BINDER BASED ON A SOLID MINERAL COMPOUND RICH IN ALKALINE-EARTH METAL OXIDE WITH PHOSPHATE-CONTAINING ACTIVATORS

Abstract

A hydraulic binder includes at least 70% by weight of a solid mineral compound consisting of at least one mixture of silica, alumina and alkaline-earth metal oxides, the total sum of CaO and MgO representing at least 10% by weight of the solid mineral compound, and an activation system of which at least 30% by weight is a phosphoric acid-derived salt. Construction products can obtained from a mortar composition including such a binder.

Claims

1. A hydraulic binder comprising: at least 70% by weight of a solid mineral compound consisting of at least one mixture of silica, alumina and alkaline-earth metal oxides, the total sum of CaO and MgO representing at least 10% by weight of the solid mineral compound, and an activation system of which at least 30% by weight is a phosphoric acid-derived salt.

2. The binder according to claim 1, wherein the solid mineral compound comprises at least 20% by weight of CaO and/or MgO.

3. The binder according to claim 1, wherein the solid mineral compound is chosen from amorphous or crystalline slags, fly ashes and/or glass powders.

4. The binder according to claim 1, wherein solid mineral compound is chosen from steelmaking slags, blast furnace slags and class C fly ashes.

5. The binder according to claim 1, wherein said salt is chosen from polyphosphates of an alkali metal chosen from sodium, potassium or lithium and mixtures thereof.

6. The binder according to claim 5, wherein said salt is a triphosphate or a diphosphate of an alkali metal.

7. The binder according to claim 1, wherein the activation system comprises, in addition to the phosphoric acid-derived salt, a silicate of an alkali metal chosen from potassium, lithium and/or sodium, in an amount ranging from 5% to 70% by weight relative to the total weight of the activation system.

8. The binder according to claim 1, wherein the activation system also comprises a source of an alkaline-earth metal, chosen from Portland cements, calcium aluminate cements, calcium sulphoaluminate cements, lime, calcium carbonate, dolomite and magnesium hydroxide, and mixtures thereof in an amount ranging from 5% to 70% by weight relative to the total weight of the activation system.

9. The binder according to claim 8, wherein the source of alkaline-earth metal is lime.

10. The binder according to claim 1, wherein the activation system consists of a mixture of a phosphoric acid-derived salt and of an alkali metal silicate.

11. The binder according to claim 1, wherein the activation system consists of a mixture of a phosphoric acid-derived salt and of a source of alkaline-earth metal.

12. The binder according to claim 1, wherein the activation system consists of a mixture of a phosphoric acid-derived salt, of an alkali metal silicate and of a source of alkaline-earth metal.

13. The binder according to claim 1, wherein the activation system comprises between 0.1% and 10% by weight, relative to its total weight, of a retarder of formula X.sup.+A.sup.− in which the cation X.sup.+ is chosen from alkali metals, alkaline-earth metals, aluminium and the ammonium ion, and the anion A.sup.− is chosen from acetate, citrate, formate, benzoate, tartrate, oleate, bromide or iodide anions.

14. The binder according to claim 1, wherein the activation system represents between 3% and 30% of the total weight of the binder.

15. The binder according to claim 1, further comprising, in an amount of less than 27% by weight relative to the total weight of binder, Portland cement, high-alumina cement, sulpho-aluminate cement, belite cement, cement formed of a pozzolanic mixture, silica fume, calcined schist, natural or calcined pozzolans, a source of calcium sulphate, such as plaster or hemihydrate, gypsum and/or anhydrite.

16. A concrete or mortar composition, comprising: a mixture of granulates, sands and/or aggregates and at least one binder according to claim 1 in the presence of water.

17. A construction product comprising: at least one of adhesive mortars, pointing mortars, grouts, adhesives, screeds, floor coating, façade mortars, internal or external wall coatings, mineral paints, smoothing mortars, undercoats, single coats, and mortars for rendering impermeable, wherein the construction product is obtained after hydration and curing of the concrete or mortar composition according to claim 16.

18. The binder according to claim 12, wherein the source of alkaline-earth metal is a calcium source.

19. The binder according to claim 14, wherein the activation system represents between 5% and 25% of the total weight of the binder.

Description

EXAMPLES

[0027] Various standardized mortar formulations were prepared. These formulations comprise 1350 g of standard sand, 450 g of binder, and an activation system. Various binders and activation systems were tested. The results obtained are presented in the form of a curve, giving the compressing strength in MPa of the samples obtained as a function of the time, expressed in days. The amount of activator is indicated in the legends and corresponds to the amount, as weight percentage, which is added to the blast furnace slags and/or to the fly ashes. The amount of water introduced in order to prepare the mortar is 225 g, which corresponds to a water/binder ratio of 0.5.

