application of mineralogy to soil mechanics - grim

8/12/2019 Application of Mineralogy to Soil Mechanics - Grim

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STATE OF ILLINOISADLAI E. STEVENSON, GovernorDEPARTMENT OF REGISTRATION AND EDUCATIONNOBLE J. PUFFER, Director

DIVISION OF THESTATE GEOLOGICAL SURVEYM. M. LEIGHTON, ChiefURBANA

REPORT OF INVESTIGATIONSNO. 146

APPLICATION OF MINERALOGYTO SOIL MECHANICS(1) SOME FUNDAMENTAL FACTORS INFLUENCINGTHE PROPERTIES OF SOIL MATERIALS

(2) THE COMPOSITION IN RELATION TO THEPROPERTIES OF CERTAIN SOILSBY

RALPH E. GRIM(1) Reprinted from Proceedings of the Second International Conference on Soil Mechanics

and Foundation Engineering, vol. 3, Rotterdam, 1948(2) Reprinted from Geotechnique, vol. 1, no. 3, The Geotechnical Soc, London, June 1949

PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS

URBANA, ILLINOIS

19 50


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ORGANIZATION

STATE OF ILLINOISHON. ADLAI E. STEVENSON, GovernorDEPARTMENT OF REGISTRATION AND EDUCATIONHON. NOBLE J. PUFFER, Director

BOARD OF NATURAL RESOURCES AND CONSERVATIONHON. NOBLE J. PUFFER, ChairmanW. H. NEWHOUSE, Ph.D., GeologyROGER ADAMS, Ph.D., D.Sc, ChemistryLOUIS R. HOWSON, C.E., EngineeringA. E. EMERSON, Ph.D., BiologyLEWIS H. TIFFANY, Ph.D., ForestryGEORGE D. STODDARD, Ph.D., Litt.D., LL.D., L.H.D.

President of the University of Illinois

GEOLOGICAL SURVEY DIVISIONM. M. LEIGHTON, Ph.D., Chief

(859142M9-49)


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SCIENTIFIC AND TECHNICAL STAFF OF THESTATE GEOLOGICAL SURVEY DIVISION100 Natural Resources Building, Urbana

M. M. LEIGHTON, Ph.D., ChiefENID TOWNLEY, M.S., Assistant to the ChiefJunior Asst. to the Chief Elizabeth Stephens, B.S., Geological AssistantVelda A. MillardHelen E. McMorris, Secretary to the ChiefBerenice Reed, Supervisory Technical Assistant

GEOLOGICAL RESOURCESArthur Bevan, Ph.D., D.Sc, Principal Geologist

CoalG. H. Cady, Ph.D., Senior Geologist and HeadR. J. Helfinstine, M.S., Mechanical EngineerGeorge M. Wilson, M.S., GeologistRobert M. Kosanke, M.A., Associate GeologistJohn A. Harrison, M.S., Assistant GeologistJack A. Simon, M.S., Assistant GeologistRaymond Siever, M.S., Assistant GeologistMary Barnes Rolley, M.S., Assistant GeologistMargaret A. Parker, B.S., Assistant GeologistKenneth E. Clegg, Technical Assistant

Oil and GasA. H. Bell, Ph.D., Geologist and HeadFrederick Squires, A.B., B.S., Petroleum EngineerDavid H. Swann, Ph.D., GeologistVirginia Kline, Ph.D., Associate GeologistWayne F. Meents, Assistant GeologistRichard J. Cassin, M.S., Assistant Petroleum En-gineerLester W. Clutter, B.S., Research Assistant

Industrial MineralsJ. E. Lamar, B.S., Geologist and HeadRobert M. Grogan, Ph.D., GeologistDonald L. Graf, M.A., Assistant GeologistJames C. Bradbury, A.B., Assistant GeologistRaymond S. Shrode, B.S., Assistant Geologist

Clay Resources and Clay Mineral TechnologyRalph E. Grim, Ph.D., Petrographer and HeadWilliam A. White, M.S., Associate GeologistHerbert D. Glass, M.A., Associate Geologist

