AU761213B2 - Cement compositions for controlling alkali-silica reactions in concrete and processes for making same - Google Patents

Description

P/01/009 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990 TRUE COPY COMPLETE SPECIFICATION STANDARD PATENT We certify that the following nineteen pages are a true and correct copy of the description and claims of the original complete specification in respect of an invention entitled CEMENT COMPOSITIONS FOR CONTROLLING ALKALI-SILICA REACTIONS IN CONCRETE AND PROCESSES FOR MAKING SAME.

Name of Applicant: FMC CORPORATION Signature: 4. (Note: An exact copy of the material attached to Form 10 must be attached to this form) CEMENT COMPOSITIONS FOR CONTROLLING ALKALI-SILICA REACTIONS IN CONCRETE AND PROCESSES FOR MAKING SAME Cross-Reference to Related Applications This application is related to commonly owned copending Provisional Application Serial No.

60/003,475, filed September 8, 1995.

Field of the Invention This invention relates generally to cement ~compositions and processes for producing the same, and more particularly cement for controlling alkali-silica .reaction in concrete which includes the cement as a S. 10 component.

o oe coo• Background of the Invention Concrete is a conglomerate of aggregate (such gravel, sand, and/or crushed stone), water, and hydraulic cement (such as portland cement), as well as 15 other components and/or additives. Concrete is *generally fluidic when it is first made, enabling it to be poured or placed into shapes, and then later hardens, and is never again fluidic, in the general sense. Typically, moisture present in normal concrete is basic (that is, has a high pH). Alkali materials can be supplied by the cement, aggregate, additives, and even from the environment in which the hardened concrete exists (such as salts placed on concrete to melt ice) Silica compounds are typically found in the aggregate components of concrete. Silica which is present in aggregates used to make concrete and mortars is subject to attack and dissolution by hydroxide ions -2present in basic solutions. Generally, the higher the pH the more basic the solution), the faster the attack.

Different forms of silica show varying degrees of susceptibility to this dissolution. If there is sufficient alkali metal ion also present in this solution (such as sodium or potassium ions), the alkali metal ions can react with the dissolved silica and form an alkali-silica gel. Under certain conditions, the resultant alkali-silica gel can absorb water and swell. The swelling can exert pressures greater than the tensile strength of the concrete and thus cause the concrete to swell and crack. This process (hydroxide attack of silica, followed by reaction with alkali such as sodium and potassium) is ereferred to generally in the art as an "alkali-silica reaction" or "ASR".

ASR has caused the failure of concrete S"structures, although rarely. Further, ASR can weaken ee 20 the ability of concrete to withstand other forms of attack. For example, concrete that is cracked due to ~this process can permit a greater degree of saturation ~and is therefore much more susceptible to damage as a result of "freeze-thaw" cycles. Similarly, cracks in the surfaces of steel reinforced concrete can *compromise the ability of the concrete to keep out salts when subjected to deicers, thus allowing corrosion of the steel it was designed to protect.

S"ASR is a common chemical process in many concretes around the world. As an indication of its importance to the concrete industry, by 1991 over 1,450 research articles had been published on the subject.

See S. Diamond, Alkali-aggregate reactions in concrete: an annotated bibliography 1939-1991, Washington, D.C.: National Research Council, Strategic Highway Research Program, SHRP-C/UWP-92-601:470 (1992).

-3- In 1987, Congress authorized a $150 million, fiveyear research program to be administered by the National Research Council to study and develop improvements in highway construction materials and construction practices. This program was called the Strategic Highway Research Program (SHRP). One of the areas addressed by this program was ASR mitigation.

Four recommendations resulted from the SHRP research for preventing ASR in concrete. D. Stark, et al., Eliminating or minimizing alkali-silica reactivity, Washington, D.C.:National Research Council, Strategic Highway Research Program, SHRP-C-343 (1993) (the "SHRP Sreport").

