CERAMIC AND STRUCTURAL CLAYS AND SHALES OF CHATTOOGA COUNTY, GEORGIA BRUCE l. O'CONNOR DEPARTMENT OF NATURAL RESOURCES ENVIRONMENTAL PROTECTION DIVISION GEORGIA GEOLOGIC SURVEY \G EORGIA \ ( ) ~I 6 6 INFORMATION CIRCULAR COVER PHOTO: View to the northwest on Ga. Hwy. 48 through Shinbone Ridge on the west side of Menlo, Georgia, Chattooga County. The majority of the roadcut exposes westward-dipping sandstones and shales of the Red Mountain Formation (Silurian) which are overlain by the Chattanooga Shale (Devonian) and Fort Payne Chert (Mississippian) at the far end of the cut. (Map location no. Cht. 64-9 and 64-10 are from this general area.) ., CERAMIC AND STRUCTURAL CLAYS AND SHALES OF CHATTOOGA COUNTY, GEORGIA By Bruce J. O'Connor Principal Economic Geologist Information Circular 66 GEORGIA DEPARTMENT OF NATURAL RESOURCES J. Leonard Ledbetter, Commissioner ENVIRONMENTAL PROTECTION DIVISION Harold F. Reheis, Assistant Director GEORGIA GEOLOGIC SURVEY William H. McLemore, State Geolgist ATLANTA, GEORGIA 1985 TABLE OF CONTENTS SUBJECT Introduction . . . . . Acknowledgements . . . . Location of Study Area Explanation of Key Terms on the Ceramic Test and Analyses Forms . . . . . . . . . I. Absorption (%) . . . . . . . . . . . . 2. App. Por. (%) - Apparent Porosity, Percent 3. App. Sp. Gr. - Apparent Specific Gravity 4. Bloating . . . . . . . . . . . . . . . 5. Bloating Test (or Quick Firing Test) 6. Bulk Density (or Bulk Dens.) 7. Color . . . . . . . . . B. Color (Munsell) . . . . 9. Compilation Map Location No. 10. Cone . . . . . . 11. Drying Shrinkage . 12. Dry Strength . 13. Extrusion Test 14. Firing Range . 15. Hardness .. 16. Hardness (Mohs') 17. HCl Effervescence 18. Linear Shrinkage (%) . 19. Modulus of Rupture (MOR) 20. Mohs' . . . . . . 21. Molding Behavior 22. Munsell . . . . 23. "MW" face brick 24. PCE - Pyrometric Cone Equivalent 25. pH . . . . . . , 26. Plasticity .. . 27. Porosity, Apparent 28. Quick Firing . . . 29. Saturation Coefficient . 30. Shrinkage 31. Slaking . . . . . . 32. Slow Firing Test . . 33. Solu-Br. (Solu-Bridge) 34. Soluble Salts 35. Strength ... , 36. "SW" face brick 37. Temp. F (C) 38. Water of Plasticity (%) 39. Working Properties (or Workability) Ceramic Tests and Analyses of Clays and Shales in Chattooga County, Georgia . . . . . . . . . ,. . . ,. . ,. Data Sources and References Cited PAGE 1 3 4 9 10 10 12 13 13 14 14 14 IS 16 16 17 17 18 18 18 19 19 20 20 20 20 20 21 21 22 22 22 22 22 23 23 24 25 25 25 26 26 26 29 44 -iii- LIST OF ILLUSTRATIONS Figure 1 Plate 1 Location of Chattooga County Report Area ...... . Clay and Shale Test Locations in Chattooga County . ..................... ~ ................. . 4 Pocket LIST OF TABLES Table 1 Summary of 20th Century Clay and Shale Mines and Companies in Chattooga County, Georgia ... 5 Table 2 Generalized Summary of Stratigraphic Units in Chattooga County, Northwest Georgia ........... . 6 Table 3 Abbreviations for Terms on the Ceramic ~iring Test Forms..................................... 11 -iv- INTRODUCTION This report presents a compilation of all available published and unpublished ceramic firing tests and related analytical data on samples from Chattooga County, Georgia. It provides information on mined and/ or undeveloped clays, shales and related materials; and is intended for use by geologists, engineers and members of the general public. The report should aid in the exploration for deposits of ceramic raw material with economic potential for future development. This information may also be of use to those who wish to obtain information on the potential use of particular deposits at specific locations. Tests by the U.S. Bureau of Mines, subsequently referred to as USBM, were performed by the Norris Metallurgy Research Laboratory, Norris, Tennessee and the Tuscaloosa Research Center, Tuscaloosa, Alabama under cooperative agreements with the Georgia Geologic Survey and its predecessors (i.e., the Earth and Water Division of the Georgia Department of Natural Resources; the Department of Mines, Mining and Geology; and the Geological Survey of Georgia). Many of the firing tests were performed on samples collected by former staff members of the Georgia Geologic Survey (and its predecessors) during uncompleted and unpublished studies (Smith, 1968?). Additional unpublished data presented in this compilation include work by TVA (see Butts and Gildersleeve, 1948, p. 124 and 125) and by L. Mitchell (Department of Ceramic Engineering, Georgia Institute of Technology). Published data include studies by Veatch (1909, p. 282 to 392), Smith (1931, p. 119 to 122 and 339 to 340), and Hollenbeck and Tyrrell (1969, p. 17 to 20). -1- Regardless of the source, all of the ceramic firing testing data presented in this report are based on laboratory tests that are pre1iminary in nature and will not suffice for plant or process design. They do not preclude the use of the materials in mixes (Liles and Heystek, 1977, p. 5). ACKNOWLEDGEMENTS The author gratefully acknowledges the help of many individuals during the preparation of this report and the work of many who contributed to the earlier, unpublished studies included here. The cooperative work of the U.S. Bureau of Mines forms the main data base of this study. During the last several years Robert D. Thomson, Chief of the Eastern Field Operations Center, Pittsburgh, Pennsylvannia, was responsible for administering the funding of costs incurred by the USBM. Others in that office who helped coordinate the program were Charles T. Chislaghi and Bradford B. Williams. Since 1966 M.E. Tyrrell, H. Heystek, and A.V. Petty, Ceramic Engineers, and Kenneth J. Liles, Research Chemist, planned and supervised the test work done at the USBM Tuscaloosa Research Center