[0028] For each of the formulations, test samples of 4×4×16 cm.sup.3 are produced according to the protocol below: [0029] the powders of slag and/or fly ashes and the pulverulent components constituting the activation system are premixed with the sand for 1 min at low speed (600 rpm); [0030] water is added and mixed at low speed (˜600 rpm) for 30 sec, followed by mixing at high speed (˜1500 rpm) for 2 min 30 s; [0031] the resulting mortar is cast in a mould, and [0032] after curing, the mortar is removed from the mould and the mechanical strength is measured (3-point bending then compression), according to standard NF EN 196-1 (August 1995).

[0033] The compressive strength measurements are carried out for all the samples at various times during the curing phase in order to monitor the evolution as a function of time.

[0034] By way of comparison, identical measurements were carried out on formulations comprising: [0035] 100% of Portland cement CEM I 52.5 (which comprises 95% of clinker), [0036] 100% of CEM III 32.5 cement which is a cement formed from a mixture comprising 70% of blast furnace slag and 30% of clinker, [0037] 100% of a virtually amorphous blast furnace slag (Ecocem) or 100% of class C fly ashes with an activation system of alkaline activation type consisting of a mixture of sodium hydroxide NaOH (VWR) and of sodium silicate Na.sub.2SiO.sub.3 (Metso 510 from PQ corporation), predissolved in water so as to ensure complete dissolution of this mixture and, consequently, total effectiveness thereof as an activator, [0038] 100% of an Ecocem slag activated by a mild activation system as described in patent application WO 2011/055063 and comprising slag microparticles and a small amount of base (composition described in Table 1 of the example).

[0039] Various slags or fly ashes were tested in the examples hereinafter. Their respective composition and the amount of amorphous compounds contained in each of the products are given in the table below. It will be noted that the Carmeuse slag is a highly crystalline slag.

TABLE-US-00001 CARMEUSE Fos-sur-Mer Merit 5000 Class C fly slag ECOCEM slag slag (Merox) ashes SiO.sub.2 10.10 37.22 33.90 34.10 CaO 45.70 42.37 30.80 25.00 Al.sub.2O.sub.3 2.40 10.41 13.40 17.30 MgO 6.28 8.49 16.50 4.48 TiO.sub.2 0.59 0.53 2.15 1.00 Fe.sub.2O.sub.3 26.40 0.60 0.40 5.02 K.sub.2O 0.10 0.34 0.50 0.39 Na.sub.2O 0.05 <0.20 0.55 1.55 P.sub.2O.sub.5 1.61 0.02 0.01 0.51 MnO 4.30 0.25 0.45 0.07 SO.sub.3 0.18 — 3.70 1.36 S.sup.2− — 0.89 — % 16 99.3 96.3 ~95% amorphous content

Example 1

[0040] Four formulations of binders according to the invention comprising Ecocem slag were prepared as described above, while varying the amount of sodium tripolyphosphate (NaTPP) used as activator. The binder 1.5 corresponds to the comparative.

[0041] Binder 1.1: 93% by weight of Ecocem slag and 7% by weight of NaTPP.

[0042] Binder 1.2: 90% by weight of Ecocem slag and 10% by weight of NaTPP.

[0043] Binder 1.3: 88% by weight of Ecocem slag and 12% by weight of NaTPP.

[0044] Binder 1.4: 75% by weight of Ecocem slag and 25% by weight of NaTPP.

[0045] Comparative binder 1.5: 78% by weight of Ecocem slag, 11% by weight of NaOH and 11% by weight of Na.sub.2SiO.sub.3, the sodium hydroxide and the sodium silicate being predissolved in water before being mixed with the slag with a water/binder ratio=0.5.

[0046] FIG. 1 represents the evolution of the compressive strength as a function of time for these various binders.

[0047] All the binders according to the present invention have a much improved strength after 7 to 14 days, compared with the performance levels obtained with an alkaline activation system. It is thus possible to obtain strengths of greater than 40 MPa after 28 days.

Example 2

[0048] Two formulations of binders according to the invention comprising Carmeuse slag, therefore highly crystalline and known to be difficult to activate, were prepared as described above, while varying the amount of sodium tripolyphosphate (NaTPP, VWR) used as activator. The binder 2.3 corresponds to the comparative.

[0049] Binder 2.1: 75% by weight of Carmeuse slag and 25% by weight of NaTPP.

[0050] Binder 2.2: 88% by weight of Carmeuse slag and 12% by weight of NaTPP.

[0051] Comparative binder 2.3: 78% by weight of Carmeuse slag, 11% by weight of NaOH and 11% by weight of Na.sub.2SiO.sub.3, the sodium hydroxide and the sodium silicate being predissolved in water before being mixed with the slag with a water/binder ratio=0.5.

[0052] FIG. 2 represents the evolution of the compressive strength as a function of time for these various binders.

[0053] The binder 2.3 comprising the Carmeuse slag and the conventional alkaline activation system does not bring about short-time setting and no strength is observed before 7 days.

[0054] The binder according to the invention makes it possible to improve the strength right from an early age (more than 6 MPa at 3 days for a binder comprising 25% by weight of sodium tripolyphosphate).

Example 3

[0055] A formulation of binder according to the present invention with another type of slag was prepared.