One recommendation was the use a lcw alkali cement, which is defined as a cement with a sodium equivalent of 0.60% or less. The sodium equivalent of :a cement is the weight percent of sodium, reported as sodium oxide, plus 0.658 times the weight percent of potassium, reported as potassium oxide. Sodium equivalent (NaO) can be represented generally by the formula NaO C.658 x K=O NaO,.

S. While the use of a low alkali cement can have some effectiveness, it is not a guarantee of ASR prevention.

Low alkali cement is not always available on a local basis, can have limited availability, and can be more S. expensive than high alkali cement. Further, if the raw feed for the cement production contains high levels of alkali, then the production of low alkali cement from such feed can generate much greater waste than would otherwise be the case. Generally, "fines" are a waste product of cement production and are normally recirculated into the cement kiln. However, when the raw feed has a high alkali level, the fines must be removed from the process to make a low alkali cemer.

and constitute a waste material. These fines are generally referred in the industry as cement kiln dust.

SUBSTITUTE SHEET AMENDED SHEET Still further, using a low alkali cement is no guarantee of ASR control, as the cement is not the sole source of the alkalies in concrete that can contribute to the problem. Alkalies also can be supplied by pozzolans that are either admixed in or part of the blended cement. Alkalies can be supplied by the mix water, admixtures used in the concrete, the aggregate itself, including recycled concrete used as aggregate, and/or deicers applied in snow and ice removal.

Another recommendation set forth by the SHRP report is the use a non-reactive aggregate. This, however, is not always possible. There are limited aggregates with no potential for reactivity, since all silica has some potential for reaction and most i aggregates contain significant amounts of silica.

Recycled concrete when used as aggregate can also be reactive, particularly if it had already had ASR occurring before it was recycled. There are environmental reasons to use recycled glass as aggregate, but this is very reactive material. Also, transporting aggregates over long distances instead of using locally available materials adds significantly to the cost of concrete production.

25 Another recommendation is the use of appropriate levels of a suitable pozzolan. A pozzolan is a siliceous material that can combine with lime and water to harden, similar to a cement with just water.

Since the hydration of cement produces lime as a byproduct (resulting in its basic nature), pozzolans can work well with cements. The pozzolan may be added as a mineral admixture at the time of concrete production, blended with the cement, or interground with the cement during the final production step of cement. The end result is about the same, as neither the cement nor the pozzolan is substantially changed as a result of the blending.

However, sources of suitable pozzolans are not always'available locally, and the supplies are limited. Also, many pozzolans used for this purpose are waste products, and thus are quite variable in composition. An example is fly ash, which is the end result of coal burned for electric generation.

Further, sufficient amounts of the pozzolan must be used, or the protection is short lived, or the ASR can actually be made worse. This is particularly true of pozzolans with significant lime contents such as many fly ashes. In a cementitious system, the Ca:Si ratio is very important to its stability with regard to ASR. The higher the Ca:Si ratio, the less capable the system is of tying up alkali present. Thus the protection against ASR is Sless with high lime fly ashes. A low lime content pozzolan will reduce the ratio and give more protection from increased alkalies. However, a high lime content pozzolan will not give this protection, 20 and further, since pozzolans carry their own alkalies into the system, this can easily make the situation ge worse.

ge ~Still another recommendation is the use a lithium-based admixture. Use of lithium was shown to **o 25 be effective in ASR inhibition in 1951 (see W.J. McCoy and A.G. Caldwell, "New approach to inhibiting alkaliaggregate expansion," J.Amer.Concrete Institute, S22:693-706 (1951)). See also Y. Sakaguchi, et al., "The inhibiting effect of lithium compounds on alkalisilica reaction," Proceedings, 8th international conference, alkali aggregate reaction, Kyoto, Japan: 229-234 (1989), and the SHRP report.

