SMSfi j«]J»TE j GEOLOGICAL SURVEY 3 3051 00005 8770 Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/surveyofsomeilli12whit *7 T ■>.' ■ ILLINOIS STATE GEOLO'GICAL SURVEY yUrbana, Illinois l.C. Frye, Chiei ILLINOIS GEOLOGICAL ILLINOIS INDUSTRIAL MINERALS NOTES Number 12, March .30, 1961 SURVEY LIBRARY MAR 31 1961 A SURVEY OF SOME ILLINOIS MATERIALS POSSIBLY USEFUL AS POZZOLANS W. A. White and J. S. Machin SUMMARY Because of the current interest in pozzolans as addivitives to Portland cement to modify its properties in certain desirable ways and because Illinois has no known deposits of the usual natural pozzolans, the Illinois State Geological Survey has made a preliminary study of four samples of Illinois shales, eight samples of various types of clays, and two samp lee of silica one each from northern and southern Illinois. In their natural state most' of the samples had little pozzolanic reactivity. When heated at various temperatures up to 1300 C, four samples - kaolin near Anna, fireclay near Hadley, an absorptive clay near Olmsted, and a residual clay at Mermet - gave results suggesting that they merit further investigation as pozzolans. All four of these samples except that from Hadley came from extreme southern Illinois. INTRODUCTION Mielenz et al. (1952b) have defined pozzolans as "natural or artificial siliceous and aluminous substances which are not cementitious in themselves, but which contain substances that react with lime at atmos- pheric temperatures in the presence of water to form cementitious compounds." This definition includes natural pozzolans, meaning naturally occurring materials that display pozzolanic activity in the raw state or that may have such activity induced in them by heating. Some of the more commonly used pozzolans are volcanic ash and pumicite. The use of fly ash from large coal-burning instal- lations also has been proposed. In recent years interest has revived in the use of pozzolanic mate- rials, due largely to the need for cements with special properties for use in fituations in which the characteristics of ordinary port land cement are in some respect- inadequate. - 2 - Pozzolans are used in two ways - to replace a portion of the port- land cement used in the preparation of concrete and to modify the properties of mortar or concrete in such ways as to improve it for use in general or special situations. For example, pozzolanic materials are used to control the generation of heat in large masses of concrete during the setting period, to minimize the effects of reactive aggregates, or to reduce expansion of concrete during setting. The pozzolan may be introduced at some suitable stage in the cement manufacturing process or may be added during the concrete mixing process, depending on the situation and on the effect desired. The current interest in pozzolans and the lack of information about possible natural pozzolanic materials in Illinois led to a preliminary study of twelve samples of clays and shales and two samples of silica from Illinois. Four samples of out-of-state materials also were tested for compara- tive purposes because they represented fairly pure clay mineral types. The Illinois samples were chosen as typical of those materials in the state that might be expected to have pozzolanic properties. No volcanic ash or pumice deposits are known in Illinois. The source and brief mineralogical and geological descriptions of the samples are listed at the end of this paper. TESTS The samples were evaluated by means of a chemical test proposed by Mielenz et al. (1952a) who believed it would indicate the ability of a poz- zolan to control expansion of mortar resulting from reaction between cement alkalies and susceptible aggregates. They showed that results of the test correlated reasonably well with the Pyrex mortar bar expansion test for 63 pozzolanic materials. The test involves heating a mixture of the sample with a standard solution of sodium hydroxide in the presence of lime and determining the amount of alkali neutralized during the test. The results are expressed in milliequivalents per liter of sodium hydroxide neutralized. The details of the test are set forth in the reference given. A "reduction in alkalinity" of 210 milliequivalents or more per liter is considered a criterion of a satisfactory pozzolan from the