Abstract:
A mixture consisting essentially of fly ash and cement kiln dust which reacts at ambient temperature with water to produce a durable mass.

Description:
This application is a division of application Ser. No. 654,211, filed Feb. 2, 1976, now U.S. Pat. No. 4,018,617. 
    
    
     This invention relates to materials which are capable of supporting surfacing such as pavement bases. 
     BACKGROUND OF THE INVENTION 
     In road paving, at one time it was thought that the base for the surfacing material should comprise a granular or gravel base. However, more recently, it has been concluded that there was a considerable difference in the performance between such bases and cement-aggregate or bituminous (asphalt)-aggregate bases. As reported in the Highway Research Board Special Report 61E, titled The AASHO Road Test, Report 5, Pavement Research, publication 954 of National Academy of Sciences - National Research Council, there is a clear superiority of such treated bases over untreated bases. In recent years, treated bases have become commonly known as stabilized bases. 
     In subsequent work, for example, use of asphalt mixtures in all courses of pavement above the subgrade has been proposed, The Asphalt Institute, Information Series No. 146, June 1968. Asphalt stabilized bases have become the most dominant stabilized base utilized to support a flexible surfacing such as asphalt concrete. In addition, asphalt concrete has found extensive use as a resurfacing material for concrete pavement. 
     It has also been proposed that a lime-fly ash-aggregate stabilized base be used in road paving. Such a base consists of a mixture of proper quantities of lime, fly ash, and graded aggregate at optimum moisture content, in which the stability is greatly enhanced by the cementing action which results from complex chemical reactions between the lime and the fly ash in the presence of water. 
     Stabilized bases are usually employed as base courses under wearing surfaces such as hot mixed, hot laid asphaltic concrete. A wearing surface is necessary to resist the high shearing stresses which are caused by traction, but the stabilized base provides the required stability to support wheel loads. 
     A serious obstacle to the expanded use of stabilized bases is the high energy costs for making the materials. 
     For example, it is well known that the production of portland cement which is used in stabilizing bases requires substantial quantities of coal in manufacture. In fact, the United States Department of Transportation has suggested that fly ash be substituted for a portion of the portland cement utilized in concrete or cement-aggregate bases, Federal Highway Administration Notice N5080.4, Jan. 17, 1974. 
     The use of asphalt in asphalt-aggregate bases which is derived from petroleum processing not only utilizes petroleum which is in short supply but also requires high energy to produce them. 
     Similarly, the lime, fly ash and graded aggregate stabilized bases utilize lime which requires coal in production. Such bases have been used in limited geographical areas of the United States where they can compete economically because of availability of lime and fly ash. 
     Thus, the predominantly used stabilized bases utilize materials that are in short supply and require substantial quantities of energy to produce them. The materials may be termed energy intensive. There is a need to avoid or minimize the use of such energy intensive materials in road paving. 
     Accordingly, among the objects of the invention are to provide a mixture of materials for producing a stabilized base comprising a hard, strong, durable mass capable of supporting surfacing which avoids or minimizes the use of materials which are energy intensive and, moreover, utilizes materials that normally are waste materials that are readily available. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, the mixture consists essentially of fly ash and cement kiln dust which reacts at ambient temperature with water to produce a durable mass. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIGS. 1-3 are curves of compressive strength versus age at test for various compositions. 
     FIG. 4 is curves of energy requirements for various pavement materials. 
    
    
     DESCRIPTION 
     In accordance with the invention, the pozzolanic load supporting composition utilizes cement kiln dust. 
     The solid waste generated by cement manufacture is primarily kiln dust. This dust contains a mixture of raw kiln feed, partly calcined material, finely divided cement klinker and alkali sulfates (usually sulfates). There is economic value in returning the dust to the kiln, but when the alkali content of the returned dust is too high for the product klinker to meet specifications, the dust must be discarded. Up to about 15% of the raw materials processed may be collected as dust and of this about half may be low enough in alkalis to be returned to the kiln. The rest is usually stockpiled as a waste material which must be disposed and may be a nuisance and possibly a hazard. 
     Although the chemical reactions occurring in the resultant cement kiln dust are not well known, typical cement kiln dust has a chemical analysis as follows: 
     SiO 2   
     Al 2  O 3   
     Fe 2  O 3   
     CaO 
     MgO 
     So 3   
     na 2  O 
     K 2  o 
     loss Ignition 
     More specifically, typical cement kiln dust may have the following analyses: 
     