Lithium salts, such as lithium hydroxide monohydrate, have been added to cement at the grinding stage of the cement production. J. Gajda, Development of a cement to inhibit alkali-silica reactivity, Skokie, IL, Portland Cement Association Research and -6- Development Bulletin RD115T (1996). As with the pozzolan blended cements mentioned above, the net effect is basically the same as if the lithium salt were admixed into the concrete separately at the time the concrete was batched. That is, by adding the lithium salt to the cement at the time of grinding, neither the cement nor the lithium salt is changed during the process. Rather, the lithium salt and cement are merely blended.

One problem associated with adding lithium salts to the concrete mixture or grinding lithium salts with cement is that substantial amounts of the lithium (about 50%, as reported in the SHRP Report) are "locked Sup" in the hydration products of the early hydration 15 reactions of the cement. A substantial portion of the 99*999 9lithium ions, therefore, is unavailable for use in controlling ASR. This generally happens within the first few days of hydration. Still further, the concentration of hydroxyl ion can increase when lithium 20 salts are admixed into concrete and mortars (see the SHRP Report). This can make the job of the lithium ion that much more difficult, and requires more lithium than would otherwise be the case.

Summary of the Invention The present invention provides a process for producing cement which, when used to make concrete or mortar mixtures, can.inhibit alkali-silica reactivity Sofrom alkali containing components. In the invention, lithium containing materials, including lithium salts, lithium ores, lithium ore concentrates, and preheated or decrepitated lithium ore and concentrates, are heated in a cement kiln with cement starting materials (ores) to form cement clinker. The lithium containing material supplies lithium ions to the cement, which enables the cement thus produced to inhibit alkalisilica reaction in concrete and mortars made with the -7cement. This is turn can minimize and/or prevent deterioration of concrete from ASR.

The process of the invention also can result in reduced energy requirements necessary to manufacture the cement for a given unit of cement because lithium can act as a flux in cement production. Further, lithium containing materials include siliceous materials which are pozzolanic by nature. In addition, when lithium bearing ores are used as the lithium source, the process of the invention can provide economic advantages as compared to lithium salts (which require extracting and purifying lithium from the ores). Still further, less lithium is required to inhibit ASR in the resultant concrete than purified forms of lithium, because lithium present in lithium i bearing ores can be more slowly released into the concrete mixture after much of cement hydration has occurred, in contrast to lithium salts.

The present invention also includes cement 20 produced according to the invention, as well as concrete and mortar which include the cement as a ooe.

eo component.

oool Brief Description of the Drawings Some of the features and advantages of the invention having been described, others will become apparent from the detailed description which follows, and from the accompanying drawings, in which: "Figure 1 is an x-ray diffraction pattern of clinker prepared at 1400 0 C without lithium; Figure 2 is an x-ray diffraction pattern of clinker prepared at 1300 0 C with lithium; and Figure 3 is a graph illustrating isothermal calorimetry of clinker made with and without lithium at 1400 0

C.

-8- Detailed Description of the Invention Cement is manufactured by introducing cement starting materials into a kiln and heating the cement starting materials to extremely high temperatures, typically about 1482°C (2700 0 Cement starting materials typically include carbonates (limestone or chalk), silica, clays, shales, slates and the like and mixtures thereof. As the skilled artisan will appreciate, other starting materials can also be used.

This stage is referred to generally in the art as "clinkering" and the resultant product is referred to as "clinker." The clinker is then cooled and ground, typically with gypsum to control the quick setting properties of the aluminate phases in the cement.

In the present invention, lithium containing materials are added with the cement starting materials in the front end of the cement kiln and heated with the cement starting materials to form clinker. The resultant cement product (or clinker) thus includes lithium and can be an effective mitigator of ASR when added to a concrete or mortar mixture.

As used herein, the term "cement" refers to, but is not limized to, hydraulic and alite cements, such as Portland cement; blended cements, such as Portland cement blended with fly ash, blast-furnace slag, ii. pozzolans, and the like, and mixtures thereof; masonry cement; oil well cement; natural cement; alumina cement; expansive cements, and the like, and mixtures thereof.

