GB1592001A

GB1592001A - Pozzolan cement compositions

Info

Publication number: GB1592001A
Application number: GB35680/77A
Authority: GB
Original assignee: Partners Ltd
Current assignee: Partners Ltd
Priority date: 1976-09-07
Filing date: 1977-08-25
Publication date: 1981-07-01
Also published as: IE45767B1; CA1103705A; AU517717B2; IN147387B; MX145543A; BR7705781A; IT1090324B; JPS5913458B2; FR2363531A1; FR2375146A1; IE45767L; DE2740114A1; AU2839077A; JPS5342215A

Description

(54) POZZOLAN CEMENT COMPOSITIONS (71) I, RAYMOND CARROLL TURPIN, Jr. of 1380 W. Paces Ferry Road, N.W.

Atlanta, Georgia 30327, United States of America, a citizen of the United States of America and The Partners Limited a partnership consisting of Christopher J. Humphreys; Allen. S. Harding; Edward A. Albright JR.; Iva H. Hardin; Christopher J. Humphreys; Earl Shell JR.; Thomas Crawford JR.; Iva H. Hardin Company; James W. Bolding; Denval B. Hamby; George R. Hemmenway and W. James Overton, all citizens of the United States of America with Iva H.Hardin Company being a Corporation organised and existing under the laws of the State of Georgia, all of 1380 West Places Ferry Road, N.W., Atlanta, Georgia, United States of America do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to cement compositions utilizing a pozzolan material, preferably fly ash.

It has been known for many years that various finely divided, silicious materials react with lime in the presence of moisture to produce cementltious material which may be mixed with sand and stone to form a product similar to modern concrete. These silicious materials, which are commonly referred to as pozzolans, occur naturally or are by-products of various manufacturing processes. Examples of pozzolan materials include blast furnace slag, volcanic ash, calcined shale, and fly ash, which is the fine, solid by-product contained in the gases from the combustion of pulverized coal.With the advent of increasing public environmental concerns and the resulting limitations imposed on gaseous and particulate emissions from such combustion reactions, increasingly large amounts of fly ash are being recovered from the stack gases of commercial coal burning facilities, especially high efficiency electric power generating plants. Despite the resulting availability of considerable quantities of fly ash, at present there is no major commercial use for fly ash.

Fly ash, as well as other pozzolan materials, has been utilized to replace a portion of the more expensive cementitious ingredients conventionally utilized in various cement compositions, but full utilization of fly ash has not been achieved. The primary obstacle to the use of larger proportions of fly ash in these cement compositions is that the reaction of pozzolan materials, including fly ash, with lime is slow compared to the normal cement reaction. Thus, pozzolan containing cement compositions have an early compressive strength (typically measured at seven or 28 days), which is significantly less than similar cement compositions based on conventional cementitious materials, such as Portland cement.If pozzolan is substituted for too large a proportion of the cement, the resulting cement composition will have a poor initial strength and will require additional time prior to imposition of the service load. It may be necessary to provide external support for the cement composition until the pozzolanic reaction has proceeded sufficiently so that the cement composition is self supporting.

The slow curing time of cement compositions having a high proportion of pozzolan material is unacceptable or undesirable for most commercial applications. Attempts have been made to solve this problem by utilizing heat to accelerate the curing rate and by adding large amounts of excess lime and/or various chemicals. These techniques have produced various specialized products, but they have not accelerated the pozzolanic reaction sufficiently to be useful in preparing cement compositions suitable for a broad range of structural applications.

The present invention is a cement composition which achieves the economic benefits of using larger amounts of pozzolan material. This result is achieved by properly proportioning the ingredients in the cement composition and by including certain alkali metal ions in the composition. By utilizing the appropriate amounts of cement, pozzolan, water and fine aggregate, it is possible to minimize the void content of the cement composition and to insure maximum compressive strength. The addition of relatively large amounts of sodium and/or potassium ions apparently accelerates the pozzolanic reaction and makes it possible to add the larger amounts of pozzolan material, in the proper proportion to the other ingredients of the cement composition, without incurring a concomitant loss in early compressive strength.

Because these benefits can be achieved when the sodium ions are added in the form of sodium chloride, the present invention has the further significant advantage that the cement compositions can be prepared from sea water or other brackish waters. Prior to the present invention it was generally believed that the incorporation of sea water in cement compositions would be deleterious to the product. The present invention now makes it possible to prepare relatively inexpensive cement compositions with sea water, an advantage which is particularly useful in localities where sea water is more readily available than fresh water.

Accordingly, the present invention maximizes the substitution of relatively inexpensive pozzolan material for Portland cement.

In particular, the present invention provides a cement composition comprising a cementitious material similar to or the same as Portland cement as hereinbefore defined, a pozzolan material, fine aggregate, water, at least one alkali metal constituent which is a sodium or potassium ion, the alkali metal constituent being present in an amount up to approximately 4.0 percent by weight, in terms of the equivalent weight of sodium ions, of the pozzolan material; and at least one anionic constituent which is a sulfate, chloride, bromide, or nitrite ion, the anionic constituent being present in an amount up to approximately 6.0 percent by weight, in terms of the equivalent weight of chloride ions, of the pozzolan material; said composition having a solid volume ratio of cement to the pozzolan material within the range of approximately 0.05 to 2.0; a ratio of the volume of paste (cement, pozzolan material, water) to the solid yolume of fine aggregate within the range of approximately 0.75 to 1.5; and the ratio of the solid volume of cement to the volume of mortar (cement, pozzolan material, water and fine aggregate) less than about 0.19.

The accompanying drawing is a graph depicting the 28-day compressive strength versus the cement content of various cement compositions, including commercially available cement compositions without pozzolan (IA), cement compositions containing pozzolan material in amounts commercially utilized at the present time (IB), and cement compositions containing a large proportion of pozzolan material in accordance with the present invention (ID).

The present invention relates to cement compositions of all types in which Portland cement or similar cementitious material as herein defined reacts with water to bind together various inert ingredients, such as sand, stone, and crushed rock. As used herein the term "cement composition" refers to all such cementitious mixtures including, for example, those generally designated in the art as mortar, grout, and concrete, that is to say having setting times and early strength characteristics similar to or the same as Portland cement.

The present invention is applicable, but not limited, to the following types of cement compositions: ready mixed concrete compositions, prefabricated concrete structural elements prepared by autoclaving or steam curing cement compositions, concrete compositions utilized in large mass structures, such as gravity dams, and concrete compositions employed as highway bases and surfaces. These cement compositions may employ additional reinforcing elements conventionally utilized in the art to supplement their structural properties.

