RU2471733C2 - Concrete with low clinker content - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of producing a wet concrete composition, including a step of mixing: portland clinker in form of grains having Dv97 from 10 to 30 mcm or having a Blaine specific surface of not less than 5300 cm²/g, preferably not less than 5500 cm²/g, the minimum quantity of the clinker in kg/m³ being determined according to formula (V) for clinker having Dv97 from 10 to 30 mcm, or according to formula (VI) for clinker having Blaine specific surface of not less than 5300 cm²/g: [(90 x ln(Dv97_k)) - 150] x (W_eff - 140) (V) wherein Dv97_k is Dv97 of clinker given in mcm, W_eff is the quantity of effective water in l/m³; [(-0.021 x BSS_k) + 263] x (W_eff - 140) (VI) wherein BSS_k is the Blaine specific surface of clinker given in cm²/g, W_eff is the quantity of effective water in l/m³; - slag, of which the minimum quantity in kg/m³ is determined according to formula (VII) in the case of a mixture with clinker having Dv97 from 10 to 30 mcm, or according to formula (VIII) in the case of a mixture with clinker having Blaine specific surface of not less than 5300 cm²/g: (3500 - BSS_S) x [-90 x ln(Dv97_k) + 310] x (W_eff - 140) (VII) wherein Dv97_k is the Dv97 of clinker given in mcm, BSS_S is the Blaine specific surface of slag given in cm²/g, (3500 - BSS_S) x [0.021x BSS_k - 103] x (W_eff - 140) (VIII) wherin BSS_k and BSS_S are respectively the Blaine specific surface of the clinker and the slag given in cm²/g, W_eff the quantity of effective water in l/m³; - calcium sulphate; additional materials having Dv90 of not more than 200 mcm, of which the minimum quantity in kg/m³ is determined according to the following formula (IX): 220- (quantity of slag)-(quantity of clinker)-(quantity of calcium sulphate); - 1500-2200 kg/m³, preferably, - 1700-2000 kg/m³ aggregates; plasticiser; - optionally an accelerator and/or an air-entraining agent and/or a thickening agent and/or a retarder and/or a clay-inhibiting agent; with 140-220 l/m³ of effective water, the total quantity of clinker in the wet concrete being not more than 200 kg/m³. The present invention also relates to a wet concrete composition obtained by mixing with water and an object made from the solidified concrete mix.

EFFECT: low consumption of clinker while preserving strength of the concrete.

4 cl, 4 ex, 4 dwg

Description

FIELD OF THE INVENTION

The present invention relates to concrete with a low content of clinker, as well as to methods for producing such concrete and compositions applicable for implementing these methods.

BACKGROUND OF THE INVENTION

In the field of conventional building concrete, in particular concrete of type C25 / 30 (i.e. those with a compressive strength measured on a cylinder of 16 × 32 cm 28 days after mixing, is at least 25 MPa, according to the EN standard 206-1), it is known that the amount of cement is usually from 260 to 360 kg per m ^{3 of} concrete. In addition, the current European standards do not provide a cement content below 260 kg / m ³ for conventional structural concrete.

Currently, methods for the production of cement, and more specifically, its essential component, clinker, are responsible for the high emission of carbon dioxide. The production of granular clinker actually requires the following operations:

a) pre-heating and decarbonization of the raw material mixture, which is obtained by grinding raw materials, which, in particular, are limestone and clay; and

b) firing and sintering the raw mixture at temperatures of 1450-1550 ° C followed by rapid cooling.

These two stages produce CO ₂ , on the one hand, as a direct product of decarbonization, and on the other hand, as a by-product of combustion, which is used in the calcination step to increase the temperature.

The emission level reaches approximately 560 kg CO ₂ per tonne of binder material, typically used for the production of concrete C25 / 30, which contains 65% clinker (based on the average emission of 850 kg CO ₂ per tonne of clinker, and this level is even higher for top quality concrete .

Currently, the high emissions of carbon dioxide in standard methods for the production of cement and concrete compositions represent a major environmental problem, and in modern circumstances they are punished economically by imposing high fines.

Therefore, there is an urgent need for a method for the production of concrete associated with reduced emissions of carbon dioxide, moreover, this concrete must provide satisfactory mechanical properties, in particular, equivalent to the properties of modern concrete, when applied in the construction industry. In particular, the desired normal compressive strength of concrete after 28 days should be at least 25 MPa, according to EN 206-1. On the other hand, the desired compressive strength of concrete should be at least 4 MPa, preferably at least 5 MPa, at 20 ° C 16 hours after mixing when measured according to EN 12390-3 on cylindrical specimens contained in accordance with EN 12390-2 at 20 ° C ± 2 ° C and relative humidity greater than 95%. The desired rheological properties of the plastic concrete mixture must also be satisfactory, in particular, so that the viscosity of the mixed mixture is low enough to handle it even 2 hours after mixing.

SUMMARY OF THE INVENTION

Therefore, the aim of the present invention is the provision of a dry pre-prepared mixture of a binder material containing in mass fractions:

- Portland cement clinker in the form of granules having Dv97 from 10 to 30 μm or having a Blaine specific surface of at least 5300 cm ² / g, preferably at least 5500 cm ² / g,

wherein the minimum amount of said clinker in percent by weight is determined according to formula (I) for clinker having a Dv97 of 10 to 30 μm, or according to formula (II) for clinker having a Blaine specific surface area of at least 5300 cm ² / g:

[26 × ln (Dv97 _k )] - 43 Formula (I)

in which Dv97 _k is the clinker Dv97 value given in microns;

[-6 · 10 ^-3 × BSS _k ] + 75 Formula (II)

in which BSS _k is the specific surface according to Blaine, given in cm ² / g;

- slag, the minimum amount of which in percent by weight is determined according to formula (III) in the case of a mixture with clinker having Dv97 from 10 to 30 μm, or according to formula (IV) in the case of a mixture with clinker having a specific surface according to Blaine of at least 5300 cm ² / g:

[1000 - BSS _s ] × [(-90 × ln (Dv97 _k )) + 310] Formula (III)

in which Dv97 _k is the clinker Dv97 value given in microns,

BSS _s is the specific surface area of the slag determined by Blaine, given in cm ² / g;

[1000 - BSS _s ] × [(0.021 × BSS _k ) - 103] Formula (IV)

in which BSS _k and BSS _s are, respectively, the specific surface of clinker and slag, determined according to Blaine, given in cm ² / g;

moreover, the total amount of clinker in a pre-prepared mixture of binder materials is strictly less than 60%.

In both formulas (I) and (III), “ln” means the natural logarithm.

According to an embodiment, the dry pre-prepared binder mixture further comprises additional materials having a Dv90 of not more than 200 μm.

According to an embodiment, the dry pre-prepared binder mixture also contains from 0.05 to 1.5%, preferably from 0.1 to 0.8% by weight of a plasticizing agent, preferably a polycarboxylate type.

According to an embodiment of the dry pre-prepared binder mixture according to the present invention, the clinker is in the form of granules having a Dv97 of 10 to 20 μm or a Blaine specific surface of at least 6500 cm ² / g, preferably at least 8500 cm ² / g.