         __________________________________________________________________________ Souce     Source         Source             Source                 Source                     Source                         Source                             Source                                 Source                                     Mid-Ingredient A   B   C   D   E   F   G   H   I   Range__________________________________________________________________________SiO.sub.2 28.5%     6.0%         22.4%             11.2%                 13.0%                     23.5%                         14.8%                             14.6%                                 14.7%                                     17.2%Al.sub.2 O.sub.3 9.6 3.4 4.71             3.2 4.0 3.77                         3.4 3.4 3.7 6.4Fe.sub.2 O.sub.3 5.9 0.8 1.77             1.4 5.0 1.71                         2.2 2.2 3.0 3.4CaO   50.1     16.0         65.0             48.8                 47.2                     61.3                         47.3                             46.3                                 46.5                                     40.5MgO   3.4 0.8 2.60             2.1 1.2 4.83                         2.1 2.0 2.0 2.8SO.sub.3 26.3     0.7 1.12             2.4 13.6                     1.48                         4.8 5.0 8.2 13.5Na.sub.2 O 3.18     0.08         0.24             0.2 0.45                     0.24                         0.9 0.9 0.8 1.6K.sub.2 O 26.23     1.08         1.3 4.2 2.9 1.85                         4.1 5.1 3.0 13.7Loss onIgnition 32.0%     7.7%         2.50%             26.6%                 12.9%                     1.84%                         21.1%                             21.4%                                 18.2%                                     17.2%__________________________________________________________________________ 
    
     
         ______________________________________RANGEIngredient    Low %      High %     Average %______________________________________SiO.sub.2    6.0        28.5       16.5Al.sub.2 O.sub.3    3.2        9.6        4.35Fe.sub.2 O.sub.3    0.8        5.9        2.66CaO      16.0       65.0       47.6MgO      0.8        4.83       2.34SO.sub.3 0.7        26.3       7.07Na.sub.2 O    0.08       3.18       0.78K.sub.2 O    1.08       26.23      5.52Loss onIgnition 2.50       32.0       16.0______________________________________ 
    
     When mixtures made in accordance with the invention and mixed with water to produce a pozzolanic reaction have been tested in accordance with the specifications given in ASTM C-593 for fly ash and other pozzolans for use with lime, it has been found that the compositions meet or exceed the specifications. 
     The term &#34;fly ash&#34; as used in connection with stabilized bases is well known and as used herein is intended to indicate the finely divided ash residue produced by the combustion of pulverized coal or lignite, which ash is carried off with the gases exhausted from the furnace in which the coal is burned and which is collected from these gases usually by means of suitable precipitation apparatus such as electrical precipitators. Those finely pulverized ashes resulting from combustion of oil and from combustion of waste materials in a large incinerator or natural pozzolans can also be utilized in the methods described herein providing their chemical compositions are reasonably similar to pulverized coal fly ashes. The fly ash so obtained is in a finely divided state such that usually at least 70% by weight passes through a 200-mesh sieve, although incinerator ashes may be considerably coarser. Fly ash may be considered an &#34;artificial pozzolan&#34;, as distinguished from a &#34;natural pozzolan&#34;. 
     The term &#34;aggregate&#34; as used in connection with load supporting compositions is also well known and refers to natural or artificial inorganic materials most of which are substantially chemically inert with respect to fly ash and lime, and substantially insoluble in water. Typically, aggregate may comprise limestone, sand, blast furnace slag, gravel, synthetic aggregate and other similar material. 
     Aggregates can comprise a wide range of types and gradations, including sands, gravels, crushed stones, and several types of slag. Aggregates should be of such gradation that, when mixed with cement kiln dust, fly ash and water, the resulting mixture is mechanically stable under compaction equipment and capable of being compacted in the field to high density. The aggregate should be free from deleterious organic or chemical substances which may interfere with the desired chemical reaction between the cement kiln dust, fly ash and water. Further, the aggregate should preferably consist of hard, durable particles, free from soft or disintegrated pieces. 
     It has been found that a preferable mixture comprises: 
     
