Method for manufacturing a concrete formulated on the basis of activated slag

Abstract

Method for manufacturing a concrete from activated slag, comprising at least the steps consisting of: a) arranging a premixture P of water and granulates, the temperature of the premixture P being at least equal to 10 C., b) arranging an activation system A comprising at least a co-binder, a chelating agent, an alkali metal carbonate and a carbonated material different from the alkali metal carbonate, c) incorporating the activation system A and a slag S by mixing them into the premixture P, the activation system A and slag S being introduced successively and/or simultaneously, d) continuing the mixing until a fresh concrete is obtained, and e) allowing the fresh concrete to cure.

Claims

1. A method for the manufacture of an activated slag concrete comprising: a) having at least one premix P comprising water and at least one aggregate, wherein the temperature of the at least one premix P is at least 10 C., b) having at least one activation system A comprising at least one cobinder, at least one chelating agent, at least one alkali metal carbonate, and at least one carbonate material distinct from the at least one alkali metal carbonate, c) mixing the at least one premix P, the at least one activation system A, and at least one slag S successively and/or simultaneously and in any order until a fresh activated slag concrete is obtained, and d) leaving the fresh activated slag concrete to harden.

2. The method of claim 1, wherein the at least one premix P has a temperature of at least 15 C. in step a).

3. The method of claim 1, wherein the at least one activation system A of step b) comprises the at least one slag S.

4. The method of claim 1, additionally comprising mixing at least one adjuvant with the at least one premix P, the at least one activation system A, and the at least one slag S successively and/or simultaneously and in any order until the fresh activated slag concrete is obtained in step c).

5. The method of claim 1, wherein the total amount of the at least one cobinder is less than 5% by weight, relative to the total weight of the at least one activation system A and the at least one slag S.

6. The method of claim 1, wherein the at least one slag S comprises at least one ground granulated blast-furnace slag.

7. The method of claim 1, wherein the at least one cobinder comprises at least one precursor of calcium ions.

8. The method of claim 1, wherein the at least one activation system A comprises the at least one alkali metal carbonate chosen from sodium carbonates, potassium carbonates, or mixtures of two or more thereof.

9. The method of claim 1, wherein the at least one carbonate material distinct from the at least one alkali metal carbonate is provided in the form of at least one material chosen from limestone, dolomite, precipitated calcium carbonate, chalk, marble, aragonite, travertine, tufa, or mixtures of two or more.

10. The method of claim 1, wherein the at least one chelating agent comprises a chelating agent for a calcium ion or for an aluminum ion.

11. The method of claim 1, wherein the at least one chelating agent is chosen from phosphonates.

12. The method of claim 1, wherein the weight ratio of the total amount of the at least one alkali metal carbonate to the total amount of the at least one slag S ranges from 2% to 12%.

13. The method of claim 1, wherein the weight ratio of the total amount of the at least one cobinder to the total amount of the at least one slag S ranges from 1% to 5%.

14. The method of claim 1, wherein the weight ratio of the total amount of the at least one chelating agent to the total amount of the at least one slag S ranges from 0.001% to 2%.

15. The method of claim 1, further comprising i) mixing the at least one activation system A, the at least one slag S, and water simultaneously or in any order at a weight ratio of the total amount of the at least one activation system A and the at least one slag S to the total amount of the water ranging from 0.1 to 1, and ii) mixing the mixture of step i) with the at least one premix P.

16. The method of claim 4, wherein the at least one adjuvant is chosen from naphthalene-based superplasticizers, polynaphthalene sulfonates, lignosulfonates, or mixtures of two or more thereof.

17. The method of claim 1, wherein step c) is carried out in a concrete mixing plant.

18. An activated slag concrete manufactured by a method comprising: a) having at least one premix P comprising water and at least one aggregate, wherein the temperature of the at least one premix P is at least 10 C., b) having at least one activation system A comprising at least one cobinder, at least one chelating agent, at least one alkali metal carbonate, and at least one carbonate material distinct from the at least one alkali metal carbonate, c) mixing the at least one premix P, the at least one activation system A, and at least one slag S successively and/or simultaneously and in any order until a fresh activated slag concrete is obtained, and d) leaving the fresh activated slag concrete to harden.

19. The activated slag concrete of claim 18, wherein the activated slag is characterized by a characteristic 28-day compressive strength on a cylindrical specimen of at least 30 MPa and on a cubic test specimen of at least 37 MPa, thus falling at least within a strength class that is C30/37 according to the standard NF EN 206/CN.

20. A fresh activated slag concrete, manufactured by a method comprising: a) having at least one premix P comprising water and at least one aggregate, wherein the temperature of the at least one premix P is at least 10 C., b) having at least one activation system A comprising at least one cobinder, at least one chelating agent, at least one alkali metal carbonate, and at least one carbonate material distinct from the at least one alkali metal carbonate, and c) mixing the at least one premix P, the at least one activation system A, and at least one slag S successively and/or simultaneously and in any order until the fresh activated slag concrete is obtained.