According to an embodiment, the additional materials constitute an inert mass.

In an embodiment of a dry pre-prepared binder mixture of the present invention, additional materials are selected from fly ash, limestone powders, calcined shale, metakaolin, silica fillers, silica powders, pozzolans, slags or clinker and mixtures thereof.

According to an embodiment, the dry pre-prepared binder mixture further comprises a setting accelerator and / or an additive involving air and / or a thickening agent and / or a setting retarder and / or a clay inhibitor and / or plasticizing additive.

The present invention also provides a dry pre-prepared mixture of a binder material containing, in volume fractions:

- at least 10% of the above dry pre-prepared mixture of a binder material; and

- up to 90% of placeholders.

According to an embodiment of a dry pre-prepared binder mixture according to the present invention, aggregates include sand and gravel, wherein the mass ratio of sand to gravel is from 1.5: 1 to 1: 1.8, preferably from 1.25: 1 to 1: 1.4, more preferably from 1.2: 1 to 1: 1.2.

The present invention also provides a plastic concrete composition containing 140 to 220 l / m ³ effective water in combination with:

- at least 10% by volume of the above dry pre-prepared mixture of a binder material in its embodiment, additionally containing additional materials; and

- up to 90% by volume of aggregates;

moreover, the percentage values correspond to fractions relative to the total dry weight.

According to an embodiment of the plastic concrete composition of the present invention, aggregates include sand and gravel, the mass ratio of sand to gravel being from 1.5: 1 to 1: 1.8, preferably from 1.25: 1 to 1 : 1.4, more preferably 1.2: 1 to 1: 1.2.

According to an embodiment of the plastic concrete composition according to the present invention, the amount of effective water used varies from 140 to 200 l / m ³ , preferably from 150 to 180 l / m ³ (see standard EN 206-1, paragraph 3.1.30).

According to an embodiment, the plastic concrete composition of the present invention is a threshold concrete.

According to an embodiment, the plastic concrete composition of the present invention has an average compressive strength of more than 4 MPa at 20 ° C. 16 hours after mixing and a typical compressive strength of more than 25 MPa 28 days after mixing.

According to an embodiment, the plastic concrete composition of the present invention has a spread of 180 to 270 mm, preferably 215 to 235 mm, using the standard ASTM C230 cone after a period of 1 minute and 45 seconds, of which 30 seconds fall at a frequency of 50 Hz and an amplitude of 0.5 mm.

According to an embodiment of the plastic concrete composition according to the present invention, the cone sludge measured using the Abrams cone (or cone sludge value) is from 0 to 250 mm, preferably from 100 to 240 mm.

The present invention also provides a hardened concrete object of the above composition.

The present invention also provides a method for producing a plastic concrete composition, comprising the steps of:

- mixing the above mixture with 140-220 l / m ³ effective water; or

- mixing the pre-prepared mixture in its embodiment, additionally containing additional materials, with fillers and 140-220 l / m ^{3 of} effective water; or

- mixing the pre-prepared mixture in its embodiment, which does not contain additional materials, with additional materials, fillers and 140-220 l / m ³ effective water.

According to a variant of the method for producing a composition of a plastic concrete mixture according to the present invention, mixing is also carried out in the presence of calcium sulfate.

The present invention also provides a method for producing a plastic concrete mixture composition comprising a mixing step:

- Portland cement clinker in the form of granules having a Dv97 of 10 to 30 μm or having a Blaine specific surface of at least 5300 cm ² / g, preferably at least 5500 cm ² / g,

wherein the minimum amount of said clinker in kg / m ³ is determined according to formula (V) for clinker having a Dv97 of 10 to 30 μm, or according to formula (VI) for clinker having a Blaine specific surface area of at least 5300 cm ² / g:

[(90 × ln (Dv97 _k )) - 150] × (W _eff - 140) Formula (V)

in which Dv97 _k is the clinker Dv97 value given in microns,

W _eff represents the amount of effective water in l / m ³

[(-0.021 × BSS _k ) + 263] × (W _eff - 140) Formula (VI)

in which BSS _k represents the specific surface of the clinker, determined by Blaine, given in cm ² / g,

W _eff represents the amount of effective water in l / m ³ ;

- slag, the minimum amount of which in kg / m ³ is determined according to formula (VII) in the case of a mixture with clinker having Dv97 from 10 to 30 μm, or according to formula (VIII) in the case of a mixture with clinker having a specific surface according to Blaine of not less than 5300 cm ² / g:

(3500 - BSS _L ) × [-90 × ln (Dv97 _k ) + 310] × (W _eff - 140) Formula (VII)

in which Dv97 _k is a clinker Dv97 and is given in microns,

BSS _s is the specific surface area of the slag, determined according to Blaine, given in cm ² / g,

W _eff represents the amount of effective water in l / m ³ ;

(3500 - BSS _s ) × [0.021 × BSS _k - 103] × (E _eff - 140) Formula (VIII)

in which BSS _k and BSS _s are, respectively, the specific surface of clinker and slag, determined according to Blaine, given in cm ² / g,

W _eff represents the amount of effective water in l / m ³ ;

- calcium sulfate;

- additional materials having a Dv90 of not more than 200 μm, the minimum amount of which in kg / m ³ is determined according to the following formula (IX):

220 - (amount of slag) - (amount of clinker) - (amount of calcium sulfate) Formula (IX)

- 1500-2200 kg / m ³ , preferably from 1700-2000 kg / m ^{3 of} aggregates;

- plasticizing additives;

- optionally, a setting accelerator and / or an additive involving air, and / or a thickener, and / or a setting inhibitor, and / or a clay inhibitor; from

- 140-220 l / m ³ effective water,

moreover, the total amount of clinker in the plastic concrete mixture is not more than 200 kg / m ³ .

In both formulas (V) and (VII), “ln” means the natural logarithm.

According to an embodiment of the method for producing a composition of a plastic concrete mixture, clinker and / or slag and / or additional materials are as defined above with respect to the previously prepared mixture.

According to an embodiment of the method for producing a plastic concrete mixture composition, the amount of effective water used varies from 140 to 200 l / m ³ , preferably from 150 to 180 l / m ³ .

The present invention also provides a method for producing a molded plastic concrete mixture, comprising the step of:

- casting the composition of the plastic concrete mixture, as defined above.

The present invention also provides a method for manufacturing a concrete object, comprising the step of:

- hardening the composition of the plastic concrete mixture, as defined above, or the cast composition of the plastic concrete mixture, as defined above.

The present invention makes it possible to satisfy the need for reducing CO ₂ emissions, which known types of concrete do not yet satisfy. Indeed, the amount of cement (and in particular clinker) used in the scope of the present invention is less than is usually required. More precisely, the induced CO ₂ emission is reduced by about 50-60% compared to standard concrete of type C25 / 30, without leading to any significant reduction in the mechanical strength of concrete, since the present invention provides concrete with a typical compressive strength of 28 days after mixing, not less than 25 MPa, and with a stripping time of about 16 hours at 20 ° C. Moreover, the rheology of the compositions of plastic concrete mix remains at the same level as that of standard concrete compositions. In addition, the present invention makes it possible, despite the very low level of clinker, to maintain the strength of quick-hardening concrete in the same order of magnitude as for concrete obtained using formulations with a standard clinker content.