in Tuscaloosa, Alabama. Prior to 1966 this test work was supervised by ceramists H. Wilson, G.S. Skinner, T.A. Klinefelter, H.P. Hamlin and M.V. Denny at the former Norris Metallurgy Research Laboratory in Norris, Tennessee. Tests by the Tennessee Valley Authority were conducted under the supervision of H.S. Rankin and M.K. Banks at the Mineral Research Laboratory on the campus of North Carolina State College, Asheville, North Carolina, using samples collected by S.D. Broadhurst. Additional tests were conducted by Professor L. Mitchell at the Department of Ceramic -2- Engineering, Georgia Institute of Technology, Atlanta, Georgia. The majority of the unpublished tests were performed on samples collected by former staff geologists of the Georgia Geologic Survey, predomi nantly by J.W. Smith, A.S. Furcron, R.D. Bentley, N.K. Olsen, D. Ray, and G. Peyton, assisted by C.W. Cressler of the U.S. Geological Survey. N.K. Olsen and C.W. Cressler also have provided the author with valuable advice and suggestions regarding sample locations and past studies. The advice and encouragement of my colleagues on the staff of the Georgia Geologic Survey are greatly appreciated. However, the contents of this report and any errors of omission or commission therein are the sole responsibility of the author. LOCATION OF STUDY AREA Chattooga County is located at the western side of the Valley and Ridge province of northwest Georgia (Fig. 1). Only two ceramic raw material mining operations are known to have been active here in the past (Table 1). The most abundant ceramic raw materials in the county are the shales and residual clays derived from the Floyd Shale and the Conasauga Group; however, other units such as the Lookout, Pennington and Red Mountain Formation shales and the residual clays of the Knox Group are locally we 11 developed. The general nature of these and other geologic units which occur in the county are summarized on Table 2. -3- N I REPORT MILES ~aru li I .\O I 0 10 20 KILOMETERS --r "'-I "\.. \ '\ -0./ .\I '"' GEORGIA .\ ~ l. ______ FIGURE 1 LOCATION OF CHATTOOGA COUNTY REPORT AREA (after Cressler, and others, 1976) -4- TABLE 1 Summary of 20th Century Clay and Shale Mines and Companies in Chattooga County, Georgia North American Chemical Co., (Ohio) (c. 1910-1914), Gore (GA.): Halloysite for alum manufacture (Butts and Gildersleeve, 1948, p. 112-116 and Broadhurst and Teague, 1954, p. 56-61). Tennessee Valley Mineral Co. (c. 1937-1941), Summerville and Harrisburg (GA.): Clay (also tripoli). NOTE: The information for the companies listed above was taken from the Mining Directories (Circular 2, 1st to 18th editions) published by the Georgia Geologic Survey and its predecessors at irregular intervals since 1937. Additional sources of information were found in the references cited at the end of each entry. -5- TABLE 2 Generalized Summary of Stratigraphic Units 1n Chattooga County, Northwest Georgia CHRONOSTRATIGRAPHIC UNIT STRATIGRAPHIC UNITS - THICKNESS AND ROCK TYPES !/ Quaternary (and Tertiary?) * Various unnamed bodies of alluvial, colluvial and residual material. Largely clay and sand, but also, locally, gravel and breccia. Pennsylvanian Pottsville Formation Crab Orchard Mts. Formation (or Group) or Walden Sandstone Sandstone, shale, coal, conglomerate and limestone. Includes: Rockcastle Member (or Sandstone or Conglomerate) - Approx. 50 ft., predominantly sandstone with dark shale; Vandever Member (or Formation or Shale)- Approx. 400ft., light to dark shale with interbedded siltstone, finegrained sandstone, and coal; Newton Member (or Sandstone or Bonair Sandstone) - Approx. 100ft., cross-bedded sandstone; Whitwell Member (or Shale) - Approx. 200ft., light-gray to black shale with some siltstone, sandstone and coal; and Sewanee Member (or Conglomerate) - Approx. 250ft., conglomeratic sandstone with minor coal. * Gizzard Formation (or Group or Member) or Lookout Sandstone (or Formation) - gray to tan shale, with interbedded siltstone, sandstone, coal and fire clay. Includes: Signal Point Member (or Shale) - Approx. 35ft., shale with some coal; Warren Point Member (or Sandstone) - App4ox. 150ft., conglomeratic sandstone with minor coal; and Raccoon Mtn. Member (or Formation)- Approx. 300ft., shale with coal. Mississippian *Pennington Formation (or Shale) - Approx. 100-300 ft., gray, green and red shale. Sandstone present in middle. Bangor Limestone- Approx. 300-480 ft., fine- to coarse-grained gray limestone with interbedded shale at top. **Floyd Shale- Approx. 100-2000 ft., silt and clay with some sandstone; limestone present at base. Approximate age-equivalent to Tuscambia Limestone and Monteagle Limestone. Hartselle Formation (or Member or Sandstone) - Approx. 15-30 ft., thin- to thick-bedded sandstone. -6- TABLE 2 Generalized Summary of Stratigraphic Units in Chattooga County, Northwest Georgia (continued) CHRONOSTRATIGRAPHIC UNIT STRATIGRAPHIC UNITS - THICKNESS AND ROCK TYPES l/ Mississippian, cont'd. Monteagle Limestone - Approx. 250 ft. Includes: Golconda Formation (or Limestone) - Approx. 15-20 ft., green fissile shale containing some thin limestone; Gasper Limestone- Approx. 150ft., gray, non-cherty limestone; and Ste. Genevieve Limestone- Approx. 245ft., gray, limestone. Tuscumbia Limestone - Approx. 125 ft. Includes: St. Louis L1mestone- Approx. 125ft., gray, very cherty limestone. Fort Payne Formation (or Chert) - Approx. 10-400 ft., thin- to thick-bedded chert and cherty limestone. Locally includes: *Lavender Shale Member- Approx. 0-200 ft., shale, massive mudstone and impure limestone. Devonian *Chattanooga Shale- Approx. 5-25ft., carbonaceous, fissile black shale. Armuchee Chert- Approx. 0-125 ft., thin- to thick-bedded chert. Silurian ** Red Mountain Formation (formerly Rockwood Formation) - Approx. 