Despite the inherent economic advantages associated with the substitution of pozzolan materials, such as fly ash, typical pozzolan cement compositions, such as concrete, presently used in commercial practice contain enough pozzolan material to replace only about 20 to 30 percent by weight of the cement normally present. (If fly is substituted for 30 percent of the cement, the cement:fly ash ratio, as hereinafter defined, is approximately 2.24). The primary obstacle to the greater utilization of fly ash is the slow reaction rate of pozzolan compared with the normal reaction of cementitious materials as hereinbefore defined. Attempts to substitute larger amounts of pozzolan material for cement have resulted in cement compositions having an undesirably slow setting time and unacceptably poor early strength characteristics. As a result costly delays are encountered before the cement composition can bear a service load. Prior to the present invention attempts to realize the economic advantages associated with the utilization of large amounts of pozzolan material in cement compositions have been unsuccessful because of the undesirable properties of the resulting products.

The present invention is applicable to cement compositions containing pozzolan and cement, in relative proportions such that the cement:pozzolan ratio is within the range of approximately 0.05 to 2.0. Preferably, the cement:pozzolan ratio is within the range of approximately 0.1 to 2.0. For present purposes the "cement:pozzolan ratio" means the ratio of the solid volume of dry cement to the solid volume of dry pozzolan material contained in the cement composition. As used herein the term "solid volume" (particularly as applied to the proportions of cement, pozzolan material and fine aggregate means the volume of the solid constituent exclusive of its voids and is determined by dividing the weight of the material by its specific gravity.

The cement composition of the present invention includes cement, pozzolan, fine aggregate, water, and entrained and entrapped air, which enters the cement composition during mixing of these ingredients. The cement constituents which may be utilized includes any of the typical Portland cements known in the art, such as those meeting the description of ASTM Standard C 150-74, Types I, II, and III. However, the proportion of cement contained in the present cement compositions is considerably less than that normally utilized in conventional cement compositions having comparable structural properties.

The pozzolan materials which may be utilized include any of the materials falling within the definition of Class N, F, or S set forth in ASTM Standard C 618-72. Suitable pozzolan materials include pozzolan, trass, volcanic ash, pumice, slag, diatomaceous earth, siliceous clays, calcined shale, and fly ash. Fly ash is the preferred pozzolan material, because it is readily available, inexpensive, and has certain desirable physical properties. The shape and size distribution of fly ash particles improves the workability of cement compositions, and acceptable workability of such compositions containing fly ash can generally be achieved with less water than with other pozzolan materials. This reduction in the water requirement aids in minimizing the void content of the cement composition and increases the compressive strength of the cement product.

The cement composition also comprises fine aggregate which may be any clean durable sand conventionally used in the art for preparing mortar or concrete. Suitable sands include those which are deficient in material passing through a No. 50 US mesh screen. The amount of sand incorporated in the cement composition is determined by the volume of the cement composition and the strength properties which are desired, taking into account that the paste:sand ratio, as defined herein, must be kept within the defined range.

The cement composition also includes sufficient water to comply with ASTM and ACI standards for workability. Within these parameters it is desirable to minimize, the quantity of water added to maximize the strength of the cement composition.

The cement composition of the present invention may also include any of the chemical ingredients commonly known to those skilled in the art as "chemical admixes". The basic types of chemical admixes are set forth in ASTM Standard C 494-71 and are generally classified according to their function, i.e., whether they are utilized to retard or accelerate the cementitious chemical reactions, to reduce the water requirement, or for a combination of these reasons. The chemical admixes which are used commonly today include derivatives of lignosulfonic acid and its salts, hydroxylated carboxylic acids and their salts, and polymer derivatives of sugar. Any of these chemical admixes may be incorporated in the present cement compositions in the amounts conventionally utilized in the art.

The foregoing cement composition constituents may be combined in any manner conventionally utilized in the art, and are generally mixed in accordance with the procedures set forth in ASTM Standard C-94.

To maximize the early compressive strength properties of the present cement composition it is desireable to minimize the voids in the cement composition, since an inverse relationship exists between the volume of such voids and the compressive strength of the cement composition. During the curing and hardening of the cement composition air and water leave voids which cause weakness in the cured product. It has now been found that these voids are minimized, if enough pozzolan material is added to a mixture comprising cement, sand, water, and air so that the volume ratio of paste (cement, pozzolan, water, and air) to fine aggregate (sand) is in the range of approximately 0.75 to 1.5 and, preferably, in the range of approximately 1.0 to 1.4.For present purposes the "paste:fine aggreagate ratio" means the ratio of the volume of the paste constituents (cement, pozzolan, water, and air) to the solid volume of dry fine aggregate. Although the optimum paste:fine aggregate ratio for any specific cement composition depends on the type of fine aggregate and cementitious ingredients utilized, the optimum amount will fall within the foregoing range.

To further prevent the loss in early compressive strength usually associated with the use of a large proportion of pozzolan material, the cement composition of the present invention also includes certain ionic constituents. It has now been found that the pozzolanic reaction can be accelerated beneficially by adding sufficient quantities of at least one alkali metal ion selected from the group consisting of sodium and potassium ions. Although the means by which these ions accelerate the pozzolanic reaction is not known precisely, it is presently believed that sodium and potassium ions increase the water solubility of the silicious constituents in the pozzolan, thereby permitting the soluble silica to react with excess lime liberated by the hydration of the cement.

Any measurable amounts of sodium and/or potassium ions will have some identifiable effect in catalyzing the pozzolanic reaction and offsetting the reduction in early compressive strength usually associated with high pozzolan content cement compositions. If sodium ions are utilized, the cement composition contains sodium ions in an amount comprising up to approximately 4.0 percent by weight of the pozzolan material present in the cement composition, and preferably, sufficient sodium ions should be present to constitute from approximately 0.2 to 1.6 percent by weight of the pozzolan. In cement compositions employing potassium ions as the alkali ion constituent, the potassium ions may be present in amounts corresponding to equal quantities of sodium ions within the described and preferred ranges set out above.It is also possible to utilize mixtures of sodium and potassium ions, with the total quantity of such ions being with the ranges set forth above, the quantity of potassium ions again being translated into the equivalent molecular weight of sodium ions. When these alkali metal ions are added in amounts in excess of 4.0 percent by weight, in terms of the equivalent weight of sodium ions, of the pozzolan material, the beneficial effects are diminished, and the resulting cement composition becomes discolored by a powdery white residue left behind on the exterior of the cement composition after the water has evaporated from its surface.

The pozzolanic reaction is further catalyzed by simultaneously accelerating the hydration of the cement and, therefore, the formation of free lime, the other principal reactant. This is accomplished by adding one or more anions selected from the group consisting of sulfate, chloride, bromide and nitrite ions. The sulfate and chloride ions are preferred. Again it has been noted that any measurable amount of these anions will have some identifiable effect on the pozzolanic reaction rate and the early compressive strength of the cement composition. The anionic constituents in the cement composition are present in an amount of up to 6.0 percent by weight, in terms of the equivalent weight of chloride ions, of the pozzolan material present and, preferably, from approximately 0.3 to 2.4 percent by weight of the pozzolan material.In cement compositions employing sulfate and/or nitrite ions these ions are present in an amount corresponding to equal quantities of chloride ions within the prescribed and preferred ranges set out above.