The concrete obtained according to the present invention also has the following advantages:

- the cost of dry pre-prepared mixtures of binders according to the present invention can usually be 7-10% less than the cost of dry pre-prepared mixtures of binders used to produce standard concrete C25 / 30.

A variety of specific goals can be achieved and a variety of advantages and embodiments of the present invention can be obtained by fully optimizing all formulation parameters, and in particular, using the following means:

- optimization of the packing of particles of various materials (allowing minimization of the amount of water for these rheological properties);

- optimization of the topology of the mixture, i.e. multiplying the number of adhesion surfaces between particles of sand and / or aggregates by means of “cement bonding points” of cement hydrates and increasing their spatial uniformity (in particular, by using clinker granules that are approximately 2-5 times smaller than granules of ordinary Portland cement);

- search for "chrono-recipes", i.e. the use of the minimum amount of clinker necessary to ensure the acquisition of short-term mechanical strength, while other binders are present in an amount that is set to provide a longer-term acquisition of mechanical strength (acting to a certain extent as a relay for clinker with increasing mechanical strength);

- regulation of the total water demand through the selection of materials with relatively low water consumption (in particular, low porosity), which also makes it possible to maximize the compressive strength;

- optimization of a variety of additives, and in particular, a plasticizing additive (superplasticizing additive), which allows you to maximize the reduction in effective water by optimizing the distribution of the powder and, therefore, styling.

Brief Description of the Figures

Figure 1 represents the particle size profile of the cement used in the examples described below. The x-axis shows the size in microns and the y-axis shows the volume percent. Curve No. 1 corresponds to “selected SPLC cement with dv97 = 16 μm”, curve No. 2 corresponds to CEM I 52.5 HTS Le Teil cement and curve No. 3 corresponds to “micronized SPLC cement with dv97 = 15 μm” (see Example 4).

Figure 2 represents the particle size distribution of limestone fillers used in the examples described below. The x-axis represents the size in microns and the y-axis represents the volume percent. Curve No. 1 represents the filler BL200, curve No. 2 represents the filler Calgar FV, curve No. 3 represents the filler Mikhart 15 and curve No. 4 represents the filler Calgar 40 (see example 4).

Figure 3 represents the particle size profile of the slag used in the examples described below. The x-axis represents the size in microns and the y-axis represents the volume percent. Curve No. 1 represents industrially milled Fos / Mer slag with a Blaine surface of 3260 cm ² / g. Curve No. 2 represents the same slag micronized to a Blaine surface of 9150 cm ² / g (see Example 4).

Figure 4 represents the particle size profile of the aggregates used in the examples described below. The x-axis represents the size in microns and the y-axis represents the cumulative volume percent. Curve No. 1 represents Honfleur 0 / 4R sand (alluvial river sand), curve No. 2 represents Cassis 0 / 3.15 sand (crushed sand), curve No. 3 represents Cassis 6.3 / 10 aggregate (crushed gravel), curve No. 4 represents St Bonnet aggregate 0 / 5R (see example 4).

Description of Embodiments of the Present Invention

Further, the present invention is described in more detail and non-limiting manner in the following description.

Clinker

"Clinker" should be understood according to the present invention as a Portland cement clinker, as defined in standard EN 197-1, paragraph 5.2.1.

The Portland cement clinker according to the present invention can be obtained from standard Portland cement, and in particular from cements described in European standard EN 197-1. For example, CEM I or CEM II 52.5 N or R or PM cement (marine construction, standard NF P 15-317) or PMES cement (marine construction, sulphated water, NF P 15-319 standard) can be used. Cement may be of the type HRI (High Initial Strength).

In certain cases, in particular for type CEM II, Portland cement does not contain pure clinker. Portland cement of type CEM II contains clinker mixed with at least one additional material (slag, finest ("fuming") silica, pozzolan, fly ash, calcined slate, limestone) in an amount up to 3.7% by weight. Therefore, if the clinker used comes from such cement, additional materials (one or more) are considered either from the slag or from the above “additional materials” (if they are materials in the form of granules with Dv90 not more than 200 μm, and preferably Dv97 no more than 200 microns).

Such cement must be ground or cut (by pneumatic classification) to provide clinker with the characteristics required by the present invention, i.e. Dv97 from 10 to 30 μm, preferably from 10 to 20 μm or with a Blaine specific surface of at least 5300 cm ² / g, preferably at least 5500 cm ² / g, according to EN 196-6, paragraph 4.

According to an embodiment of the present invention, the clinker has a Dv97 of 10 to 30 μm and a Blaine specific surface of at least 5300 cm ² / g, preferably at least 5500 cm ² / g.

According to another embodiment of the present invention, the clinker has a Dv97 of 10 to 30 μm and / or a Blaine specific surface of at least 5300 cm ² / g, preferably at least 5500 cm ² / g.

According to a third embodiment of the present invention, the clinker has a Blaine specific surface of at least 5300 cm ² / g, preferably at least 5500 cm ² / g.

According to a fourth embodiment of the present invention, the clinker has a Dv97 of 10 to 30 μm.

The clinker according to the present invention can be described as an ultra-thin clinker. Cement can be milled, for example, using a grinder, which includes a primary mill of vertical or mill type, coupled to a mill of the final grinding stage of the Horomill © type, pendulum or ball or air-jet mill. You can also use a pneumatic selector or pneumatic classifier of the second or third generation or similar devices with very high efficiency.

The goal is to maximize the diffusion length of the cement granules by reducing the size of the clinker, in order to maximize the homogeneity of the mortar part of the concrete (matrix) by optimally distributing the bonding points between the particles.

Dv97 (by volume) corresponds to the 97th percentile in the particle size distribution, i.e. 97% of the particles are smaller than Dv97 and 3% are larger than Dv97. Similarly, Dv90 corresponds to the 90th percentile in the particle size distribution, i.e. 90% of the particles are smaller than Dv90 and 10% are larger than Dv90.

Typically, Dv90, Dv97 and other quantities of the same type that are characteristic of the particle size distribution (volume distribution) of a set of particles or granules can be determined by laser granulometry for a particle size of less than 200 microns or by sieving (sieve analysis) for particle sizes of more than 200 microns.

Nevertheless, when individual particles tend to aggregate, it is necessary to determine their size by electron microscopy, provided that the effective (apparent) size measured by laser diffraction granulometry is more important than the actual particle size, which can distort the interpretation (agglomeration) and flocculation).

High soluble alkali cement may be preferred. This allows, for example, to activate the slag component.

Slag

The term “slag” should be understood according to the present invention as the slag of a blast furnace according to paragraph 5.2.2 of EN 197-1 with a glassy content of not less than 80%, ground to a minimum of fineness (Blaine specific surface area determined by the standardized method of EN 196-6, is 2500 cm ² / g).

Slag according to the present invention can be used alone or in combination with one of the others. A person skilled in the art will select appropriate slags according to their reactivity, i.e. their ability to increase compressive strength from 1 day to 28 days after mixing. This ability varies according to the type and specific origin of the slag used.