150-1200 ft., sandstone, red and green shale, with conglomerate, limestone and local hematitic iron ore. Ordovician Sequatchie Formation- Approx. 75-250 ft., sandstone, siltstone, shale, calcareous shale and limestone. *Chickamauga Group (or Limestone)- Approx. 1000-2300 ft., dominantly limestones with some dolostone and lesser shale, claystone, siltstone, sandstone, and bentonite clay horizons. Equivalent, in part, to the Moccasin Limestone and Bays Formation and to the Rockmart Slate and Lenoir Limestone. Includes: Maysville Formation and Trenton Limestone; -7- TABLE 2 Generalized Summary of Stratigraphic Units in Chattooga County, Northwest Georgia (continued) CHRONOSTRATIGRAPHIC UNIT STRATIGRAPHIC UNITS - THICKNESS AND ROCK TYPES !/ Ordovician, cont'd. Chickamauga Group, cont'd. Lowville-Moccasin Limestone; Lebanon Limestone; and Murfreesboro Limestone. Lenoir Limestone - Approx. 0-100+ ft. Includes: Mosheim Limestone Member-35ft.; and Deaton Member - 0-100+ ft, Cambrian-Ordovician (*)Knox Group- Approx. 2000-4500 ft., dominantly cherty dolostone, minor limestone. Includes: Newala Limestone- Approx. 100-400 ft., limestone and dolostone; Longview Limestone- Approx. 350ft.; Chepultepec Dolomite- Approx. 800+ ft.; and Copper Ridge Dolomite - Approx. 2500 ft. Cambrian **Conasauga Group (or Formation) - Approx. 950-5000 ft., pre- dominantly shale and limestone with minor sandstone. Includes: Maynardville Limestone- Approx. 50-300ft.; "Upper Unit" = Nolichucky Shale - Approx. 200-1000 ft., and Maryville Limestone?- Approx. 200-600 ft.; "Middle Unit" = Rutledge Limestone and Rogersville Shale? - Approx. 200-400 ft.; and "Lower Unit" = Pumpkin Valley Shale and Honaker Dolomite? - Approx. 30-500 ft. NOTES: * = Some ceramic firing tests have been made on shales or slates and clays of this unit. (*) = Same as the above, but for residual clays only. ** = Numerous firing tests have been made on this unit. ]} Descriptions based on data Bergenback and others, 1980; Butts and Gildersleeve, 1948; Chowns, 1972, 1977; Chowns and McKinney, 1980; Crawford, 1983; Cressler 1963, 1964a and b, 1970, 1974; Cressler and others, 1979; Croft, 1964; Georgia Geologic Survey, 1976; Gillespie and Crawford, in press; Thomas and Cramer, 1979. -8- EXPLANATION OF KEY TERMS ON THE CERAMIC TEST AND ANALYSES FORMS The test data and analyses which are presented here were compiled on 1t Ret of AtandRrdi:~~rd formA (Cf'rttrnic TeAt8 lilnd Analyseos) in the moRt concise manner consistent with the various laboratories represented. These forms are modified 1n large part after those used by the Pennsylvania Geological Survey (e.g., O'Neill and Barnes, 1979, 1981). It should be noted that, although the great majority of these tests were performed by the USBM, it was decided not to reproduce their data forms directly for several reasons. First, the USBM forms contain several entries which are not essential to this project (e.g., Date received) or do not make the most efficient use of space. Second, the USBM forms have been changed several times over the span of decades covered by the present compilation. Finally, investigators from other laboratories have reported parameters which were not measured by the USBM. The paragraphs which follow briefly describe, 1n alphabetical order, the more critical entries on the forms, the nature of the 1nformation included and, where possible, the various factors and implications to be considered in their interpretation. Many of the particular comments here are based on descriptive information published in the following sources. Tests by Georgia Geologic Survey authors are described in Veatch 0909, p. 50 to 64) and in Smith (1931, p. 19 to 25), while the particulars of the USBM studies are given in Klinefelter and Hamlin (1957, especially p. 5 to 41) and in Liles and Heystek (1977, especially p. 2 to 16). The discussions which follow are not intended to be exhaustive but are merely meant to remind the reader, -9- and potential user, of the key aspects of the information presented. Various technical texts and reports should be consulted for more detailed information (e.g., Clews, 1969; Grimshaw, 1972; Jones and Beard, 1972; Norton, 1942; Patterson and Murray, 1983). The abbreviations used on these test forms are defined in Table 3. 1. Absorption (%) The absorption 1s a measure of the amount of water absorbed by open pores 1n the fired specimen and 1s given as a percentage of the specimen's dry weight. For slow firing tests, it 1s measured on fired specimens which have been boiled in water for 2 to 5 hours and then kept immersed in the water for up to 24 hours while cooling (Smith, 1931, p. 22; Klinefelter and Hamlin, 1957, p. 27-28; Liles and Heystek, 1977, p. 3). For the quick firing tests, however, the specimens are not boiled but only cooled and then immersed in water for 24 hours (Liles and Heystek, 1977, p. 4). The absorption gives an indication of the amount of moisture which may be absorbed and subject to destructive freezing in outdoor structures. Less than 22% absorption is considered promising for slow-fired materials. 