5
to*/ .9-
STATE OF ILLINOIS
DWIGHT H. GREEN, Governor
DEPARTMENT OF REGISTRATION AND EDUCATION
FRANK G. THOMPSON, Director
DIVISION OF THE
STATE GEOLOGICAL SURVEY
M. M. LEIGHTON, Chief URBANA
REPORT OF INVESTIGATIONS— NO. 104
ILLINOIS SURFACE CLAYS AS BONDING CLAYS FOR MOLDING SANDS
An Exploratory Study
R. M. Grogan and J. E. Lamar
PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS
URBANA, ILLINOIS 1945
ILLINOIS STATE GEOLOGICAL SURVEY
3 3051 00005 7459
STATE OF ILLINOIS
DWIGHT H. GREEN, Governor
DEPARTMENT OF REGISTRATION AND EDUCATION
FRANK G. THOMPSON, Director
DIVISION OF THE
STATE GEOLOGICAL SURVEY
M. M. LEIGHTON, Chief URBANA
REPORT OF INVESTIGATIONS— NO. 104
ILLINOIS SURFACE CLAYS AS BONDING CLAYS FOR MOLDING SANDS
An Exploratory Study
R. M. Grogan and J. E. Lamar
PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS
URBANA, ILLINOIS
1945
ORGANIZATION
STATE OF ILLINOIS
HON. DWIGHT H. GREEN, Governor
DEPARTMENT OF REGISTRATION AND EDUCATION
HON. FRANK G. THOMPSON, Director
BOARD OF NATURAL RESOURCES AND CONSERVATION
HON. FRANK G. THOMPSON, Chairman NORMAN L. BOWEN, Ph.D., D.Sc, LL.D., Geology ROGER ADAMS, Ph.D., D.Sc, Chemistry LOUIS R. HOWSON, C.E., Engineering ♦WILLIAM TRELEASE, D.Sc, LL.D., Biology EZRA JACOB KRAUS, Ph.D., D.Sc, Forestry ARTHUR CUTTS WILLARD, D.Engr., LL.D. President of the University of Illinois
GEOLOGICAL SURVEY DIVISION
M. M. LEIGHTON, Chief
♦Deceased.
(81613— 2M— 4-45)
SCIENTIFIC AND TECHNICAL STAFF OF THE STATE GEOLOGICAL SURVEY DIVISION
100 Natural Resources Building, Urbana
M. M. LEIGHTOX, Ph.D., Chief
Enid Townley, M.S., Assistant to the Chief
Velda A. Millard, Junior Asst. to the Chief
Helen E. McMorris, Secretary to the Chief
Effie Hetishee, B.S., Geological Assistant
GEOLOGICAL RESOURCES
Coal
G. H. Cady, Ph.D., Senior Geologist and Head L. C. McCabe, Ph.D., Geologist (on leave) R. J. Helfinstine, M.S., Mech. Engineer Charles C. Boley, M.S., Assoc. Mining Eng. Heinz A. Lowenstam, Ph.D., Assoc. Geologist Bryan Parks, M.S., Asst. Geologist Earle F. Taylor, M.S., Asst. Geologist
(on leave) Ralph F. Strete, A.M., Asst. Geologist M W. Pullen, Jr., M.S., Asst. Geologist Robert M. Kosanke, M.A., Asst. Geologist Robert W. Ellingwood, B.S., Asst. Geologist George M. Wilson, M.S., Asst. Geologist Arnold Eddings, B.A., Research Assistant
(on leave) Henry L. Smith, A.B., Asst. Geologist Raymond Siever, B.S., Research Assistant (on leave) John A. Harrison, B.S., Research Assistant
(on leave) Mary E. Barnes, B.S., Research Assistant Margaret Parker, B.S., Research Assistant Elizabeth Lohmann, B.F.A., Technical Assistant
Industrial Minerals
J. E. Lamar, B.S., Geologist and Head H. B. Willman, Ph.D., Geologist Robert M. Grogan, Ph.D., Assoc. Geologist Robert T. Anderson, M.A., Asst. Physicist Robert R. Reynolds, M.S., Asst. Geologist Margaret C. Godwin, A.B., Asst. Geologist
Oil and Gas
A. H. Bell, Ph.D., Geologist and Head Carl A. Bays, Ph.D., Geologist and Engineer Frederick Squires, B.S., Petroleum Engineer Stewart Folk, M.S., Assoc. Geologist (on leave) Ernest P. DuBois, Ph.D., Assoc. Geologist David H. Swann, Ph.D., Assoc. Geologist Virginia Kline, Ph.D., Assoc. Geologist Paul G. Luckhardt, M.S., Asst. Geologist
(on leave) Wayne F. Meents, Asst. Geologist James S. Yolton, M.S., Asst. Geologist Robert X. M. Urash, B.S., Research Assistant Margaret Sands, B.S., Research Assistant
Areal and Engineering Geology
Ph.D., Geologist and Head M.S., Asst. Geologist
George E. Ekblaw, Richard F. Fisher,
Subsurface Geology
L. E. Workman, M.S., Geologist and Head Carl A. Bays, Ph.D., Geologist and Engineer Robert R. Storm, A.B., Assoc. Geologist Arnold C. Mason, B.S., Assoc. Geologist
(on leave) C. Leland Horberg, Ph.D., Assoc. Geologist Frank E. Tippie, B.S., Asst. Geologist Merlyn B. Buhle, M.S., Asst. Geologist Paul Herbert, Jr., B.S., Asst. Geologist Charles G. Johnson, A.B., Asst. Geologist
(on leave) Margaret Castle, Asst. Geologic Draftsman Marvin P. Meyer, B.S., Asst. Geologist Robert X. M. Urash, B.S., Research Assistant Elizabeth Pretzer, A.B., Research Assistant Ruth E. Roth, B.S., Research Assistant
Stratigraphy and Paleontology
J. Marvin Weller, Ph.D., Geologist and Head Chalmer L. Cooper, M.S., Assoc. Geologist
Petrography
Ralph E. Grim, Ph.D., Petrographer
Richards A. Rowland, Ph.D., Asst. Petrographer
(on leave) William A. White, B.S., Research Assistant
Physics
R. J. Piersol, Ph.D., Physicist
B. J. Greenwood, B.S., Mech. Engineer
GEOCHEMISTRY
Frank H. Reed, Ph.D., Chief Chemist
H. W. Jackman, M.S.E., Chemical Engineer
P. W. Henline, M.S., Assoc. Chemical Engineer
James C. McCullough, Research Associate
James H. Hanes, B.S., Research Assistant (on leave)
Leroy S. Miller, B.S., Research Assistant
Elizabeth Ross Mills, M.S., Research Assistant
Coal
G. R. Yohe, Ph.D., Chemist
Herman S. Levine, B.S., Research Assistant
Industrial Minerals
J. S. Machin, Ph.D., Chemist and Head Delbert L. Hanna, A.M., Asst. Chemist
Fluorspar
G. C. Finger, Ph.D., Chemist
Oren F. Williams, B.Engr., Research Assistant
X-ray and Spectrograph}'
W. F. Bradley, Ph.D., Chemist
Analytical
O. W. Rees, Ph.D., Chemist and Head L. D. McYicker, B.S., Chemist Howard S. Clark, A.B., Assoc. Chemist William F. Wagner, M.S., Asst. Chemist Cameron D. Lewis, B.A., Asst. Chemist Herbert X. Hazelkorn, B.S., Research Assistant William T. Abel, B.A., Research Assistant Melvin A. Rebenstorf, B.S., Research Assistant Marian C. Stoffel, B.S., Research Assistant Jean Lois Rosselot, A.B., Research Assistant
MINERAL ECONOMICS
W. H. Yoskuil, Ph.D., Mineral Economist Douglas F. Stevens, M.E., Research Associate Ethel M. King, Research Assistant
PUBLICATIONS AND RECORDS
George E. Ekblaw, Ph.D., Geologic Editor Chalmer L. Cooper, M.S., Geologic Editor Dorothy E. Rose, B.S., Technical Editor Meredith M. Calkins, Geologic Draftsman Beulah Featherstone, B.F.A., Asst. Geologic
Draftsman Willis L. Busch, Principal Technical Assistant Portia Allyn Smith, Technical Files Clerk Alicia Woodall, Technical Assistant Leslie D. Vaughan, Asst. Photographer
Consultants: Ceramics, Cullen W. Parmelee, M.S., D.Sc, and Ralph K. Hcrsh, B.S., University of Illinois
Mechanical Engineering, Seichi Konzo, M.S., University of Illinois Topographic Mapping in Cooperation with the United States Geological Survey. This report is a Contribution of the Industrial Minerals Division,
April 10. 1945
Digitized by the Internet Archive
in 2012 with funding from
University of Illinois Urbana-Champaign
http://archive.org/details/illinoissurfacec104grog
CONTENTS
Page
Abstract 7
Introduction 8
Basis for selection of samples 9
Distribution and character of surface clay deposits sampled 9
Till 9
Gumbotils and associated clays 9
Loess 11
Lake clays 11
Residual clays 11
Other clays 12
Chemical analyses 12
Preparation of samples for testing 12
Pulverized natural and de-pebbled clays 13
Clay concentrates 13
Air-separated fractions 13
Testing sand 17
Testing procedure 17
Results of tests 18
Interpretation of test data 18
Natural and de-pebbled clays 18
Green compressive strength 18
Dry compressive strength 18
Compressive strength and content of minus 0.002 mm. material 18
Mineral composition 19
Clay concentrates 19
Green compressive strength 20
Dry compressive strength 19
Effect of eliminating material larger than 0.002 mm 19
Air-separated fractions i 19
Green compressive strength 19
Dry compressive strength 20
Permeability 20
General effect of different size fractions 20
Particle size composition of clays and strength of minus 0.010 mm. air-separated
fractions 21
Influence of clay mineral composition 21
Illinois surface clays and beneficiation 36
Appendix — Description of deposits sampled 37
ILLUSTRATIONS
Figure Page
1 Location and type of sampled deposits of Illinois surface clays 10
2 A Curves showing green and dry compressive strengths (at various moisture contents)
of synthetic sands containing commercial bond clays and bentonites, and surface clays 28
2B Curves showing green and dry compressive strengths (at various moisture contents)
of synthetic sands containing air-separated fractions and clay concentrates 30
TABLES
1 Chemical analyses of surface clays 12
2 Location and thickness of deposits sampled and mechanical analyses of field samples
of surface clays 14
3 Sieve analyses of disc-pulverized natural and de-pebbled clays 16
4 Results of air-classification of ground surface clays 16
5 Particle size distribution of selected gumbotils and associated clays and of air-
separated fractions from the same samples 17
6 Average sieve test of testing sand 17
7 Results of bonding tests 22
8 Strength data at comparable moisture contents 32
9 Index to samples 34
10 Green compressive strengths of several clays and of the corresponding clay concentrates 34
11 Green and dry compressive strengths imparted by sample 18 and by various size
fractions derived from it 35
ILLINOIS SURFACE CLAYS AS BONDING CLAYS FOR MOLDING SANDS
An Exploratory Study
BY
R. M. Grogak and J. E. Lamar
Abstract
SAMPLES of surface clays from various parts of Illinois, including one sample of glacial till, twelve gumbotils and associated clays, one loess, three lake clays, seven residual clays, and three miscellaneous clays, were tested for green and dry compressive strength in parallel with several commercial bonding clays, including fireclays and bentonites, to determine their value as bonding clays for synthetic molding sands.