Groundwater Geology and GeophysicalExplorationArthur Bevan, Ph.D., D. Sc, Acting HeadMerlyn B. Buhle, M.S., Associate GeologistM. W. Pullen, Jr., M.S., Associate GeologistRichard F. Fisher, M.S., Assistant GeologistMargaret J. Castle, Assistant Geologic DraftsmanRobert D. Knodle, M.S., Assistant GeologistJohn W. Foster, B.A., Assistant Geologist

Engineering Geology and Topographic MappingGeorge E. Ekblaw, Ph.D., Geologist and Head

Areal Geology and PaleontologyH. B. Willman, Ph.D., Geologist and HeadJ. S. Templeton, Ph.D., Geologist

Ruth Bickell, Technical AssistantJane Teller, A.B., Technical AssistantGEOCHEMISTRYFrank H. Reed, Ph.D., Chief ChemistGrace C. Johnson, B.S., Research Assistant

CoalG. R. Yohe, Ph.D., Chemist and HeadDonald R. Hill, B.S., Research AssistantJoseph E. Dunbar, B.S., Research Assistant

Industrial MineralsJ. S. Machin, Ph.D., Chemist and HeadTin Boo Yee, M.S., Assistant ChemistPaulene Ekman, B.A., Research AssistantGrace C. Moulton, M.S., Research Assistant

FluorsparG. C. Finger, Ph.D., Chemist and HeadRobert E. Oesterling, B.A., Special Research

AssistantJames L. Finnerty, B.S., Special Research AssistantChemical EngineeringH. W. Jackman, M.S.E., Chemical Engineer andHeadP. W. Henline, M.S., Chemical EngineerB. J. Greenwood, B.S., Mechanical EngineerJames C. McCullough, Research Associate

X-rayW. F. Bradley, Ph.D., Chemist and Head

PhysicsKenneth B. Thomson, Ph.D., PhysicistR. J. Piersol, Ph.D., Physicist EmeritusJanice Helen Howard, B.S., Research Assistant

Subsurface GeologyL. E. Workman, M.S., Geologist and HeadElwood Atherton, Ph.D., Associate GeologistDonald B. Saxby, M.S., Assistant GeologistRobert C. McDonald, B.S., Research AssistantLois E. Titus, B.S., Research Assistant

Mineral Resource RecordsVivian Gordon, HeadHarriet C. Daniels, B.A., Technical AssistantDorothy Gore, B.S., Research AssistantDorothy A. Foutch, Technical AssistantZora M. Kaminsky, B.E., Technical AssistantElene L. Roberts, Technical AssistantJanice J. Pohlman, Technical Assistant

Analytical ChemistryO. W. Rees, Ph.D., Chemist and HeadL. D. McVicker, B.S., ChemistHoward S. Clark, A.B., Associate ChemistEmile D. Pierron, M.S., Assistant ChemistWilliam F. Loranger, B.A., Research AssistantAnnabelle G. Elliott, B.S., Technical AssistantAlice M. Helmuth, B.S., Research AssistantRuth E. Koski, B.S., Research AssistantCharles T. Allbright, B.S., Research Assistant

MINERAL ECONOMICSW. H. Voskuil, Ph.D., Mineral EconomistW. L. Busch, Assistant Mineral EconomistNina Hamrick, A.M., Assistant Mineral EconomistEthel M. King, Research Assistant

EDUCATIONAL EXTENSIONGilbert O. Raasch, Ph.D., Associate Geologist

in ChargeMargaret Ann Hayes, B.S., Research AssistantLIBRARY

Anne E. Kovanda, B.S., B.L.S., LibrarianRuby D. Frison, Technical AssistantMarjorie Roepke, B.S., Technical Assistant

PUBLICATIONSDorothy E. Rose, B.S., Technical EditorM. Elizabeth Staaks, B.S., Assistant EditorMeredith M. Calkins, Geologic DraftsmanArdis D. Pye, Assistant Geologic DraftsmanWayne W. Nofftz, Technical AssistantLeslie D. Vaughan, Associate PhotographerBeulah M. Unfer, Technical Assistant