Exemplary lithium containing materials include, but are not limited to, refined lithium products such as lithium salts (for example, lithium carbonate, lithium hydroxide monohydrate, lithium nitrate, lithium fluoride, lithium chloride, and the like, and mixtures thereof). Other lithium sources include lithium SUBSTITUTE SHEET A.WNDED SHEET -8abearing ores and lithium ore concentrates such as lith ium aluminum silicates, such

S

S. *S Se SUBSTITUTE SHEET ANIENDED

SH-EET

as spodumene (Lj 2 'OAl0O-4SiO2). netaJlite (L1 2 0-A1 2 0 3 8Si0J'), eucryptite (L' 2 OAl- 2

O

3 *2SiO2) tontebrasite, lepid,-lite, lithium-aluminate phosphate ores, such as amblygonize (TiF-AlPQ 4 lithium-bearing clays, and the like and mixtures thereof. As the skilled artisan will appreciate, the term "lithium bearing ore concentrate"l refers to lithium bearing ores which have been treated (beneficiated) to concentrate the lithium bearing m ineral. For ease of reference, as used herein the term nlithium bearing ores" refers to both beneficiated and non-beneficiatked lithium bearing ores.

The iithium containing material is added to the cement raw feed in the front end of the kiln in a-n amount effective to mitigate the detrimental effects of ASR in concrete manufaccured using the resultant cement 0 product.. In the present invention, the lithium containing material is added to the'raw feed in-an amount sufficient to provide a molar ratio of lithium to sodium equivalent (Na 2 O, Na 2 O 0. 58X In the resultant clinker from 0.1:1 to 10:1, preferably 1:13 to 5:1, and more preferably to In addition, in the present invention, cement clinkers can be formed at lower kiln temperatures than conventionally used. Typically, clinker is formed in cement kilns at temperatures of 1420 0 C to 1450 0 C. In contrast, in the preseat invention, 'clinkering can take p)lace at reduced temperatures of 1300 0 1C to 1420 0

C.

*Se This is believed to result from the flux effect of the olithiui.m containing COMOunds when added to the front end of a cement kiln.

Conventional clinkering processes typically require a large amount of energy to decompcsce these materials so that they can react to form the basic constLItuents of cement. Addition of lithium containing materials to th2 frcnt end of the cemer.; kiln also can SUBSTITU'r SIMEET

,~ENEOSH-EET

result in reduced energy requirements for the clinkering process (about 1% to about 3% less energy required, as compared to the energy required to produce similar units of cement without lithium containing materials). This can, in turn, result in reduced energy costs, fuel costs, and the like. This can have favorable environmental implications since less fuels need to be consumed to manufacture the same amount of cement, with the concurrent reduction in pollutants.

This can also increase the life of refractory bricks which line cement kilns per given unit of cement produced. Still further, because less energy is required, this can result in shorter kiln residence times and increased production rates.

15 To demonstrate that the lithium materials do not interfere with the formation of the clinker minerals at the levels that they would typically be used for ASR inhibition, and that clinker can form at lower temperatures, x-ray diffraction was used to 20 characterize cement clinkers made with and without lithium containing materials. Figure 1 is an x-ray diffraction pattern of clinker (with gypsum) produced from a raw feed material (or raw meal) burned at 1400 0

C

for 4 hours without lithium. The oxide concentrations 25 of the raw feed are given below in Example 1. The following peaks are labelled in Figure 1: Alite (labelled in Figure Belite C 3 A F

("C

4 AF") and L Alite refers to tricalcium silicate (C 3 Belite refers to dicalcium silicate

(C

2

C

3 A refers to tricalcium aluminate; and CAF refers to tetracalcium aluminoferrite.

Figure 2 is an x-ray diffraction pattern of clinker (with gypsum) produced from the same raw feed material (or raw meal) as in Figure 1, but which also included spodumene ore concentrate. The spodumene ore was added to the raw feed in an amount sufficient to provide about 0.51% Li 2 O in the clinker. The raw feed -11material plus the lithium ore was burned at 1300 0 C for 4 hours. The labels A, B, C, F and L have the same meaning as in Figure i.