The compressive strength tests were made according to procedures approved by the American Foundrymen's Association. They involve determining the strength of a moist mixture of silica sand and the clay being tested or of a similar mixture which has been allowed to dry. The amounts of sand, clay, and moisture present are care- fully proportioned.
The results of the tests on sand-clay mixtures containing the natural clays, un- modified except for the removal of pebbles from pebbly samples, indicate that with 8 percent clay and 2 percent moisture, six of the samples possessed green compressive strengths equal to or greater than those of three of the nonbentonitic commercial bond- ing clays. The dry compressive strengths of most of the surface clays equalled or ex- ceeded those of the nonbentonitic commer- cial bonding clays.
The bonding ability of some clays was considerably improved by removing all the material larger than 0.002 mm. by water-
classification. Tests on sand-clay mixtures containing 2 percent moisture and 8 percent of the pulverized water-separated clay con- centrate from three surface clays, in- cluding two lake clays and one gumbotil. showed an increase in green compressive strength of 2 to 9]/> times that of the un- modified clay. The green compressive strengths imparted by two of the clay con- centrates compared favorably with green strengths given by the bentonites, 4 percent clay and 2 percent moisture being used for all tests. The dry strengths were somewhat lower than those of the bentonites.
An increase in bonding ability also resulted from the removal of coarse material from a sample of gumbotil by air-separation. Before air-classification the green compres- sive strength of this clay was less than that of any of the commercial bonding clays used for comparison. However, the air- separated minus 0.010 mm. fraction gave a green strength greater than any of the four nonbentonitic commercial clays using 8 per- cent clay and 2 percent moisture for all tests.
Air-separated fractions of a number of additional gumbotils and associated clays were also prepared. Most of the minus 0.010 mm. fractions, in sand-clay mixtures employing 8 percent of clay and 2 percent moisture, exceeded in green compressive strength the two bentonites tested at 4 per- cent clay, 2 percent moisture. The dry compressive strengths imparted by 8 per- cent of these fractions approximated those given by the bentonites at 4 percent clay.
[7]
8
SURFACE CLAYS AS BONDING CLAYS
The minus 0.050 mm. and the plus 0.050 mm. air-separated fractions generally gave lower green compressive strengths than the minus 0.010 mm. fraction at the same moisture content when 8 percent clay was used in sand-clay mixtures. The dry com- pressive strengths of both fractions were generally similar to those produced by the bentonites at 4 percent clay.
The green and dry compressive strengths of the samples tested are related to the relative amounts of clay-size (minus 0.002 mm.) and silt-size (0.002 mm. to 0.053 mm.) material present in the samples. In general it was found that the more clay- size material in a surface clay the higher its green compressive strength, and the more silt-size material in a clay the higher its dry
compressive strength. These relations may prove useful in prospecting for bonding clay even if beneflciation by removal of sand is planned, for they appear to be true of the air-separated fractions as well as of the unmodified clays.
From the tests it appears that the Cre- taceous clays tested, some residual clays, and possibly some lake clays would be suit- able in their natural state, or after coarse screening, for ordinary foundry use. The other clays would need more or less bene- flciation in order to compare favorably with commercial bonding clays. Some surface clays may be made to have bond strengths comparable to those of the bentonites by either hydraulic or air-classification.
Introduction
"Surface clays" are defined for this report as those clays occurring at or near the surface of the ground, including clays resulting from the weathering of bedrock. Extensive deposits of surface clays exist at many places in Illinois, but in general they are not much used commercially except locally for the manufacture of structural clay products. Because significant data are lacking regarding the suitability of these clays for purposes other than for making clay products, a study was undertaken to secure such data. A previous report * gave preliminary information about gumbotil, one kind of surface clay, as drilling mud, bonding clay, and bleaching clay. The present report extends the study of bonding properties to include further data regarding gumbotil as well as similar information about a number of other surface clays.
In contrast to "natural bonded" molding sands which as found in nature contain enough clay to bond them, that is, to cause the sand grains to adhere to one another, "synthetic" molding sands are prepared by adding a bonding clay to a clean sand of suitable grain size. Although natural bond-
ed molding sands are extensively employed, synthetic sands 2 are also widely used and their use is increasing. In the Middle West the bonding clays commonly used for synthetic sands are fireclay and bentonite.
Although in the Middle West there is probably no scarcity of fireclay and other clays which can be used as bonding clay, few materials having properties which approach or equal those of bentonite are known. For this reason the work covered by this report had as its aim the discovery of Illinois surface clays whose bonding properties are better than those of fireclay and as nearly like those of bentonite as possible.
Twenty-seven typical Illinois surface clays, all of them noncalcareous, were selected for study together with six commer- cial bonding clays including four produced in the Middle West, a Southern bentonite from northern Mississippi, and a Western bentonite from the Black Hills area. The results of the tests on the commercial clays serve as standards for evaluating the possi- bilities of the Illinois materials.
1 Lamar, j. E., Grim, R. E., and Grogan, R. M., Gum- botil as a potential source of rotary drilling mud, bonding clay and bleaching clay: Illinois Geol. Survey, Cir. 39, July IS, 1938.
2 The term "synthetic sands" is used hereafter to denote both commercially prepared synthetic molding sands and, more commonly, the laboratory mixtures of sand and pulverized clay used in the bond clay tests.
DEPOSITS SAMPLED
Basis for Selection of Samples
The surface clays of Illinois may be classified into six general categories as follows : ( 1 ) till deposited by continental glaciers; (2) gumbotil produced by pro- longed weathering of till under special con- ditions; (3) loess formed by the deposition of fine-sized wind-borne material; (4) lake clay deposited in old lake basins; (5) re- sidual clay mostly resulting from the weathering of limestones; and (6) certain other clays, three of which are included in this investigation.
The clay samples selected for the present study comprise only a small fraction of the total number taken for the general study of Illinois surface clays. They were chosen to represent the various types of surface clays, both with respect to kind of deposit and to mineral composition. All are from deposits free from calcareous materials or are from the noncalcareous weathered por- tions of deposits which were originally cal- careous throughout. The general location of the sampled deposits is shown in figure 1.
Bonding clays are composed of one or more of the clay minerals illite, kaolinite, or montmorillonite, plus various amounts of nonclay minerals such as quartz, limo- nite, and mica. Bentonites, for example, are made up dominantly of the clay mineral montmorillonite, whereas fireclays are commonly mixtures of kaolinite, illite, and quartz. Preliminary microscopic and X-ray examination indicated that a number of the surface clays contain montmorillonite. These clays were given particular attention because of the possibility that the presence of the montmorillonite might give them properties approaching those of bentonite.
In general it was necessary to take samples where favorable conditions existed, as in cuts along streams, railroads, or roads. All the samples are believed to have come from deposits of considerable size although not necessarily from the place most suit- able for commercial development. They represent, therefore, the types of surface clays and surficial clay deposits occurring in Illinois, but there exist many other deposits
than those tested, and any attempt at development should be preceded by a study of the relation of available deposits to market areas, followed by careful prospect- ing and testing of the deposits to determine their extent and character.
Distribution and Character of Surface Clay Deposits Sampled
till
Till is a sandy pebbly clay deposited by glaciers. Unweathered till commonly con- tains many limestone pebbles and other calcareous material and is therefore unsuit- ed for use as bonding clay. During weather- ing, however, water percolating through the deposit dissolves and removes the cal- careous material, leaving behind a noncal- careous gray or brown plastic clay better suited to foundry use. Pebbles other than those composed of limestone are also left behind to form a part of the weathered deposit. These pebbles vary in abundance from place to place.
Till is widespread in Illinois, occurring over the entire State except in extreme southern Illinois, parts of Calhoun and Carroll counties, and the northwest corner of the State. In most of northeastern Illinois the thickness of the nocalcareous till rarely exceeds 2 feet, but elsewhere the thickness may be twice that great.
Sample 48, described in the appendix, is leached till.
GUMBOTILS AND ASSOCIATED CLAYS
Gumbotil is a product of the extreme weathering of glacial till on flat uplands under conditions of poor drainage. It is a highly plastic, gray or brown clay, common- ly pebbly but less pebbly than the parent till, containing silt and sand in amounts which vary widely in different localities. When dried, the clayey and silty varieties become hard and tough, whereas the sandy varieties are usually crumbly and friable.
Deposits occur in central, southern, and western Illinois. Because overburden on the gumbotil is relatively thin in south-central Illinois, the deposits in that area were
10
SURFACE CLAYS AS BONDING CLAYS
TYPE OF DEPOSIT
• Residual clay
Q T.
3 GumboHl
■ Loess
G2 Lake clay
A Other clays
J040M.LES
Fig. 1. — Location and type of sampled deposits of Illinois surface clays.
DEPOSITS SAMPLED
11
given more attention than those elsewhere. Samples from nine of these deposits were tested during the present study. Further details of the general occurrence, extent, and character of Illinois gumbotil deposits are given in Circular 39. 3
Immediately below the gumbotil there is normally a zone of noncalcareous clay 4 whose character is intermediate between that of the gumbotil above and the cal- careous relatively unaltered till below. As it lies immediately below gumbotil and might considerably increase the workable thickness of clay in a given area if proved suitable for bonding use, samples of this clay were taken for testing from three localities that were also sampled for gum- botil. They bear the same sample number as the gumbotils but are distinguished from them by the suffix A added to the sample number.
Descriptions of deposits sampled are given in the appendix and include samples 18, 55, 55A, 56, 57, 58, 58A, 59, 59A, 60, 61, and 62.
LOESS
Loess is a wind-deposited brown clayey silt occurring over large areas on the up- lands adjacent to Mississippi, Illinois, and Ohio rivers. It is the surficial material throughout much of western and southern Illinois. The unweathered loess is common- ly calcareous except in extreme southern Illinois, but the upper part of many deposits has been leached by weathering to a depth of 2 to 4 feet. Only noncalcareous loess was investigated, as calcareous material is con- sidered deleterious in bonding clay. Sample 49, described in the appendix, is loess.
LAKE CLAYS
The lake clays studied were deposited in lakes associated with glaciers which once
3 Lamar, J. E., Grim, R. E., and Grogan, R. M. Gum- botil as a potential source of rotary drilling mud, bonding clay, and bleaching clay; Illinois Geol. Survey Cir. 39, July 15, 1938.
4 Zone 3 of the "soil profile." For a detailed description of its character and origin see Leighton, M. M.. and MacClintock, Paul, Weathered zones of the drift sheets of Illinois: Illinois Geol. Survey, Report of In- vestigations No. 20, 1930.
covered most of Illinois. These clays gener- ally contain a considerable proportion of silt. Although the clays were calcareous when deposited, leaching has removed the cal- careous material from the upper part of the deposits to a depth of 2 to 5 feet. Only the leached part of the deposits was studied.
Samples 3, 53 and 150, described in the appendix, are lake clays.
RESIDUAL CLAYS
Most of the residual clays found in Illinois have been formed by the weathering of limestone and are the insoluble materials left behind when wrater leached away the soluble portions of the limestone. Obviously the character of these clays is directly related to the character of the original limestones, cherty limestones giving rise to cherty clays, for example, and sandy lime- stones to sandy clays.
The residual clays are commonly red or brow7n owing to their content of hydrated iron oxides, though in a few places white or cream-colored clays have developed from limestones. Many residual clays contain angular chert fragments, although some are free from chert.
Because the dowmward progress of leach- ing is rarely uniform, it is probable that the limestone floor of most deposits is uneven, and that as a consequence the thickness of the clay in any deposit is likely to be vari- able. It is thought likely that residual clays are generally thickest a short distance below the tops of hills, ridges, or upland flats underlain by limestone where slumping of the clays has made their thickness greater than normal. No deposits were observed whose thickness is consistently greater than 15 feet, but exposures of clay 5 to 10 feet thick are relatively common.
