceulated structure :is
present to the dry side of optimum. and a dispersed structure is
gradually obtained to the wet side of optimum.
This is carried further in F.tgure 9, whi.ch shows the thixotropic
effects to be greatest at low strains. Optimum. moisture content in this
study was 17.7% for the caapa.ctive effort used. The decrease in
thixotropy with increasing strain shows that the flocculated structure
formed duri.ng aging is somewhat destroyed by the externally applied
shearing force.
Mitchell fo1md that the method of compaction has an effect on
thixotropic action. Samples statical.ly compacted with a drop hammer
exhi.bited greater strength increases at low strains and slightly sm.aller
increases at high strains than did kneaded samples. Possibly, this is
due to the original flocculated structure consisting of tightly-held
particles very close to each other at "contact points." Slight decreases
in spacing would result in high strength increase.s since attraction
forces increase rapidly wi.th decreasing spacings beween parti.cles. For
Figure 8.
e • Axial strain at which thixotropic strength ratio determined.
1.0~~--~--~~--~--~~~-L--~~ 15 19 23 27 31 35
(After Mitchell) Thixotropic stonncth ratio tor sUty clq as a :tun.t.:ton o£ molcting water cmtent tor a. e • 1%, b. e •· ~, c. e • 5%, and d. e • 10%.
17
·~!'f -.!4
I )1:
. '
a
,~ •• ~ '<Jellteat=, ~
'· t ..• !,• .. 1 •. • . :... ··"'M'ter Seetl· & Chan) Figure 9. Thixotropic strengt.h ratios for di:f:ferent values of .~·.(!~, ~'*"·~:' ·· tltll:1&l ·at~: ~•·· ,,, b. ~,.:-o•~, Sbl· d.• 10%.
_,'')
18
19
the samples compacted by kn.eadimg, the ini-tial spacing between particles
is greater due to the aore disperse arrangement.
Te.perature Jaa7 also ha'V8 an ettect on thixotropy. Seed and Chan
found tbat a higher curing teJRperature results in a higher thixotropic
strength ratio. This couJ.d be related to .the basic equaticm for the
thickness of the d<>uhle layer in wbieb a increase in temperature
increases the double lqer thickness. However, a change in temperature
is accompanied by a corresponding change in tbe dielectric eonstant,
wh:ich decreases with increasing temperature. The overall ettect is a
decrease in the double layer thickness with increasing temperature.
Thus, increasing the aging te.perat.ure increases 'the exeess of attrae
"tive over repulsive .fwces, causing a more fioeculatecl condition.
The etf'ect of plasticity on thixotropy has been examined by
several investigators. Berger and Gnaedinger (3) found in tes.ting that
Grand Forks, M1nnesota, clay (PI•67 .S) exhibited sc:ae strength increase
but the increase was practically insignificant in terms of thixotropic
strength ratio. Moretto• s work (22) on four clay soils does not show
any direct correlation between plasticity aad. degree of thixotropy.
Likewise, Seed and Chan agree that there is DO direct relationship
between thixotro:w and the Atterberg Li:ad ts.
20
ill • RESEARCH PROGRAM
A. Research Procedure
The purpose of this investigation is to studl" the effects of grind
ing on clay soils. A ol.ay·of high plasticity (Vetters Clay) :from near
College Station, Texas, and a clay of medium pl.asticity (Lebanon Silt
Loam) t'rom near Rolla, Missouri, were used in this stud;y.
Each soU was divided into fo~ batches, being ground for lengths
of zero minutes, thirty minutes, sixty minutes, and one hundred-twenty
minutes.
Similar tests were performed on each batch in order tbat a compari-
son could be JB&de. These tests consisted of the .following:
1. Atterberg Liaits;
2 • Hydrometer analysis;
3. Speeif'ic gravity;
4. X-ray diffraction; and
5. Differential thermal analysis.
A thixotropic study was also made on prepared samples of each
batch. This study consisted of vane shear tests and Ulilcoftfined compres
sion tests. The increase in strength (from. ~ one) was used as a
measure of tbixotrow.
Finally, the data was compiled and analyzed with the results
presented in the following sections.
B. 'l'be Research Materials
The hig.bly plastic soil chosen was Vetters Clay. This material is
21
1\iescribed by Raba (24) as being a very stiff to bard over-consolidated
elay vi th an occasional sU t seam or pocket. It is f'ound in close
proximity to a darker and more plastic clay of similar qualities,
Easterwood Shale.
Through the use of' X-ray dif'traction and D.T .A. curves, it can be
seen that Vetters clay is caaposed of' an expanding lattice clay mineral
of' the montmorillonite group which shows evidence of' some illite. More
specifically, it appears f'rom the endot.bermic peak at 7000C in the
D.T.A. curve that this soU (probably monovalent because of' the lack of
a definite double peak or "shouldered" peak on the lower loop) eonf'oras
to the characteristics of' a bentonitic material as descri bed by the
Shell OU Co. (28). Its swelling character would also suppert this
belief'. The Shell OU Co. goes on to state :
n. • • the shales and clays of' the Gult Coast • • •
appear to contain both an illite aDd a very poorly
organized montmorillonite which 'I'DJq be in e.tf'eet a
degraded illite in which a large portion of the
potassium has been lost.n
This particular sample vas obtained tour miles west of College
Station, Texas, on Farm Road 6o in Brazos Comty.
The medium plastic soU is a Lebanon Sll t Loam and is described by
Marbut (16) and the Missouri State Highway COJIIIlission (20). This
residual soU is derived .frOBl the dolomite and argillaceous, thin
bedded limestone located along the rim of the Ozark Ik>me Region. It
does not cover a particularly large area, but composes many small and
irregular areas ~the Ozarks region. In caaparison to most Ozark
22
soUla, Lebanen SUt Loam is relatively" smootb and stone-free.
Fran the X-ray and D.T .A. curves it can be seen that this soU is
bivalent in nature. Tbis is deduced from the "shoulder" or double peale
on t.be lower endothermic loop.
This particular sample vas obtained from a bigbiq cut on tbe north
side o~ I-44, approximately .2 mile south of the I-44-U.s. 63 intersec
t;ion in Phelps County.
The first piece of equipment used in this study vas the Los Angeles
~brasion Machine, used to grind the tvo test soils. This particular
110del, manufactured by Cutler and Hammer Corp., is mounted on its own
:oncrete platform to minimize transmitted vibrations. It is powered by
L 3/4 horsepower motor, rated at 1800 r.p.m. The drum rotates at a
;peed o~ approximat.ely 31.$ revolutions per minute.
The equipment used in obtaining the liquid limit, plastic limit,
1brinkage limit, grain-size curve, and specific gravity of each batch
·as the standard laboratory materials as approved by A.S.T .M.
The X-ray patterns were obtained through use ~ the General
:l.ectric XRD-$. This model, incorporating a timer and automatic
ecorder, is manufactured by General Electric, Mil.vaukee, Wisconsin.
The differential thermal. analysis vas made through use of the
on trolled Environmental. DTA System. manufactured by The Robert L. Stone
o., Austin, Texas. The SY"Stem consisted of a model KA.-H recorder con
t"oller (for one sample at a time), a J-2 furnace platform, a cooling
23
rack, and two i"'ln'naces (models F-1C and F-1D). The availability of two
furnaces :facilitates the process in that one sample ean be tested while
the previously used furnace is being cooled. This particular model is
capable o:t temperatures within the range of -1500C to 15000C.
The prepared samples fer the thixotropic study were obtained through
use o:t the Vac-.Aire extrusion device. It was folUld, through the work
of Shif'fert in 1967, that this device vas capable of producing high
quality test samples from cohesive soils. He further found that these
remoldeci samples were saturated, homogeneous, and isotropic in nature.
The Vac-Aire extrusion device, consisting of a power train, loading
chamber, vacuum. chamber, and molding die, is driven by a one and one
hall horsepower motor rated at 1750 r .p.m. The sba.tt speed o:t 32 r.p.m.
is acccmplisheci through a series of reduction gears.
Three mod:Uications were necessar;r during Shif:tert• s (29) and
Mathes' (18) studies. These m.odifieations were incorporated :tor this
study, also, and are listed below:
1. Metal prongs extending from the valls ot the loading
chamber to positions between the auger train teeth
were removed.