Consultants: Geology, George W. White, Ph.D., University of IllinoisCeramics, Ralph K. Hursh, B.S., University of IllinoisMechanical Engineering, Seichi Konzo, M.S., University of IllinoisTopographic Mapping in Cooperation with the United States Geological Survey.This report is a contribution of the Clay Resourses and Clay Mineral Technology Division. August 1, 1949


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CONTENTSPageSOME FUNDAMENTAL FACTORS INFLUENCING THE PROPERTIES OF SOILMATERIALS 5

THE COMPOSITION IN RELATION TO THE PROPERTIES OF CERTAIN SOILS . . 13


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SOME FUNDAMENTAL FACTORS INFLUENCING THEPROPERTIES OF SOIL MATERIALS

RALPH E. GRIM

The important factors of composi-tion controlling the properties of soilmaterials may be classified as follows (Ref.4*) :

1 ) Clay-mineral compositionthe rela-tive abundance of the clay-mineralcomponents and their particle-sizedistribution.

2) Nonclay-mineral composition- therelative abundance of each mineraland the size-grade distribution of itsparticles.

3) Electrolyte contentthe amount andkind of exchangeable bases and anywater-soluble salts.

4) Organic contentthe amount andkind.

5) Miscellaneous textural characteristicssuch as shape of quartz grains, degreeof parallel orientation of clay-mineralparticles, and silicification.

Not all of these factors apply in anygiven soil material, and their relative im-portance is not always the same. Currentresearches in the writer's laboratory andelsewhere have shown that certain com-ponents which may be present in soil ma-terials frequently exert a tremendous in-fluence on properties, even though they arepresent in very small amounts. The addi-tion or subtraction of such components byweathering processes, groundwater move-ment, or construction activities can there-fore change greatly the properties of soilmaterial.

This paper considers some of these com-ponents and offers an explanation of theiraction on the basis of present concepts ofthe structure of soil materials. It will serveour purpose best to start with a theory ofthe structure of soil materials in the p^sticcondition.* References are given at end of paper, p. 11

Theory of the Structure of SoilMaterials in the Plastic

ConditionWater added to dry soil materials is ad-

sorbed by the clay minerals and perhapssome other components. The importantclay minerals are made up of flake-shapedunits that occur both as unit flakes and asaggregates of book-like masses of flakes(Ref. 4). Much of the water is adsorbedon the basal plane surfaces of such units.

Hendricks and Jefferson (Ref. 7) havesuggested that the water molecules have adefinite orientation (Fig. 1) in the firstlayers adsorbed on the plane surfaces ofthe clay minerals. The first water mole-cules are oriented because their configurationfits with that of the oxygen layers in thesurface of the clay mineral units. Theorientation tends to propagate itself throughlayers of water some molecules in thicknessoutward from the surfaces of the clay min-erals. Starting with this concept of thestructure of the adsorbed water, a satis-factory theory of the structure of soil ma-terials in the plastic state can be evolved.A mass or sheet of oriented water mole-cules would be rigid like ice rather than

fluid, and therefore the initial adsorbedwater would not be fluid. But as largeramounts of water are added to dry clay,the layers of oriented water molecules be-come thicker and thicker. Because the forceorienting the water molecules is the struc-ture of the surface of the clay minerals, itis not reasonable that oriented water wouldgrow to an indefinite thickness on the claymineral surfaces. Further the presence ofadsorbed ions and molecules on the claymineral surfaces would tend to restrict thegrowth of the oriented water. Therefore,at some distance from the clav mineral sur-

[5


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CLAY MINERALOGY AND SOIL MECHANICS

Silica layerof clay mineral

Oriented watermolecules

-o-Qr- o-Qr-

Silica layerof clay mineral

Fig. 1.Schematic sketch of orientation of water moleculesadsorbed on the basal surfaces of the clay minerals. Largecircles represent oxygen atoms ; small circles hydrogen atoms

;

small black or shaded circles silicon atoms (after Hendricksand Jefferson).

faces, the water molecules would not beoriented,* that is, they would be fluid.