The overburden on the residual clays is generally a few feet to as much as 25 feet of brown clayey silt. Considerable tonnages of clay can probably be obtained with less than 10 feet of overburden.
Residual clays occur in three principal areas in the State (fig. 1): (1) Union, Johnson, Pope, Massac, and Hardin coun- ties in extreme southern Illinois; (2) Cal-
12
SURFACE CLAYS AS BONDING CLAYS
houn, Pike, and possibly some adjacent counties in western Illinois; and (3) the extreme northwest corner of the State.
Samples of typical residual clay from seven deposits were chosen for study and are described in the appendix, including samples 8, 21, 24, 31, 44, 50, and 52.
OTHER CLAYS
Three samples have been placed in this category. Sample 4 is from a deposit of Cretaceous age, sample 54 is probably of Creaceous age, and sample 45 is from a glacial deposit.
Chemical Analyses
Chemical analyses are not generally reli- able guides to the bonding characteristics of clays except in a broad way. For this reason only a few analyses were made of Illinois surface clays, chiefly to supplement the information on the mineralogic and mechan- ical composition of some of the more prom- ising materials studied.
Analyses of four clays are given in table 1. Silica, alumina, and combined water (loss on ignition) are the principal con- stituents of the clays. They reflect the presence of clay minerals, which are essen- tially hydrous aluminum silicates, and in
some samples, the presence of free silica in the form of sand and silt.
Sample 18 shows more silica than the other samples because it contains more sand and silt (table 1). The total soda and potassia in each sample is in a large degree an indication of the relative amounts of soda- and potash-bearing clay minerals, such as illite and montmorillonite, in that clay. The chief clay mineral present in the kaolin is kaolinite, which contains very little soda and potassia.
Preparation of Samples for Testing
The commercial bonding clays (excepting the bentonites) were received in lump form and were ground in a disc pulverizer in preparation for bond tests. The bentonites were received already ground.
The samples of surface clays were pre- pared for testing by one of three methods : ( 1 ) grinding all of that part of the sample which passed a 4-mesh sieve; (2) concen- trating and removing from the original sample by water-separation that fraction composed of particles less than 0.002 mm. in diameter, followed by drying and grind- ing; and (3) air-separating three size frac- tions from pulverized clay from which the plus 4-mesh material had been removed before grinding.
Table 1. — Chemical Analyses of Surface Clays'
|
Sampleb 4 |
Sample0 18 |
Sample 21 |
Kaolind |
|
|
Si02 . |
59.60 0.72 26.48 2.39 0".77 0.44 0.37 1.67 8.03 |
79.04 0.51 11.04 3.47 0.03 0.72 0.39 0.85 1.45 3.18 |
56.96 0.37 23.47 8.84 6 '.82 0.53 0.30 1.56 7.92 |
51.10 |
|
Ti02 . |
0.95 |
|||
|
A1203 |
34.01 |
|||
|
Fe203 |
1.41 |
|||
|
MnO |
||||
|
MgO . . |
0.37 |
|||
|
CaO |
0.15 |
|||
|
Na20 |
0.36 |
|||
|
K20 . |
0.31 |
|||
|
Loss on ignition |
11.95 |
|||
|
Total |
100.47 |
100.65 |
100.77 |
100.61 |
a Analyses made under the direction of O. W. Rees, State Geological Survey.
b Sample 4, Cretaceous clay; 18, gumbotil ; 21, residual clay; Kaolin, Cretaceous clay.
c Average of two analyses.
d Analysis of crucible clay from deposit near Kaolin Station, Union County, similar to sample 54.
PREPARATION FOR TESTING
13
PULVERIZED NATURAL AND DE-PEBBLED CLAYS
The first method involved air-drying, breaking of lumps, and thorough mixing of the field sample, after which a small rep- resentative portion was separated by a Jones-type sample splitter and set aside for mechanical analysis. If the sample contained pebbles these were removed by hand-pick- ing. The plus 4-mesh material thus segre- gated was weighed and discarded. About 15 pounds of the pebble-free material, or of the original sample if it contained no pebbles, was then ground in a disc pulver- izer, and the resulting product was used in bonding tests. In discussing results of these tests samples prepared as indicated above are referred to as "natural" if they con- tained no pebbles and as "de-pebbled" if pebbles were removed. Mechanical analyses of the original field samples are given in table 2. Sieve analyses of the pulverized samples are given in table 3.
CLAY CONXEXTRATES
The upper size limit of the material that is believed to consist largely of clay minerals in the samples studied is about 0.002 mm. The amount of this material is less than 40 percent in many of the samples. To deter- mine the properties of this clay mineral material, especially in samples appearing to contain montmorillonite, the minus 0.002 mm. fractions of samples 3, 18, and 150 were separated by suspending the sample in water to which a small amount of sodium oxalate had been added to insure dispersion of the clay mineral material, and after an appropriate settling period the minus 0.002 mm. material in suspension was siphoned off. The clay mineral concentrates thus ob- tained were dried and pulverized in prepa- ration for use in bonding tests.
AIR-SEPARATED FRACTIONS
By means of a laboratory air classifier, selected samples that had been previously
pulverized after removing any pebbles present, were sized to three fractions: minus 0.010 mm., 0.010 to 0.050 mm., and plus 0.050 mm., which is roughly plus 270- mesh. Microscopic examination showed a small amount of particle size overlap be- tween fractions.
Average yields of the three air-separated tractions for each sample are given in table 4. The results of hydrometer analyses of unground clay and the air-separated frac- tions for samples 18, 59, and 59A are given in table 5.
A comparison of the data in table 4 and the results of hydrometer analyses of the unground samples and minus 0.010 mm. fractions, table 5, indicates that only 26 and 27 percent, respectively, of the minus 0.010 mm. material in samples 18 and 59, and 63 percent of that in sample 59A was ac- tually recovered by air-separation. This is thought to be due partly to imperfect separation of particles of various sizes in the air classifier, but more largely to in- complete disintegration of samples during grinding. Minus 0.010 mm. material is present in the plus 0.010 mm. fractions, both as particles below 0.010 mm. in size which were not removed by air-separation, and as particles bound up in aggregates not completely disintegrated into minus 0.010 mm. particles during grinding. Commercial processes are probably available which would achieve better disintegration of samples and thus permit greater recovery of minus 0.010 mm. material than was possible with the laboratory equipment em- ployed in this work.
Calculations based on the data in tables 4 and 5 indicate that a minor amount of plus 0.010 mm. material was reduced to minus 0.010 mm. size as a result of the grinding procedure used.
Bonding tests were made on the three air- separated fractions: minus 0.010 mm.; minus 0.050 mm. (obtained by recombining parts of the minus 0.010 mm. and 0.010 mm. to 0.050 mm. fractions in their proper proportions) ; and plus 0.050 mm.
14
SURFACE CLAYS AS BONDING CLAYS
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16
SURFACE CLAYS AS BONDING CLAYS
Table 3. — Sieve Analyses of Disc-pulverized Natural and De-pebbled Clays
Sample No.
+65 mesh
Percent retained
— 65 mesh + 100 mesh
—100 mesh + 150 mesh
—150 mesh +200 mesh
-200 mesh
|
48 |
2.1 |
|
|
18 |
1.3 |
|
|
49 |
1.1 |
|
|
3 53 150 |
2.2 trace 5.9 |
|
|
8 |
0.5 |
|
|
21 24 31 44 50 52 |
0.6 0.6 0.0 0.2 0.0 trace |
|
|
4 45 54 |
0.0 1.4 trace |
|
|
A |
2.7 |
|
|
B.. |
0.7 |
|
|
C |
0.3 |
|
|
D. . |
trace |
|
|
Southern Western |
bentonite bentonite |
i |
15.6
12.5
3.0
Till
Gumbotil
.5
12.7
Loess
Lake Clays
6.3
0.2
14.4
2.0
8.5
2.2 6.3
Residual Clays
13.3
6.7 7.2 2.5 6.1 2.3 0.6
Other Clays
0.3
11.4 4.4
2.3
5.6
Commercial Bonding Clays
12.4 9.6 6.6
8.2
9.3
8.3
10.2
10.1
11.3
K)
3.8
12.1
7.7 5.3
11.8 14.0 7.2 9.3 9.1 10.9 7.6
7.2 8.0
7.5
8.5 8.3 9.6 8.5
59.5
62.7
90.1
|
70.9 89.9 68.1 |
|
61.7 69.0 77.8 81.0 76.8 80.6 88.7 |
|
90.2 71.1 82.5 |
|
67.1 73.1 73.3 73.2 |
90 percent or more through 200 mesh as received.
Table 4. — Results of Air-classification of Ground Surface Clays
Sample No.
Percent of given size fraction yielded1
—0.010 mm.
0.010 mm. to 0.050 mm.
+0.050 mm.
Total —0.050 mm.
18..
55..
55A.
56..
57..
58..
58A
59..
59A
60..
61..
62..
|
11.8 |
21.5 |
66.7 |
33.3 |
|
14.4 |
15.7 |
69.9 |
30.1 |
|
18.8 |
13.5 |
67.7 |
32.3 |
|
11.0 |
19.9 |
69.1 |
30.9 |
|
15.1 |
42.8 |
42.1 |
57.9 |
|
13.6 |
15.9 |
70.5 |
29.5 |
|
14.9 |
11.9 |
73.2 |
26.8 |
|
11.4 |
15.5 |
73.1 |
26.9 |
|
13.1 |
10.7 |
76.2 |
23.8 |
|
111 |
43.4 |
45.5 |
54.5 |
|
10.5 |
28.7 |
60.8 |
39.2 |
|
11.0 |
30.1 |
58.9 |
41.1 |
1 In most cases the figures shown are the averaged results of more than one operation of grinding and air-separation.
TESTIXG PROCEDURE
17
Table 5. — Particle Size Distribution of Selected Gumbotils and Associated Clays and of Air- separated Fractions from the Same Samples.1
Sample Xo.
—0.010 mm.
Percent of given size fraction
0.010 mm. to 270 mesh
270 mesh to 14 mesh
+ 14 mesh
Unground clay
18.. 39 33 26 2
59 36 28 33 3
59A 18 25 35 22
Minus 0.010 mm. air-separated fraction
18 86 14 0 0
59 85 15 0 0
59A 86 14 0 0
0.010-0.050 mm. air-separated fraction
18 49 50 1 0
59 50 48 2 0
59A 39 58 3 0
Plus 0.050 mm. air-separated fraction
18 34 25 41 0
59 29 20 51 0
59A 12 17 70 1
1 The amounts of materials finer than 270 mesh were determined by hydrometer analyses: the amounts of coarser materials by wet sieving the samples used for the hydrometer analyses.
Testing Sand
The sand used for testing was banding sand from the Ottawa, Illinois, district. The average of four sieve tests is given in table 6.
Some variation in grain size was shown between different bags and lots of the sand. These variations, however, produced no effects of observable significance.
Table 6. — xAverage Sieve Test of Testing Sand
Percent Mesh retained
48 22.7
65 33.6
100 31.8
Pan : 11.9
100.0
Testing Procedure
Green compressive strength, dry com- pressive strength, moisture, and green per-
meability determinations were made on mixtures of sand, pulverized clay, and dis- tilled water. Standard A.F.A. specifications for these tests ° were followed with a few minor exceptions, notably the omission of a dummy batch during mulling and the use of a sample of 100 grams instead of 50 grams in moisture determinations. The equipment used for all tests was of standard design. Moisture was determined with a "moisture teller." Green permeability was measured by the orifice method.