2. Adclitio11 o:t a third spacer provided a larger con
fi.rdng sur.face where the soil is forced into the
space vacated by' the auger, and
3. Steel tubing (I.D.-3.12 in.) was out to oanplete , the
auger housing within the vacuum chamber. Several
r0111s ot holes were drilled in the tubing with the
hole size decreasing from the sides to the center
of the tubing. Thus, extrusion and draining were
simplified without clogging the vacuum chamber.
24
During the early days of the test program, extrusion o:r the high
plastic soU, the soil was loaded into the loading chamber and :torce
:ted through the use of a bearing plate and lever arm. HOilever, several
of the auger train teeth were broken when this plate came into contact
with the moving auger train during one cycle of extrusion. After this
mishap, the soil was fed by hand and packed or hand-tamped in the for
ward portion of the loading chamber. It was found that this method,
although more time-consuming and more tiring for the operators, produced
good samples.
Figures 1 0 and 11 shaw schematics of the Vac-Aire extrusion device
and the modification to the vacuum chamber respectively.
The t.hixotropic st~ data was obtained through the use of the vane
shear device and the unconfined compression testing machine. The vane
shear device, manufactured by the Leonard Farnell Co., Ltd., England,
and distributed in this country by Solltest, Inc., Chicago, illinois,
is identified as number 280. It is supplied with four accessory, cali
brated springs (Numbers 1-7534, 2-75.34, 3-75.34, and 4-7534). These
springs apply torques of 5, 4, 3, and 2 in.-lb. respectively for an
angular movement of 1' 800. These springs were interchangeable and could
be chosen depending upon the range of strengths exhibited by the test
material. The height, diameter, and thickness of t.he vane used was
13.0 mm, 12.8 mm, and .9 mm respectively. The major disadvantage of
this particular model is that it is band-driven. Therefore, it is
extremely di:tficul t to rotate the rod at a constant rate.
Gea
rbox
Mot
or
Vac
uum
===
=4
Lin
e Sp
lice
B
Fig
ure
10
. S
chem
atic
of
the V
ac-A
ire
mru
sio
n D
evic
e.
Gla
us p
lat.
ove
r va
cu'W
U c
ham
ber
FQ>r
mi.n
g T
hro
at
Die
Spa
cers
(A:t
ter
Sh
iffe
rt)
N
\1\
~ UDCoatined eoapression -.cMrtne, also dist.ri.btlte<l by SoUtest
Corpor&tion, is identified as model AP322-X. ID a.ll cases, a loading
tting constant ~ .49 pounds/lMd dial di visioD and a compressive rate
if .Oh9 inches/minute were ueed •
.,. Test Procedures and Associated SampJ..e Preparation
27
The saapl.e preparatd.an was started by dividing the air.o.dried. soU
into four batches, and grinding t.he soU tor various lengths of tiae as
followst
1 • 0 minutes • 0 revoluti.ons ot the L.A. .A..'hrasion JIS.ehine,
2. .30 minu:&es • 948 revolutions of the L ..A. J.brasion •abiDe, ). 60 minutes • 1896 revolutions ot 'the L.A. Abrasion Jl8.ehiDe, and
h. 120 Jdnutes - 3792 revolut.ions of tbe L.A. Abruian :ucb:Jne.
In all cases, twelve pounds of air-dry Ja&terial and twelve steel balls
were placed in the abrasion drum. These four batches (for the high
plastic and medium plastic) were then allowed to set tor a eonsiderable
length of time in order tba.t a fairly constant hygroscopic m.oisture
content could be reached.
After this initial proce-., special preparations and procedures
are best divided by test.
Atterberg Liaits
A portion of each soU batch passing the •o sieve was set aside
for the determination of Atterberg Limits. Since the At'terberg Limits
determination falls into the category of a ~tpersonal jud8f"«Jt" test,
each soil was treated in an. identical fashion. Due to the length and
diffiou1ty of the test, the liquid limits were determ1n84 at different
times. However, the sbriDka&e lillit.s (.four on eaeh batch) were all run
28
on the same day. Likewise, the plastic limi.ts (.four independent samples
on each batch) were all run on the same day. Thi.s procedure was pur
posely .followed so that deviations in judgment could be eJ1minated.
Therefore, a closer comparison could be drawn.
Hydrometer Anal.ysis
In preparing the sample .for the h;ydrometer analysis, .f'i.fty grams o.f'
unsieved. air-dry" soil was :mixed with 150 grams o£ 4% calgon solution.
This mixture was allowed to stand .for twenty-four hours in order that
the particles would be completely dispersed. Readings were taken (as
closely as possible) to total elapsed times o.f' 1, 2, 4, 8, 15, 30, 60.,
120, 240, 480, 1440, 1970, and 5770 minutes. Values o.f' percent remain
ing in solution and particle diameter were then determined through use
of the outline and tables given by Bauer and Thornburn (2 ).
Specific Gravity
Only standardized procedures were .follow·ed in the determination o.f'
specific gravity.
X-ray Di.f'.f'raction
In performing the X-ray analysis, dry slides were used. The
natural soU had to be ground a very slight amount in order that it
would properly adhere to the plate. This was accomplished with a
mortor and pestle. Patterns were obtained trom. 2° 29 to 200 2e with
slits o.f' 1 O/J0/ .2° and .from 200 2e to above 6oO 26 with slits o.f'
3° /m.r ./ .2°. This change in slits was made so the backgromd noise
could be minimized and the peaks maximized. .All tests were run at the
speed o.f' .4°/minute. Initially, dispersed slides were planned in
addition to the dry powder slides. However. good definite neaks vArA
29
obtained in the powder slides and dispersed slides were eliminated :f'rom
the stud;y.
D.T .A.
The dilferential thermal analysis test samples were carefully
weighed and chosen. They were chosen to be representative of the mass,
because only a small amount of sample was to be used ( .0122 grams).
Curves were obtained for each batch from ambient temperature to 100000
at a rate of 1 0°0/minute.
Thixotropic Stugy
In preparing the samples for extrusion and thus the thixotropic
study, moisture contents of 37% (high plastic) and 27% (medium plastic)
were decided upon. These values were chosen by referring to studies of
Raba (24) and Mathes (18) which shared that a soil with its moisture
ccntent apprarl.mately halfway between the plastic and liquid limits
would yield the best thixotropic phenomena.
The amount of water, needed 'to bring the batches to the desired
moisture content, was determined through use of the formula:
X+ 2 454-2 = desired m.c.
In this equation, the "desired m.c." is expressed in decimal form, "B"
is the weight in grams of hygroscopic moisture, and "X" is the weight in
grams of moisture to be added to each pound of air-dried material in
order to achieve the "desired m.c." In all cases, tap water (non
distilled) was used and mixed by hand in'to air-dry soil samples of
approximately twelve to eighteen pounds in weight. These mixes were
30
then placed in plastic-lined, sealable, pasteboard barrels and placed
in rthe moist room. This was done in o:uder to reduce moisture change,
due ' to environment.al conditions, to a minimum. Length of storage,
prior to extrusion, was dependent upon scheduling problems. However,
in accordance with Shiffert1 s study (29), a minimum aging period of
three days was adhered to.
Three people were required for the extrusion process. One person
was needed to force-feed t.he material to the auger train and another was
required to wrap and wax the samples. It was also found. that a wise
practice was to have scaeone attending the "on" and "off" switches in
ease of an accident. The samples were cut to six inches in length,
wrapped in wax paper, placed in cartons with wax bottoms, and wax
poured over and around the samples to a thickness of approximately one-
half inch. In later work, it was found that this procedure was satis-
factory, in that no moisture losses occurred during the test period.
In many instances, however, a length of six inches proved to be too
short for a good unconfined compression test sample and a vane shear
test sample.
The samples were then placed in the order of extrusion and stored
horizontally in the moist room. A minimum of two samples were removed
for each day 1 s testing program. Identical methods were used in per-
forming the daily tests of unconfined ccmpression and vane shear,
however temperature, humidity, and time of day varied wi t.h each set of
samples. Since the time of removal from ideal conditions prior to
testing was Slllal.l, the factors of temperature and humidity variation
31
The test period for the medium plastic soil was as follows: day
one, two, four, six, ten, fourteen, twenty, thirty, and forty. A similar
series was followed with the high plastic soU, but a day f'i£ty and day
sixty was added.