Oriented water would develop fromabout all basal plane surfaces of the clayminerals, and the rigid adsorbed water ofone surface would meet that of anothersurface. The rigid water would serve asa bond to hold the clay mineral units rigidlyin place. With increasing amounts ofwater the adsorbed layers would becomethicker until a thickness was reached atwhich orientation was nil or imperfect.Such water, having fluid properties, couldact as a lubricant between the flakes. Ac-cording to this concept, the plastic conditiondevelops in a clay-water system when thereis enough water to supply all the rigidwater that can develop on available surfacesand a little more water that has poor orno orientation to act as a lubricant betweenflakes (Fig. 2). Large amounts of addi-tional water provide much fluid water andgive the system the properties of a fluid.

In soil materials, the transition fromoriented to nonoriented water molecules(that is, from rigid to fluid water), maybe abrupt or somewhat gradual, but usually* A residual partial orientation of water, of course, exists

in liquid water (Ref. 12).

it is rather abrupt. If this is true thereshould be a sharp break in the plasticproperties at a given moisture content whenincreasing amounts of water are added toa dry soil material. Experimental data(Figs. 3, 4) show this. Figure 3 showsthat there is an abrupt reduction in powerrequired to extrude clay through a die whena certain moisture content is reached. Ex-trusion is exceedingly difficult until somefluid water is present. Curves that showcompression strength of sand-clay-watermixtures (Fig. 4) show that maximumstrength is developed within extremely nar-row moisture limits which probably corre-spond to the maximum amount of rigidwater that can be adsorbed. Additionalamounts of adsorbed water are at leastpartially unoriented with attendant largedecrease in compressive strength.A time factor may be involved in thedevelopment of some plastic properties.

For example, the compressive strength ofsome sand-clay-water mixtures increasesgradually within short periods of time incompacted masses (Ref. 5). The explana-tion is that a certain amount of time is re-quired for the water molecules to becomeoriented completely.


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EFFECT ON SOIL-WATER SYSTEMSNON PLASTIC STATE PLASTIC STATE

Claymineral

Orientedwater

molecules

Claymineral

Nc-n oriented/ \ -- \ -^-x ^ \/ water molecules

Fig. 2.Schematic presentation of character of water in nonplastic and plastic states.Effect of Minor Amounts of Cer-tain Components on the Properties

of Soil-Water SystemsExtremely small amounts of certain

chemicals have a tremendous influence onthe properties of soil materials. This hasbeen known for some time but the explana-tion has been obscure. An example is thelarge change in viscosity of sodium mont-morillonite-water slurries caused by theaddition of traces of sodium hexametaphos-phate (Ref. 13) (Table 1).

Table 1. Effect of (NaP03)6 on Viscosity ofSodium Montmorillonite-Water Suspension

to phosphates small amounts of magnesiumand boron are known to alter clay-bondingproperties. Small amounts of sodium,hydrogen, and aluminum as exchangeablebases greatly alter certain plastic properties.Table 2 presents Atterberg Limits fornatural clays (Ref. 14) and for some claystreated with various chemicals. The latter

data are preliminary and were obtained ina detailed study underway in the writer'slaboratory. The data show the tremendouseffect of the Na+ ion in montmorilloniteclays as compared to that of Ca++ or H + ,and the large effect of some chemicals onthe Limits of Na-montmorillonite. Theprecise effect of the treating agents onillite and kaolinite remains to be deter-mined, but the present data indicate that itis small. This is to be expected since theLimits for these natural clays are lowand the exchange capacity for illite and kao-linite are also low (20-40 and 3-15 respec-tively).

(NaP03 ) Gpercent Viscosity incentipoisesSodium

montmorillonite ....8 percent water.. .slurrv

0.20.4

482318

10o*c3

Not all the com]such an effect are

Donents whi

application of mineralogy to soil mechanics - grim

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