All the commercial bonding clays except the bentonites, all the surface clays, and all the air-separated fractions except those of plus 0.050 mm. size and one sample (18) of minus 0.010 mm. size were tested using 8 percent of the clay material. The plus 0.050 mm. air-separated fractions were used at 20 percent because they failed to give satisfactory results at 8 percent. The ben- tonites and the water-separated clay con- centrates were used at 4 percent because
5 American Foundrymen's Association, Testing and Grading Foundry Sands and Clays: 4th Ed., pp. 29-31, 32-38, 42-45, 61-62, 109-111, 122-125, 129-132, 1938.
18
SURFACE CLAYS AS BONDING CLAYS
bentonites are commonly reported to be used in about that amount in actual foundry practice.
Results of Tests
In the present study a working standard of comparison for estimating the probable usefulness of Illinois surface clays was obtained by testing four commercial non- bentonitic bonding clays and two commer- cial bentonites in the same manner as the surface clays.
The bentonites included one sample of Western bentonite from the Black Hills region and one sample of Southern benton- ite from northern Mississippi.
In presenting the results of tests and dis- cussing such data it is necessary to indicate the percentage of the sample used in making the tests. Usually the amount is 8 percent but in some cases 4 percent. For brevity the expression "8 percent clay" or "4 percent clay" is used to describe the amount of the sample employed, and when so used has no mineralogical or compositional significance although in most cases the sample would ordinarily be described as clay.
The results of green compressive strength tests for all samples and of dry compressive strength for all samples except 18, 24, 48 and 150, which were not tested for dry strength, are given in table 7. These results are shown graphically in figures 2A and 2B by curves joining points representing green and dry compressive strengths plotted against moisture contents. The strengths corresponding to certain moisture contents as indicated by the curves are compiled in table 8, to facilitate a comparison between samples. In table 8 the samples are arranged in order of decreasing green compressive strength at 2 percent moisture. This moist- ure content was chosen as a basis for com- parison because it is closest to the optimum for many of the clays tested and because the synthetic sands which contained less than 2 percent moisture were too dry to "work" well, even though they had higher green strength than they did at 2 percent moisture.
Interpretation of Test Data
In the discussion of test data which follows frequent reference is made to samples by sample number. In order to facilitate correlation of these sample num- bers with the kind of clay composing them and their general geographic location, an index to samples is included in table 9.
NATURAL AND DE-PEBBLED CLAYS
Green compressive strength. — The green compressive strengths of synthetic sands made with the six surface clays 4, 8, 21, 31, 52, and 54 (table 8) exceeded or otherwise compared favorably with those given by sands containing the commercial bonding clays B, C, and D, but did not equal those given by the mixture made with A. Samples 3, 44, 45, 50, and 53 may also have possi- bilities. The lower green strengths imparted by the remaining five clays indicate that in their natural state they are probably of the least importance of the clays tested. Of the eleven samples listed above, six are residual clays, two are lake clays, two are Cretaceous clays and one is glacial clay.
Dry compressive strength. — The dry compressive strengths of synthetic sands made with surface clays 3, 31, 44, 49 and 53 were consistently greater than those of sands made with the commercial clays A, B, C, and D. The strengths of samples 4, 8, 21, 45, and 50 were within the range shown by the commercial clays ; clays 52 and 54 were somewhat weaker. No tests were made on samples 18, 24, 48, and 150 because their low green strengths made them seem unpromising. Of the first ten samples mentioned above, five are residual clays, two are lake clays, one is loess, one is glacial clay and one is Cretaceous clay.
Compressive strength and content of minus 0.002 mm. material. — A comparison of tables 2 and 8 shows that in general the more minus 0.002 mm. material a sample contains the higher is its green compressive strength. Conversely, a large content of minus 0.002 mm. material is in many cases accompanied by a relatively low dry com- pressive strength. Silt has the opposite effect
IXTERPRETATIOX OF TEST DATA
19
on dry compressive strength as samples con- taining relatively large amounts of silt tend to have greater dry strength though this relationship is not altogether consistent.
Mineral composition. — Examination by means of the microscope and the X-ray have demonstrated the presence of two and commonly three of the clay minerals, kaolin- ite, illite, and montmorillonite, in appreci- able amounts in every sample excepting the kaolin from Union County, sample 54, which is dominantly kaolinite '. Thermal analyses of twelve samples, 3, 4, 8, 21, 24, 44, 50, 52, 56, 58, 58A, and 62 showed the probable additional presence of halloysite, and it is possible that halloysite occurs in similar samples for which no thermal analyses were made.
Accurate quantitative methods are not available for the determination of the rela- tive amounts of the various clay minerals in complex mixtures such as occur in sur- face clays. Until such methods are devised it is not feasible to attempt correlation of the bonding properties of the surface clays with their clay mineral composition.
CLAY CONCENTRATES
The studies of clay concentrates were made to determine whether superior bond- ing clays could be produced by hydraulic classification of surface clays so as to elimi- nate all materials coarser than 0.002 mm. and thus produce a concentrate of the clay mineral material present.
Green compressive strength. — The green compressive strengths of synthetic sands containing 4 percent of minus 0.002 mm. clay concentrates from samples 18 and 150, see table 8, were approximately the same as those given by 4 percent of the Western bentonite, table 8, but were lower than the values for the Southern bentonite. The clay concentrates from sample 3 showed less strength than the bentonites, indicating that more than 4 percent of this clay concentrate
8 Microscopic examinations and thermal analyses were made by the Petrographic Division of the State Geological Survey and X-ray analyses were made by W. F. Bradley also of the Survey.
7 Grim, R. E., Personal communication. Even this clay may be a mixture of kaolinite and halloysite.
would be necessary to produce equivalent strengths.
Dry compressive strength. — The dry compressive strengths imparted by the clay concentrates from samples 3, 18, and 150 at 4 percent clay were somewhat lower than those produced by the bentonites. This may be an advantage for certain foundry uses.
Effect of eliminating material larger than 0.002 mm. — An increase in the green com- pressive strengths of clays from which par- ticles larger than 0.002 mm. have been removed is indicated by a comparison of the green compressive strengths of synthetic sands made with 8 percent of the de-pebbled or natural surface clays and with 8 percent of the clay concentrates from the same clays, measured at comparable moisture contents, table 10. It is probable that the green com- pressive strength of other surface clays containing relatively small or moderate amounts of minus 0.002 mm. material might likewise be improved by a similar removal of the sand and silt which they contain.
AIR-SEPARATED FRACTIONS
The investigation of the properties of three size fractions (tables 4 and 5) pro- duced from pulverized surface clays by air- separation was made to explore the possibil- ity of producing superior bonding clays by this method and to determine the possible usefulness of any resulting byproducts. An upper size limit of 0.010 mm. was chosen for the finest fraction because material that size and finer has a high clay mineral con- tent and because a separation at that size may be a commercial possibility.
A second size limit of 0.050 mm. was chosen because material that size or finer is essentially a sand-free clay. This fraction is referred to as the minus 0.050 mm. fraction and includes all material finer than 0.050 mm.
The plus 0.050 mm. fraction is a by- product of the air-separation. Tests were made to determine its possible usefulness as a molding sand, either when used alone or with the addition of other sand.
20
SURFACE CLAYS AS BONDING CLAYS
Green compressive strength. — At 8 per- cent clay and 2 percent moisture, the minus 0.010 mm. fractions separated by air-classi- fication from 10 samples gave green com- pressive strengths (table 8) equal to or greater than commercial bonding clays B and D. Six gave green strengths equal to or exceeding the strength of clay C. Seven exceeded bonding clay A at 2 percent moist- ure but only one had a green strength equal to the optimum strength of clay A. To afford a direct comparison with the benton- ites, sample 18 was used in synthetic sands containing 4 percent clay instead of the usual 8 percent. The resulting green strengths were considerably lower than those given by the bentonites at 4 percent clay. As the strengths of sands made with 8 percent of this sample and of ten others exceeded those given by the bentonites at 4 percent clay and 2 percent moisture, it is concluded that strengths approximating those of the bentonites would have been obtained by using an amount of minus 0.010 mm. material between 4 and 8 percent.
The minus 0.050 mm. fractions of the six samples tested gave lower green strengths at the same moisture contents than the minus 0.010 mm. fractions of the same samples. At 2 percent moisture one sample gave a green strength which exceeded the strength of clays B and D but no sample gave a green strength equal to that of clays C or A. One sample, 59, gave at 8 percent clay a green compressive strength which exceeded that of the bentonites at 2 percent moisture and 4 percent clay; the others gave strengths approximately equal to the ben- tonites.
The tests on the plus 0.050 mm. fractions, approximately plus 270 mesh, are not direct- ly comparable with the results of any of the other tests because they represent the use of from 2i/? to 5 times as much clay-bearing material in synthetic sands as was used in testing other samples. They are interesting, however, in that they show that some degree of bonding power is retained in the sand- size portion of the air-classified clays, pre- sumably as a coating on the sand grains and in undisintegrated clay pellets. It is possible that the efficiency of grinding could be im-
proved commercially so as to release into the finer sizes much of the clay (see table 5) which remained in the coarse fraction.
Dry compressive strength. — The dry compressive strengths imparted by 8 percent of all three fractions were in general great- er than those given by commercial bonding clays A, B, C, and D, and practically all of them fell within the range of dry strengths shown by the Western and Southern ben- tonites at 4 percent.
Permeability. — Permeabilities were meas- ured on synthetic sands containing the air- separated fractions but not on synthetic sands containing bentonites or the other commercial bonding clays. The data, table 8, show that synthetic sands made with 8 percent of the minus 0.010 mm. fractions had generally higher permeabilities than those prepared with minus 0.050 mm. frac- tions. The probable explanation is that the fine clayey material of the minus 0.010 mm. fraction tends to coat the sand grains leav- ing clear much of the intergrain space, whereas in the case of the minus 0.050 mm. fractions the abundant silt-size particles (mostly nonclay material) tend to clog the spaces between sand grains and thereby re- duce permeability.
The permeabilities bear no recognizable relation to the relative amounts of clay, silt, or sand in the clays from which the air- separated fractions were obtained. They may, however, bear some relation to the size distribution of particles within the air- separated fractions although this is not evi- dent from the data at hand (table 5).
General effect of different size fractions. — In the tests on the air-separated fractions of samples 18, 55A, 58A, 59, 59A, and 62, the minus 0.050 mm. fractions gave lower green compressive strengths than the corres- ponding minus 0.010 mm. fractions, and it appears likely that the plus 0.050 mm. frac- tions would have given still lower green compressive strengths had they been used in the proportion of 8 percent instead of 20 percent in making synthetic sands. Hence the general effect of increasing the propor- tion of material larger than 0.010 mm. is the lessening of bonding ability, as if the
IXTERPRETATIOX OF TEST DATA
21
strength giving part of the sample were being diluted with relatively inert material. A specific example of the general relation- ships mentioned above is supplied by the data on sample 18 which includes figures on the green and dry compressive strengths of the de-pebbled clay as well as on the strengths imparted by the three air-separat- ed fractions and the minus 0.002 mm. frac- tion or clay concentrate obtained by water separation. For convenience table 1 1 shows these data assembled from their various places in table 8, and also data from tables 2 and 5 on the percent of each type of mate- rial present in the original sample. When compared on the common basis of 2 percent moisture, the data show that whereas 4 percent of the minus 0.010 mm. fraction gave essentially the same green strength as 8 percent of the de-pebbled clay, 8 percent increased the green strength almost five times. The following facts are also of im- portance: 8 percent of the minus 0.050 mm. fraction gave double the green strength resulting from the use of the same amount of de-pebbled clay; 8 percent of the minus 0.010 mm. fraction gave nearly the same green strength as 2y? times as much of the plus 0.050 mm. fraction ; 4 percent of the clay concentrate gave over two times the green strength imparted by 4 percent of the minus 0.010 mm. fraction or by 8 percent of de-pebbled clay.