Thus one or more of these anions are added to the cement composition in conjunction with the alkali metal ions to accelerate the pozzolanic reaction in two separate ways.

Examples of materials which may be added to supply both the alkali metal and anionic constituents include sodium chloride, sodium sulfate, and potassium chloride.

One of the preferred additives is sodium chloride which may be incorporated into the cement composition in the form of sea water. Sea water is particularly useful, because, in addition to sodium chloride, it contains appreciable amounts of potassium and sulfate ions which further catalyze the pozzolanic reaction. The following is a typical chemical analysis of the ionic constituents of sea water: Ion (ppm) Sodium 10,000 Potassium 700 Calcium 440 Magnesium 1,316 Sulfate 2,515 Chloride 20,750 The beneficial effect of sea water is particularly surprising, since heretofore it has been generally accepted that sea water is deleterious to cement compositions. The present invention now provides a cement composition utilizing sea water, thereby making cement compositions more readily available in areas where sea water is plentiful and fresh water relatively scarce.

In another specific embodiment it has been found that the benefits of the present invention can be achieved without adding an alkali metal constituent if the chloride ion is added in the form of calcium chloride in an amount sufficient to comprise approximately 0.5 to 4.0, and preferably from approximately 0.5 to 3.0, percent by weight of the pozzolan material present and the other ingredients of the cement composition are added in accordance with the proportions described herein. However, cement compositions in which the chloride ion is added with an alkali metal constituent demonstrate higher early compressive strengths than analogous cement compositions in which the chloride ion is added as calcium chloride.

Another advantage of the present invention is that the benefits of using relatively large amounts of fly ash can be achieved without adding extraneous lime, i.e. lime other than that produced by hydration of the cement. The cement compositions of the present invention, may tolerate extraneous lime in amounts up to approximately 4.0 percent by weight of the fly ash, although the setting time of the product is reduced. When additional lime is added in amounts exceeding 4.0 percent by-weight of the pozzolan material, the early strength of the cement composition is diminished. Accordingly, the present cement compositions may contain additional lime in amounts less than approximately 4.0 percent by weight of the pozzolan material.

EXAMPLES Example 1: This example demonstrates the procedure for determining the requisite amount of fly ash to maximize the compressive strength of a cement composition. A number of different compositions were prepared employing various amounts of cement, and the amount of fly ash for each cement composition was varied. The 28-day compressive strength of each cement composition was measured and is reported in Table I.

The cement utilized in each of the tests consisted of a blend of equal portions by weight of three Type I Portland cements, as defined in ASTM Standard C 150-74, which were obtained from three different mills. This cement was utilized throughout the examples herein except as otherwise noted.

Unless otherwise noted, the fine aggregate utilized in each of the tests in this example and the other examples herein, consisted of a mixture of equal proportions of a relatively fine (No. 109) and a relatively coarse (No. 190) sand from Ottawa, Illinois. In tests G-l through G-3 pond screenings passing through a No. 200 US mesh screen were utilized in addition to the Ottawa sand. In tests I-l through I-5 the sand consisted of equal amounts of a commercially available sand known as Waugh sand from Montgomery, Alabama, and a commercially available sand typical of those in Atlanta, Georgia.

Unless otherwise noted, the pozzolan material utilized in each of the tests in this example and the other examples herein consisted of Bowen fly ash recovered from the combustion of pulverized bituminous coal at the Bowen Plant of the Georgia Power Company. In tests H-l through H-3 and K-l through K-3 a different pozzolan material was utilized comprising fly ash collected from the McDonough Plant of the same power company.

The mixing procedure utilized in each test was the basic procedure described in ASTM Standard C 109 with a few modifications. First the cement, fly ash, and water were added to the mixer described in the standard test procedure. The amount of cement utilized remained constant for a given series of tests, but the amount of water utilized in each test was adjusted to obtain relatively equal slumps (a measure of workability) for all tests within a given series of tests, e.g. tests A-l through A-4. The cement, fly ash, and water were then mixed at the slow speed for 30 seconds, after which the fine aggregate was added to the mixer during a 30 second period while mixing at the slow speed. These ingredients were then mixed at the medium speed for an additional 30 seconds.The amount of sand added was adjusted to provide relatively equal volumes for all samples prepared.

The mixer was then turned off for 90 seconds, and during the first 15 seconds, the sides of the mixer were scraped down. The cement composition was then mixed at the medium speed for an additional 60 seconds.

During the first 90 seconds after the final mixing, the bowl was removed from the mixer.

One-half of the mortar was removed and measured for slump, the test taking approximately 30 to 45 seconds to perform. If the slump varied from the slump of the other test samples within a given series of tests, the cement composition was reformulated to achieve approximately equivalent workability of all test compositions within the series of tests. The remaining half of the test sample was then tested by the procedure defined herein to determine the void content. Following completion of these tests, both fractions were returned to the mixing bowl and were mixed for fifteen seconds at the medium speed. The cement composition was compacted into six standard 2-inch cubes for measurement of compressive strength. The cubes were cured using lime water under ASTM Standard C 109 conditions.All tests were conducted under standard conditions of temperature and humidity specified in the same ASTM Standard.

The slump was measured utilizing a measuring cone as described in paragraph 2.3 of ASTM Standard C 128-73. Initially one-half of the cone was filled with the test sample and rodded 25 times with a rounded tip having a diameter of 1/4". The remainder of the metallic cone was then filled and rodded 25 times with the rod passing through the top layer and barely into the second to consolidate the two layers. Following the second rodding, excess material was struck from the top of the cone utilizing the edge of a trowel, and the cone was slowly removed during a ten second interval. The cone was placed beside the conical mass of the test sample material, and the difference between the height of the standard cone (the original height of the sample) and the height of the sample after removal of the cone was then measured as the slump.

The volume of potential voids (water and entrained and entrapped air) was determined utilizing the following experimental procedure. A metallic cylinder, closed at one end and having a known volume and weight, was utilized to determine the density of each cement composition prepared. The cylinder was filled in three equal parts with subsequent rodding after each addition of the test sample as in the slump test. Following the rodding of the third layer, the excess test sample material was struck from the top and the density determined by dividing the volume of the cylinder by the difference in weight between the filled and unfilled cylinder. By knowing the total weight of the test sample material produced in a given test and the density, the total volume of the sample prepared could be computed.The difference between the total volume of the test sample and the total volume of the individual solid constituents in the test sample represents the void content of the sample.