Removal of the soU sample f'rom the shell of wax was found to be
difi'icul t in some cases. &me samples slipped out easily when both
ends of the shell were removed. However, in the majority of' cases, the
shell had to be chipped away with a large knife. This procedure
obviously eliminates an;y sample disturbance due to friction in remova.l,
however, variation in the samples cylindrical characteristics were
easily incurred.
A£ter removal of the sample, the soil vas trimmed into a specimen
4.5 inches in length. The remainder of' the sample, hopefully 1.5
inches or more, was used in a vane shear test. This test was performed
using the reccmmendations of Flaat (9). The unconfined compression test,
following A.S.T .H. (1) specifications, was performed on the 4.5 inch
specimen. This size gave a length to diameter ratio of 1 .8, within the
recommended range of 1. 75 to 2 .o.
Failure of an unconfined specimen was defined to be either a
decrease in load-carrying capacity or 20% strain, whichever occurred
first. One moisture content determination was taken for each sample by
cutting a cube of soil from the center of the unconfined sample.
Probably smaller deviations in :moisture content would have been present
it several moisture content determinations bad been taken and averaged
for each sample.
32
IV. DISCUSSION OF TEST RESULTS
A. Atterberg Limits, Grain Size, Specific Gravity
The data obtained from running the Atterberg L1m1 ts is presented
in tabul.ar form in Tables I and II. Table I is the high plastic,
Vetters clay, and Table II is the Lebanon silt loam of lower plasticity.
The following trends were noted:
1. The plastic limit rises with increasing grinding time.
2. The liquid limit rises with increasing grinding time.
3. The shrinkage limit decreases with increased grinding
time.
4. The plasticity index rises with increasing grinding
time.
All of these conclusions can be drawn from each test batch, with the
possible exception of the medium plastic soU ground for 120 minutes.
In this case, the liquid limit did not rise appreciably above the batch
grolBl.d for a sixty minute period. This vas reflected in the dependent
plastic index which falls out of the pattern.
Tbe general pattern of the change in plasticity can best be seen
in Figure 12 which shows Casagrande's plasticity chart. The soils
generally follow the 11A-line 11 up and to the right with increasing grind
ing time. Here again, the deviation in the 120 minute, medium plastic
batch (point 5 on the figure) is rather obvious. However, it will be
noted that this point does "rise" up tbe "A-line" in comparison to the
other batches of the same material with less grinding time (points 6,
7, and 8 on the figure). This appears to be a significant trend in
itself.
33
TABLE I. PHYSICAL IROFERTIJ:S OF HIGH PLASTIC son.
~ E-t ~
' ,..:.
j_ i ~ J ~-~ .!;3
H • ~~ t9 ,-....
JS * O"bbl () .g "t:J- ""- ~ !:1 l ~ ~ ()
;i ell ~ i H g g
Natural 21.4 14.8 26.0 2.67
30 Mln. 23.1 12.7 28.8 2.67
60 Min. 55.2 11.3 2.67
120 Min. 61.8 2.67
34
T.A.BLE n. PHYSICAL PROPERriES OF MEDIUM PLASTIC SOIL
! ~ E-4
f +> ~ ! ~ ] ~ ~ $.4-
~ 4) og
....=~- - jS ~cia ~~ ()~ () I ""- "" !l-13 1 +> +> co co ()
;i AS
~ AS Q)
..:I g 6:! ~
Natural 20.0 2.71
30 Min. 20.6 16.1 14.6
60 Min. 37.8 21.8 1.5 .8 16.0 2. 71
120 Min. 22.1 14.1 2.71
35
. '1
AA
" ·,/ CH '
,. . ,. . ' ~'tt ")J ~
' ' "~ 40 ;,,; ; ,. •-' / '"' ~i ;~ ,, ~
.. i ... y ~ ' ~~ ; " Cit \; y, ·OH~f- llln·
20 /
~· •:;
~~ ~ .. .. ·, . .: . ~ t '·. . .
J .. Cr.& «. 7 M .. &OL
. ·'
:•!!() .. k ·,..;; "'
.. ' .• .: ' . :. ,-'"
20 ~0 6o 80 .. "IU.gh;PJ.a~tic :1 •. .L:i.qUjl.f: I..b1t. • '' Low l'1.a:stic
.120 .. ~· 1 . ' 120:MiD • ~ . 60 Mi:.D .. 2 60 Min • 6
. ;-" jO·JfU Ill' J. " ·JCI tin • 7 0 Min -4 0 Min • 8 . ·,· -! Jf~ .• tf ' ,, . ..... , ''~' lK;, ' '
q~·· , ., 'j f ,' I , 'I' f•,
· FigUre i 2. Casagrande r s Plasticity Chart.
36
The writer views these results with con.f'idence in their comparative
value due to the care taken in performing the tests. As previously
stated, all tests of the same type were run successively to reduce
errors due to judgment and environment. For example, four or five
independent plastic limit determinations of each batch were taken the
same day.
Considering clay-sized particles to be smaller than .002 mm. in
diameter, the high plastic Vetters clay consists of about 63% silt
sized or larger and 37% clay-sized particles. As expected and shown in
the work of Gregg, et. al. ( 11 , 12) the grain size curve is. displaced
to the right w1 th increased grinding time. The soil is classified as
a "clay" through use of the triangular chart of the U. s. Bureau of
SoUs and Chemistry and .falls in the "A-7" Bureau of Public Roads
clas si.tication.
The medium. plastic Lebanon sU t loam is composed o.f about 30%
cl~-sized particles. It has a classification of »A-6" (Bureau of
Public Roads) and a ttsfity clay" or "s.ill.ty clay loam" (u.s. Bureau of
Soils and Chemistry). In this case, the grain size curves are not ott
set as much as they were in the high plastic soil. However, in the
range of clay-sized particles, it appears that the separation is more
similar. Figures 13 and 14 are the grain size curves for the high and
medium. plastic clays, respectively.
In the determination of specific gravity, no appreciable deviation
between batches of the same soil was noticed with changes in grinding
time. At first glance, it appears that this is in conflict with the
work of Gregg, et. al. However, the grinding period o.f zero to 120
37
100
80
70
fi ~
l .,60
~ so
,t\ h
~ ~ ~ !"-. "' ~ t-..~ v- f- 6C minutes
/ 3C mil ru.te· J ~ [\ I'. k ' " ~ ~ K
12C minutes , ~ I'-.
!'. ~'-.... c mi.:l ut.e= . N ~ !'-. !"'-... " ~ ~ ~ ~
I
40
........
20 .1 .01 .001
Particle Diameter, -.
Figure 13. Grain size anal.TSis far hiiJ:l plastic soU.
. 1 9,0H--H-t-t--!-+--+----+++-+-+-+-+---+--+----l
·, ,'·"
.. 01 .001
Particle Di•et.eiJ :a. \" r~ <"' .. , ~- , ·', \ -- *' . Grain size a.nalysis for medim pla.Btic soU ..
minutes drawn to the same scale as Figure 2, would show an insignifi
cantly small area at the beginning of the curve. Furthermore, the
chances of remaining on a. "straight line" portion at the offset of the
curve in Figure 2 throughout this study are likely. The specific
gravity was found to be 2.67 grams/co. for the high plastic Vetters
clay and 2. 71 grams/co. for the medium plastic Lebanon silt loam.
B. X-Ray Diffraction, Differential Thermal Analysis
39
An X-ray diffractogram was run on each test batch, requiring about
3.5 hours of time per run. Atter completion, these curves were compared
to see if there was any appreciable difference either in location,
magnitude, or sharpness of peaks. No change could be detected,
indicating that no new materials of definite crystalline structure had
been formed. Some sli.ght deviations did occur, of course, but these
did not indicate a trend .of' 8.'IlY type and are, in the opinion of the
writer, due to sample deviation, environmental changes in the room.
where the X-ray patterns were processed, and other inherent deviations
in the X-ray theory. Typical curves have been included in Figures 15
and 16.