Additional materials

"Additional materials" should be understood as materials in the form of granules with a Dv90 of at least 200 microns, preferably Dv97 of at least 200 microns.

These materials can serve as filling materials for the matrix (mortar part of concrete), i.e. they fill the gaps between other materials having granules large in size.

Even if it can be assumed that the additional materials may be binders, the optimization (in particular, in cost) of the cements according to the present invention leads to the preference of the additional materials as an inert mass, i.e. non-binding materials (without hydraulic or pozzolanic activity).

It will be possible, for example, to use limestone powders (limestone fillers) or fly ash or mixtures thereof as additional materials. Calcined shale, metakaolin, silica fillers, silica powders, pozzolans (see standard EN197-1, paragraph 5.2.3), slags or, again, another clinker other than the clinker according to the present invention can also be used.

Calcium sulphate

"Calcium sulfate" should be understood according to the present invention as any material that makes it possible to provide a binder with sulfate (SO ₃ ), as defined in paragraph 5.4 of EN 197-1.

The calcium sulfate according to the present invention can in particular be selected from gypsum, semi-aquatic gypsum, anhydrite or mixtures thereof. Calcium sulfate may exist in its natural state, or it may be of industrial origin in the form of a by-product of certain industrial processes.

The amount of calcium sulfate according to the present invention is adjusted in the traditional manner for optimal mechanical compressive strength after 24 hours and at 20 ° C. Preferably, the amount of calcium sulfate according to the present invention, determined according to the method described in paragraph 8 of EN 196-2, is from 2.0 to 3.5% by weight of sulfate (SO ₃ ) relative to the weight of the mixture (clinker + slag + additional material + calcium sulfate).

Water

Concrete contains various categories of water. First of all, effective water is the internal water of concrete, located between the granules of a solid skeleton formed by aggregates, clinker, slag and additional materials. Therefore, effective water is the water necessary for hydration and obtaining consistency. Concrete, on the other hand, contains water held in place by the porosity of aggregates, slag, and additional materials. This water is not taken into account as part of the effective water. It is believed that it is not free and does not participate in the hydration of cement or in obtaining consistency. Total water is all the water in the mixture (during mixing).

Dry pre-prepared binder mixes

The dry pre-prepared mixture of binders according to the present invention contains, in mass fractions:

- Portland cement clinker in the form of granules with Dv97 from 10 to 30 μm or with a Blaine specific surface of at least 5300 cm ² / g, preferably at least 5500 cm ² / g,

wherein the minimum amount of said clinker as a percentage by weight is determined according to formula (I) for clinker with Dv97 from 10 to 30 μm, or according to formula (II) for clinker with a specific surface according to Blaine of at least 5300 cm ² / g:

[26 × ln (Dv97 _k )] - 43 Formula (I)

in which Dv97 _{k is} given in microns

[-6 · 10 ^-3 × BSS _k ] + 75 Formula (II)

in which BSS _k is the specific surface according to Blaine, given in cm ² / g;

- slag, the minimum amount of which in percent by weight is determined according to formula (III) in the case of clinker with Dv97 from 10 to 30 μm, or according to formula (IV) in the case of a mixture with clinker with a specific surface according to Blaine of at least 5300 cm ² / g :

[1000 - BSS _s ] × [(-90 × ln (Dv97 _k )) + 310] Formula (III)

in which Dv97 _k is the clinker Dv97 value given in microns,

BSS _s is the specific surface area of the slag determined by Blaine, given in cm ² / g;

[1000 - BSS _s ] × [(0.021 × BSS _k ) - 103] Formula (IV)

in which BSS _k and BSS _s are, respectively, the specific surface of clinker and slag, determined according to Blaine, given in cm ² / g;

moreover, the total amount of clinker in a pre-prepared mixture of binder materials is strictly less than 60%.

Preferably, the minimum amount of said clinker as a percentage by weight is determined according to formula (I bis) for clinker with Dv97 from 10 to 30 μm, or according to formula (II bis) for clinker with a Blaine specific surface area of at least 5300 cm ² / g:

[26 × ln (Dv97 _k )] - 37 Formula (I bis)

in which Dv97 _{k is} given in microns

[-6 · 10 ^-3 × BSS _k ] + 81 Formula (II bis)

in which BSS _k is the specific surface according to Blaine, given in cm ² / g;

and the minimum amount of slag in percent by weight is determined according to formula (III bis) in the case of clinker with Dv97 from 10 to 30 μm, or according to formula (IV bis) in the case of a mixture with clinker with a specific surface according to Blaine of at least 5300 cm ² / g :

[1000 - BSS _s ] × [(-90 × ln (Dv97 _k )) + 330] Formula (III bis)

in which Dv97 _k is the clinker Dv97 value given in microns,

BSS _s is the specific surface area of the slag determined by Blaine, given in cm ² / g;

[1000 - BSS _s ] × [(0.021 × BSS _k ) - 83] Formula (IV bis)

in which BSS _k and BSS _s are, respectively, the specific surface of clinker and slag, determined according to Blaine, given in cm ² / g.

In both formulas (I bis) and (III bis), “ln” means the natural logarithm.

Preferably, the dry pre-prepared binder mixture according to the present invention further comprises additional materials with a Dv90 of not more than 200 μm.

Preferably, the dry pre-prepared binder mixture according to the present invention further comprises calcium sulfate.

Clinker, slag and additional materials can advantageously be combined according to the proportions given above to form dry pre-prepared mixtures of binders (free from added water) intended for mixing with aggregates and water.

The following dry pre-prepared binder mixtures according to the present invention are particularly advantageous:

- clinker, slag and limestone powder;

- clinker, slag and fly ash.

Advantageously, one or more of the additives commonly used in this field can also be used in these dry pre-prepared mixtures of binder materials: a setting accelerator and / or an additive involving air and / or a thickener and / or setting retarder and / or clay inhibitor and / or plasticizer. In particular, it is useful to include a plasticizing additive (superplasticizing additive), in particular of a polycarboxylate type, in particular from 0.05 to 1.5%, preferably from 0.1 to 0.8%, in percent by weight.

“Clay inhibitor” should be understood as molecules capable of reducing or eliminating the harmful effect of clays on the properties of hydraulic binders. In particular, clay inhibitors such as those described in International Patent Application Documents WO 2006/032785 and WO 2006/032786 can be used.

Placeholders

The definition of aggregates according to the present invention is the definition of XPP18-545, provided that the aggregates according to the present invention have a maximum dimension D _{max of} not more than 32 mm. Aggregates according to the present invention include sand (granules with a maximum size D _max less than 4 mm, determined by passability through a sieve, according to EN 12620, paragraph 3.8) or gravel (grains or small gravel) with a minimum size D _{min of} at least 4 mm determined by retention on a sieve according to EN 12620, paragraph 3.9.

Aggregates may be of limestone, siliceous or silica-limestone nature.

Sand and gravel may be river or crushed. Crushed sand contains a larger proportion of fine particles than river sand. According to the terminology used to describe sand, small particles are grains with a size of less than 63 microns (passing through a sieve).