The compostion of the various test samples and the results of these tests are reported in Table I. These results indicate that for a given cement composition there is an optimum amount of pozzolan material which can be added to maximize the compressive strength of The composition of the various test samples and the results of these tests are reported in cement:pozzolan ratio is in the range of approximately 0.1 to 2.0. When more than the maximum amount of pozzolan material is added to the cement composition there is a commensurate decrease in the 28-day strength. The test results indicate that the 28-day strength of such pozzolan containing cement compositions is maximized when the void content of the composition is minimized as indicated by a paste: sand ratio between approximately 1.0 and 1.4.

TABLE I Total Water Total 28 Day Cube Cement Pozzolan Sand (cc/1000 cc Voids Paste/Sand Cement/Pozzolan Strength Example (gms.) (gms.) (gms.) composition) % (vol.) (vol.) (psi) A-1 188 400 1352 231.4 26.35 0.96 0.36 2790 A-2 188 500 1248 233.4 26.44 1.12 0.29 2780 A-3 188 550 1183 239.4 27.06 1.24 0.26 2740 A-4 188 600 1112 247.1 27.52 1,38 0.24 2690 B-1 188 250 1489 247.7 27.64 0.78 0.58 2510 B-2 188 350 1395 237.4 26.86 0.90 0.42 2700 B-3 188 450 1293 235.3 26.82 1.05 0.32 2880 B-4 188 550 1188 243.3 27.39 1.23 0.26 2610 C-1 510.8 - 1373 256.3 31.99 0.93 - C-2 704.7 - 1227 267.4 31.24 1.16 - C-3 636.4 - 1286 262.4 31.14 1.06 - C-4 701.1 - 1221 271.0 31.59 1.17 - C-5 763 - 1173 276.2 31.58 1.26 - D-1 - 500 1472 204.7 23.95 0.80 - D-2 - 600 1366 207.7 23.80 0.94 - D-3 - 650 1312 209.3 24.11 1.02 - D-4 - 700 1256 212.8 24.09 1.11 - D-5 - 750 1132 222.0 24.88 1.34 - E-1 376 230 1352 247.2 27.69 0.96 1.27 7940 E-2 376 290 1286 245.5 27.61 1.06 1.00 7960 E-3 376 330 1244 248.1 27.57 1.13 0.88 8190 E-4 376 400 1152 253.1 28.20 1.30 0.73 7300 F-1 564 50 1352 261.9 28.83 0.96 8.74 10.632 F-2 564 100 1305 261.7 29.07 1.03 4.37 11.520 F-3 564 150 1250 264.6 29.22 1.12 2.91 10.960 F-4 564 200 1188 266.4 29.31 1.23 2.18 11.360 F-5 564 250 1113 271.2 29.98 1.38 1.75 10.580 TABLE I (cont) Total Water Total 28 Day Cube Cement Pozzolan Sand (cc/100 cc Voids Paste/Sand Cement/Pozzolan Strength Example (gms.) (gms.) (gms.) composition) % (vol.) (vol.) (psi) G-1 376 200* 1243 267.5 31.63 1.06 1.53* 4050 G-2 376 250 1196 272.3 31.65 1.14 1.22 4260 G-3 376 300 1138 275.7 32.09 1.25 1.02 4600 H-1 188 200** 1456 281.0 29.40 0.82 0.62 1850 H-2 188 300 1345 273.5 28.98 0.97 0.41 2060 H-3 188 400 1173 290.0 30.37 1.26 0.31 1960 I-1 188 250 1380***293.2 30.56 0.89 0.58 1750 I-2 188 350 1312 271.0 29.10 0.99 0.42 2000 I-3 188 450 1214 264.4 28.66 1.15 0.32 2190 I-4 188 550 1125 265.4 28.73 1.32 0.26 2180 I-5 188 600 1057 269.9 29.46 1.47 0.24 2100 J-1 188 290**** 1380 260.3 28.38 0.92 0.44 2430 J-2 188 390 1256 261.5 28.24 1.11 0.32 2580 J-3 188 490 1118 269.4 29.30 1.37 0.26 2430 K-1 376 160.5** 1345 273.4 29.38 0.97 1.54 5790 K-2 376 230 1256 278.0 29.50 1.11 1.07 6210 K-3 376 300 1157 284.7 30.07 1.29 0.82 6100 * Instead of a pozzolan material, the G-series examples contained the indicated amounts of pond screenings which passed through a 200 mesh screen. The cement:pozzolan ratio for this series of tests is actually the cement:fines dry volume ratio.

** The pozzolan utilized in this sample consisted of fly ash from the McDonough Plant of the Georgia Power Company.

*** The sand utilized in this sample consisted of a 50:50 blend by weight of commercially available sand known as Waugh sand from Montgomery, Alabama and a commercially available sand typical of Atlanta, Georgia sands.

The pozzolan utilized in this example consisted of New York fly ash obtained from the Army Corps of Engineers.

Example 2: A series of tests were conducted illustrating the effect of including various ions in a pozzolan containing cement composition. The base composition or control utilized in these tests was as follows: 188 grams cement 500 grams fly ash 1250 grams sand 235 milliliters water The cement:pozzolan ratio in this cement composition is 0.29, representing the optimum amount of fly ash for this composition as determined in examples A-l through A-4 and B-l through B-4 in Example 1.

The cement compositions in this example were prepared and tested as in Example 1. The water content of each test sample was adjusted in an attempt to prepare samples with equivalent workability within a given series of tests. The slump of each test sample was measured in sixteenths of an inch, and the compressive strength of the 2-inch cubes prepared from the various cement compositions was measured at the end of 7 and 28 days.

As noted in Table II various ionic materials in the amounts indicated were added in aqueous solution to the cement and pozzolan material at the beginning of the mixing procedure. The results of these tests are reported in Table II. Where tests with various ionic constituents were prepared on different days the results are compared to those of the base composition without ions prepared on the same day. The column at the extreme right in Table II indicates the ratio of the 28-day strength of the test sample to the 28-day strength of the control.

The results of these tests demonstrate that the sodium and potassium ions improve both the 7-day and 28-day strengths of high pozzolan content cement compositions. Test AD-2 also indicates that the early strength of high pozzolan cement compositions can be improved when calcium chloride is employed in the cement composition in the absence of an alkali metal ion.

