WO2016151388A1

WO2016151388A1 - Blended cement composition

Info

Publication number: WO2016151388A1
Application number: PCT/IB2016/000337
Authority: WO
Inventors: Moussa Baalbaki; Bill GONG (Chunming); David BABAYAN; Winnie MATTHES
Original assignee: Holcim Technology Ltd
Current assignee: Holcim Technology Ltd
Priority date: 2015-03-24
Filing date: 2016-03-17
Publication date: 2016-09-29
Anticipated expiration: 2017-09-24
Also published as: AT517029A1; AT517029B1

Abstract

Concrete mix composition comprising a hydraulic binder comprising 35-45 wt.-% ordinary Portland cement and 55-65 wt.-% of a supplementary cementitious material, aggregates and a water reducing agent, wherein the water/binder ratio is 0,35-0,50.

Description

Blended cement composition

The invention refers to a concrete mix composition

comprising a hydraulic binder and aggregates, wherein the water/binder ratio is 0,35-0,50.

Further, the invention refers to a hydraulic binder for producing such a concrete mix composition.

Concrete is a very widely used construction material with high strength and good durability. In addition to

aggregates and water, it also contains Portland cement as a hydraulic binder, which produces strength-forming phases by solidifying and curing in contact with water. Concrete based on Portland cement clinker is thus one of the most important binders worldwide.

By adding various mineral additions, such as, e.g.,

granulated blast-furnace slag (gbfs) , fly ash, natural puzzolans, calcined clays or ground limestone to Portland cement, Portland composite cements having different

properties can be produced. At the same time, the specific emission of CO₂ will be reduced in the production of cement by substituting the cited additives for Portland cement, because during the production of Portland cement clinker about 0,9 tons of C0₂ per ton of Portland cement clinker will be emitted by the calcination of the raw materials and from the oxidation of the fuels in the rotary tubular kiln. The addition of additives to Portland cement has been an established practice for more than 100 years and is

regulated in numerous cement and concrete standards . The mineral additions, typically between 10 and 50 wt.-% of the total binder weight, are in most applications ground granulated blast furnace slag, fly ash, pozzolans, ground limestone or mixtures thereof. It is known that in such composite binders, increasing the content of the

supplementary cementitious materials negatively affects the strength development of hardened concrete.

The water-binder ratio of a concrete composition is the ratio of the weight of water to the weight of the hydraulic binder (including Portland cement and mineral additions) used in a concrete mix and has an important influence on the quality of the concrete produced. With binders having an increased content of mineral additions, a lower water- cement ratio is often used in order to increase strength and durability, but may make the mix more difficult to place. Placement difficulties can partly be resolved by using plasticizers or super-plasticizers, but such

additives strongly increase the costs.

Various attempts have been undertaken in order to obtain concrete mix composition having a high content of mineral additions, but without decreasing the initial and the late compressive strength values.

CA 2809225 Al describes a concrete composition that

comprises water (preferably 100-150 kg per cubic meter of concrete) , Portland cement (preferably 18-89 kg per cubic meter of concrete) and secondary cementitious materials in an amount of 80% of the total binder. The resulting water- binder ratio is between 0,35-0,45. The binder composition comprises 5-30 wt.-% of Portland cement, 0-20 wt.-% silica fume, 0-50 wt.-% fly ash and 42-75 wt.-% blast furnace slag. The invention described in CA 28909225 Al requires the use of ultra-fine reactive materials in order to reach sufficiently high strength values, which in turn may negatively affect fresh concrete properties and increases the total cost for the materials of the concrete.

Furthermore the concrete described in this patent does not mention any particular durability benefit.

FR 2901268 Al describes a premixed binder composition and a concrete having a reduced CO₂ footprint. This is achieved by an optimization of the packing density of all components of the composition, from the ultra-fine binder particles to the aggregates. The use of high reactivity materials and the reduction of the water content in the concrete to very low water/cement ratios of 0,18 to 0,32 enables high strength developments.