When sand contains fine particles in an amount exceeding 1% (mass fraction of sand), this amount of fine particles introduced with sand must be taken into account, reducing the amount of “additional materials” described above by an amount equal to the amount of fine particles present in the sand (fraction less than 63 microns) above 1% threshold.

Preferably, the clay content in the sand and aggregates is less than 1%. A high clay content has a negative effect on the workability of concrete.

Preferably, the mass ratio of the amount of sand to the amount of gravel is from 1.5: 1 to 1: 1.8, more specifically from 1.25: 1 to 1: 1.4, especially from 1.2: 1 to 1: 1.2, and ideally it is either 1: 1 or is close to this ratio.

Dry Binder Mixtures

Aggregates, clinker, slag, additional materials, optional additives (in particular, a plasticizing additive) can be combined in dry mixtures of binders (free from added water). Such dry binder mixtures can be obtained either by mixing the dry pre-prepared mixture defined above with aggregates, or by directly mixing the various components from the start.

The volume fractions of the various components can then be determined as follows:

- at least 10% of the above dry pre-prepared mixture of a binder material; and

- up to 90% of placeholders.

Preferably, the dry binder mixture according to the present invention contains additional materials.

Preferably, the dry binder mixture according to the present invention further comprises calcium sulfate.

A dry mix of binders, defined in this way, may be a ready-mixed concrete mix applicable to simple mixing with water.

According to a variant of a dry mixture of binders according to the present invention, the volume fractions of various components can be determined as follows:

- at least 10% of the above dry pre-prepared mixture of a binder material; and

- up to 90% of gravel.

Preferably, the dry binder mixture according to the present invention further comprises calcium sulfate.

According to a variant of a dry mixture of binder materials according to the present invention, the volume fractions of various components can be determined as follows:

- at least 10% of the above dry pre-prepared mixture of a binder material; and

- up to 90% of sand.

Preferably, the dry binder mixture according to the present invention further comprises calcium sulfate.

Concrete

The term "plastic concrete mixture" according to the present invention should be understood as fresh concrete (see standard EN 206-1, paragraph 3.1.2).

The plastic concrete mixture according to the present invention is obtained by mixing:

- at least 10% by volume of dry pre-prepared mixture of binder materials in its embodiment, additionally containing additional materials; and

- up to 90% by volume of aggregates;

- from 140-220 l / m ³ effective water.

The percentage corresponds to fractions relative to the total dry weight.

Preferably, the plastic concrete mixture according to the present invention further comprises calcium sulfate.

A plastic concrete mixture can also be obtained directly by mixing the dry mix defined above with 140-220 l / m ^{3 of} effective water.

The concrete according to the present invention can also be obtained by directly mixing the various ingredients with each other and with water. A method of obtaining a composition of a plastic concrete mixture according to the present invention includes a mixing step:

- Portland cement clinker in the form of granules having a Dv97 of 10 to 30 μm or having a Blaine specific surface of at least 5300 cm ² / g, preferably at least 5500 cm ² / g,

wherein the minimum amount of said clinker in kg / m ³ is determined according to formula (V) for clinker having a Dv97 of 10 to 30 μm, or according to formula (VI) for clinker having a Blaine specific surface area of at least 5300 cm ² / g:

[(90 × ln (Dv97 _k )) - 150] × (W _eff - 140) Formula (V)

in which Dv97 _k is the clinker Dv97 value given in microns,

W _eff represents the amount of effective water in l / m ³

[(-0.021 × BSS _k ) + 263] × (W _eff - 140) Formula (VI)

in which BSS _k represents the specific surface according to Blaine, given in cm ² / g,

W _eff represents the amount of effective water in l / m ³ ;

- slag, the minimum amount of which in kg / m ³ is determined according to formula (VII) in the case of a mixture with clinker having Dv97 from 10 to 30 μm, or according to formula (VIII) in the case of a mixture with clinker having a specific surface according to Blaine of not less than 5300 cm ² / g:

(3500 - BSS _s ) × [-90 × ln (Dv97 _k ) + 310] × (W _eff - 140) Formula (VII)

in which Dv97 _k is the clinker Dv97 value given in microns,

BSS _s is the specific surface area of the slag, determined according to Blaine, given in cm ² / g,

W _eff represents the amount of effective water in l / m ³ ;

(3500 - BSS _s ) × [0.021 × BSS _k - 103] × (W _eff - 140) Formula (VIII)

in which BSS _k and BSS _s are, respectively, the specific surface of clinker and slag, determined according to Blaine, given in cm ² / g,

W _eff represents the amount of effective water in l / m ³ ;

- calcium sulfate;

- additional materials having a Dv90 value of not more than 200 μm, the minimum amount of which in kg / m ³ is determined according to the following formula (IX):

220 - (amount of slag) - (amount of clinker) - (amount of calcium sulfate) Formula (IX)

- 1500-2200 kg / m ³ , preferably 1700-2000 kg / m ^{3 of} aggregates;

- plasticizing additives;

- optionally, a setting accelerator and / or an additive involving air, and / or a thickener, and / or a setting inhibitor, and / or a clay inhibitor; from

- 140-220 l / m ³ effective water,

moreover, the total amount of clinker in the plastic concrete mixture is not more than 200 kg / m ³ .

“Kg / m ³ ” should be understood as the mass of material used on m ³ of concrete produced.

Preferably, the minimum amount of said clinker in kg / m ³ is determined according to the formula (V bis) for clinker with Dv97 from 10 to 30 μm, or according to the formula (VI bis) for clinker with a specific surface according to Blaine of at least 5300 cm ² / g:

[(90 × ln (Dv97 _k )) - 130] × (W _eff - 140) Formula (V bis)

in which Dv97 _k is the clinker Dv97 value given in microns,

W _eff represents the amount of effective water in l / m ³ ;

[(-0.021 × BSS _k ) + 283] × (W _eff - 140) Formula (VI bis)

in which BSS _k represents the specific surface according to Blaine, given in cm ² / g,

W _eff represents the amount of effective water in l / m ³ ;

and the minimum amount of slag in kg / m ³ is determined according to formula (VII bis) in the case of a mixture with clinker with Dv97 from 10 to 30 μm, or according to formula (VIII bis) in the case of a mixture with clinker with a specific surface according to Blaine of at least 5300 cm ² / g:

(3500 - BSS _s ) × [-90 × ln (Dv97 _k ) + 330] × (W _eff - 140) Formula (VII bis)

in which Dv97 _k is the clinker Dv97 value given in microns,

BSS _s is the specific surface area of the slag, determined according to Blaine, given in cm ² / g,

W _eff represents the amount of effective water in l / m ³ ;

(3500 - BSS _s ) × [0.021 × BSS _k - 83] × (W _eff - 140) Formula (VIII bis)

in which BSS _k and BSS _s are, respectively, the specific surface of clinker and slag given in cm ² / g,

W _eff is the amount of effective water in l / m ³ .

In both formulas, (V bis) and (VII bis), “ln” means the natural logarithm.

The amount of said clinker used is preferably less than 180 kg / m ³ , preferably less than 150 kg / m ³ , preferably less than 120 kg / m ³ .