         ______________________________________         Per Cent by         Dry Weight______________________________________Cement Kiln Dust           8.0%Fly Ash         12.0%Aggregate       80.0%Total           100.0%______________________________________ 
    
     However, the mixture for use in road stabilizer bases may preferably vary as follows: 
     
         ______________________________________         Per Cent By         Dry Weight______________________________________Cement Kiln Dust             4 - 16%Fly Ash          6 - 24%Aggregate       60 - 90%______________________________________ 
    
     As indicated above, tests were conducted in accordance with ASTM C-593. More specifically, the test specimens were molded using a mechanical compactor, having a 10 pound hammer with an 18 inch drop. The material was placed in the molds in three equal layers, and compacted by 25 blows per layer. The machine has a revolving turntable to evenly distribute the blows over the surface of the layer being compacted. 
     After molding, the samples were carefully removed from the molds, weighed, and sealed in plastic bag, labeled for identification, and placed in a constant temperature oven at 100° F to cure until tested. Two cylinders of each mix were marked for testing at 7, 14 and 28 days of curing. After removal from the oven, the samples are submerged in water for four hours, removed, and allowed to drain on a non-absorbant surface, capped, and tested within one hour after removal from the water. The capping compound used is &#34;Hydro-Stone&#34; a lime based, quick-hardening compound. Plate glass was used to obtain even, parallel caps on the test specimens. 
     Examples of various tests and compositions are as follows: 
     
         __________________________________________________________________________EXAMPLE I                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   8.0%       2.4#     Fly Ash       12.0%      3.6#     Limestone     80.0%      24.0#     Total         100.0%     30.0#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    10.8 4.73    141.9 128.1 12.57                              10-16                                  13,140                                      1050B    10.8 4.72    141.6 127.8 12.57                              10-16                                  14,370                                      1140C    10.8 4.73    141.9 128.1 12.57                              10-23                                  15,780                                      1260D    10.8 4.73    141.9 128.1 12.57                              10-23                                  15,530                                      1240E    10.8 4.73    141.9 128.1 12.57                              11-06                                  17,800                                      1420F    10.8 4.73    141.9 128.1 12.57                              11-06                                  17,800                                      1420__________________________________________________________________________ Remarks: Slight bleeding at bottom of mold. 
    
     
         __________________________________________________________________________EXAMPLE II                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   8.0%       2.4#     Fly Ash       12.0%      3.6#     Limestone     80.0%      24.0#     Retarder      --         0.96 oz     Total         100.0%     30.0#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    10.1 4.73    141.9 128.9 12.57                              10-16                                  --  --B    10.1 4.73    141.9 128.9 12.57                              10-16                                  --  --C    10.2 4.73    141.9 128.8 12.57                              10-23                                  1,650                                      130D    10.2 4.73    141.9 128.8 12.57                              10-23                                  1,930                                      150E    10.3 4.73    141.9 128.6 12.57                              11-06                                  2,300                                      180F    10.3 4.73    141.9 128.6 12.57                              11-06                                  2,100                                      170__________________________________________________________________________ Remarks: Slight bleeding. Samples 2-A and 2-B fell apart during the four (4) hour soaking. There wa no intact sample to subject to compression test. Samples C, D, E, and F were not subjected to the four (4) hour soaking, prior to testing. 
    
     
         __________________________________________________________________________EXAMPLE III                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   8.0%       2.4#     Fly Ash       12.0%      3.6#     Limestone     80.0%      24.0#     Calcium Chloride Solution                   --         (0.24#)     Total         100.0%     30.0#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    10.4 4.77    143.1 129.6 12.57                              10-16                                  15,160                                      1210B    10.4 4.77    143.1 129.6 12.57                              10-16                                  15,750                                      1250C    10.0 4.73    141.9 129.0 12.57                              10-23                                  17,250                                      1370D    9.9  4.73    141.9 129.1 12.57                              10-23                                  18,950                                      1510E    9.8  4.73    141.9 129.2 12.57                              11-06                                  20,600                                      1640F    9.7  4.72    141.6 129.1 12.57                              11-06                                  20,700                                      1650__________________________________________________________________________ Remarks: Slight bleeding 
    
