AU598912C - Cement composition curable at low temperatures - Google Patents

Description

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CEMENT COMPOSITION CURABLE AT LOW TEMPERATURES

BACKGROUND OF THE INVENTION

Blended hydraulic cements are well known for their use materials, such as fly ash and other pozzolans, that result in durable concrete and good ultimate strengt Unfortunately, these blended cements of the prior art do generally achieve usable strengths for a substantial per of time and, thus, construction schedules are delayed. addition, most of these compositions are portland cem compositions where the recommended cure is at 60 to 80° and absolutely no cure is obtained below 35°F.-

While the ability to construct structures using ceme such as roads, air fields, and the like, at low temperatu has long been sought, and is desirable, for structures this type, repair at temperatures below 35°, substantially below that, is absolutely essential in mod society. Prior cement compositions have not permitted th and, thus, the search has continued. In addition to ability to cure at these low temperatures, the ra attainment of usable strength is essential.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with the present invention, a blend hydraulic cement has been developed that provides high ear strengths, high ultimate strengths, durability and continu to gain strength at temperatures below freezing. This cement can be utilized for rapid concrete constru tion or repair for hot weather or cold weather concreting well as concreting under less extreme conditions th a owing all weather concreting. This cement can be us for precast and prestressed concrete with or without he curing^

The ^' composition of the present invention includes t following components:

From 50 parts to about 80 parts portland cement

From 13 parts to about 35 parts fly ash

From 0 parts to about 10 parts metakaolin

From 0 parts to about 6 parts slag

From 0 parts to 4 parts admixture

From 1 parts to about 5 parts potassium carbonate

When the cement of the present invention is used concrete or mortar, the resulting hardened material h sufficient strength so that it can be put in service a f hours after being placed. This strength can be obtain without heat curing and continues to increase even when t hardened material is below the freezing point of water.

While it is indicated that the amount of metakaolin the. composition can vary from 0 to 10 parts, and that t amount of potassium carbonate can be between 1 and 5 part in order to achieve the continuing cure at temperatur below the freezing point of water, there must be at least parts of metakaolin present, or 2 parts of potassi carbonate, or a combination of the two to provide a total 2 parts based upon the formula:

Parts = parts potassium carbonate + 1/2 (par metakaolin) While the cured concrete formed in accordance with t present composition is primarily intended for rapid repair or reconstruction, it is not so limited, and can effectively used for^' new construction, as well. T composition can obtain a compressive strength within a mon of 12,000 psi, or even more. Such compressive strengths a above the compressive strengths readily attainable wi present portland cement compositions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The blended hydraulic cement of the present inventi has, as previously indicated, the following essenti components:

From 50 parts to about 80 parts portland cement

From 13 parts to about 35 parts fly ash

From 0 parts to about 10 parts metakaolin

From 0 parts to about 6 parts slag

From 0 parts to 4 parts admixture

From 1 parts to about 5 parts potassium carbonate

The portland cement which is employed in the compositi can be any of the types set forth in ASTM C 150-85A, or a desired blend of these compositions. Preferably, the amou of portland cement employed is in the range of from 55 to parts, by weight.

The amount of fly ash is, to some extent, dependent up the amount of portland cement employed in the compositio Preferably, the amount of fly ash is between 20 and parts, by weight. The total of portland cement, fly as and slag, is also interdependent, and, in general, the tot of these three items should be between 83 and 91 parts, weight. Further, as the amount of fly ash is decreased, can be compensated for, in part, by increasing use metakaolin.

The type of fly ash to be employed is that defined either Class F or Class C in ASTM designation C618-85. T Class C fly ash is preferred, because of the increased calcium oxide content; however, the Class F fly ash can used with higher amounts of portland cement and/or sla Either type of fly ash imparts sulfate resistance to t blended cement.

The metakaolin ( l2θ3.Siθ2) is obtained by dehydrox lating kaolinite by heating at temperatures above 500° until the ^' characteristic crystal structure is destroye The optimum temperature range is 600°C. to 800°C. T metakaolin essentially meets the classification requiremen for a Class N calcined natural pozzolan as described in AS C618-85. The preferred amount of metakaolin to be employ is between 4 and 6 parts, by weight, though lower amoun can be employed. However, as indicated above, the inclusi of metakaolin in the formulation is preferable where t utilization of the composition at temperatures below t freezing point of water is contemplated. When little, no, metakaolin is present, there is less durability in t finished product in successive freeze/thaw cycles. Wh metakaolin in the range of 6 to 10% is employed, more wat is required for curing the cement, and the cost of t composition is increased beyond a desirable amount.