Preferably, the minimum amount of additional materials in kg / m ³ is determined according to the following formula (IX bis):

250 - (amount of slag) - (amount of clinker) - (amount of calcium sulfate) Formula (IX bis)

According to an embodiment of the method for producing a plastic concrete mixture according to the present invention, the amount of effective water used varies from 140 to 200 l / m ³ , preferably from 150 to 180 l / m ³ . In certain embodiments, this amount of effective water is therefore reduced relative to standard concrete.

Preferably, aggregates include sand and gravel, and the mass ratio of sand to gravel is from 1.5: 1 to 1: 1.8, more specifically from 1.25: 1 to 1: 1.4, especially from 1.2: 1 to 1: 1.2 and ideally it is 1: 1 or is close to this value.

The materials in question have, according to particular embodiments, the same characteristics as the materials described above with respect to mixtures of binder materials and pre-prepared mixtures according to the present invention.

Mixing is carried out using a traditional mixer on a concrete mixing plant or directly in a concrete mixer during the mixing time that is usual in this field.

Compositions of plastic concrete mixtures obtained according to the present invention have mechanical properties comparable to those of standard concrete types C25 / 30, preferably no worse or even better than theirs, especially with regard to compressive strength after 16 hours and after 28 days and regarding rheology.

In particular, according to an embodiment of the present invention, the average compressive strength is at least 4 MPa, preferably at least 5 MPa, at 20 ° C. 16 hours after mixing, and at least 25 MPa, preferably at least 28 MPa 28 days after mixing.

According to an embodiment of the plastic concrete mixture according to the present invention, the cone sludge measured using the Abrams cone (or cone sludge value) is from 0 to 250 mm, preferably from 100 to 240 mm, when measured in December 1999 in accordance with with European standard EN 12350-2.

According to an embodiment of the plastic concrete mixture according to the present invention, the spread after one minute is from 50 to 140 mm, preferably from 85 to 105 mm, using the standard ASTM C230 cone in the absence of vibrations.

According to an embodiment of the plastic concrete mixture according to the present invention, the spread after one minute is from 180 to 270 mm, preferably from 215 to 235 mm, using the standard ASTM C230 cone in the presence of vibrations in the measurements carried out as described below in Example 6.

Therefore, the concretes according to the present invention have rheological properties equivalent to standard C25 / 30 concretes.

Preferably, the concretes according to the present invention are threshold concretes. "Threshold concrete" is understood as concrete (wet), requiring the application of positive energy (eg, shear, vibration or shock) to initiate the flow. In contrast, non-threshold concrete flows spontaneously without imparting external energy. So, below the energy threshold, threshold concrete behaves substantially like a deformable elastic solid, and above this energy threshold it behaves like a viscous fluid.

The amount of clinker used to produce concrete according to the present invention is much less than that required to produce standard C25 / 30 concrete, which provides a means for an impressive reduction in CO ₂ emission. Compared with the reference formulation C25 / 30, which contains 95 kg / m ^{3 of} limestone and 260 kg / m ^{3 of} cement, the concrete according to the present invention, containing, for example, from 100 to 120 kg / m ^{3 of} clinker, provides a reduction in CO ₂ emission by a value of the order of 50-60%.

The concrete according to the present invention can be cast by conventional methods; after hydration / hardening, hardened concrete objects are obtained, such as structural elements, structural and other elements.

EXAMPLES

The following examples illustrate the present invention without limiting it.

Example 1: Laser Granulometry Method

Granulometric curves of various powders are obtained using a Malvern MS2000 laser granulometer. The measurement is carried out in a wet manner (aqueous medium); particle size should be from 0.02 microns to 2 mm. The light source is provided by a red He-Ne laser (632 nm) and a blue diode (466 nm). The optical model is a Fraunhofer model, a computational matrix of a polydisperse type.

The background noise is first measured at a pump speed of 2000 rpm, a stirrer speed of 800 rpm and when measuring noise for 10 s in the absence of ultrasound. During the instrument calibration / blank measurement phase, verify that the laser light intensity is at least 80% and that a falling exponential curve is obtained for background noise. Otherwise, clean the lenses of the cell.

Then, a first measurement is carried out on the sample with the following parameters: pump speed: 2000 rpm, stirrer speed: 800 rpm, absence of ultrasound. The sample is introduced so as to have a darkening of 10 to 20%. "Darkening" should be understood as the quenching (extinction) of the laser signal by a suspension circulating between the emitter and the central sensor (turbidimeter). 100% darkening corresponds to complete signal quenching. In contrast, a 0% darkening corresponds to a clear, transparent liquid without any particles. Darkening depends on the concentration of solids in the suspension and the refractive index of the particles. After stabilization of the browning, measurements are taken with a fixed period between immersion and the measurement set for 10 s. Duration of measurement 30 s (analyze 30,000 diffraction images). The resulting granulogram should take into account the fact that part of the powder population can be agglomerated.

Then conduct a second measurement (without emptying the tank) with ultrasound. The speed of the pump leads to 2500 rpm./min, mixing - to 1000 rpm./min, ultrasound is emitted at 100% (30 W). These conditions are maintained for 3 minutes, then the initial parameters are restored: pump speed 2000 rpm, stirrer speed 800 rpm, absence of ultrasound. At the end of the 10 second period (to remove possible air bubbles), a measurement is taken for 30 s (30,000 images are analyzed). The second dimension corresponds to a powder deagglomerated by ultrasonic dispersion.

Each measurement is repeated at least two times to verify the stability of the result. The device is calibrated before each working period according to a standard sample (silica Sifraco C10), for which the particle size curve is known. All measurements given in the description and the indicated ranges correspond to the values obtained with ultrasound.

Example 2: Method for measuring specific surface area

BET specific surface:

The specific surface of various powders is measured as follows. A powder sample of the following mass is taken: 0.1-0.2 g for the expected specific surface area exceeding 30 m ² / g; 0.3 g for an estimated specific surface area of 10-30 m ² / g; 1 g for an estimated specific surface area of 3-10 m ² / g; 1.5 g for the expected specific surface area of 2-3 m ² / g; 2 g for the estimated specific surface area of 1.5-2 m ² / g; 3 g for an estimated specific surface area of 1-1.5 m ² / g.

Depending on the volume of the sample, a cell with a volume of 3 cm ³ or 9 cm ^{3 is used} . Weigh the cell assembly (cell + glass rod). Then add a sample to the cell: the product should not be less than one millimeter from the top of the cell neck. Weigh the collected cell (cell + glass rod + sample). The measuring cell is placed in a degassing unit and gas is removed from the sample. Degassing parameters: 30 min / 45 ° C for Portland cement, gypsum, pozzolans; 3 hours / 200 ° С for slag, the finest (fuming) silica, fly ash of alumina cement, limestone; and 4 hours / 300 ° C for control alumina. After degassing, the cell is quickly closed with a stopper. The collected cell is weighed and the result is noted. All weighings are carried out without plugs. The mass of the sample is obtained by subtracting the mass of the cell from the sum of the mass of the cell and the degassed sample.