Brindley (4) and Bram (5) state that two major difficulties in
running X-ray diffraction patterns are the multiplicity of lines when
many products are present and poorly defined diagrams from poor
crystallin! ty and/ or small size of crystals.
D.T .A. curves were run on each test batch, requiring about three
hours of time per run. Gregg, et.. al. (11, 12) found that during his
thermogravimetric analysis that the peaks shifted to a slightly lower
temperature and decreased in magnitude with increasing grinding time
Mon
tmor
illo
nite
80
n.&
reea
29
Mon
tmor
illo
nite
Qua
rtz
Sli
t C
hang
e
ll'ig
ure
15.
Typ
ical
I•rq
dit
f'ra
ctio
n p
atte
rn f
or
hig
h p
last
ic c
lq (
0 m
inu
t.a
gri
nd
ing
tim
e).
g
illi
t-e
80
72
64
56
Illi
te
48
40
Deg
rees
29
Qua
rtz
Sli
t C
hang
e
Fig
ure
16
• T
ypic
al.
x ... r
ay
dif
fracti
on
patt
ern
fo
r m
ediu
m p
last
ie c
lay
( 0
min
ute
s g
rin
din
g t
ime).
,r::- ....
(Figure 3) • In this study, the differential thermal. analyses showed on
deviation with grinding time. Since no uniform trends were developed
in the tests, slight differences can be attributed to sample deviation.
The sample selection is extremely crucial in this test and both
homogeneity and amount must be considered carefully. The sample was
weighed on an electric balance to an accuracy of .0001 grams in order
to reduce this inherent error, and great care was taken to select a
homogenioua sample. Typical. D. T .A. curves are shown in Figure 17.
Both soUs demonstrated the low temperature endothermic loop
characteristic of the departing of surface or atmospheric water. The
mid-range endothermic loops are characteristic of the loss of bound
water or the dissociation of hydro:xyls !'rom the lattice. High tempera
ture loops, characteristic of the final. breakdown of the lattice and
the formation of new materials, are absent in both soils below 1 ,000
degrees Centigrade.
C. Thixotropic Sampl.es
The saaples extruded from the Vac-Aire extrusion device have been
shown by Mathes ( 18), Shitfert (29), Matlock, et. al. ( 19), and others
to be capable of extruding highly consistent samples with a high degree
of saturation. This high degree of saturation is desirable in that it
is necessary to assimilate good undisturbed samples. Seed and Mitehel.l
(27) emphasize that a high degree of saturatim is essential to maximze
thixotropic characteristics. During early work with the developntent of
the machine, a definite swirl was seen in the pattern o:f rupture cracks.
This so-ea.lled helical strueture or orientation is a characteristic
peculiar to the extruded sample. It has, however, shown no evidence of
~ "' J.t bl)
"1"'1 -!-) s::: ~ m· (I) (I) J.t bl)
!
1000
800
600
4oo
200
9 eXQthU"Jd,e <, endotbendc >
.~~~~~~--~~~~~~--~~~--~
a.
e'1cothemie < ~l"..de >-
'Fig1n-~ 17. 'Tf.P:iC::a1 D.T .;A. ;patterns, a. High PJ.ast!c--natural, b~ ~~um. J;Uastic--na1:,:uraL
\, :,<'·,, ·!.:,;· :.-.; ,"•i • ;;1\J'\'; "
43
detrimental etteet.s and seems to be :reprodu&ed to a certain extent in
all extruded soUs. It should be noted here tbat samples extruded from
the Vae-Aire device are mal"e coasi.stent and tmifo:ra than samples
produced in arrr other way in the laboratol7. Another aspect supporting
the quality ot extruded S&llples is presented by- Rutledge (2.$). Be
noted. taat good tens on undisturbed samples give stress-strain curves
that are straight lines up to thirty or forty percent of their lii8Xill1um
value. Contr81")" too tbe general curvature characteristic of a remolded
material, saaples Curing this test prograa aeet Rutl.edge 1 s requireaent.
Nearly" all stress-st.rain curves can be depicted by a straight line to
this value, lll8ll7 'being straight for a m.uch grener percent of tae:lr
Mxhmm values.
In Tables III aDd IV, the degree of saturation and void ratio :lor
random. samples are shOND. These values cannot be confidently computed
tor each test speed--. due to the previousl7 aeationed ditf'icul ty in
removal. of the sample from. its Walt sbel.l and waxed paper surrounding.
It is included to show that there is no trend for a change in these
values over the t:bae of the test period.
Figures 18 through 2.$ show stress-strain relationship at various
ages throughout the test period. These curves clearly show two things.
First, that the samples do meet Rutledge's requ.i.relaalt of a straight
line relationship for tllirty to forty percent of the -.x1mum value.
Second, they show that the stress at low strain increases vi th age.
This thixotropic phenomena has been shown by nearly all investigators
working in the f'ield of' thixotropic behavior.
45
TA.Bt.E III. DFJJRD: OF SA.TUJU.TIOfi .OD VOID R.lTIO FOR lU.HOOM SAMPLES--HIGH !LASTIC CLAY
Degree of Batch Sample .Age Saturation Void Ratio
~Jla3rs) <~l
Natural B!f6 4 91.98 1.05 Natural HN8 6 92.o6 1.05 Natural mns 30 91.20 1.05 Natural. HR19 50 92-52 1.04 Natural HH22 60 91.72 1.04
30 H:!n. H.30-4 2 f7.44 1.o6 30 Min. !1.30-9 6 91.39 1.03 30 Min. H)0-15 20 93.74 1.07 30 Min. H)0-18 40 96.82 1.05 30 Min. B)0-21 50 94.92 1.0S
60 Min. H60-7 4 91.09 1.02 6o Min. B60-9 6 93.46 1.01 60 Min. H6o-14 14 93.08 1.05 60 Min. H6o-19 30 93.79 1.05 60 Min. H60-25 60 92.79 1.05
120 Min. H120-10 4 94.80 1.05 120 Min. H120-13 10 92.91 1.03 120 Min. H120-17 20 93.04 1.04 120 Min. H120-22 40 94.72 1.o6 120 Min. H120-27 6o 94.86 1.04
46
TABLE IV. DEGREE OF SATUJ.W'ION AND VOID RATIO FOR R.ANlDM S.AHPLES--MEDIUM PLASTIC CLAY
Degree of Batch Sample Age Saturation Void Ratio
~Dazs) (%)
Natural LN101 2 9~.69 .7~ Natural LN96 6 9~.05 .76 Natural LN92 14 9~.61 .74 Natural LN82 30 9~-73 .74
30 Min. L30-100 1 96.94 .74 30 Min. L30-93 6 96.96 .73 30 Min. LJ0-90 14 97.78 .74 30 Min. LJ0-84 40 97.99 .75
60 Min. L60-101 1 97.57 .7~ 60 Min. 1.60-96 6 96.58 .73 6o Min. L60-89 14 96.51 .72 60 Min. L60-83 30 94-39 .76
120 Min. L120-101 1 9~.78 .77 120 Min. 1120-95 6 94.28 .78 120 Min. 1120-90 14 96.46 .77 120 Min. L120-86 30 9~-33 .76
-fH !l -...
1111 CG • ~ ~ .l=)
1 .o
.8
.6
.. 4
.. 2
Pel'Cent ~:Fai:fl
Fi~e 18. Uilcun!fned compression test ~S'Ill ts on high plastic son ground. tor 0 m!tiutes (natural.) after 1tarious ag'irig :Periods in days.
-~ .p .6 • --1111 • i ... .,.. .. 4 §
2
Percea.t strain
t':tigtl!'e 1 9. ' tftleo:d"!.Md caapresston 'kart. reaul. '-s on b:lgh plastic > sMl.:<·IP"dliid for 30 ~- e..:Aer '9"8rlous ag!Bg · ~!Ods in dqs.
48
1 .. 0
.. 8
........ ~· 30 .p .. Q, ........,.
"'\ 10 Ill 11.1 G)
~ +>' .. ~ "'"' .. ~
.. 2
Fi~e 20 .. ,, U-~~ compressicn test .resuJ.ts on high pla.$1:-io · s~~ grQund for ... ·60 ~1\MS . a:f'ter various aging
pc-iod$ in Cl.qs. .