As shown in Figure 2, when lithium was present, no new peaks were formed, and only subtle differences in intensities were present. The fact that there is no difference in the locations of the main peaks demonstrates that the phases present are essentially the same. Further, Figure 2-demonstrates that clinker is formed at about 13000C.

Hydration calorimetry of ground powders from clinkers made with and without lithium bearing materials also give very similar results. Figure 3 is ~a graph illustrating isothermal calorimetry properties at 38 0 C of clinker made with and without lithium. "A" represents the hydration properties of clinker made oe from raw feed of the same composition as described above with regard to Figure 1 (without lithium); "B" represents the hydration properties of clinker made coo• 20 from raw feed of the same composition as described above with regard to Figure 2, with lithium, except that the lithium carbonate was added in an amount sufficient to provide 0.75% Li 2 0O in the clinker. Both clinkers were produced from materials burned at 1400 0

C

25 for four hours.

SAs illustrated in Figure 3, there is also some increased and earlier hydration with added lithium. This demonstrates greater hydraulic activity of the clinker prepared with lithium containing materials. Because of the greater hydraulic activity of the cement made with lithium in accordance with the present invention, the resultant cement does not need to be ground as fine as would otherwise be the case for equivalent rate of reaction, resulting in a further reduction in production costs.

The present invention is also useful for making high alkali cement which also is capable of -12stabilizing concrete against alkali-silica reactivity.

High alkali cement is generally defined as cement having a sodium equivalent (as defined above) of about 0.60% or greater. However, some standards require that low alkali cement have a sodium equivalent of about 0.40% or less. In such circumstances, high alkali cement also can be defined as cement having a sodium equivalent of about 0.40% or greater.

As discussed above, if the raw feed for the cement production contains high levels of alkali, then the production of low alkali cement (less than about 0.60% sodium equivalent) from such feed can generate ~much greater waste than 4ould otherwise be the case.

Generally, cement prQduction generates "fines" or cement kiln dust. Fines are a waste product of cement 0 production and are normally recirculated into the 0:00 cement kiln. However, when the raw feed has a high alkali level, the fines must be removed from the process to form low alkali cement, and thus constitute 20 a waste material.

eoe Thus, prior techniques require the removal of fines from the cement making process when using high 0 0alkali cement starting materials to provide low alkali 09*0 cement. In this aspect of the invention, lithium 25 containing materials are added in the front end of the S. kiln along with high alkali starting materials. In contrast to prior techniques, because of the ASR mitigating properties imparted to thecement by the lithium containing materials, the fines do not have to be removed. Rather, the fines can be recirculated in the kiln. Although the resultant cement can be a high alkali cement, the use of the lithium containing materials in the front end of the kiln results in a high alkali cement with ASR mitigating properties.

This can provide process advantages, i.e., eliminate the need for removing fines. This also can have favorable environmental implications, a -13reduction in fines as a hazardous waste which must be properly disposed of.

The present invention also provides lithium containing cements useful for making concrete and mortar resistant to alkali-silica reactivity from alkali containing components. The concrete compositions generally include cement, aggregate, and water. The cement is present in the fluid concrete mixture in an amount from 5% to 20% by weight based on the total weight of the concrete mixture.

Aggregates can include, but are not limited to natural and crushed quarried aggregate, sand, recycled concrete aggregate, glass, and the like, as well as mixtures thereof. Aggregate is present in the fluid concrete mixture in an amount from 75% to 95% by weight, based on the total weight of the concrete mixture.

The fluid concrete mixture also includes water, in an amount ranging from 2% to 10%.by weight based on the total weight of the mixture. The fluid concrete mixture also can include other materials as known in the art for imparting various properties to concrete, including, but not limited to, air-entraining admixtures, water reducing admixtures, accelerating admixtures, pozzolans, such as, but not limited to, fly ash, metakaolin, and silica fume, and the like. These agents can be present in conventional amounts.