21. The fresh activated slag concrete of claim 20, wherein the fresh activated slag concrete: exhibits an Abrams cone slump of greater than or equal to 160 mm according to the standard NF EN 12350-2, and falls at least within a consistency class that is S4 or S5 according to the standard NF EN 206/CN, for a period of time of at least 60 minutes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 represents the Abrams cone slump results of an activated slag concrete obtained by the process of the invention according to example 1 ( symbols) or 2 ( symbols) or obtained by a method outside the invention according to example 3 ( symbols).

(2) FIG. 2 represents the results of spreading with the Abrams minicone (expressed as percentage) of an activated slag mortar obtained by the process of the invention according to the form of introduction of example 2 with water and aggregates at 20 C. ( symbols), water at 60 C. and aggregates at 5 C. ( symbols) and water and aggregates at 5 C. ( symbols).

(3) FIG. 3 represents the mean shrinkage measured on 3 test specimens of one and the same activated slag concrete obtained by the process according to the invention.

(4) FIG. 4 represents the compressive strength of an activated slag concrete obtained by a process according to the invention with a water/binder ratio of 0.34 ( symbols), 0.36 ( symbols) and 0.38 ( symbols).

EXAMPLES

Materials and Methods

(5) The following starting materials were used: Semi-crushed silico-calcareous aggregates with a density of 2530 kg/m.sup.3 and a water absorption of 1.3%; Slag originating from the Ecocem factory at Fos-sur-Mer, produced according to the European standard (NF EN 15167-1). The particle size distribution is characterized by D10=1.38 m; D50=12.16 m and D90=34.87 m. The particle size distribution values are determined with a laser diffraction particle sizer from Malvern named Mastersizer 3000, according to the liquid dispersion method. The Blaine fineness is 4500 cm.sup.2/g; Cobinder: it is a clinker, the Blaine fineness of which is 3100 cm.sup.2/g and the main chemical components of which are as follows: CaO (67% by weight), SiO.sub.2 (21% by weight), Fe.sub.2O.sub.3 (5% by weight), SO.sub.3 (3% by weight); Anhydrous sodium carbonate (Na.sub.2CO.sub.3), 99% purity, sold by Solvay; Calcium carbonate, with a median diameter D50=1 m and with a BET specific surface of 80 000 cm.sup.2/g; Chelating agent HEDP.Math.4Na; Superplasticizer of PNS type (solids content 32%).

(6) The Abrams cone slump measurements are carried out on concrete (FIG. 1) according to the standard NF EN 12350-2 at a temperature of 20 C. and the Abrams minicone spreading measurements are carried out on mortar (FIG. 2) according to the provisions of the standard NF EN 12350-8 using the CEM minicone (Abrams cone at scale) instead of the Abrams cone.

(7) The shrinkage is measured on test specimens with dimensions of 7728 cm.sup.3 stored at 20 C. and 50% relative humidity according to the standard NF P 15-433.

(8) The compressive strength is measured for the concretes on test specimens with a diameter of 110 mm and a height of 200 mm according to the standard NF EN 12390-3. For the mortars, the compressive strength is measured on 4 cm4 cm16 cm prisms according to the standard NF EN 196-1.

Example 1

(9) Preparation of a Concrete According to the Invention (Method 1)

(10) An activation system is prepared by dry mixing sodium carbonate, calcium carbonate, chelating agent and cobinder in the proportions indicated in table 2 as percentage by weight.

(11) The concrete is prepared by incorporation, under mixing, of the following constituents in the mixer, in the proportions described in detail in table 2, according to the following sequence: Aggregates; Water at a temperature making it possible to obtain an equilibrium temperature with the aggregates of between 15 C. and 25 C.; Mixing for 30 seconds; Activation system; Mixing for 30 seconds; Slag; Mixing for 30 seconds; Superplasticizer; Final mixing for 3 minutes.

(12) TABLE-US-00002 TABLE 2 Composition A Competition B Composition C (according to the (outside the (according to the invention) invention invention Slag (kg/m.sup.3) 400 400 400 Activation (sodium carbonate (sodium carbonate (sodium carbonate system 51% + calcium 61.8% + calcium 51.5% + calcium (kg/m.sup.3) carbonate 25.5% + carbonate 37.5% + carbonate 25.8% + chelating agent chelating agent cobinder 20.6% + 3.1% + cobinder 0.7%): chelating agent 20.4%) 53.4 kg/m.sup.3 2.1%): 78.4 kg/m.sup.3 77.6 kg/m.sup.3 Aggregates 1642 1642 1642 (kg/m.sup.3) Effective water 177 172 172 (kg/m.sup.3) Superplasticizer 5 5.7 5 with a solids content of 32% (kg/m.sup.3)

Example 2

(13) Preparation of a Concrete According to the Invention (Method 2)

(14) The activation system is prepared as in example 1.