Pereent st.rain
~ 21~ ~ eQIIIp"easiQD test reaul'ts on high plutic aoU peUJld 1or 120 Jlirlutes at'• vari.ous aging perieds a .4W1J.
so
-! -ft to
J Ill
i
51
1.0
.. 8
14
·'
.h
.2
0~--~--~----~--~--~--~L---~--~~--~---L 0 8 10 12
Percent st.rain
~~. ·!~d_c~reasi~~ te~~ re~uits on medium plastic 1011~ #t)\ttld f'or 0 :mimltetr {natural) after various ~ perto<b!· 1n days.
-~ ~ -.. Ill Ill (I)
~ Ill
~
~
.p
.4
.2
0 2 8 10 12 ~-tram
figure 2). Unconfined campressico test resul. ts on medillltl plastic ' l 1¥:'; ·.· ~:; ~ j ·~d ··~f~J! )Q '!lin'd.We af'tefP "VVicUs apng
~ois 1a ~· ~··, · ' ·; '.
1.0
.2
Percent strain
Ff~e 24. Unooll!ined com.pre$sion te$t resW.ts on medium plastic soU ground !or 6o minut.es after various aging periods in days.
1 .. 0
j() .. 8
......... ;~ ....,
,6 -,,.... fl.) fl.) (I)
~ fl.)
...., or!
'~4 ~
?erl:~ntJi strain
,, , ft.g,w,r$ 25.. , Unoonf~ eompre•,:Loa test resul.ts 0111 :medium pl.asttc soil ground for 120 minutes after various aging pe;rto~ in,W{B• ,
ss
D. Vane Shear 1 Unconfined Compression
Unconfined compression tests were run on each sample for shear
strength determinations. Shear strength values were also determined by
the vane shear test and results compared t.o values obtained from the
corresponding unconfined campression test (see Figures 26 through 3.3).
The results, along with individual water contents, are listed in tabular
fOl'DI. in Appendix A.
All the s1lear strength versus l.og time curves were fitted statis
ticall.7 t.o eliw1nate the <}'U8tionabl.e procedure ot visual fitting.
Frca a prerl.ous study (18), a linear equatim was found to fit the data
best. The equation used in this work is as follows:
S • A0 + A1logT,
where "5" is tbe shear strength, "T" is tbe time of aging in day-s, and
"A0 " and "!1 " are constants determined through use of the least
squares method of curve fitting.
These curves show that the vane shear values are alway-s greater
than the corresponding unconfined compression values. naat (9) states
that the speed ot rotation, the time delay before start of testing, the
calibration tor a particular situation, the effect of vane dimensions,
and soil iDbOJD.Ogeneities are some of the factors affecting the value
of vane shear tests. Of these, the speed of rotation is the most
variable. The wr1 ter believes that. the speed of rotation is the most
importet variable in tbis case due to the non-motorized device
available tor use. C&dling and Odenstad (7) :Investigated the rate of
strain and fO'Uild tbat 01'le degree per second gave shear strength values
wenty percent higher tban correspOilding unconfined compression tests.
IH
«<
+> J:i ~ i ~ I ·t5!
.. s
···" .1 0
van
e
she
ar
unco
nfin
ed c
ompr
essi
on
,~----~--~~~~~~~~~----~--~~~~~~~~--~--~--~~~~~-
Tim
e m
Days
1iJu
re 2
6.
Com
pari
son
of
shM
r st
ren
gth
va
lue
s de
term
i.ned
bT
the
un
con
fin
ed e
anp
ress
ion
and
va
ne s
b.ea
:r te
ste f
or
the h
igD
. p
last
ie s
oil
gro
und
for
0 m
inu
tes
(natu
ral)
.
~
.5
.. 4
· van
e sh
ear
~
conf
ined
com
pres
sion
....,
;i
.3
i f.t
6)
f..t ~ ~
.2
.. 1 0 L-----~---L~--~-LJ-W-----~--~--~~~~~------~--~-L~~~~
1 1
0
10
0
1000
Ti
me
in D
ays
Fig
ure
2 7
. C
ompa
riso
n o
f sh
ear
stre
ng
th v
alu
es d
eter
min
ed b
y t
he u
nco
nfi
ned
co
mp
ress
ion
an
d
van
e sh
ear
tests
fo
r th
e h
igh
pla
stic
so
il g
rou
nd
fo
r 3
0 m
inu
tes.
\1
\ ....
..:!
.>
vane
sh
ear
tt -j.)
·u
ncon
fine
d co
mpr
essi
on
.~ J &!
l
.3
J
.1 Q 11
I I
I I
I I
I I ~ Q
I
I I
I I
I I
111 0
0 I
I t
I I
I I
I i Q
OQ
Tim
e in
Da
ys
Fig
ure
28
. C
ompa
.:ria
on o
f sh
ear
stre
ng
th v
alu
es d
eter
min
ed b
y t
he u
nco
nfi
ned
co
mp
ress
ion
an
d
vane
sh
ear
tests
fo
r th
e h
igh
pla
stic
so
il g
rou
nd
fo
r 60
min
utes
..
'63
1.0
.&L
l ~
.6··
vane
sh
ear
j J .h
f4
---
unco
nfin
ed c
ompr
essi
on
.2 0 ~
1 I
1 1
1 I
1 I
I I
I I
I I
I I
I ~
I I
I I
I I
I I
I 1
" 00
10
00
Tim
e ill
Dq
s
Fig
ure
29
. C
ompa
riso
n o
f sh
ear
stre
nat
.h v
alu
es d
eter
min
ed b
y t
he
unc
onfi
ned
com
pres
sion
and
va
ne s
hea:
r te
sts
for
the b
ish
pl.e
.sti
c so
U g
roun
d fo
r 12
0 m
inu
tes.
\A
'l
)
.sr t--
----
----
----
----
----
----
----
----
----
---v
an• ~
•
; ~--------------------------------------------unconfined co
mpr
essi
on
!l
• i u.l i .21
.1"
10
1
00
T
ime
in D
aym
ll'ig
ul"
e 3
0.
Com
pari
son
o£ s
he
ar
str
en
gth
val
ues
det
erm
ined
by
th
e u
ncon
fine
d co
mpr
essi
on a
nd
va
ne s
haa
r te
sts
'lo
r th
e M
diU
IIl p
last
ic s
oil
gro
und
tor
0 m
inut
es (
natu
ral)
.
00
0
0\
0
.51
•Ui
vane
sh
ear
'~
-t) ~
.3
~ w
~ !if
.2
~
.1 l_ _
______
______
______
______
______
______
______
___ unc
onfi
ned
com
pres
sion
10
1
00
T
ime
in D
a.ys
Fig
ure
31.
. C
ompa
riso
n o
f sh
ear
stre
ng
th v
alu
es d
eter
min
ed b
y t
he u
nco
nfi
ned
com
pres
sion
and
v
ane
shea
r te
sts
for
tbe m
.ediu
m.
pla
stic
so
ll g
rou
nd
fo
r 30
min
ute
s.
()'.
....
l ~ j O
l j
·' L-----------~---
·T&
lte
sN
Nr
L------------------~ -~«i CC~
~~PN
•sio
n
.)'
.2
.1 .. 0 I
I I
I I
I I
I I
I h
I I
I I
I I
I I
I 1
I I
I I
1 1
I
1 1
0
10
0
1000
T
ime
in
Da
ys
Fig
ure
32.
C
ompa
riso
n o
f sh
ear
stre
ag
th v
alu
es d
eter
m.in
ed 'b
y tM
unc
onfi
ned
com
pres
sion
an
d
vane
sh
ear
teats
fo
r th
e m
ediu
m p
last
ic e
oU
gro
und
far
60 m
inu
tes.
~
..
It appears that • 1 degree per ~~nd will give equal values. This
speed would be extremely dif'ficult to match uniformly by band. It was
attempted to maintain a rotation of oo.e degree per second for these
tests. utilizing Cadling and Odenstad' s criteria, it appears that
this sp:>eed was successfully maintained in the majority of cases. It
has also been stated that the shear vane should be inserted to a
depth of' one-half' ineh with an undisturbed mass of soil one-half inch
in depth below the peaetration. A.s mentioned before, many of the
samples were too short to meet these requiraaen:ts. Therefore, a
sample ot about one inch in overall length had to be used in JIWlY
cases.