2. Appr. Por. (%) - Apparent Porosity, Percent The apparent porosity is a measure of the amount of open pore space in the fired sample, relative to its bulk volume, and is expressed as a percent. As in the case of absorption values, it is based on the weight and volume of the specimen which has been boiled in water for 2 to 5 hours and then kept immersed in water for several hours as it cools (Klinefelter and Hamlin, 1957, p. 27 to 28; Liles and Heystek, -10- TABLE 3 Abbreviations for Terms on the Ceramic Firing Test Forms ABBREVIATIONS Appr. Por. = Apparent Porosity App. Sp. Gr. = Apparent Specific Gravity Btw. = Bartow County C = Degrees Celsius Ct. =Catoosa County Cht. = Chattooga County Dd. = Dade County Dist. =District DTA = Differential Thermal Analysis E = East oF = Degrees Fahrenheit Fl. =Floyd County g/cm3 = Grams per cubic centimeter Gdn. = Gordon County Lab. & No. =Laboratory (name) and number (assigned in laboratory) Lat. =Latitude LOI = Loss on Ignition Long. = Longitude lb/in2 = Pounds per square inch lb/ft3 = Pounds per cubic foot Mry. = Murray County N = North NE = Northeast NW = Northwest org. = Organic Plk. = Polk County S = South SE = Southeast SW = Southwest Sec. = Section -11- Table 3. Abbreviations for Terms on the Ceramic Firing Test Forms (continued) 7 1/2' topo. quad. = 7 and 1/2 minute topographic quadrangle Temp. = Temperature TVA = Tennessee Valley Authority USBM = U.S. Bureau of Mines USGS =U.S. Geological Survey W = West Wkr. =Walker County Wf. = Whitfield County XRD = X-ray diffraction 1977, p. 3). The apparent porosity 1s an indication of the relative resistance to damage during freezing and thawing. Less than 20% apparent porosity is considered promising for slow-fired materials (O'Neill and Barnes, 1979, p. 14, Fig. 4). 3. App. Sp. Gr. -Apparent Specific Gravity As reported in earlier USBM studies, the apparent specific gravity is a measure of the specific gravity of that portion of the test specimen that is impervious to water. This is determined by boiling the sample in water for 2 hours and soaking it in water overnight or 24 hours (Klinefelter and Hamlin, 1957, p. 27 to 28). These data were replaced by bulk density and apparent porosity measurements after the USBM moved its laboratories from Norris, Tennessee to Tuscaloosa, Alabama in 1965. -12- 4. Bloating Bloating 1s the term g1ven to the process in which clay or shale fragments expand (commonly two or more times their original volume) during rapid firing. It results from the entrapment of gases which are released from the minerals during firing but which do not escape from the body of the host fragment due to the viscosity of the host at that temperature. Bloating is a desirable and essential property for the production of expanded lightweight aggregate where an artificial pumice or scoria 1s produced. Expanded lightweight aggregate has the advantages of light weight and high strength compared to conventional crushed stone aggregate. Bloating is not desirable, however, in making other structural clay products such as brick, tile and sewer pipe where the dimensional characteristics must be carefully controlled. In these cases bloating is extremely deleterious since it leads to variable and uncontrollable warping, expansion and general disruption of the fired clay body (Klinefelter and Hamlin, 1957, p. 39-41). 5. Bloating Test (or Quick Firing Test) The Bloating Test refers to the process of rapidly firing (or 11 burning 11 ) the raw sample in a pre-heated furnace or kiln to determine its bloating characteristics for pass ible use as a lightweight aggregate. Although specific details of the different laboratory methods vary, all use several fragments of the dried clay or shale placed in a refractory plaque (or 11boat 11 ) which in turn is placed in the pre-heated furnace for 15 minutes (Klinefelter and Hamlin, 1957, p. 41; Liles and Heystek, 1977, p. 4). -13- 6. Bulk Density (or Bulk Dens.) The bulk density is a measure of the overall density of the fired specimen based on its dry weight divided by its volume (including pores). Determinations are the same for slow firing and quick firing test samples, although for the latter the results are given in pounds per cubic inch as well as grams per cubic centimeter units (Klinefelter and Hamlin, 1957, p. 27 to 28 and 41; Liles and Heystek, 1977, p. 3 and 4). If quick-fired material yields a bulk density of less than 62.4 lb/ft3 (or if the material floats in water), it is considered promising for lightweight aggregate (K. Liles, oral communication, 1984). 7. Color The color of the unfired material, unless otherwise stated, repre- sents the crushed and ground clay or shale. In most cases this is g1ven for descriptive purposes only since it is generally of no practical importance for ceram1c applications (only the fired color 1s significant). Here only broad descriptive terms such as light-brown, cream, gray, tan, etc. are used. Fired colors are more critical and therefore more specific descriptive terms and phrases are used (Klinefelter and Hamlin, 1957, p. 18 and 19). In many cases the Munsell color is g1ven for a precise description (see discussion below). 8. Color (Munsell) This is a system of color classification based on hue, value (or brightness) and chroma (or purity) as applied to the fired samples in this compilation. It was used by Smith ( 1931, p. 23-25) and by the -14- USBM s1nce the early 1970's (Liles and Haystek, 1977, p. 3; Liles, oral communication, 1982). In all other cases the fired color was estimated visually. 9. Compilation Map Location No. This number or code was assigned by the author to provide a syste- matic designation to be used in plotting sample locations on the base maps as shown by the typical example below. Example: Map Locn. No. County Name - Abbreviation (Chat tooga) Cht. 31 S - 2la I Date ( 19 31) . Author's last initial (Smith) -for published data only Sample sequence number (one ffo per loc at ion). De signation used only for cases of more than one test per location. The map location number Cht. 31S-2la is derived from the county name (e.g., Cht. for Chattooga County), the year the tests were performed (e.g., 31 for 1931) plus the last initial of the author for major published sources (e.g., S for Smith), followed by a sequence number assigned in chronological order or sequential order for published data. (The only exceptions to this are the tests reported in Smith, 1931, wherein the sequence number of the present report is the same as the "Map location No." of Smith . ) Each map location number represents a -15- specific location, or area, sampled at a particular time. In cases where several separate samples were collected from a relatively restricted area, such as an individual property, such samples are designated a, b, c, etc. Different map location numbers have been assigned to samples which were collected from the same general locality, such as a pit or quarry, but which were collected by different investigators at different times. 