Due to the very low water/cement ratio, the concrete described in this patent would exhibit relatively poor fresh concrete properties, unless costly high performance water reducers are used. Furthermore the complexity of the binder composition and the use of many different components makes this invention difficult to manufacture in cement plants. The very low water content of this concrete makes. its implementation in ready-mix operations difficult because of the high impact that small variations of

admixture dosage has on the concrete properties, especially the fresh concrete properties. Variations typically in the range of the accuracy of the scales used in ready mix plants would significantly increase the variability of fresh concrete properties, such as initial slump and slump retention. Due to these reasons the invention disclosed in FR 2901268 Al would prove to be difficult to implement in ready-mix operations and its total cost per cubic meter would be high.

Therefore, it is an object of the instant invention to provide a concrete- mix composition that has both, high initial and late compressive strength values, and high durability, but does not require the use of low water- cement ratios or ultra-fine reactive binder particles.

Furthermore, critical fresh concrete properties, such as initial slump and slump flow retention shall be very good.

To solve these and other objectives, the invention is characterized in that the concrete mix composition

comprises a hydraulic binder comprising 35-45 wt.-%

ordinary Portland cement and 55-65 wt.-% of a supplementary cementitious material, aggregates and a water reducing agent, wherein the water/binder ratio is 0,35-0,50.

Preferably, the concrete mix composition essentially does not comprise any other constituents and therefore consists essentially of a hydraulic binder consisting of 35-45 wt.-% ordinary Portland cement and 55-65 wt.-% of a supplementary cementitious material, aggregates and a water reducing agent, wherein the water/binder ratio is 0,35-0,50.

It was found that the association of specific types of Portland cements with some supplementary cementitious materials in a specific concrete mix design (having the narrow range of cement and supplementary cementitious material contents indicated above) results in surprisingly high strength values of hardened concrete, even at

temperatures corresponding to winter conditions, has very good fresh concrete properties, and excellent durability. In particular, the hydraulic binder comprises ordinary Portland cement and supplementary cementitious materials in a weight ratio of 2:3.

It was also found that this high performance concrete does not require the use of materials known for their higher reactivity, such as ultrafine Portland cement, ultrafine ground slags, or silica fume. Rather, standard reactivity cement such as a CEM I 32.5N (according to EN 197

classification of cements) is sufficient to reach suitable strength at 24 hours.

According to a preferred embodiment of the invention ground granulated blast furnace slag is used as the only

supplementary cementitious material. However, other

supplementary cementitious material compositions may also be used. For example, a mixture of ground granulated blast furnace slag and fly ash may be used as said supplementary cementitious material. Other supplementary cementitious materials such as pozzolans and ground limestone may also be used. In general, the supplementary cementitious

material can be ground granulated blast furnace slag, fly ash, pozzolans, ground limestone or mixtures thereof.

The supplementary cementitious material content in the concrete mix design preferably lies between 160 and 230 kg per cubic meter of concrete. Preferably 180 kg of the supplementary cementitious material is used per cubic meter concrete .

The inventive concrete mix composition also contains a water reducing agent, in order to improve the workability and to increase the initial setting time of the concrete. Water-reducing admixtures usually reduce the required water content for a concrete mixture by about 5 to 10 %.

Consequently, concrete containing a water-reducing

admixture needs less water to reach a required slump than untreated concrete.

The admixtures used are typical commercially available water reducing agents, such as poly-carboxylate ether water reducers or polynaphthalene sulfonate based water reducers. According to a preferred embodiment, the water reducing agent is present in an amount between 1,5 and 4,0 kg, preferably 2,1 kg, per cubic meter of concrete. Preferably, the water reducing agent may be added in an amount suitable to reach a flow of the freshly mixed concrete at 10 min of 180 mm +/- 20 mm.

According to a preferred embodiment of the invention, is present in an amount of 130-145 1, preferably 135 cubic meter of concrete.

Commercial available accelerators, setting time modifiers, air entrainers, shrinkage reducing agents or other

admixtures as defined in EN-234, may also be used to improve specific properties of the concretes of the

invention. Retarding admixtures, which slow the setting rate of concrete, are used to counteract the accelerating effect of hot weather on concrete setting. High

temperatures often cause an increased rate of hardening, which makes placing and finishing difficult. Retarders keep concrete workable during placement and delay the initial set of concrete. The preferred Portland cement content in the concrete mix design is 110-130 kg, preferably 120 kg per cubic meter of Concrete .

In order to reach the described results the C3A (tricalcium aluminate) content of the ordinary Portland cement

preferably is ≥ 5 wt.-%, more preferably ≥ 8 wt.-%.