Particle size composition of clays and strength of minus 0.010 mm. air-separated fractions. — The data in tables 2 and 8 in- dicate that in general the air-separated minus 0.010 mm. fraction from a natural or de-pebbled clay containing a relatively large amount of minus 0.002 mm. material
gave higher green compressive strengths to synthetic sands than did the minus 0.010 mm. fractions from clays containing less clay-sized material. As the minus 0.002 mm. fraction contains most of the clay mineral material present in the original sample this may be interpreted to mean that the greater the percentage of clay mineral material the greater is likely to be the green compressive strength imparted by the minus 0.010 mm. air-separated fraction. In the case of dry compressive strength, the minus 0.010 mm. fraction separated from a clay containing much clay mineral material gave generally lower strengths than the minus 0.010 mm. fractions obtained from more silty clays.
Similar relations of compressive strength to particle size composition and amount of clay mineral material also have been noted for the natural and de-pebbled surface clays. Apparently the size composition of the minus 0.010 mm. fraction reflects to a con- siderable degree the size composition of the original clay from which it was separated.
Influence of clay mineral composition. — The minus 0.002 mm. fractions of the air- separated gumbotils and related clays have been shown by a combination of optical, X-ray, and thermal analyses to contain mix- tures of the clay minerals illite, kaolinite, halloysite, and montmorillonite. As in the case of the natural and de-pebbled surface clays, it was not possible to determine accu- rately the relative proportions of the various clay minerals, and therefore it is not now possible to relate the variation in bonding ability of the several samples to differences in kind and relative amount of the clay mineral constituents, although such differences prob- ably do have an effect on the bonding abil- ity.
22
SURFACE CLAYS AS BONDING CLAYS
Table 7. — Results of Bonding Tests
Sample No.
Clay percent
Water percent
Green com- pressive strength
lb. per sq. in.
Dry com- pressive strength lb. per sq. in.
Green perme- ability
Commercial bonding clays
1)
Southern bentonite.
Western bentonite
|
4.5 |
|
3.6 |
|
2.7 |
|
2.3 |
|
1.7 |
|
4.0 |
|
3.1 |
|
2.4 |
|
1.8 |
|
1.3 |
|
4.0 |
|
3.3 |
|
2.4 |
|
1.8 |
|
1.5 |
|
4.0 |
|
3.2 |
|
2.4 |
|
1.8 |
|
1.3 |
|
4.6 |
|
3.2 |
|
2.1 |
|
1.2 |
|
4.3 |
|
3.1 |
|
2.1 |
|
2.0 |
|
1.1 |
|
11.5 |
|
13.9 |
|
18.2 |
|
14.1 |
|
9.7 |
|
2.9 |
|
5.0 |
|
7.5 |
|
9.2 |
|
7.8 |
|
3.6 |
|
5.7 |
|
10.0 |
|
12.8 |
|
12.1 |
|
3.8 |
|
5.7 |
|
8.1 |
|
8.7 |
|
7.2 |
|
3.6 |
|
4.9 |
|
8.2 |
|
12.9 |
|
3.9 |
|
4.4 |
|
5.3 |
|
5.6 |
|
9.4 |
114.4 82.8
55.6 40.8
17.5
50.3
38.7
24.8
15.3
7.6
96.6 68.2 38.8 30.5 17.0
36.8 34.9 20.3 14.2
6.5
61.6
51.4
36.3
8.3
>93.5
74.8 13.9
Till
|
48 |
8 |
3.6 3.1 2.3 1.1 |
1.4 2.4 3.2 4.0 |
Gumbotil
18
3.5 3.0 2.1 1.3
1.4 2.0 2.8 3.6
Loess
49,
3.7 2.9 1.8 1.2
2.1 3.1 4.9 5.0
101.3
67.5
32.7
4.6
RESULTS OF BOXDIXG TESTS
Table 7. — Results of Bonding Tests — Con't.
23
Sample No.
Clay
percent
Water percent
Green com- | Dry com- pressive pressive strength strength
lb. per sq. in. lib. per sq. in.
Lake clays
Green perme- ability
|
3 |
8 |
3.9 3.3 |
2.1 3.3 |
||
|
3.2 |
3.5 |
86.2 |
|||
|
2.6 |
5.1 |
||||
|
2.4 |
5.4 |
||||
|
2.3 |
51.8 |
||||
|
1.8 |
6.9 |
||||
|
1.7 |
35.2 |
||||
|
1.2 |
7.7 |
22.3 |
|||
|
53 |
8 |
3.7 |
2.4 |
118.5 |
|
|
2.9 |
4.0 |
76.4 |
|||
|
2.0 |
6.8 |
39.1 |
|||
|
1.2 |
5.8 |
8.6 |
|||
|
150 |
8 |
5.0 3.8 3.1 2.2 1.3 |
1.5 1.8 2.5 2.8 4.5 |
|
Residual clays |
|||||
|
8 |
8 |
5.6 4.0 |
1.8 2.4 |
||
|
3.4 |
4.0 |
58.1 |
|||
|
3.3 |
4.1 |
||||
|
2.5 |
6.4 |
||||
|
2.4 |
6.8 |
28.1 |
|||
|
2.2 |
32.9 |
||||
|
1.9 |
9.4 |
||||
|
1.8 |
20.7 |
||||
|
1.2 |
11.2 |
7.3 |
|||
|
21 |
8 |
5.5 4.1 3.4 3.2 2.4 2.3 1.9 1.8 1.4 1.3 |
1.8 3.0 5.0 10.0 14.1 8.9 |
41.3 22.3 11.4 4.6 |
|
|
24 |
8 |
3.8 3.1 2.3 1.7 1.1 |
2.0 2.5 3.3 4.6 7.0 |
||
|
31 |
8 |
4.2 |
2.4 |
135.7 |
|
|
3.2 |
3.9 |
90.5 |
|||
|
2.4 |
6.7 |
46.6 |
|||
|
1.9 |
9.9 |
31.2 |
|||
|
1.6 |
10.2 |
25.7 |
24
SURFACE CLAYS AS BONDING CLAYS
Table 7. — Results of Bonding Tests — Con't.
Sample No.
Clay percent
Water percent
ureen com- pressive strength
lb. per sq. in,
Dry com- pressive strength lb. per sq. in,
perme- ability
|
Residual clays - |
—Concluded |
||||
|
44 |
8 |
5.0 |
1.4 |
||
|
3.4 |
2.5 |
101.1 |
|||
|
3.3 |
2.5 |
||||
|
2.5 |
4.0 |
54.0 |
|||
|
2.4 |
4.1 |
||||
|
2.2 |
47.5 |
||||
|
2.0 |
6.4 |
||||
|
1.8 |
30.1 |
||||
|
1.3 |
20.2 |
||||
|
1.2 |
8.9 |
||||
|
50 |
8 |
3.2 |
3.2 |
49.0 |
|
|
2.2 |
5.5 |
26.1 |
|||
|
1.8 |
8.4 |
14.9 |
|||
|
1.3 |
6.7 |
4.0 |
|||
|
52 |
8 |
4.3 |
3.1 |
42.6 |
|
|
3.2 |
5.0 |
30.2 |
|||
|
2.2 |
9.3 |
17.0 |
|||
|
1.7 |
11.1 |
8.7 |
|||
|
1.3 |
7.4 |
Other clays
|
4 |
8 |
3.9 |
3.6 |
93.7 |
|
|
3.4 |
4.9 |
61.9 |
|||
|
2.5 |
7.7 |
36.4 |
|||
|
1.7 |
10.9 |
21.6 |
|||
|
1,4 |
9.4 |
12.7 |
|||
|
45 |
8 |
4.0 |
2.1 |
||
|
4.0 |
2.2 |
117.0 |
|||
|
3.5 |
3.2 |
78.5 |
|||
|
3.3 |
2.6 |
||||
|
2.5 |
5.7 |
46.2 |
|||
|
2.5 |
5.0 |
||||
|
2.0 |
8.1 |
||||
|
1.8 |
9.9 |
15.2 |
|||
|
1.8 |
20.0 |
||||
|
1.4 |
8.1 |
5.8 |
|||
|
54 |
8 |
4.0 4.0 |
2.2 2.0 |
||
|
3.3 |
4.2 |
||||
|
3.2 |
4.2 |
35.1 |
|||
|
2.8 |
6.4 |
26.7 |
|||
|
1.8 |
10.3 |
13.4 |
|||
|
1.4 |
8.3 |
9.5 |
Clay concentrates
|
3 |
8 |
3.3 |
9.1 |
||
|
4 |
5.0 |
<10 |
|||
|
3.9 |
1.4 |
69.9 |
|||
|
2.9 |
2.7 |
39.7 |
|||
|
1.9 |
4.1 |
29.0 |
|||
|
1.0 |
5.5 |
4.6 |
RESULTS OF BOXDIXG TESTS
25
Table 7. — Results of Bonding Tests — Con't.
Sample No.
Clay percent
Water percent
ureen com- pressive strength
lb. per sq. in.
Dry com- pressive strength lb. per sq. in.
Green perme- ability
Clay concentrates — Concluded
|
18 |
8 |
3.6 |
14.5 |
||
|
4 |
5.2 4.1 |
2.0 2.6 |
|||
|
3.4 |
4.2 |
51.2 |
|||
|
2.8 |
4.7 |
||||
|
2.1 |
6.9 |
||||
|
2.0 |
6.0 |
25.9 |
|||
|
1.1 |
9.0 |
7.0 |
|||
|
150 |
8 4 |
3.3 4.1 |
15.9 2.4 |
||
|
3.2 |
4.5 |
40.3 |
|||
|
3.0 |
4.4 |
||||
|
2.1 |
7.3 |
19.9 |
|||
|
1.1 |
8.7 |
7.1 |
|
Air-separated fractions, |
minus 0.01C |
mm. size |
|||
|
18 |
8 |
3.9 |
5.5 |
144.4 |
|
|
2.7 |
9.5 |
87.1 |
|||
|
1.9 |
14.8 |
45.8 |
|||
|
1.3 |
15.1 |
18.8 |
|||
|
1.2 |
4.1 |
||||
|
1.1 |
4.3 |
90 |
|||
|
18 |
4 |
3.6 2.4 |
2.5 2.5 |
90.3 58.9 |
|
|
1.6 |
4.1 |
32.6 |
|||
|
1.1 |
4.3 |
||||
|
55 |
8 |
3.9 2.9 |
4.7 9.4 |
87.9 72.1 |
|
|
2.2 |
14.5 |
48.1 |
|||
|
1.4 |
15.3 |
21.9 |
85 |
||
|
1.2 |
9.3 |
10.7 |
|||
|
55A |
8 |
3.9 2.8 |
3.2 6.0 |
102.3 72.8 |
100 |
|
95 |
|||||
|
2.0 |
8.7 |
36.5 |
100 |
||
|
1.4 |
9.7 |
20.9 |
90 |
||
|
1.1 |
9.2 |
60 |
|||
|
56 |
8 |
3.4 |
5.2 |
134.0 |
|
|
2.5 |
8.1 |
86.9 |
|||
|
1.9 |
12.7 |
55.9 |
|||
|
1.3 |
15.1 |
33.2 |
85 |
||
|
0.9 |
8.4 |
||||
|
57 |
8 |
3.9 |
2.6 |
132.7 |
|
|
2.9 |
4.1 |
94.5 |
|||
|
2.3 |
6.2 |
74.7 |
|||
|
1.3 |
8.9 |
15.9 |
85 |
||
|
1.2 |
7.3 |
10.0 |
|||
|
58 |
8 |
3.8 2.8 |
5.8 11.3 |
78.1 46.1 |
|
|
2.0 |
17.9 |
29.0 |
|||
|
1.4 |
15.6 |
13.6 |
85 |
||
|
1.0 |
6.8 |
26
SURFACE CLAYS AS BONDING CLAYS
Table 7. — Results of Bonding Tests — Con't.