TABLE II Total Water 7-Day Cube 28-Day Cube 28-Day Cube Test (cc/1000 cc Slump Chemical Paste/Sand Strength Strength Strength Sample composition) (16th") Chemical (grams) (vol.) (psi) (psi) vs. Control AA-1 233.8 10 - - 1.13 1530 2890 1.00 AA-2 231.0 11 NaCl 8.9 1.13 2900 5290 1.83 AA-3 228.2 11 NaCl 17.9 1.13 3200 6250 2.16 AA-4 223.2 12 KCl 11.9 1.12 2780 4830 1.67 AA-5 218.5 12 KCl 23.9 1.12 3150 5900 2.04 AB-1 237.7 12 - - 1.13 1540 2660 1.00 AB-2 235.6 14 Na2SO4.IOH2O 25.9 1.34 2580 3790 1.42 AB-3 227.0 14 Na2SO4.IOH2O 51.7 1.34 3690 5340 2.01 AB-4 228.9 14 NaNO2 11.1 1.12 2360 3810 1.43 AB-5 222.1 12 NaNO2 22.2 1.12 2560 4330 1.63 AC-1 230.9 12 - - 1.14 1340 2950 1.00 AC-2 228.2 11 NaCl 10.6 1.12 2560 5650 1.92 AD-1 228.9 11.5 - - 1.11 1450 2890 1.00 AD-2 214.2 9 CaCl2 11.3 1.11 2030 3950 1.37 Example 3:: Tests were conducted with cement compositions containing various amounts of sodium chloride. In tests BA-1 through BA-4, the base cement composition or control consisted of the following ingredients: 188 grams cement 250 grams fly ash 1475 grams sand 250 milliliters water The cement:pozzolan ratio of this cement composition is 0.58.

In tests BB-1 through BB-4, the base cement composition consisted of the following ingredients: 188 grams cement 550 grams fly ash 1222 grams sand 250 milliliters water The cement:pozzolan ratio of this cement composition is 0.27.

The balance of the ingredients in the various test samples are set forth in Table III. These test samples were prepared and tested in accordance with the procedure set forth in Example 2, and the results are reported in Table III. These results indicate that the sodium and chloride ions increase the early compressive strength of high pozzolan content cement compositions.

TABLE III Total Water 7-Day Cube 28-Day Cube 28-Day Cube Test (cc/1000 cc Slump Chemical Paste/Sand Strength Strength Strength Sample composition) (16th") Chemical (grams) (vol.) (psi) (psi) vs. Control BA-1 247.6 14 - - 0.80 1150 2510 1.00 BA-2 248.3 15 NaCl 2.4 0.80 1440 2770 1.10 BA-3 241.7 15 NaCl 8.3 0.80 1950 3430 1.37 BA-4 231.8 14 NaCl 16.6 0.80 1940 4510 1.80 BB-1 243.3 14 - - 1.23 1380 2610 1.00 BB-2 239.9 14 NaCl 5.2 1.23 2310 4610 1.77 BB-3 231.3 14 NaCl 18.2 1.22 3040 6890 2.64 BB-4 224.0 12 NaCl 36.6 1.22 3090 7580 2.90 Example 4: A series of tests were conducted to demonstrate that the advantages of the present invention can be achieved utilizing different sands and different pozzolan materials.

In tests CA-1 and CA-2 the base cement composition or control consisted of the following ingredients: 188 grams cement 400 grams of Bowen fly ash 1260 grams of a 50/50 blend of commercially available sands comprising Waugh sand from Montgomery, Alabama and a commercially available sand typical of Atlanta, Georgia 276 milliliters water The cement:pozzolan ratio of this cement composition is 0.36.

The base cement composition or control utilized in test samples CB-1 through CB-3 consisted of the following constituents: 188 grams cement 390 grams of a New York fly ash 1260 grams of a 50/50 blend of sands from Ottawa, Illinois 262 grams water The cement:pozzolan ratio for this cement composition is 0.32.

Finally, tests CC-1 through CC-3 utilized the following control cement composition: 188 grams cement 444 grams of a Class N (natural) pozzolan obtained from the Oregon P.C. Co., Lime, Oregon 1290 grams of a 50/50 blend of sands from Ottawa, Illinois 253 milliliters water.

The cement:pozzolan ratio for this cement composition is 0.36.

TABLE IV Total Water 7-Day Cube 28-Day Cube 28-Day Cube Test (cc/1000 cc Slump Chemical Paste/Sand Strength Strength Strength Sample composition) (16th") Chemical (grams) (vol.) (psi) (psi) vs. Control CA-1 276.9 19 - - 1.07 1120 2190 1.00 CA-2 264.6 19 NaCl 13.3 1.07 2180 4500 2.06 CB-1 261.5 21 - - 1.11 1430 2580 1.00 CB-2 249.6 18 NaCl 12.9 1.11 2410 4890 1.90 CB-3 244.2 20 NaCl 25.9 1.12 2420 5050 1.96 CC-1 250.5 14 - - 1.08 1480 3140 1.00 CC-2 248.0 14 NaCl 13.3 1.10 2470 4230 1.35 CC-3 238.1 13 NaCl 26.6 1.09 2590 4640 1.48 The remaining ingredients in each of the test samples is set forth in Table IV. The test samples were prepared and tested in accordance with the procedure described in Example 2, and the results are reported in Table IV.These results indicate that the present invention is applicable to cement compositions containing various types of pozzolan material and fine aggregate.

Example 5: To demonstrate the effect of varying the cement:pozzolan ratio and the proportion of ionic constituents included within the cement composition the following series of tests were performed.

In test DA-1 through DA-5 the control cement composition consisted of the following ingredients: 376 grams cement 330 grams fly ash 1240 grams sand 250 milliliters water The cement:pozzolan ratio for this composition is 0.88.

The base cement composition utilized in samples DB-1 through DB-6 consisted of the following: 376 grams cement 125 grams fly ash 1450 grams sand 254 milliliters water The cement:pozzolan ratio of this sample composition is 2.33.

The following composition was utilized as the control cement composition in test samples DC-1 through DC-4: 564 grams cement 50 grams fly ash 1343 grams sand 260 milliliters water The cement:pozzolan ratio for this sample is 8.74.

Finally, test samples DD-1 through DD-4 were prepared based on the following control composition: 564 grams cement 250 grams fly ash 1115 grams sand 270 milliliters water This composition has a cement:pozzolan ratio of 1.75.

Again the test samples were prepared and tested according to the procedure described in Example 2. The results and the remaining constituents in each test sample are reported in Table V.

The results indicate that the advantages of the present invention were achieved in the DA series of tests wherein the ingredients were proportioned in accordance with the present invention. For the DB and DC series of tests significant increases in the early compressive strength were not realized, because of the relatively low proportion of fly ash in these tests as indicated by the cement:pozzolan ratios of 2.33 and 8.74 respectively for each series. In test series DD significant improvement in the compressive strength of the cement composition was not achieved because of the large amount of cement already in the cement composition. It has been found that the benefits of the present invention are achieved if the ratio of the solid volume of cement to the volume of mortar (cement, pozzolan, water, air, ionic constituents and fine aggregate) is less than about 0.19.