The slag which is employed is a finely ground, granulat blast furnace slag as set forth for blended hydraul cements in ASTM standard C595-86. Preferably, the amount slag to be employed is between 4 and 5 parts, by weight. desired, as indicated by the overall formulation, the s component of the composition can be omitted complete However, it does supply some glassy silicate components, well as calcium compounds. Further, the use of slag d provide some sulfate resistance, but that resistance is a provided by fly ash.

While a variety of materials could be employed as admixtures to be used in this composition, the preferred materials are citric acid and a material sold as Cor 2000. When these are employed, the citric acid preferably used in amounts of up to 3 parts and the Cor in in amounts of_. up to 1 part, preferably 0.5 to 1.5 pa by weight citric acid and 0.15 to 0.40 part by weight Cor 2000.

The citric acid can be used in any of its availa grades, including fine crystal, liquid, or powd Additionally, salts of citric acid can be used in place the citric acid, itself. The material is a known retar for aluminate phases in portland cement, calcium fluoroal inate, and calcium aluminate cements. In the composition the present invention, it functions as a retarder for t hydration reactions and, at the same time, reduces the wat requirement and shortens mixing time. Because of t relatively high cost of the material, the minimum requir should be used. However its total elimination results less workability and lower strengths. While, as indicate salts of the citric acid, such as potassium and sodi citrate can be employed, the use of too great an amount these materials results in a composition which will n harden. The citric acid also reduces the mixing ti required to achieve fluidity.

The reason for desiring less water is that great strength in the final concrete is obtained at a giv plasticity. Further, use of less water provides improv permeability and strength in the final composition. T citric acid can be employed in conjunction with oth retarders and, under those circumstances, the amount citric acid would be less in the overall composition.

The Cormix 2000 is the sodium salt of a copolymer of unsaturated carboxylic acid and the hydroxyalkyl ester that acid. The material meets the requirements of ASTM C494-86, as a type G admixture, one which is water-reducin high range, and retarding. As with the citric acid, t Cormix 2000 reduces the amount of water required to give workable mix, therefore increasing the strength and co weather performance of the final concrete. While the Corm has been found to be effective, it could be replaced wi many other admixtures which are also high range, wat reducers. However, there is a cost effectiveness fact which must be considered.

An essential component of the cement composition of t present invention is potassium carbonate. Preferably, it used as a fine powder and all, or part of it, can replaced with sodium carbonate. Additionally, kiln du could be used in place of the potassium carbonate, but provides problems in that it also contains potassium sulfa and calcium carbonate. While the use of potassium carbona as an accelerator has previously been disclosed, it has n been used with the components of the present invention provide the particularly surprising properties accomplishe While it is possible to substitute alkali hydroxides for t potassium carbonate, the composition does not perform well in low temperature curing. Up to one-third of t potassium carbonate can be replaced with alkali me hydroxides. When using alkali hydroxides, there are a greater storage problems.

The potassium carbonate, which is preferably used in amount of from 2 to 4 parts, by weight, accelerates pozzolaniσ reactions between hydroxides and siliceous siliceous-aluminous materials. It is particularly effect for this purpose, both at ambient temperatures and temperatures below the freezing point of water. W employed in higher amounts, higher early strengths obtained, but there is less working time available placement of the concrete. The order of mixing the various materials which make the composition of the present invention is immaterial. A of the components can be interground or interblended, a used as a complete cement formulation. If desired, some all of the pozzolan materials can be added at the concre mixer, and the functional additions added in a wat solution at the concrete mixer.

Employing the formulations of the present invention, previously indicated, contrary to the prior art, cures c be effected at temperatures well below the freezing point water and, in fact, cure can be accomplished at temperatur as low as -16°F. Even at these low temperature substantial strengths are obtained, so that repair work possible, particularly on roads and airports, even duri winter months, something which cannot be accomplished wi portland cement.