As mentioned above, the concrete mix composition of the invention does not require highly reactive, ultra-fine cement or supplementary cementitious materials. Therefore, according to a. preferred embodiment of the invention the hydraulic binder has a Blaine fineness of 3000-5000 cm²/g. In particular, the ordinary Portland cement has a Blaine fineness of 3000-5000 cm²/g, preferably 4500 cm²/g, and the supplementary cementitious material has a Blaine fineness of 3500-6500 cm²/g, preferably 4500-5000 cm²/g.

Further, the specific types of Portland cements that achieve particularly good results within the instant invention preferably are such that have C3S (tricalcium silicate) content of the ordinary Portland cement of 55-65 wt.-%. The C3S content reflects the amount of 3CaO-Si0₂ in the Portland cement. Preferably, the S0₃ (sulphate) content of the ordinary Portland cement is ≥ 3,7 wt.-%.

With regard to the supplementary cementitious material, particularly good results within the instant invention have been achieved with a supplementary cementitious material having a basicity (CaO/Si0₂ ratio) of ≥ 1,0.

With regard to the aggregate, a preferred embodiment of the invention provides that the aggregate is present in an amount of 1700-2100 kg, preferably 1850-2000 kg, per cubic meter of concrete.

In particular, the aggregate may comprise the following particle size distribution:

- 800-900 kg/m³ sand having a particle size of 0-4 mm,

- 250-350 kg/m³ aggregate having a particle size of 4-8 mm,

- 300-400 kg/m³ aggregate having a particle size of 8-16 mm,

- 300-400 kg/m³ aggregate having a particle size of 16-32 mm

The inventive concrete mix design results in an excellent compressive strength and durability. In particular, the concrete has a 28d compressive strength of > 45 MPa, preferably > 50 MPa, in particular > 60 MPa. Further, the concrete preferably has. a Id compressive strength of

> 4 MPa, preferably > 6 MPa, in particular > 8 MPa.

With regard to the durability of the concrete, the

inventive concrete preferably has a 0₂ permeability of ≤ 0,5 m².10^~16. Further, the concrete preferably has a chloride penetration resistance of ≤ 1000 Coulomb.

In a particularly advantageous embodiment, the concrete has a carbonation speed of ≤ 6 mm/Va. In a further preferred embodiment, the concrete has resistivity of ≤ 1500 Q.m.

According to a further aspect of the invention, a hydraulic binder is provided that is suitable for producing the inventive concrete mix composition, comprising 35-45 wt.-% ordinary Portland cement and 55-65 wt.~% of a supplementary cementitious material. The invention will now be described with reference to the following exemplary embodiments.

Example 1

Mortar was mixed with the mortar compositions as given in Table 1. In the mortar compositions of Table 1, a hydraulic binder was used, consisting of 40 wt . -% ordinary Portland cement and 60 wt.-% of ground granulated blast furnace slag (ggbfs). Further, sand was used as the aggregate in an amount resulting from the sand/mortar ratio (S/M) as indicated. The sand/mortar ratio represents a volume ratio of the sand to the water, sand and binder. Further, water was added to the mixture of hydraulic binder and aggregate in an amount resulting from the water/binder ratio (W/B) as indicated. The water/binder ratio represents a weight ratio of the water content to the binder (cement and ggbfs) .

Further, a water reducing agent was added to the mixture, the admixture dosage having been adjusted in order to reach a mortar flow at 10 min of 180 mm +/- 20 mm. The mortar flow was measured on a dry glass plate.

Table 1

Mortar

Ground

Ordinary- flow at

System granulated blast S/M W/B

Portland Cement 10 min furnace slag

[mm]

General Use OPC GranCem®

1 (Holcim Canada, (Holcim Canada, 0.56 0.55 192

Mississauga) Mississauga)

General Use OPC GranCem®

2 (Holcim Canada, (Holcim Canada, 0.58 0.50 200

Mississauga) Mississauga) General Use OPC GranCem®

(Holcim Canada, (Holcim Canada, 0.60 0.45 193 Mississauga) Mississauga)

CEM I 5N GranCem®

(Holcim (Holcim Canada, 0.56 0.55 184 Germany, Hover) Mississauga)

CEM I 5N

GGBFS

(Holcim 0.56 0.55 174

(SIN, JP Nippon)