Then, after the sample is placed in the measuring unit, the sample is analyzed. The analyzer is Beckman Coulter SA 3100. The measurement is based on the adsorption of nitrogen by the sample at a given temperature, in this case, at the temperature of liquid nitrogen, i.e. -196 ° C. The device measures the pressure in the reference cell in which the adsorbate is at saturated vapor pressure and the pressure in the cell with the sample into which a known volume of adsorbate is injected. The curve obtained from these experiments is an adsorption isotherm. In this measurement method, it is necessary to know the dead volume of the cell: therefore, before analysis, they measure this volume with helium.

The mass of the sample, calculated in advance, is introduced as a parameter. The BET surface is determined by a linear regression program for the experimental curve. Reproduction standard deviation obtained from 10 measurements on silica with a specific surface of 21.4 m ² / g is 0.07. Control is carried out every two weeks on a reference product. Twice a year, control is carried out with reference alumina provided by the manufacturer.

Blaine specific surface:

This value is determined according to EN 196-6, paragraph 4.

Example 3: Raw Materials

The following materials are more specifically used in the description below.

Cement: CPA CEM I 52.5 cement is used (from the Lafarge Cements cement plant - Saint-Pierre la Cour, designated as “SPLC”). To obtain it, two methods are used: selection and micronization.

The selection is carried out using an Alpine Hosokawa AFG100 separator. Following this method, receive quality cement: "selected cement SPLC dv97 = 16 μm" (turbine speed: 13000 rpm, material yield: 42.95%).

Micronization is carried out using an air-jet mill, opposed to Alpine Hosokawa AFG200. The turbine rotational speed is set in such a way as to obtain a dv97 value of 15 μm. This micronized cement will hereinafter be referred to as “micronized SPLC dv97 = 151 μm”.

The particle size profile of these two grades of cement is shown in FIG. This cement is obtained from a basic mixture with 95% clinker, 2% limestone and 3% filler, to which 5% gypsum or anhydrite and, optionally, a grinding aid and chromium VI reducing agents are added. Thus, this cement contains at least 90% clinker.

Le Teil HTS CEM I 52.5 PMES cement (supplied by Lafarge) is used for reference concrete (reference C25 / 30).

Slag comes from Fos sur Mer. It is ground industrial. Two grinding fineness values are used: 3260 and 3500 cm ² / g (Blaine surface). A slag sample with a Blaine surface of 3260 cm ² / g was micronized to a Blaine surface of 9150 cm ² / g using an air-jet mill opposed to Alpine Hosokawa AFG200. The names of the different batches of slag as follows indicate the values of the surfaces according to Blaine:

- “Slag 3500 cm ² / g”;

- “Slag 3260 cm ² / g”;

- "Micronized slag 9150 cm ² / g."

Granulometric slag profiles with a Blaine surface of 3260 cm ² / g and 9150 cm ² / g are shown in FIG. 3.

Additional materials: use limestone fillers according to the following list.

- Calgar 40 (Provençale SA) with a BET specific surface area of 0.99 m ² / g and a methylene blue value of MB _F of 0.6 g / 100 g according to NF EN 933-9;

- Mikhart 15 (supplier of Provençale SA) with a BET specific surface area of 1.2 m ² / g and a methylene blue MB _F of 0.27 g / 100 g according to NF EN 933-9;

- BL200 (supplier Omya) with a BET specific surface area of 0.86 m ² / g and a methylene blue value, MB _F of 0.3 g / 100 g, according to NF EN 933-9;

- Calgar FV (Provençale SA) with a BET specific surface area of 1.08 m ² / g and a methylene blue value, MB _F of 0.3 g / 100 g, according to NF EN 933-9.

The particle size profile of these materials is shown in FIG. 2.

Additives:

The products used in the examples are as follows:

- Optima 203 superplasticizer from Chryso, which belongs to the polycarboxylate type;

- Plasticizer "Chrysoplast 209" from Chryso, which refers to the lignosulfonate type;

- Premia 180 superplasticizer from Chryso, which belongs to the polycarboxylate type;

- Plasticizer "Optima 100" from Chryso, which refers to the polyphosphonate type;

- Plasticizer "Omega 101" from Chryso, which refers to the polycarboxylate type;

- Anti-foam agent “TBP”, with tributyl phosphate base.

Aggregates: use the materials indicated in the following list:

- Sand Cassis 0 / 3.15 (crushed sand);

- Sand Honfleur 0 / 4R (alluvial river sand);

- Sand St Bonnet 0 / 5R (alluvial river sand);

- Fillers Cassis 6.3 / 10 (crushed gravel).

The particle size profile of these materials is shown in FIG. 4.

Example 4: Concrete Formulations According to the Present Invention

The formulations that follow are formulations of the concrete compositions of the present invention, with the exception of C25 / 30, which is a control. The materials used are those described in example 3. Each number corresponds to the mass of material (in kg) used to produce 1 m ^{3 of} concrete.

Formula G3-1

Placeholders Cassis 6.3 / 10 941.5 Sand Honfleur 0 / 4R 941.5 Selective cement SPLC dv97 = 16 μm one hundred Filler BL200 218.8 Slag 3500 cm ² / g 60 Optima 203 supplement 2,3 Total water 164.2 Effective water 142

Formula G3-2

Placeholders Cassis 6.3 / 10 941.5 Sand Cassis 0 / 3.15 941.5 Selective cement SPLC dv97 = 16 μm one hundred Filler BL200 93.8 Slag 3500 cm ² / g 60 Optima 203 supplement 2,3 Total water 164.2 Effective water 145

The amount of filler in the recipe G3-2 is reduced compared to the recipe G3-1, since the sand used (crushed, not river) contains a significant amount of fine particles, which are taken into account in the fraction of additional materials.

Formula G3-3

Placeholders Cassis 6.3 / 10 941.5 Sand Honfleur 0 / 4R 941.5 Selective cement SPLC dv97 = 16 μm one hundred Filler Calgar FV 218.8 Slag 3500 cm ² / g 60 Optima 203 supplement 2,5 Total water 164 Effective water 142

Formula G3-4

Placeholders Cassis 6.3 / 10 941.5 Sand Honfleur 0 / 4R 941.5 Selective cement SPLC dv97 = 16 μm one hundred Filler Calgar 40 217.9 Slag 3500 cm ² / g 60 Optima 203 supplement 3 Total water 163.6 Effective water 142

Formula G3-5

Placeholders Cassis 6.3 / 10 941.5 Sand Honfleur 0 / 4R 941.5 Selective cement SPLC dv97 = 16 μm one hundred Filler Mikhart 15 217.9 Slag 3500 cm ² / g 60 Optima 203 supplement 3,5 Total water 163.2 Effective water 142

Formula G4-1

Placeholders Cassis 6.3 / 10 920 Sand Honfleur 0 / 4R 920 Selective cement SPLC dv97 = 16 μm 120 Filler BL200 126 Slag 3500 cm ² / g one hundred Additive CHRYSOPLAST 209 0.80 Total water 193 Effective water 171

Formula G4-2

Placeholders Cassis 6.3 / 10 920 Sand Honfleur 0 / 4R 920 Selective cement SPLC dv97 = 16 μm 120 Filler BL200 144 Slag 3500 cm ² / g 80 Additive CHRYSOPLAST 209 1,02 Total water 195 Effective water 173

Formulations G4-3 and G4-4 emphasize the effect of fineness grinding slag on its dose.