standpoint of control of alkali-aggregate expansion. The samples, collected from the sources and/ or locations described under "Materials," were air-dried and ground in a small laboratory hammer mill, using a screen with holes one-eighth inch in diameter. The material thus ranged from fine dust to particles about one millimeter in diameter. The silicas were ground at the supplier's plant and were considerably finer. Portions of each sample were heated in an electric furnace to the temperatures indicated at the tops of the various columns in the accompanying table. The numbers in the first column serve to identify the raw material as described in the section "Materials." The numbers in the columns are the "reduction in alkalinity" expressed in milliequivalents per liter. The higher this number, the greater is the probability that the material may be useful as a pozzolan. - 3 - DISCUSSION On the basis of the results set forth in table 1, four of the 14 Illinois samples studied may merit further consideration as pozzolans - sample 996N, a kaolinitic clay from near Hadley in western Illinois; sample 869, a kaolin clay from near Anna in extreme southern Illinois; sample Fe 101, a montmorillonite clay (Porters" Creek Clay) from Olmsted, and 1520B, a residual clay with a kaollnite content of about 50 percent. Sample Fe 101 (principally montmorillonite) exhibited good alkali reduction even in the raw state and continued to do so until the calcination was carried above 900° C. The Anna kaolin (sample 869) was nearly as good as sample Fe 101 through the lower temperatures, and samples heated to 1100° C were still active Sample 996N, a kaolinitic clay from near Hadley, was a borderline material, but it developed quite good alkali reduction capacity when heated to temperatures in the range 900° to 1100° C. None of the shales tested gave promise. Samples SIS, a southern Illinois silica, and 1520B, a residual clay, may be of questionable worth as prospective pozzolans. The four out-of-state samples - 877, 868, D3, and 882 - as well as the Illinois sample 410 were included because they represent a very high, well crystallized kaolinite content (877), a western type montmorillonite (868), a southern type montmorillonite (DB) , a quite pure illite (410), and an attapulgite (882) . Because most common clays and shales contain kaolinite, montmoril- lonite, illite, and silica in varying proportions, it is to be expected that, qualitatively at least, their properties (pozzolanic properties included) will be more or less directly influenced by the amount and kind of minerals of which they are constituted. Sample 410, which has high illite content, gave low alkali reduction values. Therefore is is not surprising that sample 866, similar in clay mineral content to sample 410 but containing less illite, gives somewhat higher alkali reduction values. Sample NIS, almost pure quartz, gave very low alkali reduction values. Therefore clays .or shales with high quartz and high illite content may be expected to give low alkali reduction valves. Conversely, high-kaolinite or high-montmorillonite contents tend to increase the probability that the material will be useful as a pozzolan. REFERENCES Mielenz, R. C, Greene, K. T., Benton, E. J., and Geier, F. H., 1952a, Chemical test for alkali reactivity of pozzolans: ASTM Proc . , v. 52, p. 1128-1144. Mielenz, R. C, Witte, L. P., and Glantz, 0. J., 1952b, Effect of calcination on natural pozzolans: ASTM Spec. Tech. Pub. No. 99. - 4 o o o o CO O m -tf •* m O CM <+ no *o i-l r-l CN co co oo m CM o o o o CM vo m m co o\ vo on on m oo co on l ON CM CM O on o on cm CO r-l vO o o o v© f»» sf CO i-( SO CM m m CO vO o CM CM CO CO i-i «tf o •-* i-l r-4 CO cm i>» oo m m > N 4J CM •H O ti o P- •H r-l o 3 ctf o o u r-l ON § c H •H o O 0-i d o o a •H o o 4J u co CO 3 H •o CO 0) u W M r-4 o o b 4J o O CO U r^ to •r4 H •o ►J c o D •H CO o § to U o o OJ vO i .Q s r-i 3 a o 3 o § o & m «* m «-i CO CO vD m CM CO ^ IAN N r-» CM CO HONCO CO CO 3 m \£> r*. CM CM O 00 * oo on cm m vO 00 ^ vO o m oo r>« co WMflO CO CM r-4 o r-l CM CM CM r-4 CM CM CM m CO m r-N o CM CO on o o 00 CO CM r» <»• O 00 i-4 r-4 CM r-4 CM i-H CM CM m m r-4 CM a O NO v.o Oi i—( Oft vO <1 00 ON CO r- co rs j) vO pj CO tx. CO Q < ca CO r-l O CM CM CM C4 co <■ pi m 00 r-l <-l r-4 CO CO H W 2 CO ■u OJ e CD