Abstract:
A mixture consisting essentially of fly ash, cement kiln dust and aggregate which through pozzolanic reactions produces a hard, strong, durable mass capable of supporting surfacing.

Description:
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 
     Basically, the invention comprises a mixture consisting essentially of fly ash, cement kiln dust and aggregate which through pozzolanic reactions produces a hard, strong, durable mass capable of supporting surfacing. 
    
    
     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 clinker 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 to 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: 
     
         __________________________________________________________________________ Source      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%__________________________________________________________________________ 
    
     
                       RANGE______________________________________Ingredient 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 pozzalan,&#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 limestones, 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: 
     
         ______________________________________              Percent by              Dry WeightCement 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: 
     
         ______________________________________             Percent By             Dry WeightCement 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  BatchCement Kiln Dust            8.0%     2.4 lbs.Fly Ash          12.0%    3.6 lbsLimestone        80.0%   24.0 lbs.Total           100.0%   30.0 lbs.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                  BatchCement Kiln Dust           8.0%   2.4 lbs.Fly Ash         12.0%  3.6 lbs.Limestone       80.0% 24.0 lbs.Retarder               0.96 ozTotal          100.0% 30.0 lbs.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 was 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                   BatchCement Kiln Dust  8.0%  2.4 lbFly Ash           12.0%                   3.6 lbLimestone         80.0%                  24.0 lbCalcium Chloride Solution            --    (0.24 lb)Total            100.0%                  30.0 lbSpecimenPercent     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                  BatchCement Kiln Dust           8.0%   2.4 lbStack Dust      3.0%   0.9 lbFly Ash        12.0%   3.6 lbLimestone      77.0%  23.1 lbTotal          100.0% 30.0 lbSpecimenPercent     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                 BatchCement Kiln Dust           12.0%  3.6 lbFly Ash         88.0% 26.4 lbTotal          100.0% 30.0 lbSpecimenPercent     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                    BatchCement Kiln Dust    8.0%  2.4 lbFly Ash             8.0%  2.4 lbLimestone           79.0%                    23.7 lbLimestone Fines     5.0%  1.5 lbTotal              100.0%                    30.0 lbWater 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                    BatchFly Ash             8.0%  2.40 lbKiln Dust           10.0%                     3.00 lbNo. 304 Limestone   82.0%                    24.60 lb  (Screened over 3/4&#34; screen)Total              100.0%                    30.00 lbCyl.   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 (-No. 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                   BatchFly Ash             10.0%                    3.00 lbKiln Dust           8.0%                    2.40 lbNo. 304 Limestone   82.0%                   24.60 lb   (Screened over 3/4&#34; screen)Total              100.0%                   30.00 lbCyl.   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  BatchFly Ash      8.0%     2.40 lbKiln Dust    10.0%    3.00 lbFill Sand    82.0%   24.60 lbTotal       100.0%   30.00 lbCyl.   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 BatchFly Ash      8.0%     2.40 lbKiln Dust    10.0%    3.00 lbGlass (Crushed toapprox. 1/2&#34; size)        32.0%    9.60 lbFill Sand    50.0%   5.0 lbTotal        100.0%  30.00 lbCyl.   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                   BatchCement Kiln Dust  16.0   3.2 lbFly Ash           24.0   4.8 lbNo. 304 Crushed Limestone             60.0  12.0 lbTotal             100.0 20.0 lbSpecimenPercent     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.T.__________________________________________________________________________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                   BatchCement Kiln Dust  4.0    0.8 No.Fly Ash           6.0    1.2 No.No. 304 Crushed Limestone             90.0  18.0 No.Total            100.0  20.0 No.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                    BatchCement Kiln Dust   6.9%   140 lbFly Ash            11.8%  240 lbLimestone Screenings              39.4%  800 lbNo. 57 Crushed Limestone              39.4%  800 lbWater              2.5%   50 lbTotal             100.0% 2030 lbSpecimenPercent    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                    BatchCement Type I      1.0%   20 lbCement Kiln Dust   6.8%   140 lbFly Ash            11.7%  240 lbLimestone Screenings              39.0%  800 lbNo. 57 Crushed Limestone              39.0%  800 lbWater              2.5%   50 lbTotal             100.0% 2050 lbSpecimenPercent    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                    BatchCement Kiln Dust   7.8%   160 lbFly Ash            11.7%  240 lbLimestone Screenings              39.0%  800 lbNo. 57 Crushed Limestone              39.0%  800 lbWater              2.5%   50 lbTotal             100.0% 2050 lbSpecimenPercent     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       6,030 480D    7.8  4.25     127.5   118.3   12.57  11-29       7,220 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 November 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                   BatchFly Ash           11.6%  232 lbLime               3.4%  68 lbNo. 304 Crushed Limestone             85.0% 1700 lbWater            --     --Total            100.0% 2000 lbSpecimen  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.__________________________________________________________________________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 Reserach Circular titled &#34;Fuel Usage Factors for Highway Construction,&#34; Number 158, July, 1974. It can 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 of 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.