Although reference has been made to the components of concrete, it will be appreciated that the present invention also includes mortar compositions, which generally are similar in composition to concrete, except that mortar is typically made with sand as the sole aggregate, in contrast to concrete which includes larger aggregates. Sand in this sense is aggregate of 0.95 cm and smaller diameter.

SUBSTITUTE SHEET AMENDED

SHEET

-14- The present invention will be further illustrated by the following non-limiting examples.

Example 1 Making an ASR Resistant Cement with Spodumene Ore Concentrate In this example, the target is a Li 2 O content of 0.51% by weight in the clinker, which would be sufficient for a high degree of ASR.

The constituents of a mixture of cement starting materials (60.5% raw feed,. 30.9% calcium carbonate, 0.2% silica), and 8.5% spodumene ore concentrate are given below, along with the clinker m composition that would result from the use this mixture: 15 Oxide Raw Feed Ore Concentrate Clinker SiO 2 21.74 59.5 21.25 A1 2 0 3 5.75 24.1 6.39 CaO 66.33 2.30 66.66 FeO, 3 3.48 2.30 2.66 20 MgO 2.96 0.70 2.14 ooo Na 2 Oeq 1.20 1.70 1.01 0 5.20 0.51 Figure 2 is an x-ray diffraction pattern of the resultant clinker of this example.

Example 2 Making an ASR Resistant Cement with Lithium Carbonate In this example, 0.1% to 10% Li 2

CO

3 by weight of the combined ingredients was added to a raw feed as described above in Example 1 into the kiln.

Example 3 Making an ASR Resistant Cement with Lithium Hydroxide In this example, 0.1% to 10% LiOH-HO by weight of the combined ingredients was added to a raw feed as described above in Example 1 into the kiln.

Kh (i Example 4 Making an ASR Resistant Cement with Decrepitated Spodumene Ore Concentrate In this example, the target is a Li 2 O content of 0.42% by weight in the clinker, which would be sufficient for moderately high degree of ASR.

The constituents of a mixture of cement starting materials (64.7% raw feed, 38.2% calcium carbonate, 0.2% silica), and 7.0% decrepitated spodumene ore concentrate are given below, along with the clinker composition that would result: Oxide SiO 2 A1 2 0 3 15 CaO MgO Na 2 Oeq Li20 Raw Feed 21.74 5.75 66.33 3.48 2.96 0.8 0 Ore Concentrate 59.5 24.1 2.30 2.30 0.70 1.70 5.20 Clinker 21.00 6.17 67.14 2.75 2.24 0.73 0.42 The foregoing examples are illustrative of the present invention and are not to be construed as limiting thereof.

Claims (24)

1. A process for making cement capable of stabilizing concrete against alkali- silica reactivity (ASR) from alkali containing components, the process including heating cement starting materials and lithium bearing ore in an amount sufficient to minimize ASR in concrete under conditions sufficient to chemically react the cement starting materials and the lithium bearing ore to form cement clinker.

2. The process of claim 1, further including grinding the cement clinker.

3. The process of claim 2, wherein said lithium bearing ore is selected from the group consisting of spodumene, petalite, eucryptite, amblygonite, montrebrasite, lepidolite, lithium-bearing clays, and mixtures thereof. 0

4. The process of claim 3, wherein said lithium bearing ore is decrepitated lithium bearing ore. oo The process of claim 1, wherein said lithium bearing ore is present in said cement starting materials in an amount sufficient to provide a molar ratio of lithium to sodium equivalent in the resultant cement clinker between 0.1:1 to 10:1. S..

6. The process of claim 5, wherein said lithium bearing ore is present in said cement starting materials in an amount sufficient to provide a molar ratio of lithium to sodium equivalent in the resultant cement clinker between 1:10 to 5:1.

7. The process of claim 6, wherein said lithium bearing ore is present in said cement starting materials in an amount sufficient to provide a molar ratio of lithium to sodium equivalent in the resultant cement clinker between 0.5:1 to 2:1.