10. Cone Standard pyrometric cones, or cones, are a pyrometric measure of firing temperature and time in the kiln. They are small, three-sided pyramids made of ceramic materials compounded in a series, so as to soften or deform in progression with increasing temperature and/or time of heating. Thus, they do not measure a specific temperature, but rather the combined effect of temperature, time, and other conditions of the firing treatment. The entire series of cones ranges from about lll2F (600C) to about 3632F (2000C) with an average interval of about 20C between cones for a constant, slow rate of heating (Klinefelter and Hamlin, 1957, p. 29). For the past several decades the use of these cones has been limited to the Pyrometric Cone Equivalent (PCE) test (Liles and Heystek, 1977, p. 16). However, all of the ceramic firing tests reported by Veatch (1909) and Smith (1931) as well as some of the earliest USBM tests report firing conditions in terms of the standard cone numbers. 11. Drying Shrinkage The drying shrinkage is a measure of the relative amount of shrinkage (in percent) which the tempered and molded material undergoes -16- upon drying. Although there are a variety of ways by which this can be measured, in this report the shrinkage values represent the percent linear shrinkage based on the linear distance measured between two reference marks or lines imprinted on the plastic specimen before drying. Even though the methods have varied in detail, the drying is usually accomplished 1n two stages: first, by air drying at room temperature (usually for 24 hours) and second, by drying in an oven followed by cooling to room temperature in a desiccator (Klinefelter and Hamlin, 1957, p. 30-31; Liles and Heystek, 1977, p. 3). In most cases the heating was at 212F (100C) for 24 hours; however, studies by Smith (1931, p. 20 and 21) employed 167F (75C) for 5 hours followed by 230F (110C) for 3 hours. 12. Dry Strength The dry strength (or green strength) is a measure of the appar- ent strength of the clay or shale after it has been molded and dried. Unless otherwise indicated, it represents the tranverse, or crossbreaking, strength as opposed to either tensile strength or compressive strength. For the great majority of cases only the approximate dry strength is indicated as determined by visual inspection, using such terms as low, fair, good, or high (Klinefelter and Hamlin, 1957, p. 32-33; Liles and Heystek, 1977, p. 2). Smith (1931, p. 12-13) reports a quantitative measurement of this strength using the modulus of rupture (MOR) expressed in units of pounds per square inch (psi). 13. Extrusion Test More extensive tests are sometimes made on clays and shales which -17- show good plasticity and long firing range in the preliminary test. In the Extrusion Test several bars are formed using a de-airing extrusion machine (i.e., one which operates with a vacuum to remove all possible air pockets). These bars are fired and tested for shrinkage, strength (modulus of rupture) and water saturation coefficient (Liles and Heystek, 1977, p. 8). 14. Firing Range The term firing range indicates the temperature interval over which the material shows favorable firing characteristics. For slowfired materials such desirable qualities include: a) good strength or hardness; b) good color; c) low shrinkage; d) low absorption; and e) low porosity. For quick-fired materials these include: a) good pore structure; b) low absorption; and c) low bulk density. For slow-firing and quick-firing tests the firing range should be at least 100F (55C) to be considered promising (O'Neill and Barnes, 1979, p. 15-18). 15. Hardness The hardness, as measured on fired materials, indicates the resistance to abrasion or scratching. It is designated either in verbal, descriptive terms or in numerical terms using Mobs' hardness (Liles and Heystek, 1977, p. 3). It is used as an indication of the strength of the fired materials. Smith (1931), however, measured the fired strength with the modulus of rupture. 16. Hardness (Mobs') The hardness of fired specimens using the Mohs' scale of hardness -18- is currently used by the USBM as a numerical measure of the fired bodies' strength (Liles and Heystek, 1977, p. 3). The values correspond to the hardness of the following reference minerals: Mohs' Hardness No. 1 2 3 4 5 6 7 8 9 10 Reference Minerals Talc Gypsum Calcite Fluorite Apatite Orthoclase Quartz Topaz Corundum Diamond A Mohs' hardness greater than 3 1s considered promising for slow- fired materials. 17. HCl Effervescence The effervescence in HCl is visually determined as none, slight or high based on the reaction of 10 ml of concentrated hydrochloric acid added to a slurry of 10 grams powdered clay or shale (minus 20 mesh) in 100 ml of water (Klinefelter and Hamlin, 1957, p. 17; Liles and Heystek, 1977, p. 4). This test gives a general indication of the amount of calcium carbonate present in the sample. An appreciable effervescence could be an indication of potential problems with lime pops and/or frothing of slow-fired ceramic products. 