Sample No.
Clay
percent
Water percent
Green com- pressive strength
lb. per sq. in,
Dry com- pressive strength lb. persq. in,
Green perme- ability
|
Air-separated fractions, minus |
0.010 mm. |
size — Concluded |
|||
|
58A |
8 |
3.8 2.7 |
3.8 7.5 |
118.3 65.5 |
115 |
|
115 |
|||||
|
2.1 |
11.1 |
39.9 |
120 |
||
|
1.8 |
12.3 |
33.9 |
130 |
||
|
1.4 |
14.2 |
15.2 |
100 |
||
|
1.1 |
10.5 |
70 |
|||
|
59 |
8 |
3.9 2.7 |
6.7 10 6 |
173.9 99.7 |
|
|
2.1 |
16.8 |
57.7 |
|||
|
1.4 |
16.4 |
30.5 |
95 |
||
|
1.1 |
12.8 |
12.8 |
|||
|
59A |
8 |
3.7 2.6 |
4.0 8.0 |
99.8 63.0 |
110 |
|
110 |
|||||
|
1.9 |
10.8 |
41.3 |
115 |
||
|
1.4 |
12.0 |
26.0 |
100 |
||
|
0.9 |
9.7 |
70 |
|||
|
60 |
8 |
3.6 2.6 |
4.1 7.3 |
110.6 73.4 |
|
|
2.0 |
11.0 |
62.4 |
|||
|
1.3 |
13.6 |
30.9 |
95 |
||
|
1.0 |
7.3 |
6.5 |
|||
|
61 |
8 |
3.6 2.6 |
5.6 9.6 |
||
|
1.9 |
14.0 |
||||
|
1.7 |
15.5 |
47.5 |
135 |
||
|
1.3 |
16.0 |
31.4 |
90 |
||
|
1.0 |
10.5 |
||||
|
62 |
8 |
3.8 2.7 |
5.1 8.4 |
||
|
1.9 |
12.8 |
||||
|
1.4 |
13.3 |
40.7 |
120 |
||
|
1.0 |
10.7 |
|
Air-separated fractions, |
minus 0.050 mm. size |
|||||
|
18 |
8 |
3.9 2.9 |
2.6 4.0 |
147.1 101.9 |
||
|
2.2 |
6.2 |
55.1 |
||||
|
1.3 |
8.4 |
16.0 |
||||
|
1.1 |
7.8 |
6.5 |
55 |
|||
|
0.9 |
3.6 |
|||||
|
55A |
8 |
2.7 2.1 |
4.4 6.3 |
60.2 |
140 |
|
|
140 |
||||||
|
1.5 |
8.1 |
17.5 |
90 |
|||
|
1.1 |
7.3 |
10.6 |
90 |
|||
|
0.9 |
6.3 |
|||||
|
58A |
8 |
2.7 2.0 |
3.7 6.7 |
65.9 39.1 |
140 |
|
|
140 |
||||||
|
1.5 |
10.2 |
23.7 |
100 |
|||
|
1.1 |
7.7 |
7.4 |
105 |
|||
|
0.9 |
3.5 |
RESULTS OF BONDING TESTS
27
Table 7. — Results of Bonding Tests. — Concluded.
Sample No.
Clay percent
Water percent
Green com- pressive strength
lb. per sq. in.
Dry com- pressive strength lb. per sq. in,
perme- ability
Air-separated fractions, minus 0.050 mm. size — Concluded
59
59 A.
62.
4.2 3.1 2.2 1.4 1.1 0.9
2.9 1.5 1.3 1.0
4.0
3.1 2.3 1.3 1.1 0.8
4.2 5.8 9.0 13.0 8.6 5.1
3.7 7.3 7.9 7.2
2.2 3.1 3.9 7.7 6.5 3.4
185.7
120.1
82.2
24.3
7.0
62.1
25.2
18.1
7.9
185.4 123.9
73.5
24.1
8.3
55
90 85 70
45
55
Air-separated fractions, plus 0.050 mm. size
|
18 |
20 |
3.8 |
7.3 |
154.3 |
110 |
|
2.7 |
11.8 |
88.2 |
120 |
||
|
1.9 |
15.6 |
39.8 |
100 |
||
|
1.3 |
6.3 |
21 |
|||
|
55A |
20 |
3.0 |
1.7 |
62.6 |
130 |
|
1.7 |
2.9 |
28.3 |
130 |
||
|
1.2 |
3.9 |
14.4 |
80 |
||
|
0.9 |
3.3 |
4.9 |
60 |
||
|
58A |
20 |
3.0 |
2.4 |
92.8 |
90 |
|
1.6 |
5.5 |
27.4 |
85 |
||
|
1.3 |
6.4 |
14.5 |
75 |
||
|
1.0 |
5.5 |
3.6 |
60 |
||
|
59 |
20 |
3.6 |
7.6 |
178.3 |
130 |
|
2.6 |
12.2 |
110.6 |
150 |
||
|
1.9 |
17.3 |
61.5 |
120 |
||
|
1.3 |
10.5 |
11.2 |
45 |
||
|
59A |
20 |
2.8 |
1.7 |
48.7 |
110 |
|
1.4 |
3.1 |
14.1 |
105 |
||
|
1.2 |
3.2 |
10.0 |
105 |
||
|
1.1 |
3.1 |
6.9 |
65 |
||
|
62 |
20 |
3.7 |
5.9 |
194.7 |
70 |
|
2.6 |
9.3 |
119.1 |
70 |
||
|
1.9 |
13.7 |
56.7 |
55 |
||
|
1.3 |
8.1 |
9.6 |
20 |
28
SURFACE CLAYS AS BONDING CLAYS
^120
Z
|
/ |
||
|
/ |
||
|
// // // |
S* |
|
|
/ / |
* |
|
|
// |
,S: |
|
|
4 |
6% C |
_AY |
COMMERCIAL BOND CLAYS
WESTERN BENTONITE SOUTHERN BENTONITE
4% CLAY
J
|
^ ' |
||
|
/ / // |
/ |
|
|
/ * '/ |
4% |
CLAY |
12 3 4
MOISTURE (PERCENT)
COMMERCIAL BENTONITES
— 8(R) \\^
— 21 (R) V
•- 31 (R)
— 52 (R)
8% CLAY
RESIDUAL CLAYS
Fig. 2A. — Curves showing green and dry compressive strengths (at various moisture contents) of synthetic sands containing commercial bond clays, bentonites, and surface clays.
RESULTS OF TESTS
29
|
GT GUMBOTIL OC OTHER CLAY L LOESS R RESIDUAL CLAY LC LAKE CLAY NB N ONBENTONITIC COMMERCIAL T TILL BONDING CLAY |
||||||||||||
|
1 1 24 (R) 4 4 (R) 5 0 (R) |
1 4 (OC) 4 5 (OC) 54 (OC) |
l 3 (LC) 18 (GT) 48 (T) 49 ( I. ) |
14 ^ z a 1 2 <n a u |
|||||||||
|
• 53 (LC) |
||||||||||||
|
P |
^ |
'•5 i tt t- H W |
||||||||||
|
/Ja |
f |
|||||||||||
|
• |
! ■ |
\\ |
/ N |
|||||||||
|
» • V. |
\ |
^>\ |
w 10 UJ ■ a. 4 2 o o z UJ o |
|||||||||
|
V V*. |
sN... |
|||||||||||
|
6'A C |
.AY |
8% CI |
.AY |
8% CLAY l |
||||||||
|
I |
2 3 * |
I |
2 3 - |
1 |
||||||||
|
/ |
i / |
// |
z d 100 a u ■ eod z o 60 u OC t- <0 u 40 > 10 (0 UJ E Q. 5 20 O O V tr a |
|||||||||
|
/ i 1 |
/ // |
|||||||||||
|
t 1 |
f |
/ / // |
||||||||||
|
/ i |
/ |
// |
// // 0 |
|||||||||
|
/ § / |
// |
// // |
||||||||||
|
8% C |
.LAY |
^ |
8% |
CLAY |
'/ |
Q% |
:lay |
|||||
|
1 2 3 « |
1 |
2 3 * MOISTURE (PERCENT) |
1 |
2 3 4 |
||||||||
|
RESIDUAL CLAYS OTHER CLAYS TILL, GUMBOTIL AND LAKE CLAYS |
Fig. 2A. — Curves showing green and dry compressive strengths (at various moisture contents; of synthetic sands containing commercial bond clays, bentonites, and surface clays.
30
SURFACE CLAYS AS BONDING CLAYS
I I
18 (GT) (4%)
18 (GT)
56 (GT)
60 (GT)
62 (GT)
|
;K |
||
|
ts |
||
|
• \ |
||
|
•J |
V |
|
|
\ |
i V |
|
|
V |
||
|
58 58A 59 " 59A i 8% CLAY 1 |
'GT )X [CTA) [GT ) (GTA) |
1 I
- 55 (GT )
55A (GTA)
57 (GT )
6 1 (GT )
|
/ / |
||
|
/ / / / |
||
|
/ / / |
||
|
/ . 1 :j 1 :/ |
||
|
4 |
f / |
|
|
/// If |
||
|
Q% C |
LAY |
12 3 4 12
MOISTURE (PERCENT)
MINUS O.OIOMM. SIZE FRACTIONS FROM Al R - SE PAR AT ION
Fig. 2B. — Curves showing green and dry compressive strengths (at various moisture contents) of synthetic sands containing air-separated fractions and clay concentrates.
RESULTS OF TESTS
31
GT GUMBOTIL
GTA CLAY ASSOCIATED
WITH GUMBOTIL LC LAKE CLAY
I I
55A (GTA)
. 58A (GTA)
6 2 (GT )
|
/ / |
||
|
/ / / |
||
|
/ / / |
||
|
/ / / |
||
|
/ . ' // |
f |
|
|
y / / |
||
|
/ / |
||
|
/ |
e% c |
LAY |
18 (GT)
59 (GT)
59A(GTA)
6% CLAY
|
y ' |
s t |
|
|
'2r |
4% C |
:lay |
z
IT W
a.
2 3 4 12 3 4
MOISTURE (PERCENT)
MINUS 0.050MM. SIZE FRACTIONS FROM AIR-SEPARATION CLAY CONCENTRATES
Fig. 2B. — Curves showing green and dry compressive strengths (at various moisture contents) of synthetic sands containing air-separated fractions and clay concentrates.