Germany, Hover)

CEM I 5N GranCem®

(Holcim (Holcim Canada, 0.56 0.55 168 Germany, Hover) Mississauga)

CEM I 5N GGBFS

(Holcim (Holcim Germany, 0.58 0.50 177 Germany, Hover) Salzgitter )

CEM I 5N

GGBFS

(Holcim 0.58 0.50 167

(SIN, JP Nippon)

Germany, Hover)

CEM I 5N GranCem®

(Holcim (Holcim Canada, 0.58 0.50 182 Germany, Hover) Mississauga )

CEM I 5N GGBFS

10 (Holcim (Holcim Germany, 0.60 0.45 168 Germany, Hover) Salzgitter)

CEM I 5N

GGBFS

11 (Holcim 0.60 0.45 162

(SIN, JP Nippon)

Germany, Hover)

CEM I 5N GranCem®

12 (Holcim (Holcim Canada, 0.60 0.45 186 Germany, Hover) Mississauga )

As can be seen from Table 1, different types of ordinary Portland cement and of ggbfs were used. The relevant parameters of the types of ordinary Portland cement and ggbfs used in the examples are given as follows:

General Use OPC (Holcim Canada, Mississauga)

C3A content: 8,4 wt.-%

C3S content: 53,4 wt.-%

Blaine fineness: 4320 cm²/g

S0₃ content: 4,1 wt.-% CEM I 5N (Holcim Germany, Hover)

C3A content: 11,1 wt.-%

C3S content: 60,7 wt.-%

Blaine fineness: 4510 cm²/g

S0₃ content: 3,7 wt.-%

High Early Strength Cement (Holcim Canada, Mississauga) :

C3A content: 8,4 wt.-%

C3S content: 53,4 wt.-%

Blaine fineness: 5070 cm²/g

S0₃ content: 4,2 wt.-%

GranCem® (Holcim Canada, Mississauga)

Blaine fineness: 6540 cm²/g

C/S ratio: 1,0

GGBFS (SIN, JP Nippon)

Blaine fineness: 4190 cm²/g

C/S ratio: 1,3

GGBFS (Holcim Germany, Salzgitter)

Blaine fineness: 3900 cm /g

C/S ratio: 1,0

The mortar was prepared and cured at 20 °C and their flow measured on a glass plate, strength was measured by casting 4x4x16 prisms, and setting times were measured according to ASTM. As can be seen from Table 2, the compositions of Table 1 have good early strength development, excellent 28 day strength value, and good setting times. In some cases, the strength is above 80 MPa at 91 days. Table 2

Compressive Compressive Initial Final

Compressive

strength strength setting setting

Sys em s rength

28 days 91 days time time 1 day [MPa]

[MPa] [MPa] [min] [min]

1 4.4 59.3 66.9 502 662

2 6.0 70.9 80.0 494 614

3 3.4 49.0 61.0 437 567

4 5.2 55.9 70.5 359 479

5 7.6 60.7 71.8 322 442

6 4.6 55.3 64.9 401 506

7 6.9 67.0 77.3 383 508

8 10.0 72.4 82.8 354 474

9 6.1 61.3 71.5 442 552

10 9.6 77.1 84.4 419 534

11 12.9 81.3 91.6 424 549

12 9.4 * 85.1 471 576

Example 2

A concrete was produced using the following

composition :

Component kg/m3

Ordinary Portland Cement 120

Ground Granulated Blast Furnace Slag 180

Water 135

Sand (particle size 0-4 mm) 857

Aggregate (particle size 4-8 mm) 297

Aggregate (particle size 8-16 mm) 359

Aggregate (particle size 16-32 mm) 358

Water reducer - Plastol 341 Adjusted to reach

15 cm slump Plastol 341 is a polycarboxylate based plasticizing admixture.

The mix design of Example 2 was varied by using different types of Portland cement and of ggbfs and by choosing different admixtures. Table 3 shows three compositions using general use limestone cement. Table 4 shows two compositions using high early strength cement. Table 3

Mix compositions using General Use Limestone Cement

General Use Limestone

cement (Holcim 120 kg.m^"3

Canada, Mississauga)

GranCem

(Holcim Canada, 180 kg.m^"3

Missaussaga)

Water 135 L.rtf³

CHRYSO Optima

Water reducer Plastol 341 Plastol 341

EUCON CIA -

Accelerator - - 2%

DIN B22 crushed aggr.