8. The process of claim 1, further including prior to said heating step the step of mixing said lithium bearing ore with said cement starting materials.

9. The process of claim 1, further including adding said lithium bearing ore to said cement starting materials during said heating step. The process of claim 1, wherein said heating step includes heating said cement starting materials and said lithium bearing ore at a temperature between 1300'C and 14200C.

11. The process of claim 1, wherein said heating step requires 1% to 3% less energy per unit of cement clinker produced than heating without lithium bearing ore.

12. Cement produced according to the process of claim 1. .oo..i

13. A process for making concrete stabilized against alkali-silica reactivity (ASR) from alkali containing components, the process including mixing cement, aggregate, and water, said cement produced by heating cement starting materials and lithium containing materials in an amount sufficient to minimize ASR in concrete under conditions sufficient to chemically react the cement starting materials.

14. The process of claim 13, wherein said lithium bearing material includes lithium bearing ore.

15. The process of claim 14, wherein said lithium bearing ore is selected from the group consisting of spodumene, petalite, eucryptite, amblygonite, montrebrasite, lepidolite, lithium-bearing clays, and mixtures thereof.

16. The process of claim 14, wherein said lithium bearing ore is decrepitated lithium bearing ore.

17. The process of claim 13, wherein said lithium bearing material includes lithium salt. "li 18

18. The process of claim 17, wherein said lithium bearing salt is selected from the group consisting of lithium carbonate, lithium hydroxide monohydrate, lithium nitrate, lithium fluoride, lithium chloride, and mixtures thereof.

19. The process of claim 13, wherein said lithium containing material is present in said cement starting materials in an amount sufficient to provide a molar ratio of lithium to sodium equivalent in the resultant cement clinker between 0.1:1 to 10:1. The process of claim 19, wherein said lithium containing material is present in said cement starting materials in an amount sufficient to provide a molar ratio of lithium to sodium equivalent in the resultant cement clinker between 1:10 to 5:1.

21. The process of claim 20, wherein said lithium containing material is present in said cement starting materials in an amount sufficient to provide a molar ratio of lithium to sodium equivalent in the resultant cement clinker between 0.5:1 to 2:1.

22. Concrete produced according to the process of claim 13.

23. A process for making concrete stabilized against alkali-silica reactivity (ASR) from alkali containing components, the process including mixing cement, aggregate, and water, said cement produced by heating cement starting materials 00°a and lithium bearing ores in an amount sufficient to minimize ASR in concrete under 06 conditions sufficient to chemically react the cement starting materials.

24. Concrete produced according to the Irocess of claim 23. A process for making concrete stabilized against alkali-silica reactivity (ASR) from alkali containing components, the process including mixing cement, aggregate, and water, said cement produced by heating cement starting materials and lithium bearing salt in an amount sufficient to minimize ASR in concrete under conditions sufficient to chemically react the cement starting materials.

26. Concrete produced according to the process of claim 0 19

27. A process for making high alkali cement capable of stabilizing concrete against alkali-silica reactivity (ASR) from alkali containing components, the process including heating cement starting materials having a high alkali content and lithium containing materials in an amount sufficient to minimize ASR in concrete under conditions sufficient to chemically react the cement starting materials to form cement clinker.

28. A process for making cement capable of stabilizing concrete against alkali- silica reactivity (ASR) from alkali containing components, the process including heating in a cement kiln high alkali content cement starting materials and lithium e containing materials in an amount sufficient to minimize ASR in concrete under *conditions sufficient to chemically react the cement starting materials to form high alkali cement clinker, wherein said heating step results in the production of cement kiln dust, and wherein said process further includes recirculating said cement kiln dust in the cement kiln. DATED this 7h day of October, 1999. FMC CORPORATION WATERMARK PATENT TRADEMARK ATTORNEYS 4TH FLOOR "DURACK CENTRE" 263 ADELAIDE TERRACE PERTH WA 6000 RHB:MSE:JAH DOC 29 AU7155196