     
         __________________________________________________________________________EXAMPLE IV                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   8.0%       2.4#     Stack Dust    3.0%       0.9#     Fly Ash       12.0%      3.6#     Limestone     77.0%      23.1#     Total         100.0%     30.0#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    8.5  4.53    135.9 125.3 12.57                              10-17                                   8,200                                       652B    8.5  4.54    136.2 125.5 12.57                              10-17                                   8,900                                       708C    8.7  4.58    137.4 126.4 12.57                              10-24                                  10,950                                       871D    8.8  4.56    136.8 125.7 12.57                              10-24                                  11,775                                       937E    9.0  4.58    137.4 126.1 12.57                              11-07                                  16,050                                      1280F    9.0  4.56    136.8 125.5 12.57                              11-07                                  14,850                                      1180__________________________________________________________________________ Remarks: No bleeding. 
    
     
         __________________________________________________________________________EXAMPLE V                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   12.0%      3.6#     Fly Ash       88.0%      26.4#     Total         100.0%     30.0#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    9.5  2.87    86.1  78.6  12.57                              10-17                                  2,350                                      187B    9.7  2.90    87.0  79.3  12.57                              10-17                                  2,300                                      183C    9.7  2.90    87.0  79.3  12.57                              10-24                                  2,075                                      165D    9.7  2.90    87.0  79.3  12.57                              10-24                                  1,900                                      151E    9.7  2.90    87.0  79.3  12.57                              11-07                                  3,040                                      240F    10.0 2.96    88.8  80.7  12.57                              11-07                                  3,230                                      260__________________________________________________________________________ Remarks: Had difficulty in reaching the desired moisture content because of the dust&#39;s extremely dry condition. Extremely &#34;fluffy&#34; material. 
    
     
         __________________________________________________________________________EXAMPLE VI                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   8.0%       2.4#     Fly Ash       8.0%       2.4#     Limestone     79.0%      23.7#     Limestone Fines                   5.0%       1.5#     Total         100.0%     30.0#     Water added: 1158 + 136 = 1294SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    9.8  4.85    145.5 132.5 12.57                              10-20                                  13,900                                      1110B    9.8  4.81    144.3 131.4 12.57                              10-20                                  15,000                                      1190C    9.8  4.79    143.7 130.9 12.57                              10-27                                  17,350                                      1380D    9.9  4.81    144.3 131.3 12.57                              10-27                                  18,200                                      1448E    9.9  4.81    144.3 131.3 12.57                              11-10                                  17,050                                      1356F    9.9  4.78    143.4 130.5 12.57                              11-10                                  16,600                                      1321__________________________________________________________________________ Remarks: Good compactability. Material was relatively easy to work with. 
    
     
         __________________________________________________________________________EXAMPLE VII                              Weight of                   Percent    Batch__________________________________________________________________________     Fly Ash       8.0%       2.40#     Kiln Dust     10.0%      3.00#     No. 304 Limestone                   82.0%      24.60#     (Screened over 3/4&#34; screen)     Total         100.0%     30.00#Cyl. Percent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________1    11.5 4.73    141.9 127.3 12.57                              4-01                                   9350                                       7452    11.1 4.71    141.3 127.2 12.57                              4-01                                   8610                                       6853    11.1 4.73    141.9 127.7 12.57                              4-01                                   9290                                       7404    11.1 4.74    142.2 128.1 12.57                              4-22                                  14050                                      11205    11.0 4.75    142.5 128.4 12.57                              4-22                                  13500                                      10756    10.7 4.74    142.2 128.5 12.57                              4-22                                  13620                                      1085__________________________________________________________________________ A. Slight bleeding at bottom of mold during compaction. B. Material appeared deficient in limestone fines (-#4 material). C. Some free moisture noted, giving slight &#34;glossy&#34; appearance. D. Samples slumped, following extraction from molds. 
    