TABLE V Total Water 7-Day Cube 28-Day Cube 28-Day Cube Test (cc/1000 cc Slump Chemical Paste/Sand Strength Strength Strength Sample composition) (16th") Chemical (grams) (vol.) (psi) (psi) vs. Control DA-1 249.6 15 - - 1.16 4630 7440 1.00 DA-2 250.1 13 NaCl 4.7 1.16 5130 8710 1.17 DA-3 244.3 13 NaCl 11.0 1.16 5900 9820 1.32 DA-4 238.9 15 NaCl 21.9 1.15 6030 10,540 1.42 DA-5 233.5 15 NaCl 31.4 1.15 5630 9720 1.31 DB-1 256.8 12 - - 0.84 4450 6490 1.00 DB-2 256.5 15 NaCl 0.2 0.84 4590 6400 0.99 DB-3 251.9 12 NaCl 2.3 0.84 4970 6490 1.00 DB-4 249.6 11 NaCl 4.6 0.85 5090 6420 0.99 DB-5 241.3 12 NaCl 9.1 0.86 5420 7000 1.08 DB-6 232.8 11 NaCl 17.9 0.87 5230 7000 1.08 DC-1 263.2 14 - - 0.98 9170 10,120 1.00 DC-2 256.8 14 NaCl 3.3 0.99 9500 10,270 1.02 DC-3 249.8 13 NaCl 9.5 1.00 9670 10,130 1.00 DC-4 245.1 13 NaCl 14.2 1.00 9170 10,000 0.99 DD-1 273.2 14 - - 1.39 8420 11,000 1.00 DD-2 267.8 14 NaCl 3.3 1.39 8790 11,020 1.00 DD-3 265.1 14 NaCl 9.5 1.39 9290 11,690 1.06 DD-4 260.8 13 NaCl 14.3 1.39 9060 11,370 1.03 Example 6: To demonstrate that the advantages of the present invention are achieved because of the interaction of the pozzolan material and the ionic constituents, cement compositions were prepared in which the pozzolan material was replaced by granite dust, an inert material with a fine particle size. The control cement composition utilized in these test samples (EA-1 through EA-5) comprised the following: 376 grams cement 250 grams of granite dust passing through a 200 US mesh screen 1240 grams sand 270 milliliters water The ratio of cement to fine granite dust on a dry volume basis is 1.22.

The procedure described in Example 2 was followed in the preparation and testing of the test samples. The remaining constituents in each test sample and the results of the tests are reported in Table VI. These test results indicate that the presence of ionic constituents which are effective in increasing the early strength of high pozzolan cement compositions are ineffective for the same purpose in cement compositions including a high content of fine inert material.

Example 7: A series of tests were conducted to demonstrate that the present invention is applicable to cement compositions containing different types of Portland cement.

TABLE VI Total Water 7-Day Cube 28-Day Cube 28-Day Cube Test (cc/1000 cc Slump Chemical Paste/Sand Strength Strength Strength Sample composition) (16th") Chemical (grams) (vol.) (psi) (psi) vs. Control EA-1 270.4 16 - - 1.14 3230 4600 1.00 EA-2 264.4 15 NaCl 3.6 1.14 3520 4540 0.987 EA-3 261.7 14 NaCl 8.0 1.14 3830 4640 1.009 EA-4 261.0 20 NaCl 16.6 1.14 3590 4490 0.976 EA-5 252.3 16 NaCl 23.8 1.16 3470 4500 0.978 In test samples FA-1 through FA-3 the control cement composition contained the following ingredients: 188 grams of a Type II Portland cement 500 grams fly ash 1250 grams sand 253 milliliters of water In test FB-1 through FB-3 the same control composition was utilized except that the cement utilized was a Type III Portland cement. The cement:pozzolan ratio in each of the control samples for the FA and FB Series of tests is 0.29.

Again the test samples were prepared and tested according to the procedure described in Example 2. The remaining constituents in each test sample and the results of the tests are reported in Table VII. The tests demonstrate that excellent results are achieved with the cement compositions of the present invention regardless of the type of cement which is utilized.

Example 8: The purpose of this series of tests was to demonstrate that the present invention is applicable to cement compositions, such as those employed in manufacturing prefabricated structural elements, which are subjected to thermal treatment of autoclaving to accelerate the curing rate. The composition of the test samples are indicated in Table VIII. Unless otherwise indicated the samples utilized a blend of three Type I Portland cements, Bowen fly ash, and a 50/50 blend of fine and coarse sands from Ottawa, Illinois as the major constituents as previously described in Example 1.The test procedure described in Example 2 was followed, except that the cubes formed from the various test samples were maintained in the laboratory for 24 hours at atmospheric conditions and then cured for 17 hours at a minimum temperature of 167"F. The compressive strength of the cubes was then measured and the results are reported in Table VIII.

The test results indicate that the present invention can be applied to cement compositions which are subjected to accelerated curing by heating. Again the presence of the ionic constituents improved the early compressive strength characteristics of these cement compositions.

TABLE VII Total Water 7-Day Cube 28-Day Cube 28-Day Cube Test (cc/1000 cc Slump Chemical Paste/Sand Strength Strength Strength Sample composition) (16th") Chemical (grams) (vol.) (psi) (psi) vs. Control FA-1 232.5 15 - - 1.12 930 1790 1.00 FA-2 220.0 15 NaCl 16.6 1.11 2550 5040 2.82 FA-3 213.8 14 NaCl 33.3 1.12 2270 5640 3.15 FB-1 238.4 14 - - 1.13 1750 2930 1.00 FB-2 232.8 14 NaCl 16.6 1.15 3430 6360 2.17 FB-3 226.9 15 NaCl 33.3 1.14 3330 6940 2.37 TABLE VIII Total Water Compressive Compressive Test Cement Pozzolan Sand (cc/1000 cc Chemical Paste/Sand Cement/Pozzolan Strength Strength Sample (gms.) (cc.) (gms.) composition) Chemical (gms.) (vol.) (vol.) (psi) vs.Control GA-1 188 102.46 1475 248 - - 0.79 0.58 2900 1.00 GA-2 188 102.46 1475 232 NaCl 16.6 0.79 0.58 4500 1.55 GB-1 188 225.41 1222 243 - - 1.23 0.27 4180 1.00 GB-2 188 225.41 1222 222 NaCl 36.6 1.24 0.27 8310 1.99 GC-1 376 135.24 1240 250 - - 1.16 0.88 6580 1.00 GC-2 376 135.24 1240 239 NaCl 21.9 1.15 0.88 10,310 1.57 GD-1 188* 204.92 1250 233 - - 1.12 0.29 3250 1.00 GD-2 188 204.92 1250 221 NaCl 16.6 1.11 0.29 6050 1.86 GE-1 188** 204.92 1250 238 - - 1.13 0.29 5100 1.00 GE-2 188 204.92 1250 227 NaCl 16.6 1.15 0.29 7150 1.40 GF-1 188 163.84*** 1290 251 - - 1.07 0.36 3950 1.00 GF-2 188 163.84 1290 238 NaCl 29.5 1.07 0.36 6050 1.53 GG-1 188 204.92 1250 234 - - 1.13 0.29 3930 1.00 GG-2 188 204.92 1250 229 NaCl 17.8 1.13 0.29 7330 1.87 GG-3 188 204.92 1250 215 KCl 23.9 1.13 0.29 6450 1.64 GH-1 188 204.92 1250 238 - - 1.13 0.29 4130 1.00 GH-2 188 204.92 1250 198 Na2SO4.IOH2O 51.7 1.14 0.29 4780 1.16 GH-3 188 204.92 1250 222 NaCO2 22.2 1.14 0.29 6200 1.50 GI-1 188 204.92 1250 231 NaCl 10.7 1.13 0.29 6180 GI-2 188 204.92 1250 229 CaCl2 11.3 1.13 0.29 6230 * In samples GD-1 and GD-2 a Type II Portland cement was utilized.