64
Table V shows thixotropic strength ratio values canputed for the
maxilnum unconfined compressive strength and the vane shear values.
These are computed using least square data as presented in the . preVious
figures (26 through 33).
Originall;r, it vas believed that increased grinding times might
have a direct relationship to thixotropic strength gain. It appears
that this is not the case. Therefore the results of studies by
Moretto ( 22 ) , Berger and Gnaedinger ( 3), and Seed and Chan ( 26),
mentioned earlier, are not repudiated.
It should be noted, however, that the initial strength O·f each
batch had some proportionality to grinding time. In each ease
{Qu and V .s.) t.he initial shear strength increased with increased
grinding time. In effect, the soU is in a physically drier state
witp in~~a~ea ·p-ip,.cUng tiule even though the moisture content remains
constant. This was noted during the extrusion process and should be
65
.OOMPARIOO_ !l()TROP1 20 'P~ ·~. .OOMPARIOO • :Of ~HI!{)TROPIC STRENGTH RATIOs*
Strength~ to (tsfJ
Thixotropic Strength Ratio Batch
High Plastic--Natural High Plastic--30 Min. High Plastic--60 Min. High Plastic--120 Min.
Medium Plastic--Natural Medium Plastic--30 Min . Medium Plastic- -60 Min. Medium Plastic--120 Min.
.123
.1)2
.187 -333
.329
.323
.)80
.314
t1o t3o
1.61 1. 72 1.46 1 .19
1.00 1.01 1.00 1.14
1 .81 2.07 1.67 1 .27
1.00 1. 09 1.03 1.21
*These values are computed for MAXIMUM unconfined compression values, independent of that corresponding strain.
66
expected with tbe correspo.U:ns iDGrease ill liqQid limit with grinding
time.
V • SUMMARY Aim OOHCLUSIOll5
Existing studies on the ettects of griMing are very li:mi:ted in
quantitT and scope. To futber investigate these ef'tects a high plas
tic soU and. a medillDl plastie soU were chosen. The highly plastic
Vetters cl.a7 (Taas) beloags to tb.e DlOB'taorillonit:ic gr&llpt a Tery"
act.ive elq .-.ral. Tliae ..s.i'Dl pl.anic Le'banon sil1i loam (Missouri)
appears~ he an 1llite.
67
Various 1iests (.A.1iterberg Limits, specitic gravity, grain size,
X-ray analysis, D.'f .A.) were run on each batch (a total ot. eight, f'our
for each soil) to pin-point. any deTiations. 'fhe res'Ul.ts of tbis
investigation indicate the following:
1 • Griading a:Uects the A:\terberg LiJdts in that the
shriDkace lilait is red'aeed and the liquid lla11i,
plastic limit, anci plastic 1n<lex rise vi'th iacreas
iBg gr.iD.di.Dg ti..
2. Points representing each sample rise up and to the
right in a pattern ro~ parallel to the •A-line"
(oasagrancle•s plas1iicity chart) with mcreased
grinding time.
}. 'f1le speeif'ic grarl v is not appreot.abJ.7 a.tt~ 'b.J'
gruuUng. " .
-~ The·. grain sise. is seaeral.l.T reduced vi t.h i:acreased.
grin~.
s. X-1"8.7' aael7sis· ahara teat neither e17st-all.iue
strutrare;ia·Reken ·~ aor is a nar material of
a de.tinitel:y ccyst.alline structure formed during the
period of grinding.
6. D.T .A. curves show no deviation with grinding time.
The deviation in !tterberg Limits can be explained through an
energy concept. With increased grinding time, the internal energy
68
of the soU is increased and the structure is more dispersed. This
accounts for the reduction in shrinkage limit with increased grinding
time. The lack of change in speci:rio gravity indicates that vi th a
grinding t:bne of only two hours, a sufficient aaount of heat (to drive
off surface ~dro:xyls) is not developed. Also, the ~er of breaks
in the platelet form is not large enough to expose a oontroll:ing
nUlllber of vacancies in the la'ttiee.
It should be kept in mind "that the above results ae for only
two particular soils that are ground for time periods of zero to
120 minutes.. 'Where applicable, these results coincide with and serve
to validate the work of Gregg, et. al. (11, 12) in England.
A. thixotropic study was al.so conducted to see U grinding bad an
affect on this strength regain phenomena. Increase in shear strength
was used as a measure of thixotropic effects.
Realizing that moisture content greatly influences thixotropic
behavior, each batch of Vetters clay was extruded as closely as
possible to a constant water content of 37%. The Lebanon silt loam
was, likewise, extruded at a constant water content of 27%. A
comparison of thixotropic strength ratio for each batch was made to
note any affects of increased grinding time.
69
It is noted that the present.day" hypotheses concerning correlation
of vane shear and unconfined compression test results~ increase with
strength and stiffness with age~ and greatest strength increases at low
strains were reproduced. The attempt to compare increasing thixotropic '\ -
strength with grinding time did not show ~ direct correlation. . '. . '• . ·· ~
However~ an increase in initial shear strength with grinding time did
occur.
In conclusion~ it is obvious that the et.f'ect of grinding in
sample preparation should be given caretul consideration. Special
care should be taken in identifying exactly what procedures are
followed in sample preparation so that the work will be of value in
the advancement o£ the science of soil mechanics.
VI. SUGGESTIONS
The writer would like to suggest that a study be conducted in
which grinding times are increased well above two hours in length.
This study, with tests performed on random samples, would serve to
enforce and extend the .findings o.f this investigation.
70
71
·, '
VII... APPENDIX A
72
TABLE I. 'fEST RESULTS .'FOR ·HIGH PI.A.SriC SOll..--NATURAL
Ratio Age v .s. Qu VS w.c.
Sample # (Days) (ts:r) (tst) Qu (%)
HN-1 1 .190 .111 1.71 * HN-2 1 .220 * * * HN-3 2 .230 .172 1.34 36.63 HN-4 2 .220 .1$1 1.45 36.67 HN-5 4 .240 .173 1.38 35.49 HN-6 h .26.3 .171 1.54 36.07 HN-7 6· .26~ .204 1.29 36.68 HN-8 6 .2$8 .165 1.$6 36.39 HN-9 1'0 .215 .212 1.30 36.26 HN-10 10 .290 .223 1.30 36.32 HN-11 14 .290 .212 1.)6 )6.37 HN-12 14 .}20 .208 1.53 36.59 HN-13 20 .J30 .202 1.63 36.67 HN-14 20 .:ns .217 1.56 36.75 HN-15 jO .)23 .251 1.29 36.00 HN-16 30 .)03 .231 1.)1 36.78 HN-17 40 .)28 .219 1.49 )6.64 HN-18 40 .140 .216 1 • .57 37.08 HN-19 5·o .J55 .236 1.50 36.04 HN-20 $0 .355 .261 1.36 35.92 HN-21 60 •. )65 .275 1.33 35.79 HN-22 6o .340 .259 1.31 36.34
Average = 36.37
*' NOTE--These values are not attainable, due to either poor t.est -~oced~~ .. ~r a,eeident~~~~~ ~e test program.
TABLE II. TEST RESULTS FOR HIGH PLASTIC SOli.--.30 MlmJirES
Ratio Age v.s. Qu vs
Sai!lPle # (Days) (tat) (ts!) QU
H30-1 1 .23.5 * * H30-2 1 .2h8 * * HJ0-.3 2 .22~ .163 1 .)8 H30-h 2 .235 .172 1 .)7 H30-.5 h .263 .1.56 1.66 H30-6 ~ .2~0 .193 1.29 H.30-7 ' .26$ .162 1.6.3 H.30-9 6 .280 .216 l •. JG HJ0-11 10 .270 .2)0 1.~ H30-10 10 .29.J .236 1.24 HJ0-12 14 .)26 .266 1.22 HJ0-13 1h .}).$ •. 251 1.3~ H30-14 2:0 .3)$ •. 269 1.32 HJ0-1.5 20 .350 .268 1.)1 HJ0-16 30 • .350 .267 1.31 HJ0-17 .30 .)60 .260 1.46: H30-18 40 •. 138 .274 1.2$ H30-19 40 .. 365 .272 1.3k H30-20 so .175 .277 1.,3~ H30-21 so .)60 .293 1.23 H30-23 60 .}83 .3o6 1 .25 H30-22 60 .375 .310 1.21
Average :ll
~*lJoTE--Ta~se values are not atta!liabl.e, due to either poor "test proeed'ln"EJ or aeei'deri1is d.ll.rlng tbe test program.