18. Linear Shrinkage (%) The term linear shrinkage represents the relative shrinkage of the clay body after firing. In most cases it represents the percent total linear shrinkage from the plastic state and is based on measurements -19- between a pair of standard reference marks imprinted just after molding (Klinefelter and Hamlin, 1957, p. 30-32; Liles and Heystek, 1977, p. 3). (Also see the discussion under Drying Shrinkage.) Smith (1931, p. 22) gives the shrinkage relative to both the dry, or green, state (under the column headed Dry) as well as the plastic state (under the column headed Plastic). A total shrinkage of 10% or less is considered promising for slow-fired materials. 19. Modulus of Rupture (MOR) The modulus of rupture is a measure of the strength of materials (for crossbreaking or transverse strength in this compilation) based on the breakage force, the distance over which the force was applied and the width and thickness of the sample. The MOR is expressed in psi units (pounds per square inch) for the limited MOR data reported here (determined by Smith, 1931, p. 21 and 23). 20. Mohs' See Hardness (Mohs'). 21. Molding Behavior See Working Properties. 22. Munsell See Color (Munsell). 23. "MW" face brick "MW" stands for moderate weather conditions. This is a grade of brick suitable for use under conditions where a moderate, non-uniform -20- degree of frost action is probable (Klinefelter and Hamlin, 1957, p. 36 and 37; ASTM Annual Book of Standards, 1974). (Also see SW 11 11 face brick.) 24. PCE - Pyrometric Cone Equivalent The PCE test measures the relative refractoriness, or temperature resistance, of the clay or shale; it is indicated in terms of standard pyrometric cones. The value given is the number of the standard pyrometric cone which softens and sags (or falls) at the same temperature ~s a cone made from the clay or shale being studied. These tests are usually only made on refractory materials which show favorable potential in the preliminary slow firing tests (i.e., high absorption, low shrinkage, and light fired color). The results are usually given for the upper temperature range Cone 12 (1337C; 2439F) to Cone 42 (2015C; 3659F) where the temperature equivalents are based on a heating rate of 150C (270F) per hour. With increasing temperature resistance the sample is designated as either a low-duty, medium-duty, high-duty, or super-duty fire clay (Klinefelter and Hamlin, 1957, p. 29-30 and 57-58; Liles and Heystek, 1977, p. 16). 25. .!! The pH is a measure of the relative alkalinity or acidity with values ranging from 0 to 14. (A pH of 7 is neutral. Values greater than this are alkaline whereas those which are less than 7 are acid.) Most, but not all, of the ceramic tests by the USBM presented here show pH values as determined on the crushed and powdered raw material (in a water slurry) prior to firing (Klinefelter and Hamlin, 1957, p. 28; Liles and Heystek, 1977, p. 4). -21- Strongly acid or alkaline pH values may give some indication of potential problems with efflorescence and scum due to water-soluble salts in the clay. Unfortunately, no simple and direct interpretation is possible from the pH data alone. The best method for determining these salts is through direct chemical analysis as described under Soluble Salts. (Also see Solu-Br.) 26. Plasticity See Working Properties. 27. Porosity, Apparent See App. Por. 28. Quick Firing See Bloating Test. 29. Saturation Coefficient The saturation coefficient 1s determined only for spec1mens which have undergone the more extensive Extrusion Test. It is determined by submerging the fired specimen in cool water for 24 hours, followed by submerging the specimen in boiling water for 5 hours. The saturation coefficient is found by dividing the percent of water absorbed after boiling into the percent of water absorbed after the 24-hour submergence (Liles and Heystek, 1977, p. 8). 30. Shrinkage See Drying Shrinkage and Linear Shrinkage. -22- 31. Slaking I See Working Properties. 32. Slow Firing Test Slow Firing Test refers to the process of firing ("burning") the dried specimen 1.n a laboratory furnace or kiln. Although specific details of the different laboratory methods vary, all specimens are started at room temperature and are slowly heated to the desired temperature over a specific interval of time. The majority of the slow firing tests by the USBM reported here were made using 15-minute draw trials. In this method a set of molded and dried test specimens are slowly fired in the kiln or furnace. The temperature is gradually raised to 1800F (982C) over a period of 3 to 4 hours (to avoid dis integration of the specimen as the chemically combined water is released) and the temperature is held constant for about 15 minutes. One specimen is removed from the kiln (a draw trial) and the temperature is raised to the next level (usually in intervals of 100F). At each interval the temperature is again held constant for a 15-minute soak and then one specimen is withdrawn. This process is repeated until the final temperature is achieved (usually 2300 or 2400F; 1260 or 13l6C) - see Klinefelter and Hamlin (1957, p. 19 and 30). The disadvantage of this draw trial method is that it tends to underfire the specimens, compared to the industrial process, since they are soaked for a relatively short time and quickly cooled by removal from the kiln. Since the early 1970's the USBM has abandoned the draw trials and has adopted a method which more closely resembles the conditions of -23- commercial manufacture. As described by Liles and Heystek (1977, p. 2 and 3), one of the test specimens is slowly fired, over 24 hours, to 1832F (1000C), where it is held for a one-hour soak. The kiln is then turned off, but the specimen remains in the kiln as it