(15) A premix of the activation system and of the slag is prepared by dry mixing.

(16) The concrete is prepared by incorporation, under mixing, of the following constituents in the mixer, in the proportions described in detail in table 2, according to the following sequence: Aggregates; Water at a temperature making it possible to obtain an equilibrium temperature with the aggregates of between 15 C. and 25 C.; Mixing for 30 seconds; Premixing of the activation system and of the slag; Mixing for 30 seconds; Superplasticizer; Final mixing for 3 minutes.

Example 3

(17) Preparation of a Concrete Outside the Invention (Method 3)

(18) The activation system is prepared as in example 1.

(19) A premix of the activation system and of the slag is prepared as in example 2.

(20) The concrete is prepared by incorporation, under mixing, of the following constituents (which are at ambient temperature of the laboratory, i.e. 20 C.) in the mixer, in the proportions described in detail in table 2, according to the following sequence: Aggregates; Premixing of the activation system and of the slag; Dry mixing for 30 seconds; Water; Mixing for 30 seconds; Superplasticizer; Final mixing for 3 minutes.

Example 4

(21) Abrams Cone Slump Test

(22) Abrams cone slump tests are carried out for methods 1, 2 and 3, described in detail respectively in examples 1, 2 and 3, with composition A of table 2.

(23) The results, represented in FIG. 1, show that methods 1 and 2 according to the invention make it possible to maintain a fluid concrete consistency, characterized by a slump of greater than 160 mm, for more than 2 hours. On the contrary, in the case of method 3 outside the invention, the concrete lost its fluid concrete consistency after 45 minutes.

(24) Abrams minicone spreading tests are also carried out according to method 2, described in detail in example 2, with the concrete equivalent mortar proportions corresponding to composition A (see table 3 below) for a premix of aggregates and of water at different temperatures.

(25) TABLE-US-00003 TABLE 3 Activation system (sodium carbonate 51% + calcium carbonate 25.5% + chelating agent 3.1% + cobinder Effective Constituent Slag 20.4%) Aggregates water Superplasticizer Proportion 1184 232 2597 338 15 (g)

(26) The following three tests are carried out: i) The water and the aggregates are conditioned at 20 C. before they are mixed, and the premix P obtained has a temperature of 20 C.; ii) The aggregates are conditioned at 5 C. and are mixed with water at 60 C., forming a premix P having a temperature of 27 C.; iii) The water and the aggregates are conditioned at 5 C. before they are mixed, and the premix P obtained has a temperature of 5 C.

(27) FIG. 2 represents the results of the minicone spreading obtained. In the two cases where the premix of water and of aggregates obtained has a temperature of greater than 15 C. (case i) and ii) above), the consistency of the mortar is kept fluid for at least 1 hour. On the contrary, the use of materials which do not respect the recommendations of temperatures, as in the case of the premix of water and of aggregates at 5 C. (case iii) above), causes a rapid stiffening of the mortar and does not make it possible to obtain the maintenance of a fluid consistency.

Example 5

(28) Results of the Shrinkage

(29) The measurements of the shrinkage are carried out for three test specimens obtained with composition A.

(30) The curve of FIG. 3 corresponds to the mean of the deformations measured on each of the three prisms of one and the same concrete. It shows that the shrinkage of a concrete according to the invention is comparable to the shrinkage of a conventional cement concrete.

Example 6

(31) Robustness of Concrete Composition in Accordance and not in Accordance with the Invention

(32) Strength measurements are carried out for concretes prepared with composition B (outside the invention) and composition C (according to the invention).

(33) In addition, concretes, the composition of which comprises: an excess of water of 10 liters (composition B or C with 182 kg/m.sup.3 of water per 400 kg/m.sup.3 of slag), or a deficiency in water of 10 liters (composition B or C with 162 kg/m.sup.3 of water per 400 kg/m.sup.3 of slag),
are produced in order to evaluate the robustness of the composition.

(34) The results for composition C according to the invention are given in FIG. 4. The impact of the amount of water in the mixture virtually does not modify the mechanical strength of the test specimens obtained. In addition, a compressive strength of greater than 40 MPa is measured at 28 days.

(35) On the contrary, the results for composition B outside the invention, given in table 4, show that the concrete experiences an extreme slowdown in its hardening in the case of an excess of water. CS represents the compressive strength measured at different ages of the concrete.

(36) TABLE-US-00004 TABLE 4 CS48h CS72h CS7d CS28d Batch (MPa) (MPa) (MPa) (MPa) Composition B 0.8 1.0 28.8 48.2 (20 C.) Composition B + 0 0 0 n.m. 10 liters (20 C.)