1990

[kg.nf³]

Compressive Strength

1 day 6.4 6.8 7.0

Compressive 3 days 18.6 19.1 20.5 strength 28

[MPa] - Cubes 45.4 49.6 51.3

days

91

51.5 53.2 55.9 days

Durability properties

28

CEMBUREAU 0₂ 0.34 (Low) 0.39 (Low) 0.16 (Low) days

permeability

[m².l(T¹⁶] 91

0.17 (Low) 0.17 (Low) 0.12 (Low) days Chloride 28 536 505 424 diffusion / days (Negligible) (Negligible) (Negligible) ASTM C1202 91 403 350 291

[Coulomb] days (Negligible ) (Negligible) (Negligible)

Carbonation - 5.07 5.22 4.95 speed [mm/ a]

182

days 1491 1196 1326

Resistivity wet

[Ω.πι] 182

days 2148 2359 2132 dry

Table 4

Mix compositions using High Early Strength cement

High Early Strength

Cement (Holcim 120 kg.rrf³

Canada, Mississauga)

GranCem

(Holcim Canada, 180 kg.nf³

Missaussaga)

Water 135 L.rrf³

Water reducer Euclid Plastol 341 CHRYSO Optima 256EMx

DIN B22 crushed aggr.

1990

[kg.nf³]

Compressive Strength

1 day 9.5 10.3

3

Compressive 22.2 23.7

days

strength [ Pa]

28

- Cubes 50.9 52.4

days

91

53.8 57.7 days

Durability properties

28

CEMBUREAU 0₂ 0.12 (Low) 0.10 (Low)

days

permeability

[m².10^"16] 91

0.11 (Low) 0.13 (Low) days Chloride 28

414 (Negligible) *

diffusion / days

ASTM C1202 91

[Coulomb] 357 (Negligible) 317 (Negligible) days

Carbonation - 4.39 4.69 speed [mm/Va]

182

days 1019 946

Resistivity wet

[Q.m] 182

days 1851 2013 dry

As shown in tables 3 and 4, with all combinations of cement types and admixtures, the concrete mix designs of the invention have excellent strength development and excellent durability.

By comparing the strength values of table 3 with those of table 4, it can be seen that by increasing the reactivity of the cement combined with the use of specific admixtures one can obtain 1 day strength values of 10 MPa .

The concrete of the invention has a C0₂ footprint of approx. 100 kg/m³.

Claims

Claims :

1. Concrete mix composition comprising:

a hydraulic binder comprising 35-45 wt.-% ordinary Portland cement and 55-65 wt.-% of a supplementary cementitious material,

aggregates,

a water reducing agent,

wherein the water/binder ratio is 0,35-0,50.

2. Composition according to claim 1, wherein the

supplementary cementitious material is ground granulated blast furnace slag, fly ash, pozzolans ground limestone mixtures thereof.

3. Composition according to claim 1 or 2, wherein the supplementary cementitious material is comprised of ground granulated blast furnace slag and/or fly ash.

4. Composition according to claim 1, 2 or 3, wherein water is present in an amount of 130-145 1, preferably 135 1, per cubic meter of concrete.

5. Composition according to any one of claims 1 to 4, wherein ordinary Portland cement is present in an amount of 110-130 kg, preferably 120 kg per cubic meter of concrete.

6. Composition according to any one of claims 1 to 5, wherein the C3A (tricalcium aluminate) content of the ordinary Portland cement is ≥ 5 wt.-%, preferably ≥ 8 wt . -

7. Composition according to any one of claims 1 to 6, wherein the supplementary cementitious material, in

particular blast furnace slag, is present in an amount of 160-230 kg, preferably 180 kg, per cubic meter of concrete.

8. Composition according to any one of claims 1 to 7, wherein the hydraulic binder has a Blaine fineness of 3000- 5000 cm²/g.

9. Composition according to any one of claims 1 to 8, wherein the ordinary Portland cement has a Blaine fineness of 3000-5000 cm²/g, preferably 4500 cm²/g.

10. Composition according to any one of claims 1 to 9, wherein the supplementary cementitious material has a

Blaine fineness of 3500-6500 cm²/g, preferably 4500 to 5000 cm²/g.