The following are given as examples of the formulatio of the cement of the present invention. They should considered only as illustrative and not as limiting, in a way, the full scope of the invention as covered in t appended claims of the invention. All parts are by weigh

EXAMPLES

Example 1 A binder was prepared consisting of:

58.20 parts portland cement 28.77 parts Class C fly ash

4.41 parts metakaolin

4.82 parts slag

1.18 parts citric acid

0.35 part Cormix 2000

2.27 parts potassium carbonate Example 2 A concrete was prepared employing the bind of Example 1 and other necessary materials as indicat below:

747.4 parts of Binder of Example 1

1148 parts sand

1722 parts gravel 175 parts water The various materials were mixed in a concrete mixer. T resulting concrete had a slump of 0 inches and remain workable for 105 minutes. The concrete was cast in mol and cured at ambient temperatures (73°F.). This concre had compressive strengths of 4,000 psi at 4 hours, 5,800 p at 1 day, 10,000 psi at 7 days, and 12,000 psi at 28 days.

Example 3 This was the same as Example 2, except th 185 parts of water were used. This concrete had t following properties: 2- 1/2 inch slump, 90 minutes wor ability, compressive strengths of 3,200 psi at 4 hour 5,100 psi at 1 day, 9,600 psi at 7 days, and 12,500 psi 28 days.

Example 4 The same concrete as in Example 3 when mix and cast in molds at ambient temperatures (73°F.), and th cooled to 6 ± 2°F, when brought to ambient temperature, ju prior to testing had compressive strengths of 2,200 psi at hours, 3,400 psi at 1 day, and 4,100 psi at 7 days. this, and subsequent examples when the material was fir cooled to 6 ± 2°F., and then brought to ambient temperatur sufficient samples were made for each of the tests. Ea sample was allowed to warm to ambient temperature for i test, only. Example 5 This was the same as Example 2, except th 195 parts of water were used. This concrete had t following properties: 6 inch slump, 80 minutes wor ability, compressive strengths of 2,700 psi at 4 hour 4,500 psi at 1 day, 9,000 psi at 7 days and 10,800 psi at days.

Example 6 A binder was prepared similar to Example except that 2.54 parts of potassium carbonate were us instead of 2.27 parts of potassium carbonate.

Example 7 A concrete was prepared employing the bind of Example 6 and other necessary materials as indicat below:

749.4 parts of Binder of Example 6 1148 parts sand 1722 parts gravel

175 parts water This concrete had the following properties: 0 inch slum 75 minutes workability, compressive strengths of 4,000 p at 4 hours, 6,000 psi at 1 day, 10,000 psi at 7 days, a 12,000 psi at 28 days.

Example 8 This was the same as Example 7, except th 185 parts of water were used. This concrete had t following properties: 1/4 inch slump, 75 minutes wor ability, compressive strengths of 3,500 psi at 4 hour 5,600 psi at 1 day, 9,800 psi at 7 days, and 11,900 psi 28 days. Example 9 The same concrete as in Example 8 when mi and cast in molds at ambient temperatures (73°F.), immediately cooled to 6 ± 2° F. , and warmed to ambient j prior to testing had compressive strengths of 2,900 psi a hours, 3,500 psi at 1 day, and 4,200 psi at 7 days.

Example 10 This was the same as Example 7, except t 195 parts of water were used. This concrete had following properties: 6 inch slump, 90 minutes wo ability, compressive strengths of 2,800 psi at 4 hou 4,600 psi at 1 day, 9,200 psi at 7 days, and 11,100 psi 28 days.

Example 11 A binder was prepared similar to Example except that 2.79 parts of potassium carbonate were u instead of 2.27 parts, of potassium carbonate.

Example 12 A concrete was prepared employing the bin of Example 11 and other necessary materials as indica below:

751.4 parts of Binder of Example 11

1148 parts sand

1722 parts gravel 175 parts water This concrete had the following properties: 0 inch slu 65 minutes workability, compressive strengths of 4,200 at 4 hours, 6,200 psi at 1 day, 10,600 psi at 7 days, 12,000 psi at 28 days.

Example 13 This was the same as Example 12, except t 185 parts of water were used. This concrete had following properties: 1 1/2 inch slump, 60 minutes wo ability, compressive strengths of 3,700 psi at 4 hou 5,900 psi at 1 day, 9,800 psi at 7 days, and 11,500 psi 28 days. Example 14 The same concrete as in Example 13, wh mixed and cast in molds at ambient temperatures (73°F.) a immediately cooled to 6 ± 2° F., and warmed to ambient ju prior to testing had compressive strengths of 3,200 psi at hours, 3,600 psi at 1 day, and 4,300 psi at 7 days.