     
         __________________________________________________________________________EXAMPLE VIII                              Weight of                   Percent    Batch__________________________________________________________________________     Fly Ash       10.0%      3.00#     Kiln Dust     8.0%       2.40#     No. 304 Limestone                   82.0%      24.60#     (Screened over 3/4&#34; screen)     Total         100.0%     30.00#Cyl. Percent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________1    9.3  4.72    141.6 129.6 12.57                              4-01                                   8060                                      6402    9.4  4.71    141.3 129.2 12.57                              4-01                                   7750                                      6153    9.4  4.71    141.3 129.2 12.57                              4-01                                   8000                                      6354    9.5  4.69    140.7 128.5 12.57                              4-22                                   9730                                      7755    9.6  4.68    140.4 128.1 12.57                              4-22                                  10450                                      8306    9.5  4.69    140.7 128.5 12.57                              4-22                                  11490                                      915__________________________________________________________________________ A. Samples retained shape following extraction from molds. B. No free water noticed bleeding during compaction. 
    
     
         __________________________________________________________________________EXAMPLE IX                              Weight of                   Percent    Batch__________________________________________________________________________     Fly Ash       8.0%       2.40#     Kiln Dust     10.0%      3.00#     Fill Sand     82.0%      24.60#     Total         100.0%     30.00#Cyl. Percent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________1    9.8  4.09    122.7 111.7 12.57                              3-31                                  1800                                      1452    10.0 4.12    123.6 112.4 12.57                              3-31                                  1700                                      1353    9.9  4.10    123.0 111.9 12.57                              3-31                                  1690                                      1354    9.9  4.11    123.3 112.2 12.57                              4-21                                  2810                                      2255    10.0 4.10    123.0 111.8 12.57                              4-21                                  2880                                      2306    9.8  4.09    122.7 111.7 12.57                              4-21                                  2670                                      210__________________________________________________________________________ A. No bleeding of sample during compaction. B. Material stayed in a ball when packed by hand. C. Slight bulking noticed. D. Easily compacted. 
    
     
         __________________________________________________________________________EXAMPLE X                              Weight of                   Percent    Batch__________________________________________________________________________     Fly Ash       8.0%       2.40#     Kiln Dust     10.0%      3.00#     Glass (Crushed to approx.     1/2&#34; size)    32.0%      9.60#     Fill Sand     50.0%      15.00#     Total         100.0%     30.00#Cyl. Percent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________1    9.4  4.50    135.0 123.4 12.57                              4-02                                  4390                                      3502    9.4  4.50    135.0 123.4 12.57                              4-02                                  4590                                      3653    9.3  4.51    135.3 123.8 12.57                              4-02                                  4200                                      3354    9.2  4.52    135.6 124.2 12.57                              4-23                                  6750                                      5355    9.1  4.51    135.3 124.0 12.57                              4-23                                  6870                                      5456    9.1  4.47    134.1 122.9 12.57                              4-23                                  6280                                      500__________________________________________________________________________ A. Material originally mixed to 10.3% moisture, looked wet, probably because non-absorbancy of glass. B. Air dried the mix out to approximately 9.4% moisture, did not bulk at this moisture content. C. Surprisingly good cohesion of mix, even with the smooth faces of glass particles. D. Strength of cylinders higher than expected, thought the mix would slip off the smooth glass faces, when put under compression. 
    
     
         __________________________________________________________________________EXAMPLE XI                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   16.0       3.2#     Fly Ash       24.0       4.8#     No. 304 Crushed Limestone                   60.0       12.0#     Total         100.0      20.0#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    16.6 4.50    135.0 115.8 12.57                              12/22                                  5890                                      470B    15.1 4.46    133.8 116.2 12.57                              12/22                                  6000                                      480C    15.0 4.46    133.8 116.3 12.57                              12/22                                  6150                                      490__________________________________________________________________________ 
    
     
         __________________________________________________________________________EXAMPLE XII                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   4.0        0.8#     Fly Ash       6.0        1.2#     No. 304 Crushed Limestone                   90.0       18.0#     Total         100.0      20.0#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    11.1 4.94    148.2 133.4 12.57                              12/22                                  2950                                      230B    11.2 4.93    147.9 133.0 12.57                              12/22                                  3570                                      280C    11.2 4.93    147.9 133.0 12.57                              12/22                                  3250                                      260__________________________________________________________________________ 
    