11. Composition according to any one of claims 1 to 10, wherein the C3S (tricalcium silicate) content of the ordinary Portland cement is 50-65 wt.-%, preferably 55-65 wt. -% .

12. Composition according to any one of claims 1 to 11, wherein the SO₃ (sulphates) content of the ordinary Portland cement is ≥ 3,7 wt.-%.

13. Composition according to any one of claims 1 to 12, wherein the basicity (CaO/Si0₂ ratio) of the slag is ≥ 1,0.

14. Composition according to any one of claims 1 to 13, wherein the aggregate is present in an amount of 1700-2100 kg, preferably 1850-2000 kg, per cubic meter of concrete.

15. Composition according to any one of claims 1 to 14, wherein the aggregate comprises the following particle size distribution :

- 800-900 kg/m³ sand having a particle size of 0-4 mm,

- 250-350 kg/m³ aggregate having a particle size of 4-8 mm,

- 300-400 kg/m³ aggregate having a particle size of 8-16 mm,

- 300-400 kg/m³ aggregate having a particle size of 16-32 mm

16. Composition according to any one of claims 1 to 15, wherein the water reducing agent is present in an amount between 1,5 and 4,0 kg, preferably 2,1 kg, per cubic meter of concrete.

17. Composition according to any one of claims 1 to 16, wherein the water reducing agent comprises poly-carboxylate ether or polynaphthalene sulfonate.

18. Composition according to any one of claims 1 to 17, wherein the composition further contains setting

accelerators, setting time modifiers, air entrainers and/or shrinkage reducing agents.

19. Composition according to any one of claims 1 to 18, wherein the concrete has a 28d compressive strength of

> 45 MPa, preferably > 50 MPa, in particular > 60 MPa.

20. Composition according to any one of claims 1 to 19, wherein the concrete has a Id compressive strength of

> 4 MPa, preferably > 6 MPa, in particular > 8 MPa.

21. Composition according to any one of claims 1 to 20, wherein the concrete has a 0₂ permeability of ≤ 0,5 m².10

22. Composition according to any one of claims 1 to 21, wherein the concrete has a chloride penetration resistance of < 1000 Coulomb.

23. Composition according to any one of claims 1 to 22, wherein the concrete has a carbonation speed of ≤ 6 mm/- ^"a.

24. Composition according to any one of claims 1 to 23, wherein the concrete has resistivity of 1500 Ω.πι.

25. A hydraulic binder for producing a concrete mix composition according to any one of claims 1 to 24, comprising 35-45 wt.-% ordinary Portland cement and 55-65 wt.-% of a supplementary cementitious material.

26. Hydraulic binder according to claim 25, wherein the supplementary cementitious material is ground granulated blast furnace slag, fly ash, pozzolans, ground limestone or mixtures thereof.

27. Hydraulic binder according to claim 25 or 26, wherein the supplementary cementitious material is comprised of ground granulated blast furnace slag and/or fly ash.

28. Hydraulic binder according to claim 25, 26 or 27, wherein the C3A (tricalcium aluminate) content of the ordinary Portland ^' cement is ≥ 5 wt.-%, preferably ≥ 8 wt . -

29. Hydraulic binder according to any one of claims 25 to 28, wherein the hydraulic binder has a Blaine fineness of 3000-5000 cm²/g.

30. Hydraulic binder according to any one of claims 25 to

29, wherein the ordinary Portland cement has a Blaine fineness of 3000-5000 cm²/g, preferably 4500 cm²/g.

31. Hydraulic binder according to any one of claims 25 to

30, wherein the supplementary cementitious material has a Blaine fineness of 3500-6500 cm²/g, preferably 5000 cm²/g.

32. Hydraulic binder according to any one of claims 25 to

31, wherein the C3S (tricalcium silicate) content of the ordinary Portland cement is 50-65 wt.-%, preferably 55-65 wt.-%.

33. Composition according to any one of claims 25 to 32, wherein the S0₃ (sulphates) content of the ordinary Portland cement is ≥ 3,7 wt.-%.

34. Composition according to any one of claims 25 to 33, wherein the basicity (CaO/Si0₂ ratio) of the slag is > 1,0.

35. A construction element comprising concrete or made- of concrete produced using a concrete mix composition

according to any one of claims 1 to 24.