32
SURFACE CLAYS AS BONDING CLAYS
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STRENGTH DATA
33
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34
SURFACE CLAYS AS BONDING CLAYS
Table 9. — Index to Samples
|
Sample No. |
Kind of clay |
Nearest town |
County |
|
3 4 |
Lake Cretaceous |
Karnak Grand Chain Mermet |
Pulaski |
|
8 |
Residual |
Massac |
|
|
18 21 24 |
Gumbotil Residual Residual |
Louisville Eichorn Kampsville |
Clay Hardin Calhoun |
|
31 44 45 |
Residual Residual Glacial |
Council Hill Stockton Stockton |
Jo Daviess Jo Daviess Jo Daviess |
|
48 49 50 |
Leached till Loess Residual |
Chicago Heights Bartonville Eichorn |
Cook Peoria Hardin |
|
52 53 54 |
Residual Lake Cretaceous |
Eichorn Harrisburg Anna |
Hardin Saline Union |
|
55 55A 56 |
Gumbotil Gumbotil Gumbotil |
Marshall Marshall Montrose |
Clark Clark Cumberland |
|
57 58 58A |
Gumbotil Gumbotil Gumbotil |
Toledo Brownstown Brownstown |
Cumberland Fayette Fayette |
|
59 59A 60 |
Gumbotil Gumbotil Gumbotil |
Brownstown Brownstown Walnut Hill |
Fayette Fayette Marion |
|
61 62 150 |
Gumbotil Gumbotil Lake |
Swanwick Kinmundy Gilberts |
Perry Marion Kane |
Table 10. — Green Compressive Strengths of Several Clays and of the Corresponding
Clay Concentrates
|
Amount of |
Amount of |
Green com- |
||
|
minus 0.002 mm. |
ground sample |
Moisture |
pressive |
|
|
Sample No. |
material in |
used in bond |
content |
strength |
|
sample |
tests |
percent |
lb. per |
|
|
percent |
percent |
sq. in. |
3, natural
3, clay concentrate . .
18, de-pebbled....;. 18, clay concentrate .
150, natural
150, clay concentrate
|
35.6 100.0 |
8 8 |
3.3 3.3 |
3.3 9.1 |
|
31.4 100.0 |
8 8 |
3.6 3.6 |
1.4 14.5 |
|
35.3 100.0 |
8 8 |
3.3 3.3 |
2.4 15.9 |
STRENGTH DATA
35
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36
SURFACE CLAYS AS BONDING CLAYS
ILLINOIS SURFACE CLAYS AND BENEFICIATION
The data previously given on samples of various types of Illinois surface clays indi- cate that certain of them may be useful in their natural state as bonding clays whereas others require various amounts of beneficia- tion to bring them to their optimum con- dition. Although these data apply to a limit- ed number of samples it is believed that the following generalizations may be made regarding the surface clays found through- out Illinois and their need for beneficiation.
Leached glacial till and gumbotil and associated clays commonly contain relatively large amounts of silt and sand plus some pebbles. In their natural state the clay mineral material in these clays, which is the effective bonding agent in them, is too dilut- ed by the sand, silt, and pebbles to produce useful bonding strengths. However, in the case of several samples studied, removal of these diluting grains down to 0.010 mm. in size leaves a clay-rich material having good to superior bonding ability. Similar treat- ment doubtless would considerably improve other clays of this general type. Thus it appears that in general the commercial use of till, gumbotil, and associated clays is apt to depend in part upon their being bene- ficiated by suitable processes to eliminate the pebbles, sand, and much of the silt.
Leached loess clays are of variable com- position but usually are characterized by a relatively high silt content, a low sand con- tent and few, if any, pebbles. Here again the clay mineral material is diluted by silt and sand, and although the natural clays may be expected to give moderately high dry compressive strengths and low green compressive strengths, it is believed that the
green strength would be increased by proc- essing to remove most of the silt.
Leached lake clays as a rule contain no pebbles and only a relatively small amount of sand, but like loess they are high in silt. Tests on three samples show that lake clays in their natural state may be expected to impart low to medium green compressive strengths and high dry strengths. Elimina- tion of silt and sand from laboratory samples yielded a product which had green strengths comparable to the bentonites tested as a standard in this work. Thus it is believed that lake clays in general will be improved as bonding clays by the elimination of all or much of their sand and silt content.
Residual clays are of diverse kinds. Some are high in clay mineral materials and may be used in the natural state for bonding clays. Others are sandy or silty and may be improved by processing to remove these diluting materials. One of the most common undesirable materials in residual clays is chert. When fragments of chert occur in important amounts their removal will facil- itate the preparation of the clay for the market and will improve the quality of the finished product.
Cretaceous clays include both sandy and silty clays and also clays which are low in these constituents and therefore suitable for use as bonding clays in their natural state. The use of the varieties requiring processing would therefore seem to be un- justified.
The choice of methods for beneficiating Illinois surface clays to remove nonclay substances will depend on many diverse factors. However, it is believed there exist tried methods, including pneumatic and hydraulic classification, by which the desired aims may be accomplished.
APPENDIX
37
APPENDIX Description of Deposits Sampled
SAMPLE 3
Lake Clay
Cen. S. line SE. \/A SW. \/A SE. J4 sec. 26, T. 14 S., R. 2 E., Pulaski County About two miles southeast of Karnak, 5h feet of tough waxy noncalcareous silty clay from which sample 3 was taken, is exposed in the east bank of a drainage ditch known as Post Creek Cutoff. The noncalcareous clay stratum is covered by 7 to 10 feet of silt and is underlain by calcareous clay. The 7 to 10 feet of silt over- burden probably was overcast when the ditch was dug, and it is believed that the normal overburden on the noncalcareous clay is about 1 to 2 feet of silt and silty soil. A large quantity of noncalcareous clay is believed to be avail- able in adjoining areas.
SAMPLE 4
Cretaceous Clav
T. 14 S.
Cen. S. line SW. *4 SW. % sec. 27, R. 2 E., Pulaski County In a ditch and beneath the ditch bottom along an east-west road about two miles east of Grand Chain occur the following strata:
Ft.
6. Loess 8
5. Gravel, composed of chert pebbles
partly cemented with iron oxide .2 4. Clay, gray and brown mottled,
noncalcareous 3
3. Clay, gray, plastic, noncalcareous,
lower 2 feet somewhat browner 10 2. Clay, brown, and silt, brown and yellow, interbedded, both non- calcareous 3
1. Iron crust Strata 4, 5, and 6 crop out in the sides and bottom of the ditch; strata 1, 2, and 3 were explored with a soil auger. Because stratum 4 is closely similar to stratum 3 except in color, it was mixed with the latter in the proportion of 3 parts to 10 parts to form the composite sample referred to in this report as sample 4. The clay is of Cretaceous age and crops out on the west slope of an irregular ridge which trends approximately north-south. The deposit probably caps most of the ridge, and other deposits like it may cap similar hills and ridges in the vicinity. The loess and gravel overburden is probably thickest on the crest of the ridge and thinner on its flanks. It is believed, however, that a considerably quantity of clay may be available in the vicinity of the outcrop with an average of 10 to 15 feet of overburden.
SAMPLE 8
Residual Clay
E. line, SE. % NE. % sec. 22, T. 14 S., R. 3 E., Massac County Red cherty clay overlying the Ste. Genevieve limestone is exposed in a cut along the Chicago, Burlington & Quincy Railroad about one mile north of Mermet. It ranges up to 3 feet in thick- ness and is overlain by 8 feet or more of loess and possibly a thin layer of brown cherty gravel. The top of the ridge to the west of the outcrop is about 25 feet above the clay exposed in the cut, and a greater thickness of clay might be revealed by exploration there.
SAMPLE 18
Gumbotil
SE. cor. SW. 14 NE. 14 sec. 3 5, T. 5 N., R. 6 E., Clay County In a road-cut on the east side of Panther Creek about four miles north of Louisville, 3j feet of gumbotil is exposed, from which sample 18 was taken. The gumbotil is overlain by l£ to 2 feet of soil and silt and underlain by gumbo sand. The appearance of a considerable number of additional exposures of gumbotil in the gen- eral vicinity of the sampled outcrop suggests that the upland flats of the area are probably underlain by 2 to 4 feet of gumbotil having 3 to 5 feet of overburden. A large tonnage of gumbotil appears to be available in this general area.
SAMPLES 21, 50, AND 52
Residual Clays
Sees. 26, 35, and 36, T. 11 S., R. 7 E., Hardin County Samples 21, 50, and 52 were all taken from the same general locality and are therefore discussed together. Sample 21 was obtained from an outcrop in the cen. S. V2 S. V2 SW. XA SE. */£ sec. 26 in a gully on the west side of State Highway 34 and 2.3 miles north of Eichorn. The strata exposed are as follows:
Ft. In.
Soil 6
Silt, brown, clayey; probably
loess 6
Gravel, angular, brown and
yellow chert 6—9
Clay, red, plastic; contains a few chert fragments (Sample 21). A yellow zone occurs about
3l feet below the top 7
Clay, mottled red and reddish brown, silty, firm; contains scattered chert fragments. . .3 Covered
38
SURFACE CLAYS AS BONDING CLAYS
The deposit occurs on the north slope and some distance below the crest of a roughly east- west ridge underlain by the St. Louis limestone. As much as 5 feet of red clay may lie between the bottom of the exposed strata and the top of the underlying limestone. The thickness of the silty overburden probably increases toward the crest of the ridge. It is believed possible, how- ever, that a relatively large tonnage of clay with an overburden 10 feet thick or less may be available along the ridge.
About x/4 mile southwest of the above outcrop, in the NW. % NW. hi NE. % sec. 35, sample 50 was taken from an outcrop of 62 feet of red clay that contains chert fragments, especially in its upper 3 feet. The overburden consists of 2 feet of lighter colored silty clay, followed above by a 1 foot layer of chert pebbles which is capped by 1 foot of brown silt. This sample is from the same deposit of clay as sample 21 but is not necessarily residual from the same lime- stone strata. At the outcrop limestone does not appear below the clay, but in a nearby test pit, located higher on the hillside, limestone is reported to have been encountered beneath 10 to 15 feet of red clay.
Sample 52 was obtained in the NW. ^ NW. i/i NW. x/4 sec. 36 from a deposit of red clay containing chert fragments varying locally in abundance. Exposures occur in several road-cuts along the northeastern slope of a ridge. The maximum thickness of red clay observed was 6 feet, and sample 52 represents this thickness of clay. The overburden is brown silt approximate- ly 1 foot thick. The clay is believed to have been formed from the St. Louis limestone and hence to be related to the clay in the deposit from which samples 21 and 50 were obtained. Numerous outcrops of similar red clav in several gullies in the NE. M sec. 35, T. 11 S., R. 7 E., indicate that much of the surrounding area is underlain by red clay, a considerable part of which may have 10 feet or less of overburden.
SAMPLE 24
Residual Clay
NE. y4 SW. V4 SW. % sec. 4, T. 9 S., R. 2 W., Calhoun County Eight feet of cherty red clay, probably de- veloped from the Burlinton limestone, is exposed in a ditch along a gravel road west of Kamps- ville. The outcrop is in the north end of a gently sloping hill, the top of the hill being about 75 feet above the level of the outcrop. The overburden on the clay is clayey silt 3 feet or more thick. This outcrop and numerous others nearby suggest that there is a considerable quantity of similar residual clay in the area.
SAMPLE 31
Residual Clay
Cen. SE. V4 SW. % sec. 30, T. 29 N., R. 2 E., Jo Daviess County At this locality 1 to 3 feet of the reddish- brown, noncherty clay underlying l£ feet of clayey silt crops out in a cut on the south side
of a road. This clay is thought to have been derived from the Galena dolomite which is exposed immediately under the clay near the place where the sample was taken. The thickness of the clay probably exceeds 3 feet at places. The deposit occurs on the gently sloping east side of a ridge which trends roughly northwest. Council Hill Station on the Illinois Central Railroad is half a mile south of the sampled locality. Other deposits of the same kind of residual clay are exposed in other road-cuts in the vicinity and a considerable tonnage of clay may be available with less than 5 feet of overburden.