73
w.c. ~~2
* * 38.78
38.64 37.26 37.04 37.81 37.51 37.80 )7.50 37.37 .37 .01 37.26 )7.71 )7.$0 37.34 37.8S 31.53 31.99 J,1.h5 36.28 37.06
37.S3
TABLE III. TEST RESULTS FOR HIGH PLASTIC son.--6o MINUTES
Ratio Age v.s. Qu vs
Sample# (Dazs) (tsf) (ts.f) Qii
H60-3 1 .173 .183 1.49 H60-4 1 .283 .187 1.51 H60-5 2 .290 * * H60-6 2 .218 .205 1.3.5 H60...7 4 .)25 .26.5 1.23 H60-8 4 .:no .264 1.17 H60-9 6 .. :335 .266 1 .• 26 H60-l0 6 .:no .(a1.3 1.5.5 H60-12 10 i325 .285 1.14 H60-13 10 ,a~~ .292 1.11 H60-1.4 14 ·400 .284 1.41 H60-15 14 .. koo .288 1 • .39 H60-17 20 ·315 .290 1.29 H60-16 20 .405 .312 1.29 HW-19 .30 .410 .304 1.35 H60-18 30 .)90 .)28 t .19 H6o-20 40 .. k33 ·309 1.40 H60-21 40 .420 .333 1.26 H6o-22 .so .448 .336 1.34 H6o-23 .so .453 .324 1.40 H60-24 6o .420 .319 1.32 H60-25 60 .393 .341 1.15 H60-26 6o .415 .329 1.26
Average =
*NoTE-_;.These vaJ.ues are no't attainable, sue t.o either poor test pr'crcedure or accident'S d.uribg the test. program.
74
w.c. ~%)
* * * * 36.8.5
36.97 3.5.4.5 36.75 35.47 36.18 36.96 37 .o8 37.00 36.96 )6.82 36.38 36.78 36.64 37.05 36.69
* 36.54 37.22
36.66
TABLE IV. TEST RESULTS FOR HIGH PLASTIC SOD..--120 MINU'fES
Ratio Age v .s. Qu vs
Sample# (Dazs) (tsf) ~tsf) Q\i
H120-3 1 .385 .349 1.10 H120-4 1 .380 * * H120-5 2 .k08 .300 1.32 H120-6 2 .440 .388 1.08 H120-9 4 .4JJ • .343 1.26 H120-10 4 .h~ .386 1.05 H120w11 6 .435 .381 1 .14 H120-12 6 .}68 .317 1.21 H120-13 10 .450 .391 1.15 H120-14 10 .435 .)92 1.11 H120-15 14 .485 .408 1.19 H120-16 14 .490 .400 1.23 H120-18 20 .550 .421 1.30 H120-17 20 .505 .392 1 .. 29 H120-20 .30 .$13 .459 1 .. 12 H120-19 30 ..540 .440 1.23 H120-22 40 .$48 .425 1.29 H120-21 40 • .520 <0'425 1.23 H120-23 50 .513 .462 1.24 H120-24 50 .590 .469 1.26 H120-25 60 .490 .455 1.06 H120-26 60 .540 .374 1.44 H120-27 60 .588 .475 1.22
Average =
*ND1E--These values are riot atta~ble, due to either ~or test procedUTe or aseidents ciur:lng the test program.
75
w.c. (%)
* * * * 36.80
31.09 35.75 35.79 ,36.00 )h.01 31.29 37.03 34.90 )6.09 37.50 ,36 •. 28 3'7.53 37.35 )6.89 37.12
* )6.66 36.77
36.49
, Ratdo •" '
Age v.s. Qu !§ w.P.~ Sample # (Days) (tsf) (tsf) QU ' < ·(~'}
,:; .> '
LN.-102 1 .36.5 .321 1 .Jl a:~.98 LN-103 1 .390 .323 1 .20 26~63 LN-104 2 .Jt30 .. 332 1.2.9 ,;1*
LN-101 2 -41.5 J,34 1.~ ~6.58 LN-98 h .. 463 • .313 1.,~ 26.49· LN-99 4 .. 443 .337 1.)1 ~ .. ;;o LN-96 6 -~ -.325 1.,31 ~~.Qb LN-97 Q .440 .322 1~,36 26.73 LN-95 10 .. 423 .)41 1.ah t6,")2 LN-94 10 .40o .3Lh 1.~ ao .. >a LN-92 14 .a>s .325 t.l¥1 t'"'31 'V
LN~93 14 .453 .341 1.3~ i5:9o LN-90 20 .423 .325 1.,.30 26.,0:1 LN-89 20 .423 .338 1,.25 if* LN-84 .30 .440 .337 1.,30 ~6.2~ LN-83 30 .430 ,337 1.~11 2:6.lt7 LN-86 40 .36o .285 1._26 ?1.4} LN-88 40 .355 .339 1 .. 05 2( . .,27
:. ·~ <"l;f >li.~( i
26.49 Average =
*NOTE--These values are not attainable, due to either poor tesh ~~ procedure or accidents during the test program.,
TABLE VI. TEST RESULTS FOR MEDIUM PLASTIC SOIL--30 MINUTES
Ratio Age v .s. Qu vs w.c.
~le# (Days~ (t.sf') (ts:f) QU (%)
L30-100 1 .338 .330 1.02 26.45 L30-99 1 .410 .313 1.31 26.63 L30-97 2 .398 .347 1.14 26.35 L30-98 2 .418 .340 1.23 26.65 L30-95 4 .. 415 .317 1.31 26.71 L30-96 4 .415 .333 1.25 26.67 L30-94 6 .420 .342 1.23 26.50 LJ0-93 6 .430 .345 1.25 26.26 L30-92 10 .398 .342 1.16 26.35 LJ0-91 10 .413 .348 1.19 26.83 L)0-90 14 -458 .331 1.38 26.73 LJ0-89 14 .435 .341 1.28 26.50 L)0-88 20 .418 .)60 1.16 26.21 L)0-87 20 .413 .)38 1.22 26.33 L)0-85 30 .420 .370 1.13 26.67 LJ0-86 30 .433 .361 1.19 26.32 L30-84 40 .380 .. 353 1.08 27.07 L30-83 40 .355 .353 1 .01 27.25
Average = 26.66
77
/0
TABLE vn. TEST RESULTS FOR MEDIUM H-ASTIC SOU.--60 MINUTES
Ratio Age v.s. Qu vs w.c.
Ba.mp!e I (Dazs) (tsf') (ts:t) QU {%)
L60-103 1 .453 .409 1.12 26.31 L6o-102 1 .443 .374 1.18 26.67 !.60-101 2 .475 .393 1 .21 27.50 L60-95 2 .415 .36S 1.13 27.46 L60-99 4 .448 .375 1.20 26.52 L60-100 4 .460 .388 1.18 27.00 L6o-96 6 .475 .358 1.32 27.01 L60-97 6 .475 .381 1.25 25.18 L60-94 10 .460 .386 1 .19 27.03 L60-93 10 .475 .371 1.28 26.73 L6o-89 14 .490 .378 1.30 26.64 L6o-88 14 .508 .396 1 .28 26.75 L6o-S7 20 .495 .410 1 .21 26.78 L60-85 20 .433 .393 1.10 26.58 L60-84 30 .450 .367 1.22 26.52 L6o-83 30 .510 .404 1 .26 26.49 L6o-8o 30 .540 .423 1.27 26.10 L60-74 40 .423 .410 1 ~03 27.00 L6o-78 40 .440 .357 1.23 27.27 L6o-76 40 .415 .387 1.07 27.41
Average = 26.75
78
TABLE VIII. TEST RESULTS FOR MEDIUM PLASTIC OOTI.--120 MINUTES
Ratio Age v.s. Qu vs w.c.