Formula G4-3

Placeholders Cassis 6.3 / 10 920 Sand St Bonnet 0 / 5R 920 Micronized cement SPLC dv97 = 15 μm 120 Filler BL200 144 Slag 3260 cm ² / g 80 OMEGA 101 supplement 0.86 TBP supplement 0,03 Total water 184.1 Effective water 161

Formula G4-4

Placeholders Cassis 6.3 / 10 920 Sand St Bonnet 0 / 5R 920 Micronized cement SPLC dv97 = 15 μm 120 Filler BL200 181 Slag 9150 cm ² / g 40 OMEGA 101 supplement 1,07 TBP supplement 0,03 Total water 184.1 Effective water 161

Formula C25 / 30 (reference)

Placeholders Cassis 6.3 / 10 900 Sand Honfleur 0 / 4R 900 Cement CEM I 52.5 N HTS by Le Teil 257 Filler BL200 95 Additive CHRYSOPLAST 209 0.54 Total water 189 Effective water 173

Example 5: Concrete Quality According to the Present Invention

The quality of the concrete according to the present invention is evaluated according to the following points.

- Compressive strength. This parameter is determined according to EN 12390-3 on cylindrical samples contained in accordance with EN 12390-2 at 20 ° C ± 2 ° C and relative humidity over 95%.

The results of measuring the average compressive strength are recorded below in table 1: it, in particular, shows that the above formulations provide an average compressive strength of at least 4 MPa after 16 hours and at least 25 MPa (even close to 30 MPa) after 28 days.

Table 1
Average compressive strength (in MPa) up to 28 days, measured on a cylinder with a diameter of 70 mm Duration: 16 hours Duration: 24 hours Duration: 28 days Ref. C25 / 30 Not measured 9.8 32,2 G3-1 5,4 6.3 29.8 G3-2 Not measured 7.5 Not measured G3-3 5,4 6.5 29.1 G3-4 5,4 6.9 29.1 G3-5 5.5 6.7 29.2 G4-1 6.1 7.9 36.8 G4-2 Not measured Not measured 30.1 G4-3 4.1 6.1 29.4 G4-4 4.1 6.2 28.1

The rheology of the above concrete compositions is also evaluated. To do this, as follows, conduct a "static" and "vibrational" measurement of the spread of concrete mix.

The ASTM cone described in ASTM C230 is used. The cone is placed on a SINEX TS100 vibrating electromagnetic table with a square plate of 600 mm × 600 mm (frequency 50 Hz, amplitude 0.5 mm). The spread measurement is carried out on a dry surface. The spread is measured in three directions, the average value rounded to the nearest 5 mm is recorded.

Preparation: 2 liters of dry mixture are added to the tank; this mass is stirred for 30 seconds at low speed; stop the mixer; make the total amount of water and liquid additives; stirring for 2 minutes at low speed. At the end of mixing, i.e. 2 minutes after contact with water (T = 2 min), the cone is filled in one step and leveled, then the cone is raised.

At T = 3 min, a “static” spread is measured after waiting for one minute

At T = 3 min 15 s, vibration begins at 50 Hz and an amplitude of 0.5 mm for 30 seconds.

At T = 3 min 45 s, the “vibrational” spread is measured.

Concrete is collected and stored in a closed plastic bag to avoid drying out between measurements. Before each sampling, the paste is lightly mixed with a spatula.

At T = 10 min, the cone is filled in one step and leveled, then the cone is raised.

At T = 11 min, a “static” spread is measured after waiting for one minute.

At T = 11 min 15 s, vibration begins at 50 Hz and an amplitude of 0.5 mm for 30 seconds.

At T = 11 min 45 s, the “vibrational” spread is measured.

The results are given below in table 2. They show that the concretes made according to the present invention have acceptable rheology characteristics, no worse than standard concrete C25 / 30. Differences between the results obtained with and without vibration emphasize the liquid-threshold properties (like standard concrete C25 / 30).

table 2
Rheological characteristics (spread values are given in mm) 3 minute static 11 minute static Vibratory spread 3 min 45 Vibration Blur 11 min 45 C25 / 30 95 95 225 225 G3-1 95 95 230 230 G3-2 one hundred one hundred 225 225 G3-3 90 90 225 220 G3-4 90 90 225 220 G3-5 90 90 225 225 G4-1 one hundred one hundred 220 215 G4-2 Not measured 95 Not measured 225 G4-3 95 Not measured 215 Not measured G4-4 one hundred Not measured 215 Not measured

Claims (4)

1. A method of obtaining a composition of a plastic concrete mixture, comprising a mixing step:
- Portland cement clinker in the form of granules having a Dv97 of 10 to 30 μm or having a Blaine specific surface of at least 5300 cm ² / g, preferably at least 5500 cm ² / g,
wherein the minimum amount of said clinker in kg / m ³ is determined according to formula (V) for clinker having a Dv97 of 10 to 30 μm, or according to formula (VI) for clinker having a Blaine specific surface area of at least 5300 cm ² / g:

in which Dv97 _k is the clinker Dv97 value given in microns, W _eff is the amount of effective water in l / m ³ ;

in which BSS _k represents the specific surface of the clinker according to Blaine, given in cm ² / g,
W _eff represents the amount of effective water in l / m ³ ;
- slag, the minimum amount of which in kg / m ³ is determined according to formula (VII) in the case of a mixture with clinker having Dv97 from 10 to 30 μm, or according to formula (VIII) in the case of a mixture with clinker having a specific surface according to Blaine of not less than 5300 cm ² / g:

in which Dv97 _k is the clinker Dv97 value given in microns,
BSS _s is the specific surface area of the Blaine slag given in cm ² / g,
W _eff represents the amount of effective water in l / m ³ ;

in which BSS _k and BSS _s are respectively the specific surface of clinker and slag, determined according to Blaine, given in cm ² / g,
W _eff represents the amount of effective water in l / m ³ ;
- calcium sulfate;
- additional materials having a Dv90 of not more than 200 μm, the minimum amount of which in kg / m ³ is determined according to the following formula (IX):
220 - (amount of slag) - (amount of clinker) - formula (IX) (amount of calcium sulfate);
- 1500-2200 kg / m ³ , preferably 1700-2000 kg / m ^{3 of} aggregates;
- plasticizing additives;
- optional setting accelerator and / or additives involving air, and / or thickener, and / or setting retarder, and / or clay inhibitor, with
- 140-220 l / m ³ effective water,
moreover, the total amount of clinker in the plastic concrete mixture is not more than 200 kg / m ³ . 2. A method of obtaining a composition of a plastic concrete mixture according to claim 1, in which the applied amount of effective water varies from 140 to 200 l / m ³ , preferably from 150 to 180 l / m ³ . 3. The composition of the plastic concrete mixture obtained by the method according to claim 1 or 2. 4. The hardened concrete object obtained from the composition of a plastic concrete mixture according to claim 3.

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