     
         __________________________________________________________________________EXAMPLE XIII                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   6.9%       140#     Fly Ash       11.8%      240#     Limestone Screenings                   39.4%      800#     No. 57 Crushed Limestone                   39.4%      800#     Water         2.5%        50#     Total         100.0%     2030#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    5.6  4.49    134.7 127.6 12.57                              11-22                                  8,950                                      712B    5.1  4.51    135.3 128.7 12.57                              11-22                                  8,225                                      654C    5.5  4.51    135.3 128.2 12.57                              11-22                                  9,050                                      720D    5.4  4.50    135.0 128.1 12.57                              11-29                                  9,610                                      760E    5.5  4.49    134.7 127.7 12.57                              11-29                                  8,080                                      640F    4.9  4.50    135.0 128.7 12.57                              11-29                                  9,630                                      770G    5.1  4.46    133.8 127.3 12.57                              12-13                                  8,820                                      700H    5.3  4.51    135.3 128.5 12.57                              12-13                                  9,380                                      750I    5.4  4.50    135.0 128.1 12.57                              12-13                                  9,400                                      750J    5.3  4.46    133.8 127.1 12.57                              02-03K    5.1  4.51    135.3 128.7 12.57                              02-03L    4.9  4.48    134.4 128.1 12.57                              02-03M    5.0  4.54    136.2 129.7 12.57                              For Durability TestN    4.9  4.54    136.2 129.8 12.57                              For Durability TestO    4.8  4.47    134.1 128.0 12.57                              For Durability Test__________________________________________________________________________ 
    
     
         __________________________________________________________________________EXAMPLE XIV                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Type I 1.0%        20#     Cement Kiln Dust                   6.8%       140#     Fly Ash       11.7%      240#     Limestone Screenings                   39.0%      800#     No. 57 Crushed Limestone                   39.0%      800#     Water         2.5%        50#     Total         100.0%     2050#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    5.4  4.58    137.4 130.4 12.57                              11-21                                  10,030                                       800B    5.4  4.58    137.4 130.4 12.57                              11-21                                  11,780                                       940C    5.4  4.58    137.4 130.4 12.57                              11-21                                  14,120                                      1120D    5.3  4.58    137.4 130.5 12.57                              11-28                                  15,500                                      1230E    5.0  4.58    137.4 130.9 12.57                              11-28                                  18,500                                      1470F    5.8  4.46    133.8 126.5 12.57                              11-29                                  14,910                                      1190G    5.8  4.46    133.8 126.5 12.57                              12-13                                  17,900                                      1420H    5.7  4.46    133.8 126.6 12.57                              12-13                                  20,010                                      1590I    5.7  4.46    133.8 126.6 12.57                              12-13                                  14,980                                      1190J    5.7  4.46    133.8 126.6 12.57                              02-13K    5.6  4.46    133.8 126.7 12.57                              02-13L    5.6  4.46    133.8 126.7 12.57                              02-13M    5.4  4.49    134.7 127.8 12.57                              For Durability TestN    5.4  4.49    134.7 127.8 12.57                              For Durability TestO    5.4  4.49    134.7 127.8 12.57                              For Durability Test__________________________________________________________________________ 
    
     
         __________________________________________________________________________EXAMPLE XV                              Weight of                   Percent    Batch__________________________________________________________________________     Cement Kiln Dust                   7.8%        160#     Fly Ash       11.7%       240#     Limestone Screenings                   39.0%       800#     No. 57 Crushed Limestone                   39.0%       800#     Water         2.5%         50#     Total         100.0%      2050#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    8.1  4.24    127.2 117.7 12.57                              11-22                                  4,650                                       370*B    7.9  4.24    127.2 117.9 12.57                              11-22                                  5,700                                      450C    8.3  4.29    128.7 118.8 12.57                              11-22                                  6,030D    7.8  4.25    127.5 118.3 12.57                              11-29                                  7,200                                      570E    7.7  4.24    127.2 118.1 12.57                              11-29                                  6,850                                      540F    7.6  4.26    127.8 118.8 12.57                              11-29                                  8,080                                      640G    7.6  4.30    129.0 119.9 12.57                              12-13                                  10,000                                      800H    7.6  4.27    128.1 119.0 12.57                              12-13                                  9,500                                      760I    7.6  4.27    128.1 119.0 12.57                              12-13                                  8,980                                      710J    7.5  4.27    128.1 119.2 12.57                              02-13K    7.3  4.28    128.4 119.7 12.57                              02-13L    7.2  4.26    127.8 119.2 12.57                              02-13M    7.2  4.27    128.1 119.5 12.57                              For Durability TestN    7.1  4.24    127.2 118.8 12.57                              For Durability TestO    7.2  4.25    127.5 118.9 12.57                              For Durability Test__________________________________________________________________________ *Sample fractured horizontally during capping Remarks: This product was produced on November 6, and sampled on Novemeber 13. Materials are the same as in Example XIII - This example is a check to se if the age of the product, before use, has any effect on the strength results. 
    