** In samples GE-1 and GE-2 a Type III Portland cement was utilized.

*** The pozzolan material utilized in samples GF-1 and GF-2 was a natural pozzolan obtained from Oregon P.C. Co.

Example 9: Tests were performed to demonstrate that the advantages of the present invention are achieved when the ions are supplied in the form of sea water. The composition of the test samples is recorded in Table IX. Unless otherwise noted all samples utilized a blend of three Type I Portland cements, Bowen fly ash, and a 50/50 blend of fine and course sands from Ottawa, Illinois. The tests samples were prepared and tested according to the procedure outlined in Example 2. The test results are reported in Table IX.

The test results indicate that the use of sea water in a high pozzolan content cement composition significantly increases the early strength of the product.

TABLE IX Paste/ Cement/ 7-Day Cube 28-Day Cube 28-Day Cube Test Cement Pozzolan Sand Water Sand Pozzolan Strength Strength Strength Sample (gms.) (cc.) (gms) Water Type Amount (vol.) (vol.) (psi) (psi) vs. Control HA-1 188 102.46 1475 City 248 0.79 0.58 1150 2510 1.00 HA-2 188 102.46 1475 Sea Water 240 0.79 0.58 1790 3940 1.57 HB-1 188 143.44 1380 City 237 0.90 0.42 1400 2700 1.00 HB-2 188 143.44 1380 Sea Water 230 0.89 0.42 2350 5130 1.90 HC-1 188 184.43 1380 City 235 1.05 0.32 1520 2880 1.00 HC-2 188 184.43 1380 Sea Water 235 0.92 0.32 2580 5530 1.92 HD-1 188 183.96* 1260 City 261 1.11 0.32 1430 2580 1.00 HD-2 188 183.96 1260 Sea Water 255 1.11 0.32 2230 4090 1.59 HE-1 188 163.84** 1290 City 251 1.08 0.36 1480 3140 1.00 HE-2 188 163.84 1290 Sea Water 252 1.08 0.36 2550 4200 1.34 HF-1 188*** 204.92 1250 City 233 1.12 0.29 930 1790 1.00 HF-2 188 204.92 1250 Sea Water 235 1.12 0.29 1750 3860 2.16 HG-1 188*** 204.92 1250 City 238 1.13 0.29 1750 2930 1.00 HG-2 188 204.92 1250 Sea Water 227 1.13 0.29 2870 5090 1.74 HH-1 564 - 1400 City 260 0.93 - 7530 9960 1.00 HH-2 564 - 1400 Sea Water 251 0.95 - 7940 9840 0.99 HH-3 564 20.49 1343 Sea Water 257 0.99 8.74 8690 10,520 1.06 HH-4 564 61.48 1240 Sea Water 256 1.14 2.91 9500 11,330 1.14 HH-5 564 102.46 1115 Sea Water 268 1.40 1.75 8530 11,500 1,16 * The pozzolan material utilized in samples HD-1 and HD-2 was a New York fly ash.

** The pozzolan material utilized in samples HE-1 and HE-2 was a natural pozzolan obtained from Oregon P.C. Co.

*** In samples HF-1 and HF-2 a Type II Portland cement was utilized.

**** In samples HG-1 and HG-2 a Type III Portland cement was utilized Example 10: To demonstrate the economic advantages of the present invention a series of tests were performed comparing the relative cost of typical commercially available cement compositions not containing pozzolan material (tests IA-1 through IA-5), cement compositions containing pozzolan material as presently used in the industry (test samples IB-1 through IB-4), cement compositions containing a large proportion of pozzolan (test samples IC-1 through IC-4), and cement compositions containing a large proportion of pozzolan and sodium chloride in an amount equal to 6.65 wt percent of the pozzolan material (test samples ID-1 through ID-8).The test compositions employed cement comprising a blend of three Type I Portland cements, Bowen fly ash, and a 50/50 mixture of fine and coarse sands from Ottawa, Illinois.

The composition of these test samples is reported in Table X. Test samples were prepared and tested in accordance with the procedure set forth in Example 2, and the results of those tests are also reported in Table X. The cost of the cementitious material per yard of concrete was based on a cement cost of $1.80 per 100 pounds and a pozzolan cost of $0.50 per 100 pounds.

The figure is a graph of these test results for the IA, IB and ID series of tests, indicating the relationship between the amount of cement in a cement composition versus the 28-day strength of that composition. The graph indicates that for a given amount of cement the strength can be improved by adding pozzolan up to the normal amount used in commercially available cement compositions. However, as indicated by the IC series of tests, the early strength of the cement composition decreases if additional pozzolan is added without utilizing ionic constituents as employed in the present invention. Thus, any economic advantage associated with the use of pozzolan material in excess of the normal amount is offset by a decrease in structural properties.

As indicated by the figure, significant economic advantages are achieved when excess pozzolan material is utilized in conjunction with the proper amounts of ions which accelerate the pozzolanic reaction. Cement compositions prepared in accordance with the present invention are significantly less expensive per unit volume than commercially available cement compositions having equivalent compressive strengths.

The line representing cement compositions of the present invention intersects the line corresponding to normal pozzolan cement compositions at the point where the ratio of the solid volume of cement to the volume of mortar is about 0.19.