Example 15 This was the same as Example 12, except th 195 parts of water were used. This concrete had t following properties: 4 inch slump, 80 minutes wor ability, compressive strengths of 2,800 psi at 4 hour 4,800 psi at 1 day, 9,500 psi at 7 days, and 11,200 psi 28 days.

Example 16 A binder was prepared similar to Example except that 3.05 parts of potassium carbonate were us instead of 2.27 parts of potassium carbonate.

Example 17 A concrete was prepared employing the bind of Example 16 and other necessary materials as indicat below:

753.4 parts Binder of Example 16

1148 parts sand

1722 parts gravel 175 parts water This concrete had the following properties: 0 inch slum 35 minutes workability, compressive strengths of 4,200 p at 4 hours, 6,500 psi at 1 day, 10,700 psi at 7 days, a 12,400 psi at 28 days.

Example 18 This was the same as Example 17, except th 185 parts of water were used. This concrete had t following properties: 3/4 inch slump, 45 minutes wor ability, compressive strengths of 3,900 psi at 4 hour 6,200 psi at 1 day, 9,800 psi at 7 days, and 12,200 psi 28 days. Example 19 The same concrete as in Example 18, wh mixed and cast in molds at ambient temperatures (73°F.) a immediately cooled to 6 ± 2° F. and warmed to ambie temperature just prior to testing, had compressive strengt of 3,400 psi at 4 hours, 3,600 psi at 1 day, and 4,300 p at 7 days.

Example 20 This was the same as Example 17, except th 195 parts of water were used. This concrete had t following properties: 2 1/2 inch slump, 55 minutes wor ability, compressive strengths of 3,000 psi at 4 hour 5,600 psi at 1 day, 9,800 psi at 7 days, and 12,000 psi 28 days.

Example 21 A binder was prepared consisting of: 58.16 parts portland cement 29.21 parts Class C fly ash

4.54 parts metakaolin

4.80 parts slag

0.93 part citric acid

0.17 part Cormix 2000

0.19 part borax

2.00 parts potassium carbonate

Example 22 A concrete was prepared employing the bin of Example 21 and other necessary materials as indica below:

749.7 parts Binder of Example 21 2870 parts sand and gravel

200 parts water The various materials were mixed in a concrete mixer. resulting concrete remained workable for 80 minutes. concrete was mixed, cast in molds and cured at ambient temperatures (73° F.). This concrete had compress strengths of 3,100 psi at 4 hours, 5,200 psi at 1 day, 10,600 psi at 3 days.

Example 23 A binder was prepared consisting of 57.28 parts portland cement 29.31 parts Class C fly ash

4.95 parts metakaolin

5.35 parts slag

0.67 part citric acid

0.20 part Cormix 2000

0.23 part borax

2.01 parts potassium carbonate

Example 24 A concrete was prepared employing the bind of Example 23 and other necessary materials as indicat below:

747.2 parts Binder of Example 23 2870 parts sand and gravel

200 parts water The various materials were mixed in a concrete . mixer. T resulting concrete remained workable for 115 minutes. T concrete was mixed, cast in molds, and cured at ambie temperatures (73°F.). This concrete had compressi strengths of 2,700 psi at 4 hours, 5,100 psi at 1 day, a 10,200 psi at 3 days.

Example 25 A binder was prepared consisting of 58.05 parts portland cement 24.02 parts Class C fly ash

4.40 parts metakaolin

4.80 parts slag

1.17 parts citric acid 0.35 part Cormix 2000

2.54 parts potassium carbonate

4.67 parts kiln dust

Example 26 A concrete was prepared employing the bin of Example 25 and other necessary materials as indica below:

749.4 parts Binder of Example 25

1148 parts sand

1722 parts gravel 180 parts water The various materials were mixed in a concrete mixer. concrete was mixed, cast in molds and cured at ambi temperatures (73°F.). This concrete had compress strengths of 2,300 psi at 2 hours, 3,300 psi at 3 hours, 3,800 psi at 4 hours.