slowly cools. (This gives a much closer approximation of most commercial firing processes.) This is subsequently repeated, one specimen at a time, for successive 50C intervals usually up to 2282F (1250C). Unfortunately, only a relatively small part of the current data set LS represented by USBM tests using this newer method. The firing test methods used by Smith (1931, p. 21 and 22) are somewhat intermediate to the two methods described above. First, the specimens were slowly fired from 200 to 1200F (93 to 649C) over a period of 11 hours. The temperature was subsequently increased at a rate of 200F per hour for approximately 4 hours followed by 100F per hour until final temperature conditions were reached. At these later stages firing conditions were monitored using standard pyrometric cones 1n the kiln. The max1mum firing temperature was determined from observed pyrometric cone behavior. This temperature was based on the temperature equivalent to 2 cones below the desired final cone. The kiln temperature was then held constant until the desired cone soaked down. Test specimens were then removed from the kiln and allowed to cool. Smith's firings averaged about 17 hours in the kiln and all specimens were fired to cones 06, 04, 02, 1, 3 and 5 wherever possible. No specific information is available on the methods employed by Veatch (1909) or the unpublished data from TVA or Georgia Tech . . . 33. Solu-Br. (Solu-Bridge) Solu-Bridge measurements were used in the 1950's and 60's by the -24- USBM as a measure of the soluble salts (e.g., calcium sulfate) in the unfired raw material which might cause scum and efflorescence on fired products. In this method the pulverized clay or shale is boiled in water, left to stand overnight, and filtered. The content of soluble salts in the solution is then measured using the Solu-Bridge instrument readings applied to suitable calibration tables (Klinefelter and Hamlin, 1957, p. 28-29). These data are no longer collected because consistent and meaningful results are difficult to achieve. 34. Soluble Salts Excessive water-soluble salts can cause problems with efflores- cence or scum on fired clay products. (More than 3 to 4% calcium sulfate, and 1/2% magnesium or alkali sulfates are considered excessive.) The most accurate determinative method ~s to boil the finely powdered sample in distilled water for 1/2 to 1 hour and let it soak overnight. The decanted solution ~s then analyzed for the soluble salts using standard chemical methods. The Solu-Br idge readings may also be used as a general measure of the soluble salts (Klinefelter and Hamlin, 1957, p. 28). 35. Strength See Dry Strength and Modulus of Rupture. 36. "SW" face brick "SW" stands for severe weather conditions. This is a grade of brick suitable for use under conditions where a high degree of frost action is probable (Klinefelter and Hamlin, 1957, p. 36 and 37, and the -25- ASTM Annual Book of Standards, 1974). (Also see "MW" face brick.) 37. Temp. F ( C) The temperature at which the material was fired (both slow and quick firing tests) is given in Fahrenheit (F) followed by the Celsius ( C) conversion in parenthesis. In cases where only pyrometric cone values are available (e.g., Smith, 1931), the approximate temperature is given on the form and is based on the table of temperature equivalents in Norton (1942, p. 756, Table 128). 38. Water of Plasticity (%) This is a measure of the amount of water (as weight percent relative to the dry material) required to temper the pulverized raw clay or shale into a plastic, workable consistency. This is not a precise measurement, being dependent upon the experience of the technician, the type of equipment used and the plasticity criteria. In most cases it represents the amount of water necessary for the material to be extruded into briquettes from a laboratory hydraulic ram press. In general, high water of plasticity values tends to correlate with a greater degree of workability, higher plasticity and finer grain size. Unfortunately, high values also correlate with a greater degree of shrinkage, warping and cracking of the material upon drying. (See Klinefelter and Hamlin, 1957, p. 20-22; Liles and Heystek, 1977, p. 2.) 39. Working Properties (or Workability) This area of working properties includes comments on the slaking, -26- plasticity, and molding, or extruding behavior of the tempered material (Klinefelter and Hamlin, 1957, p. 5, 19-22 and 33-34). The term slaking refers to the disintegration of the dry material when immersed in water. It may range in time from less than a minute to weeks, but generally in the present report it is given only a relative designation such as rapid, slow, or with difficulty. Plasticity likewise is designated in a comparative manner in order of decreasing plasticity: plastic, fat (or sticky), semiplastic, short (or lean), semiflint and flint. Molding behavior is referred to as good, fair, or poor and is a general designation for the ease with which the material can be molded into test bars or briquettes. These working properties are very imprecise and strongly dependent upon the judgement and experience of the operator. They do, however, give a general indication of how the material might respond to handling in the industrial process. -27- -28- Ceramic Tests and Analyses of Clays and Shales in Chattooga County, Georgia * * The data presented in this report are based on laboratory tests that are preliminary in nature and will not suffice for plant or process design. -29- CERAMIC TESTS AND ANALYSES Material Bauxitic clay. Compilation Map Location No. Cht. 09V-l County Chattooga. Raw Properties: Sample Number - - - - - - - - Lab & No. Ga. Geol. Survey. ------------- Date Reported 1909 Ceramist 0. Veatch, Ga. Geol. Survey. Water of Plasticity -------%Working Properties -P-l-as-t-i-c-. ------------------ Color White and pink. Drying Shrinkage _______% Dry Strength Slow Firing Tests: Approx. Temp. "F ("C) Color Hardness Linear Absorption Appr. Por. Shrinkage, % % % 3254 White (unfused) (1790) to cream (= Cone 33) High Other data: Remarks Cracked badly Remarks I Other Tests This cl ay "should be of value for refractory purposes." (Veatch, 1909, p. 282-283). Preliminary Bloating (Quick Fir i ng) Tests: Not determined. -30- locn. no. Cht. 09V-l, cont. Crushing Characteristics (unfired material) _______..._..._.... Particle Size --------------- Retention Time ----------------- Chemical & Mineralogical Data: Chemical Analysis (partial) Oxide Weight % Si02 Ti02 Al203 Fe203 FeO 1. 