     
         __________________________________________________________________________EXAMPLE XVI                              Weight of                   Percent    Batch__________________________________________________________________________     Fly Ash       11.6%       232#     Lime          3.4%        68#     No. 304 Crushed Limestone                   85.0%      1700#     Water         --         --     Total         100.0%     2000#SpecimenPercent     Wt. As  Wet Wt.                   Dry Wt.                         Area Date                                  Mach.No.  Water     Molded (Lbs.)             Per Cu. Ft.                   Per Cu. Ft.                         (Sq. In.)                              Tested                                  Load                                      P.S.I.__________________________________________________________________________A    10.4 4.60    138.0 125.0 12.57                              11-28                                  10,325                                       820B    10.4 4.70    141.0 127.7 12.57                              11-28                                  11,950                                       950C    10.2 4.62    138.6 125.8 12.57                              11-28                                  10,650                                       850D    10.2 4.67    140.1 127.1 12.57                              12-05                                  19,600                                      1559E    10.2 4.66    139.8 126.9 12.57                              12-05                                  18,950                                      1508F    11.1 4.65    139.5 125.6 12.57                              12-05                                  19,825                                      1577G    10.8 4.66    139.8 126.2 12.57                              12-19                                  21,860                                      1740H    10.8 4.66    139.8 126.2 12.57                              12-19                                  20,790                                      1650I    10.8 4.64    139.2 125.6 12.57                              12-19                                  21,000                                      1670J    10.8 4.70    141.0 127.3 12.57                              02-19K    10.9 4.65    139.5 125.8 12.57                              02-19L    10.9 4.68    140.4 126.6 12.57                              02-19M    10.9  4.66   139.8 126.1 12.57                              For Durability TestN    10.9 4.68    140.4 126.6 12.57                              For Durability TestO    9.6  4.63    138.9 126.7 12.57                              For Durability Test__________________________________________________________________________ 
    
     The results of the tests are summarized in FIGS. 1-3. 
     As shown in FIG. 1, mixtures containing cement kiln dust vary but in each instant produce a base that is stabilized. 
     As shown in FIG. 2, the addition of additives or admixtures generally do not affect the strength except that a retarder tends to prevent the early development of strength as might be expected. 
     As shown in FIG. 3, the strength of mixtures including cement kiln dust compare favorably with a lime, fly ash, aggregate mixture. In addition, even a mixture of cement kiln dust and fly ash produces a stabilized base. 
     Thus, the mixtures of the present invention result in a stabilized base that is comparable in strength and required performance characteristics to cement-aggregate or lime-fly ash-aggregate stabilized bases and yet are not energy intensive. The mixtures of the present invention cost less than the predominantly used asphalt-aggregate bases. Also, the use of mixtures of the invention releases asphalt for use in resurfacing or as a heavy industrial fuel. 
     FIG. 4 is a curve showing the BTU&#39;s per mile versus thickness for various road paving materials taken from Highway Research Circular titled &#34;Fuel Usage Factors for Highway Construction&#34;, Number 158, July, 1974. It ca be seen that asphalt concrete and cement type mixtures require substantial energy and only granular base or sub-base of aggregate has minimal energy requirements in hauling, spreading, compacting and finishing. Since the mixtures of the present invention utilize waste materials, namely, cement kiln dust and fly ash, the energy requirements for making a stabilized base are only in hauling, spreading, compacting and finishing. As a result, the mixtures of the present invention have minimal energy requirements and thereby obviate the energy intensive materials or prior stabilized bases. 
     The mixtures of the present invention utilize cement kiln dust which is a waste product that is relatively available from cement plants and fly ash which is readily available from power plants.