Example 27 A binder was prepared consisting of:

56.52 parts portland cement

29.06 parts Class C fly ash

4.93 parts metakaolin

5.33 parts slag

1.20 parts citric acid

0.20 part Cormix 2000

0.23 part borax

0.93 part potassium hydroxide

1.60 parts potassium carbonate

Example 28 A concrete was prepared using the binde Example 27 and other necessary materials as indicated be

750.2 parts Binder of Example 27 2870 parts sand and gravel 183 parts water The various materials were mixed in a concrete mixer. resulting concrete remained workable for 70 minutes. concrete was mixed, cast in molds, and cured at ambi temperatures (73?F.). This concrete had compress strengths of 4,000 psi at 4 hours, and 5,600 psi at 1 day

Example 29 A binder was prepared similar to Example except that a Class F fly ash was used instead of Clas fly ash, and 3.34 parts of potassium carbonate were u instead of 2.27 parts of potassium carbonate.

Example 30 A concrete was prepared employing the bin of Example 29 and other necessary materials as indica below:

755.4 parts of Binder of Example 29 2870 parts sand and gravel 188 parts water The various materials were mixed in a concrete mixer. resulting concrete had a slump of 1 inch. The concrete cast in molds and cured at ambient temperatures (73°F. This concrete had compressive strengths of 2,300 psi a hours, 4,500 psi at 1 day, 9,600 psi at 7 days, and 12, psi at 28 days.

Example 31 The same concrete as in Example 30 when mi and cast in molds at ambient temperatures (73°F.) immediately cooled at 6 ± 2° F. and then warmed to ambi temperature just prior to testing, had compressive streng of 1,700 psi at 4 hours, 2,600 psi at 1 day, 4,000 psi a days, and 5,800 psi at 28 days. Example 32 A binder was prepared consisting of:

58.54 parts portland cement 28.52 parts Class C fly ash 4.46 parts metakaolin 4.80 parts slag 0.83 part citric acid 0.16 part Cormix 2000 0.21 part WRDA 79 2.48 parts potassium carbonate WRDA 79 is a modified lignosulfate, wi catalyst, meeting the requirements of ASTM C494-86 as a T A admixture and Type D admixture.

Example 33 A concrete was prepared employing the bin of Example 32 and other necessary materials as indica below:

605 parts Binder of Example 32

1300 parts sand

1817 parts gravel 155 parts water The various materials were mixed in a concrete mixer. concrete was mixed, cast in molds and cured at ambi temperature (73°F.). This concrete had compress strengths of 2,200 psi at 4 hours, 5,300 psi at 1 d 11,400 psi at 7 days, and 12,000 psi at 28 days.

Example 34 The same concrete as in Example 33 when mi and cast in molds at ambient temperatures (73°F.) immediately cooled to 6 ± 2°F. and warmed to ambi temperature just prior to testing had compressive streng of 900 psi at 4 hours, 3,300 psi at 1 day, 3,900 psi a days, and 6,300 psi at 28 days. Example 35 A mortar was prepared employing the binder Example 11 and other necessary materials as indicated bel

752 parts of Binder of Example 11 1200 parts sand

176 parts water The various materials were mixed in a mortar mixer. mortar was mixed and cast in molds at ambient temperat (73°F.). One third of the specimens were stored in ambie air (73^βF.) and this mortar had compressive strengths 13,000 psi at 7 days, 14,700 psi at 22 days, and 14,900 p at 29 days.

One third of the specimens were immediately cooled to 6 ± F. and subjected to repeated heatings- to ambient temperatu and cooling to 6 ± 2°F., in air. This mortar had co pressive strengths of 9,500 psi after ten cycles of cooli and heating (7 days age), 12,800 psi after 15 cycles ( days age), and 13,800 psi after 20 cycles (29 days age).

One third of the specimens were immediately cooled to 6 2°F. and subjected to heating and cooling, in water. Th mortar had compressive strengths of 8,800 psi after t cycles of heating and cooling (7 days age), 9,700 psi aft 15 cycles (22 days age), and 11,200 psi after 20 cycles ( days age) .

Example 36 A binder was prepared consisting of:

56.90 parts portland cement 29.25 parts Class C fly ash

4.96 parts metakaolin

5.37 parts slag

1.21 parts citric acid

0.20 part Cormix 2000

0.23 part borax

1.88 parts potassium carbonate Exa ple.37 A mortar was prepared employing the binder Example 36 and other necessary materials as indicated belo

745 parts of Binder of Example 36 1200 parts sand

190 parts water The: various materials were mixed in a mortar mixer. T mortar was mixed and cast in molds at ambient temperatur (73^βF.^*. ) . This mortar when cured at ambient temperatur (73°F.) had compressive strengths of 3,100 psi at 2 hour 4,300 psi at 3 hours, 4,700 psi at 4 hours, 6,500 psi at day, and 12,000 psi at 7 days.