57 38.10 1. 18 MnO MgO CaO Na 2o K20 P2os s c (total) (org.) HCO2 oz - H2o+ Other 44.63 (insoluables) Mineralogy Not determined. Mineral volume % Quartz Feldspar Carbonate Mica Chlorite- vermiculite Montmorillonite Others Total Total 88.48 Analyst ~U~S~B~M~---------------------- Date c.l943 (in White and Denson, 1966, p. M36). _________ Method Standard "wet". Sample Location Data: County Chattooga. Land Lot ------- Sec. 71/2' topo quad. Summerville (NW. 1/4) Lat. Field No. Collected by 0. Veatch. Dist. Long. _____ Date c. 1909 Sample Method Auger boring (?) Weathering/alteration ---------------------- Structural Attitude East limb of NE.-trending anticline. Compiled by B.J. O'Connor Date 11-12-82 -31- 1966, P M CERAMIC TESTS AND ANALYSES Material Residual clay (Knox Group). : Compilation Map Location No. Cht. 09V-2 County Chattooga. Raw Properties: Sample Number - - - - - - - Lab & No. Ga. Geol. Survey. Date Reported 1909 Ceramist 0. Veatch, Ga. Geol. Survey. --~-------- Water of Plasticity --------%Working Properties Color Bluish gray. Drying Shrinkage Slow Firing Tests: 8 ..~5____% Dry Strength (tensile) Approx. 100 psi. Approx. Temp. OF (oC) Color Hardness 1994 Dull gray (1090) (= Cone 3) 2174 Dull gray ( 1190) (= Cone 3) 2498 Dull gray (1370) (= Cone 12 Linear Absorption Shrinkage, % % 5.3 2.3 Appr. Por. % Other data: Remarks Dense body Vitrified, swelled, Vesicular, warped Remarks I Other Tests "The cl ay might be used for common pottery, but it is not a fire-clay." (Veatch, 1909, p. 303). Preliminary Bloating (Quick Firing) Tests: Not determined. -32- locn. no. Cht. 09V-2, cont. Crushing Characteristics (unfired material) -------------- Particle Size ----------- Retention Time Chemical & Mineralogical Data: Not determined. Chemical Analysis Oxide Weight % SiOz Ti02 Al Fe 22oo33 FeO MnO MgO CaO Na 2o KzO PzOs s c (total) (org.) C02 H2o- H2o+ Total Mineralogy Mineral Quartz Feldspar Carbonate Mica Chlorite- vermiculite Montmorillonite Others Total volume % Analyst ------------------------Date Method ------------------------Sample Location Data: County Chattooga. Land Lot ------- Sec. 71/2' topo quad. Lyerly (NW. 1/4) Lat. Dist. Long. Field No. Collected by 0. Veatch. Date c. 1909 Sample Method ------------- Weathering/alteration Washed residual clay. Structural Attitude --------------------------------------------------- Stratigraphic Assignment Eocene (?) residual clay from the Knox Group (Cambrian-Ordovician) rocks. ' Sample Description & Comments Sam le is from a small de osit at the bas e of a ridge on the Robert McWhorter property near Men lo Veat ch, 1909, P 303 Compiled by B.J. O'Connor Date. 11-12-82 -33- CERAMIC TESTS AND ANALYSES Material Conasauga shale. Compilation Map Location No. Cht. 09V-3 County Chattooga. Raw Properties: Sample Number --------------Lab & No. Ga. Geol. Survey. Date Reported _1~9~0~9--------------- Ceramist 0. Veatch, Ga. Geol. Survey Water of Plasticity ___________%Working Properties Fair plasticity when finely ground. Color Brown. Drying Shrinkage ----~7____% Dry Strength (tensile) 75 psi. Slow Firing Tests: Approx. Temp. OF (oC) Color 1922 Red (1050) ( = Cone OS) 2102 0150) (= Cone 1) Hardness Linear Absorption Appr. Por. Shrinkage, % % % 1.8 Other data: Remarks Dense body Cinder Remarks I Other Tests This material shows " romise of bein suited for colTUIIon buildin brick and would burn to a dense bod at a low tern erature." Veatch, 1909 , . J91 . Pr e liminar y Bloating (Quick Firing) Tests: Not determined. -34- locn. no. Cht. 09V-3, cont. Crushing Characteristics (unfired material) ---------- Particle Size ---------- Retention Time ------------ Chemical & Mineralogical Data: None. Chemical Analysis Oxide Weight % SiOz TiOz Al Fe 22oo33 FeO MnO MgO CaO Na 2o KzO PzOs s (total) (org.) Mineralogy Mineral Quartz Feldspar Carbonate Mica Chlorite- vermiculite Montmorillonite Others Total volume % Total Analyst Date Method ------------------------- Sample Location Data: County Chattooga. ---- Land Lot Sec. 71/2' topo quad. Lyerly (SE. 1/4) Lat. Dist. Long. Field No. Collected by 0. Veatch. Date c. 1909 Sample Method ------------- Weathering/alteration ---------------- Structural Attitude ----------------------------------------------- Stratigraphic Assignment Conasauga Group (Cambrian). Sample Description & Comments Fissile brown shale which is minutely jointed, and weathers into small an ular fra me nts or "shin le11 Located 1 mile E. o f Lyerly Ve atch, 1909, p. 391 . Compiled by B.J. O'Connor Date 11-12-82 -35- CERAMIC TESTS AND ANALYSES Material Micaceous shale ("bentonite"). Compilation Map Location No. Cht. 09V-4 County Chattooga. Raw Properties: Sample Number --------------Lab & No. Ga. Geol. Survey, location no. 16 Date Reported --~1~9~0~9____________ Ceramist 0. Veatch, Ga. Geol. Survey Water of Plasticity -----------% Working Properties Color Light green. Drying Shrinkage ----~8~~4___% Dry Strength --------------- Slow Firing Tests: Approx. Temp. OF