[0056] Binder 3.1: 88% by weight of Merit slag and 12% by weight of NaTPP.

[0057] Comparative binder 3.2: 78% by weight of Merit slag, 11% by weight of NaOH and 11% by weight of Na.sub.2SiO.sub.3, the sodium hydroxide and the sodium silicate being predissolved in water before being mixed with the slag with a water/binder ratio=0.5.

[0058] FIG. 3 represents the evolution of the compressive strength as a function of time for these various binders.

[0059] The binder according to the present invention exhibits improved strengths compared with those obtained with an alkaline activation system.

Example 4

[0060] Two formulations of binder based on class C fly ashes according to the present invention were prepared.

[0061] Binder 4.1: 75% by weight of class C fly ash and 25% by weight of NaTPP.

[0062] Binder 4.2: 88% by weight of class C fly ash and 12% by weight of NaTPP.

[0063] Comparative binder 4.3: 78% by weight of Merit slag, 11% by weight of NaOH and 11% by weight of Na.sub.2SiO.sub.3, the sodium hydroxide and the sodium silicate being predissolved in water before being mixed with the slag with a water/binder ratio=0.5.

[0064] FIG. 4 represents the evolution of the compressive strength as a function of time for these various binders.

[0065] The binders according to the present invention again exhibit much improved strengths compared with those obtained with an alkaline activation system.

Example 5

[0066] Two formulations of binders according to the present invention were prepared, with different activation systems.

[0067] Binder 5.1: 86% by weight of Ecocem slag, 10% by weight of NaTPP and 4% by weight of sodium silicate (Metso 510, PQ corporation).

[0068] Binder 5.2: 84% by weight of Ecocem slag, 10% by weight of NaTPP, 4% by weight of sodium silicate and 2% by weight of lime (VWR).

[0069] These binders are compared to a binder of CEM I 52.5 type (comparative binder 5.3) and to a binder of CEM III 32.5 type containing at least 70% of blast furnace slag (comparative binder 5.4). FIG. 5 represents the evolution of the compressive strength as a function of time for these various binders.

[0070] The compressive strengths obtained with the binders according to the present invention are entirely comparable to those which are obtained with a binder of CEM I type and are higher after 7 days for the binder 5.2.

Example 6

[0071] Two formulations of binders according to the present invention were prepared and are compared to a binder formulation in which the activation system is of “mild alkaline” type as described in application WO 2011/055063.

[0072] Binder 6.1: 84% by weight of Ecocem slag, 10% by weight of NaTPP, 4% by weight of sodium silicate and 2% by weight of lime (VWR).

[0073] Binder 6.2: 89% by weight of Ecocem slag, 4.5% of NaTPP, 4.5% by weight of sodium silicate and 2% by weight of lime.

[0074] Comparative binder 6.3: 80% by weight of Ecocem slag and 20% by weight of a mixture of activators which includes in particular slag microparticles, as described in WO 2011/055063.

[0075] FIG. 6 represents the evolution of the compressive strength as a function of time for these various binders.

[0076] The compressive strengths of the binders according to the present invention are much improved compared with a binder for which the activation is obtained with slag microparticles, in the presence of a small amount of base. It is also noted, when comparing the strengths of the binders 6.1, 6.2 and 6.3, that the activation system comprising lime makes it possible to improve the mechanical properties at an early age. By comparing the strengths of the binders 6.2 and 6.3, it is noted that, even at a reduced amount of activator, the mechanical properties remain higher than the mild activation system which includes a mixture of activators, in particular slag microparticles.

Example 7

[0077] The following formulations were prepared:

[0078] Binder 6.1: 84% by weight of Ecocem slag, 10% by weight of NaTPP, 4% by weight of sodium silicate and 2% by weight of lime (VWR).

[0079] Binder 7.1: 83% by weight of Ecocem slag, 10% by weight of NaTPP, 4% by weight of sodium silicate, 2% by weight of lime (VWR) and 1% of potassium acetate.

[0080] Binder 7.2: 82% by weight of Ecocem slag, 10% by weight of NaTPP, 4% by weight of sodium silicate, 2% by weight of lime (VWR) and 2% of potassium acetate.

[0081] Setting time tests were carried out on the basis of the sinking of a Vicat needle into the mortar according to standard NF EN 196-3. The measurement of the evolution of the degree of sinking is characteristic of the evolution of the curing and of the setting of the material.

[0082] FIG. 7 represents the degree of sinking of the Vicat needle as a function of time. The various curves represented in this figure show that the addition of potassium acetate delays the setting of the binder. The greater the amount of retarder added, the greater the delay in setting.

[0083] Spreading tests consisting in causing the mortar to spread under its own weight after raising a metal cone containing the mortar were carried out, in accordance with standard EN1015-3 which describes the determination of consistence of a fresh mortar paste with a flow table.

[0084] The results obtained are represented in FIG. 8 which shows that the addition of potassium acetate increases the spreading of the mortar, all the more so the higher the amount of retarder in the formulation.