Example 38 A binder was prepared, similar to Examp 36, except that 2.15 parts" of potassium carbonate were us instead of 1.88 parts of potassium carbonate.

Example 39 A mortar was prepared, similar to Example 3 except that the binder of Example 38 was employed. Th mortar was cured at ambient temperatures (73°F.). Th mortar had compressive strengths of 4,000 psi at 2 hour 4_>.400 psi at 3 hours, and 4,800 psi at 4 hours. With ste curing (190°F.), the compressive strength was 7,300 psi at hours.

Example 40 A binder was prepared consisting of:

57.43 parts portland cement 28.98 parts Class C fly ash

4.39 parts metakaolin

4.78 parts slag

1.20 parts citric acid

0.20 part Cormix 2000

0.22 part borax

1.20 parts potassium hydroxide

1.60 parts potassium carbonate Example 41 A mortar was prepared employing the binder Example 40 and other necessary materials as indicated bel

752 parts Binder of Example 40 1200 parts sand 170 parts water The various materials were mixed in a mortar mixer. mortar was mixed and cast in molds at ambient temperatu (73°F.). This mortar when cured at ambient temperatu (73°F.) had compressive strengths of 3,300 psi at 2 hou 4,300 psi at 3 hours, and 4,500 psi at 4 hours.

Example 42 A binder was prepared consisting of:

58.05 parts portland cement ?

28.69 parts Class C fly ash 4.40 parts metakaolin 4.80 parts slag 1.17 parts citric acid : 0.35 part Cormix 2000 2.54 parts potassium carbonate

Example 43 A concrete was prepared employing the bin of Example 42 and other necessary materials as indicat below:

749.4 parts Binder of Example 42

1290 parts sand

1580 parts gravel 190 parts water The portland cement, 96% of the fly ash, metakaolin, a slag were preblended and added as a dry component to t concrete mixer. The remaining 4% of the fly ash, the citr acid, Cormix, and potassium carbonate were preblended a added separately as a second dry component. The resulti concrete remained workable for 140 minutes. The concrete was cast in molds and cured at ambient temperatures (73°F. The concrete had compressive strengths of 2,900 psi at hours, 5,200 psi at 1 day, 9,700 psi at 7 days, and 11,4 psi at 28 days.

Example 44 A binder was prepared consisting of:

55.97 parts portland cement 27.66 parts Class C fly ash

4.25 parts metakaolin 4.63 parts slag

2.26 parts citric acid 0.34 part Cormix 2000 4.89^'parts potassium carbonate

Example 45 A concrete was prepared employing the bin of Example 44 and other necessary materials as indicat below:

777.2 parts Binder of Example 44

1148 parts sand

1722 parts gravel 175 parts water The portland cement, fly ash, metakaolin, and slag w preblended and added as a dry cement to the concrete mix The citric acid, Cormix, and potassium carbonate were ad as liquid admixtures which were added at the mixer. resulting concrete remained workable for 135 minutes. concrete was cast in molds and cured at ambient temperatu (73°F.). The concrete had compressive strengths of 3, psi at 4 hours, 5,500 psi at 1 day, 10,000 psi at 7 da and 12,000 psi at 28 days. Example 46 A mortar, as in Example 35, was prepa employing the binder of Example 11. The various materi were mixed without an air entraining agent in a mor mixer. Suitable specimens were cast and subjected to 3 repeated cycles of heating and cooling, as previou defined, in water. The Durability Factor for this mater was 96, according to ASTM C666-84 Method A.

Example 47 A mortar, as in Example 46, was prepared suitable specimens were cast and placed in a solution sodium and magnesium sulfate, according to ASTM C1012-84 The average length change after 100 days of exposure sulfate attack was 0.06% with no visible deterioration.

Example 48 A binder was prepared consisting of:

61.39 parts portland cement 30.33 parts Class C fly ash

4.67 parts metakaolin

0.99 part citric acid

0.21 part Cormix 2000

2.41 parts sodium carbonate

Example 49 A concrete was prepared employing the bind of Example 48 and other necessary materials as indicat below:

706 parts Binder of Example 48 1435 parts sand 1755 parts gravel 175 parts water

The various materials were mixed in a concrete mixer. T concrete was cast in molds and cured at ambient temperatur (73°F.). This concrete had compressive strengths of 2,4 psi at 4 hours and 5,400 psi at 1 day. Example 50 -A mortar was prepared employing the binder Example 48 and other necessary materials as indicated belo

709 parts Binder of Example 48

1236 parts sand 170 parts water The various materials were mixed in a mortar mixer. T mortar was mixed and cast in molds at ambient temperatur (73°F.). The specimens were stored in ambient air (73°F and this mortar had compressive strengths of 3,500 psi at hours and 6,700 psi at 1 day.