SAMPLE 44 Residual Clay
SW. cor. NW. % NE. *4 sec. 23, T. 27 N., R. 4 E., Jo Daviess County
A road-cut about 70 yards long along State Highway No. 78 about lj miles south of Stockton exposes a maximum of 4 feet of red noncherty clay resting on the Galena dolomite. The overburden consists of 1 to 3 feet of soil and silt. Other outcrops in the vicinity suggest that a deposit of workable size may be present in this area.
SAMPLE 45
Glacial Clay
SW. 14 NW. i/4 NE. 14 sec. 3, T. 26 N.,
R. 4 E., Jo Daviess County
About 5 miles south of Stockton on State
Highway No. 78, a cut-bank along the west
side of Plum River exposes the following strata:
Ft. In.
Soil, black 1
Clay, light yellowish-brown,
calcareous 3 6
Clay, brown and dark red, non- calcareous; contains a few pebbles of worn chert
(Sample 45) 4
Limestone The clay stratum from which sample 45 was taken is of uncertain origin. It may be an old glacial till from which weathering has eliminat- ed all calcareous material or possibly a water- laid clay of glacial origin. Although the extent of the deposit is not definitely known, an area of 100 acres or more situated between the main course of Plum River and the valley of Middle Fork may be underlain by noncalcareous clay of a generally similar nature.
SAMPLE 48 Till
NE. cor. NW. % SE. % sec. 16, T. 35 N., R. 14 E., Cook County
In the bank of a ditch near Chicago Heights, 2 feet of sandy, pebbly noncalcareous till, from which sample 48 was taken, is exposed below 10 inches of soil. The noncalcareous till grades downward into calcareous till which also con- tains a greater proportion of pebbles. A large
APPENDIX
39
quantity of material similar to sample 48 is available in the vicinity of the sampled locality. Samples of noncalcareous till could have been obtained at many places in northern Illinois, but the above site was selected because it is near Chicago and also near deposits of sand which may have value as molding sand but are low in natural bond.
SAMPLE 49
Loess
SE. % NE. % sec. 26, T. 8 N., R. 7 E, Peoria County Sample 49 was taken from an exposure half a mile southwest of Bartonville and approxi- mately 150 yards north of a main road. It represents 2 feet 8 inches of noncalcareous loess having an overburden of 1 foot of soil. Large quantities of similar loess are available.
SAMPLES 51 AND 52 (See Sample 21)
SAMPLE 53
Lake Clay
Cen. S. V2 SW. *4 sec. 15, T. 9 S., R. 6 E., Saline County Sample 53 was taken from 30 inches of dark gray plastic noncalcareous silty clay covered by about 1 foot of soil which was exposed in a ditch, now filled in, on the south edge of Harrisburg. At the base of the bed of noncal- careous clay is a zone 3 inches thick containing numerous nodules of impure calcium carbonate. Buff or gray calcareous silty clay lies below this zone. It is believed that the noncalcareous stratum may possibly extend over a large part of the flat area lying east and southeast of Harrisburg and that a large tonnage of this material may be available.
Because of the irregular shape of the clay bodies and the possible variability in the char- acter of the clay, careful prospecting is recom- mended to determine their extent and character. The deposits are located near the Gulf Mobile and Ohio Railroad. Detailed descriptions of the occurrence and characteristics of kaolin may be found in publications of the Survey and else- where. 1
SAMPLES 55 AND 55A
Gumbotil
NW. V4 SW. % NW. 14 sec. 27, T. 11 N.,
R. 12 W., Clark County The following succession of beds is exposed in a roadcut on the north side of U. S. Highway No. 40 where it descends the east bluff of Mill Creek approximately two miles southwest of Marshall :
Ft. In.
Soil, bu,F, silty 1 2
Silt, gray to light buff, silty, becoming pebbly toward
base 3 6
Gumbotil, gray and buff mottled, sandy, more pebbly, noncal- careous (Sample 55) 3
Till, gray and buff mottled sandy, more pebbly, noncal- careous (Sample 55A) 2 8
Till, grayish-brown, sandy, very
pebbly, calcareous 15
Road level
Much of the same sequence of beds is exposed in other cuts southwest along the same highway, and it is probable that gumbotil underlies siz- able areas of flat upland in the vicinity.
SAMPLE 56 Gumbotil
SAMPLE 54 Cretaceous Clay
Sec. 35, T. 11 S., R. 2 W., Union Co.
This sample is white kaolin from a commer- cial pit near Kaolin Station. The clay is prob- ably of Cretaceous age and occurs in bodies which are believed to occupy depressions in the surface of the bedrock. The deposits contain white, pink, bluish-gray, or chocolate-colored clays which are noncalcareous and plastic. Al- though in general free from impurities, the deposits locally contain lignitic material and in places layers or irregular masses of sand. The overburden is chiefly sand, gravel, and loess ranging from 5 to about 40 feet in thickness.
In recent years clay has been mined commer- cially in the area by W. E. Kreitner and Kreit- ner Kaolin Co., both of Cairo, and by the South- ern Illinois Minerals Co. of Murphysboro, and by the Eastern Clay Products Co., Eifort, Ohio. Part of the Eastern Clay Products Company's production is reported to have been bonding clay.
SW. 14 NW. i/4 NW. !/4 sec. 13, T. 9 N., R. 7 E., Cumberland County
Sample 56 was taken from a 5-foot thickness of noncalcareous clay exposed in a cut along the east side of a road about four miles north of Montrose. Above the clay is 2 feet, 2 inches of grayish-brown silt overlain by 2 feet of buff silty soil. Below the clay is a 1— to 4— inch heavily iron-stained zone succeeded by 5 feet of grayish-brown calcareous till. It is believed that the upper 3 feet of the sampled bed is gumbotil and that the lower 2 feet is the non- calcareous clay which characteristically occurs between the gumbotil and the underlying cal- careous till. Extensive flat areas extending north and east suggest the probable existence of an abundance of material like that sampled.
1 Parmalee, C. W.. and Shroyer. C. R., Further in- vestigations of Illinois fireclays; Illinois Geol. Survey Bull. 3sD. 1921. pp. 43-63.
Piersol, R. J.. Lamar. J. E.. and Voskuil, W. H., Anna "kaolin" as a new decolorizing agent for edible oils: Illinois Geol. Survey. Rept. Inv. No. 27, 1933.
Grim. R. I*'... Petrology of the kaolin deposits near Anna. Illinois: Econ. Geologv, vol. 29, No. 7, Nov. 1934, pp. 659-670.
40
SURFACE CLAYS AS BONDING CLAYS
SAMPLE 57 Gumbotil
Near cen. S. line, SE. *4 sec. 30, T. 10 N., R. 8 E., Cumberland County
A cut along the north side of State Highway No. 121 in the east bluff of a small creek about rive miles west of Toledo exposes 4 feet of gray and buff mottled silty gumbotil from which sample 57 was taken. The gumbotil is overlain by 20 inches of dark buff silt and above this 8 inches of brown sandy soil. Beneath the gum- botil appears 5 feet of very pebbly, yellow and gray, noncalcareous till and below that 3 feet of calcareous till. A large quantity of similar gumbotil probably underlies the flat areas which continue to the east and south.
SAMPLES 58 AND 58A
Gumbotil
West line, SW. V± NW. 14 NW. V± sec. 14, T. 7 N., R. 2 E., Fayette County Samples 58 and 58A were taken from an ex- posure of glacial clay in a cut along the east side of a gravel road about four miles north of Brownstown.
Ft. In.
Soil, dark gray to dark buff 1 3
Gumbotil, gray and brown mottled, sandy, contains a few small pebbles (Sample
58) 2
Till, gray and brown mottled, more sandy and pebbly than the gumbotil, noncalcareous
(Sample 58A) 3
Till, gray to chocolate-brown,
calcareous 4±
Till, brownish-gray, calcareous,
hard 5
Covered Numerous other road-cuts in this vicinity show from 2 to 1\ feet of gumbotil under 1] to 2 feet of soil and silt overburden, and it appears likely that a considerable amount of gumbotil is available.
(Sample 59A from upper- most Z\ feet) 4 4
Covered
An extensive flat upland north of this outcrop is probably underlain by the same type of gum- botil.
SAMPLE 60 Gumbotil
Near cen. N. line, NW. 14 NW. V± sec. 4, T. 1 S., R. 2 E., Jefferson County
Sample 60 is from 33 inches of gray silty gum- botil appearing in an outcrop on the south side of a gravel road some 50 feet west of the bridge over a shallow creek, about three miles east of Walnut Hill. The overburden consists of 20 inches of buff to gray silt overlain by 6 inches of soil. Below the gumbotil is exposed about 12 inches of noncalcareous till, browner and more pebbly than the gumbotil.
The land surface east and south of the sampled outcrop is gently rolling and probably underlain by gumbotil. Outcrops visible east- ward along the road show a greater thickness of overburden, and it seems probable that the usual thickness of overburden in this general area is 4 feet or more.
SAMPLE 61 Gumbotil
Near cen. E. line, NE. % NE. ^ NE. 14 sec. 33 T. 4 S., R. 4 W., Perry County
This outcrop is situated on the west side of a gravel road in the south valley wall of a shallow gully about 1\ miles south of Swanwick. Sample 61 represents 28 inches of mottled gray and brown pebbly gumbotil. It is overlain by 44 inches of gray to buff noncalcareous silt and 10 inches of soil. About 10 inches of noncalcareous gray till is exposed beneath the gumbotil.
Similar exposures in several nearby road-cuts show about the same thickness of gumbotil under 4 to 5 feet of overburden, and it is probable that this relation exists over a sizable area.
SAMPLES 59 AND 59A
Gumbotil
SW. ^4 SE. % NW. 1,4 sec. 14, T. 6 N., R. 2 E., Fayette County An outcrop along the east side of a gravel road in the north bluff of a small creek approxi- mately two miles south of Brownstown exposes the following beds:
Ft. In.
Soil, dark gray to gray 3 4
Gumbotil, brownish-gray above, mottled gray and brown be- low, sandy, pebbly (Sample
59) 2 6
Till, gray to brown, noncal- careous, more sandy and pebbly than the gumbotil
SAMPLE 62 Gumbotil
Cen. N. line, NW. 14 SE. V± sec. 25, T. 4 N., R. 2 E., Marion County
Sample 62 was taken from 30 inches of gray pebbly gumbotil in an exposure on the south side of a gravel road near the top of the east valley wall of a shallow gully about 3h miles west-southwest of Kinmundy. From 24 to 28 inches of gray to buff soil and silt occurs above the gumbotil, and 8 inches of noncalcareous gray till succeeded by 14 inches of mixed gray and buff slightly calcareous till lies below it.
Large quantities of gumbotil like sample 62 are probably available from extensive flat up- lands in the vicinity of the sampled deposit.
APPENDIX
41
SAMPLE 150
Lake Clay
SE. V± NW. 14 NW. V± sec. 24, T. 42 N.,
R. 7 E., Kane County The abandoned pit of the Walker Clay Products Co. at Gilberts exposes 2\ feet of gray
and brown, noncalcareous, silty clay from which sample 150 was obtained. The overburden con- sists of 14 inches of black soil. A considerable quantity of this clay is believed to be available in the vicinity of the pit.
Illinois State Geological Survey
Report of Investigations No. 104
1945