Sample# (Dazs) (tsf) (tsf) Qu (%)
L120-102 1 .46o .336 1 .36 * L120-103 1 .448 -351 1.28 27.94 L120-101 1 .470 .324 1.45 27.25 L120-100 2 . 425 -.334 1.27 27.32 1120-99 2 .423 • .318 1.32 27.62 L120-98 4 .433 • .341 1 .27 * L120-97 4 .433 -3.37 1.28 27.44 L120-95 6 .448 -349 1 .28 27.14 L120-96 6 .405 .321 1 .12 25.24 L120-94 10 .423 .355 1 .19 27.18 1120-9.3 10 .435 • .347 1.25 27.76 1120-92 14 .470 .321 1.46 27.86 1120-91 14 .465 .341 1..38 27.57 1120-90 14 .445 -341 1 • .30 27.52 1120-88 20 .478 .. .383 1.24 27.09 1120-87 20 .448 .387 1 .16 27.08 1120-89 30 .530 .415 1.28 26.76 1120-86 .30 .465 .J85 1.21 26.84 1120-84 30 .550 .433 1.27 27.02 1120-81 40 .460 -373 1.23 27.37 1120-83 40 .458 .396 1.16 27.47
Average • 27.24
*NOTE--These values are not attainable, due to either poor test procedure or accidents during the test program.
79
Vlli. BIBLIOGRAPHY
1 • JJIJlRICAll SOCDTY OF TESTIHG MATJRIA.IS STANDARDS ( 1961) •
2. BAUER, E. E. and 'r. H. 'm<ENBURN (1962) Introductory soU testing, Stipes PU. Co., Champaign, Illinois.
3. BERGER, L. and J. GHlEDDGJiR ( 1949) Thixotropic strength regain of cl&Ts. American Society of Testing Materials Bulletin, p. 64-68.
4. BRDILEr, G. W. (19SS) Identification of clay minerals by x-ray dit.traetion anal7sis. Clays and clay technology, Departaent of Natural Resources, Division of Mines, Bul.l.etin 169, San Francisco, Galitornia, p. 119-129.
5. lliOWI, G. (1961} The X:-ray identification and cr,ystal. structures ot clay miDeral.s. Hineralogieal Society- (ClayMinerals Groups), London, 554 p.
6. BURGH:ES, J. H. and G. W. SCOTT BLAIR ( 1 948) Report on the prlaeipl.es of rheological nomenclature. Joint eo.dttee on Rheology" of the International Council of Scientific Unions, Proceedings International Rheological Congress, Amsterdam.
1. CA.DLING, L. and s. OIUSTAD (1950) The vane borer' an apparatus ft;~r cleteraining the shear strength of clay soils directly in the ground. Royal SWedish Geotechnical bstitute. Proe. 2.
6. OA.84GIWIDI, A. (1932} The structure of clay and its engineering Smportance in foundation engineering. Journal of t.be Boston Society of Civil Engineers, p. 72-113.
9. ~~ 1. (1966) factors iDf'luencing the results of vane tests. Canadian Geotechnical Journal, Vol. III, No. 1, p. 16-31.
10. :r.uoKlLIGa, H. (193S) Tbixotrop;y. Herman et cie, Paris, SO P•
11 • ORmG, S. J., K. J. HILL, aad T. W. PA.RKER ( 1954) The grinding of kaalinite, I., A pre11minary study. Journal of Applied Cheldstry, 4, P• 631-632.
00
12. CJB.JGG, s. J., If. V. PARDR, and H. J. STEPHENS {1954) The grinding o~ kaolinite, II, A more detailed study'. Journal ot Applied. ChaistrT, 4, P• 666-673.
13. mur.r, H. It. (1fS2) Colloid science, I, irreversible srstem.s. Jnserler Pub. Co., Nar York.
14. LAMBE, T. w. (1958) The structure of compacted clay. Proceedings A.S.C.E., Vol. 84, No. SM2, 34 P•
15. LAMBE, T. W. (1953) The structure of inorganic soil. A.s.c.E. Separate 315, 47 p.
16. MARBUT, c. F. (1914) SoU reconnaissance of the Ozark region of Missouri and Arkansas. U .s.D.A., Bureau of Soils, P• 66-70.
1 7. MARSHALL, C. E. ( 1 949) The colloid chemistry of the silicate mineral.s. Academic Press Inc., New York, 195 p.
18. MA.THES, J. A. ( 1968) Thixotropic e!fec'ts in a clay -water system. Thesis, University of Missouri at Rolla, 68 p.
19. MATLOCK, H. JR., C. W. FEKSKE, and R. F. DAWSON (1951) De-aired, extruded soil specimens !or research and far evalua'tion of test procedures, American Society of Testing Materials Bulletin, p. 51-55.
20. MISSOURI STATE HIGHWAY COMMISSION GEOLOGY AND son. MANUAL ( 1962 ) •
21. MITCHELL, J. K. (1960) Fundamental aspects of thixotropy in soils. Proceedings A.s.c.E., Vol. 86, No. SMJ, 52 p.
22. MORETTO, o. (1948) Effect of natural hardening on the unconfined compressive strength of remolded clays. Proceedings, Second International Conference on Soil Mechanics, p. 137-144.
23. PETERFI, A. F. {1927) Entwichlungsmech d organism, p. 689.
24. RABA., C. F. JR. ( 1968) The static and dynamic response of a miniature .friction pile :in remolded clay. Thesis, Texas A & M University, 164 p.
25. RUTLEDGE, P. C. ( 1944) Relation of undisturbed sampling to laboratory testing. Transactions, A.s.c.E., Vol. 109, Paper 2229, p. 1155-1174.
26. SEIID, H. B. and c. K. CHAN (1957) Thixotropic characteristics of compacted clays, Proceedings A .s. C.E, Vol. 83, No. SM4, 35 P•
2 7. SEED, H. B. and J. K. MITCHELL ( 1963) Test interpretation and errors. Laboratory Shear Testing of Soils, A.S.T .M., ottawa, Ganada, p. 405.
28. SHELL OIL OOMPANY, EXPLORATION AND PRODUCTION TECHNICAL DIVISION.
81
D.T .A. of clays and carbonates, public paper no. 25, Houston, Texas, P• 151-163.
29. SHD'FIRT, J. B. (1967) An eval.uaticm. o£ the vac-aire extrusion machine and an investigation of properties of extruded samples. Thesis, Texas A & M University, 15 p.
30. SDMP'fOR, A.. W. and R. D. :troR!HEI (1952) The sensitiviilJ' of clays. Geotecbnique, Vol. III, No. 1.
31. TERZAGHI, K. (1941) Undisturbed clay- samples and undisturbed .elqs. Journal of the Boston Socie't;y of Civil &l.gineers, p. 1&5-¥.
32. VAN OLPHEN, H. (1956) Forces baween suspended bentoni'te particl.es. Clays and Minerals, Proceedings, Fourth liational. Conference on Clays and Olay MineraJ.s, Publication 456, National A.cad.eal7 o:t Sciences., National Besearch Co1mcU.
)). vmwEI, E. J. amd J. T. OVERBEV (1948) Theory ot the stability of lyophobic colloids. ELsevier Publishing Co • ., Hew York.
82
IX. VITA
Thomas Michael McMillen was bam on Noveniber 1 7, 1944, in Boston,
Massachusetts. He received his primary education in the Dallas public
schools, Dallas, Texas, and in the St. Louis, Missouri, area. His
secondary education was received in the St. Louis County public schools,
St. Louis, Missouri.
After high school graduation, he attended the University of
Missouri at Rolla and was graduated with the degree of Bachelor of
Science in Civil Engineering on May 28, 1967. In September, 1967, he
entered graduate school at the University of Missouri at Rolla with
the appointment of' graduate assistant.
He is a member of Scabbard and Blade, Chi Epsilon, and Phi Beta
Iota (Pi Kappa Phi Colony) social fraternity. He presently is
registered as an "Engineer in Trainingn with the Missouri State Board
of Registration for Architects and Professional Engineers and is a
meniber (E.I. T.) of' the Missouri Society of Professional Engineers.