In the examples above. Class C fly ash had the followi analysis:

Si0₂ 37.60

A1₂0₃ 20.47

Fe₂03 . AA

CaO 21.54-

MgO 4.61

S0₃ 1.71

Na₂0 2.78

K₂0 0.52

Ti0₂ 1.05

SrO 0.65

Class F fly ash had the following analysis:

Si0₂ 51.31

A1₂0₃ 25.03

Fe₂03 ⁷*²⁸

CaO 6.93

MgO 1.91

S0₃ 0.59

Na₂0 0.42

K₂0 3.15

Ti0₂ 1.25

SrO 0.16 The ground slag had the following analysis:

Si0₂ 34.48

A1₂0₃ 10.15

Fe₂0₃ 0.39

CaO 36.44

MgO 12.56

S0₃ 2.89

Na₂0 0.17

K₂0 0.31

Ti0₂ 0.39

SrO 0.04

Thus, in accordance with the present invention, composition has been given for a blended hydraulic ceme for varying uses. This cement can be used with aggregat to form a concrete or mortar with high early strengt suitable for use under various curing conditions, resulti in a hardened material that can be placed in service in matter of a few hours with high ultimate strengths and wi good durability under freeze-thaw and sulfate attack.

The invention should not be considered as limited to t specific examples shown, but only as set forth in t appended claims.

Claims (18)

WE CLAIM:

1. A blended hydraulic cement composition comprising: From 50 parts to about 80 parts portland cement

From 13 parts to about 35 parts fly ash

From 0 parts to about 10 parts, metakaolin

From 0 parts to about 6 parts slag

From 0 parts to 4 parts admixture

From 1 parts to about 5 parts potassium carbonate

2. The composition of Claim 1 wherein the admixt comprises from 0 to 3 parts, by weight, citric acid, from 0 to 1 part, by weight, of a water reducing, h range, retarding admixture.

3. The composition of Claim 2 wherein the amount citric acid is from 0.5 to 1.5 parts, by weight.

4. The composition of Claim 2 wherein the amount of water reducing, high range, retarding admixture is f about 0.15 to 0.40 part, by weight.

5. The composition of Claim 1 wherein the amount portland cement is from 55 to 60 parts, by weight.

6. The composition of Claim 1 wherein the amount of ash is from about 20 to 30 parts, by weight.

7. The composition of Claim 1 wherein the amount metakaolin is from about 4 to 6 parts, by weight.

8. The composition of Claim 1 wherein the amount of s is from about 4 to 5 parts, by weight.

9. The composition of Claim 1 wherein up to one-third the potassium carbonate is replaced by an alkali me hydroxide.

10. A blended hydraulic cement composition comprising: From 50 parts to about 80 parts portland cement

From 13 parts to about 35 parts fly ash

From 0 parts to about 10 parts metakaolin

From 0 parts to about 6 parts slag

From 0 parts to 4 parts admixture

From 1 parts to about 5 parts sodium carbonate

11. The composition of Claim 10 wherein the admixtu comprises from 0 to 3 parts, by weight, citric acid, a from 0 to 1 part, by weight, of a water reducing, hi range, retarding admixture.

12. The composition of Claim 11 wherein the amount citric acid is from 0.5 to 1.5 parts, by weight.

13. The composition of Claim 11 wherein the amount the water reducing, high range, retarding admixture, is fr about 0.15 to 0.40 part, by weight.

14. The composition of Claim 10 wherein the amount portland cement is from 55 to 60 parts, by weight.

15. The composition of Claim 10 wherein the amount fly ash is from about 20 to 30 parts, by weight. -

16. The composition of Claim 10 wherein the amount metakaolin is from about 4 to 6 parts, by weight.

17. The composition of Claim 10 wherein the amount slag is from about 4 to 5 parts, by weight.

18. The composition of Claim 10 wherein up to one-thi of the sodium carbonate is replaced by an alkali met hydroxide.