TABLE X Net Net Paste/ Cement/ 7-Day Cube 28-Day Cube Test Cement Pozzolan Sand Water Net Slump Sand Pozzolan Strength Strength Cost Sample (gms.) (gms.) (gms.) (cc) Voids (16th") (vol.) (vol.) (psi) (psi) ($) IA-1 289.5 - 1380 336.7 365.3 14 0.84 - 1300 1890 5.21 IA-2 462.7 - 1380 300.3 332.6 12 0.92 - 4580 6960 8.33 IA-3 643.9 - 1260 292.6 323.2 12 1.12 - 9000 11,790 11.59 IA-4 842.7 - 1030 311.8 339.4 12 1.54 - 11,250 14,080 15.17 IA-5 1033.6 - 800 339.9 365.5 14 2.26 - 12,500 15,120 18.60 IB-1 285.0 126.3 1400 303.2 315.6 13 0.84 1.75 1900 3240 5.76 IB-2 472.7 125.7 1280 291.7 305.2 15 1.03 2.91 6000 8820 9.14 IB-3 664.8 126.3 1090 303.1 315.3 14 1.37 4.08 9250 12,000 12.60 IB-4 844.1 124.7 880 324.3 344.5 15 1.97 5.24 11,250 13,820 15.81 IC-1 92.0 645.8 1140 255.4 278.7 13 1.34 0.11 500 850 4.89 IC-2 276.9 471.3 1140 272.0 290.1 15 1.33 0.46 2450 4140 7.34 IC-3 468.6 279.2 1140 286.1 301.4 14 1.30 1.30 6100 8940 9.83 IC-4 667.2 81.1 1140 291.0 312.0 15 1.26 6.37 9500 12,030 12.42 ID-1 92.7 651.1 1140 235.8 272.5 14 1.32 0.11 1380 3200 4.93 ID-2 277.4 472.2 1140 246.9 288.7 16 1.33 0.46 4150 8130 7.35 ID-3 469.2 279.6 1140 268.6 300.4 13 1.29 1.23 7500 10,370 9.85 ID-4 664.5 80.8 1140 285.8 314.8 13 1.27 6.37 9750 11,630 12.36 ID-5 275.1 501.4 1100 259.0 296.1 14 1.43 0.42 4130 8000 7.46 ID-6 468.6 367.9 1020 278.2 310.8 15 1.57 0.99 6700 10,880 10.27 ID-7 670.1 227.1 950 298.0 323.5 13 1.70 2.29 9500 12.130 13.20 ID-8 868.3 80.0 880 321.3 345.5 15 1.89 8.41 11,250 13,380 16.03 Example ll: Tests were performed to demonstrate the efficacy of utilizing potassium bromide as the source of the ionic constituents in cement compositions of the present invention.The control cement composition utilized in each of the tests HA-1 through HA-3 is as follows: 188 grams Type 1 cement 550 grams of fly ash 1170 grams Waugh sand 247 milliliters water Each of the samples utilized in this series of tests has a cement:pozzolan ratio of 0.26 and a paste:sand ratio of 1.26.

As indicated in Table XI, sample HA-1 contained 22.0 grams of sodium chloride or approximately 4 percent by weight of the fly ash. Otherwise stated, sample HA-1 contained 1.6 percent sbdium ions and 2.4 percent chlorine ions by weight of the fly ash present. In sample HA-2 and HA-3 sufficient amounts of potassium bromide and potassium iodide were added respectively to supply ions in an equivalent weight of the sodium and chloride ions present in sample HA-1.

The tests procedures previously identified were followed with respect to samples HA-1 through HA-3 with the exception that the compressive strength was measured at the end of 33 rather than 28 days. The results are reported in Table XI. These results indicate that cement compositions of the present invention employing potassium bromide demonstrate strength characteristics at least as good as, if not better, than those employing sodium chloride. However, the same degree of strength improvement was not achieved when potassium iodide was utilized.

TABLE XI Total Water 7-Day Cube 33-Day Cube Test (cc/1000 cc Slump Chemical Paste/Sand Strength Strength Sample composition) (16th") Chemical (grams) (vol.) (psi) (psi) HA-1 241 18 NaCl 22.0 1.26 3550 7200 HA-2 234 16 KBr 44.7 1.26 3650 7250 HA-3 232 16 KI 62.4 1.26 2500 4600

Claims

WHAT WE CLAIM IS:

1. A cement composition comprising a cementitious material similar to or the same as Portland cement as hereinbefore defined, a pozzolan material, fine aggregate, water, at least one alkali metal constituent which is a sodium or potassium ion, the alkali metal constituent being present in an amount up to approximately 4.0 percent by weight, in terms of the equivalent weight of sodium ions, of the pozzolan material; and at least one anionic constituent which is a sulfate, chloride, bromide, or nitrite ion, the anionic constituent being present in an amount up to approximately 6.0 percent by weight, in terms of the equivalent weight of chloride ions, of the pozzolan material; said composition having a solid volume ratio of cement to the pozzolan material within the range of approximately 0.05 to 2.0; a ratio of the volume of paste (cement, pozzolan material, water) to the solid volume of fine aggregate within the range of approximately 0.75 to 1.5; and the ratio of the solid volume of cement to the volume of mortar (cement, pozzolan material, water and fine aggregate) less than about 0.19.

2. The composition of Claim 1, wherein sodium ions comprise the alkali metal constituent.

3. The composition of Claim 1, wherein potassium ions comprise the alkali metal constituent.

4. The composition of Claim 1, 2 or 3, wherein the anionic constituent is present in an amount within the range of approximately 0.3 to 2.4 percent by weight, in terms of the equivalent weight of chloride ions, of the pozzolan material.

5. The composition of any one of Claims 1 to 4, wherein the ratio of the volume of paste to the solid volume of fine aggregate is within the range of approximately 1.0 to 1.4.

6. The composition of any one of claims 1 to 5, wherein the alkali metal constituent is present in an amount within the range of approximately 0.2 to 1.6 percent by weight, in terms of the equivalent weight of sodium ions, of the pozzolan material.

7. The composition of any one of Claims 1 to 6, wherein extraneous lime is present in an amount less than 4.0 percent by weight of the pozzolan material.

8. The composition of any one of Claims 1 to 7, including at least one chemical admix selected from derivatives of lignosulfonic acid and its salts, hydroxylated carboxylic acids and their salts, and polymer derivatives of sugar.

9. The composition of any one of Claims 1 to 8, wherein fly ash comprises the pozzolan material.

10. The composition of any one of Claims 1 to 9, wherein sea water comprises the alkali metal constituent and the anionic constituent.

11. The composition of any one of Claims 1 to 10, wherein the solid volume ratio of cement to the pozzolan material is within the range of approximately 0.1 to 2.0.

12. A cement composition of any one of Claims 1 to ii wherein alkali metal constituent is replaced by calcium chloride in an amount comprising approximately 0.5 to 4.0 percent by weight of the pozzolan material.

13. The composition of Claim 12, wherein the calcium chloride is present in an amount comprising approximately 0.5 to 3.0 percent by weight of the pozzolan material.

14. The composition of either one of Claims 12 and 13, wherein the solid volume ratio of cement to the pozzolan material is within the range of approximately 0.1 to 2.0.

15. A cement composition as herein described with particular reference to Examples 2 to 11, and claims 1 to 11.

16. A cement composition as herein described with particular reference to Examples 2 and 8, and claims 12 to 14.