Dry mortar composition

Abstract

The invention relates to a dry mortar composition comprising aggregates and a hydraulic binder, said hydraulic binder comprising 0-40% by weight of a calcium sulfate (CS) source, 0-50% by weight of Portland cement (PC) and 40-90% by weight of an aluminum oxide source, based on the weight of hydraulic binder, wherein the aluminum oxide source comprises treated aluminum salt slag (TASS) and optionally at least one of aluminous cement (CAC) and sulfoaluminous cement (SAC), the weight ratio (TASS:(CAC+SAC)) between the treated aluminum salt slag content and the sum of the aluminous cement and sulfoaluminous cement contents ranging from 10:90 to 100:0.

Description

Title of the invention: Dry mortar composition

[0001] The invention relates to a dry mortar composition.

[0002] A dry mortar composition is a powdery mixture comprising a hydraulic binder and aggregates. After mixing with water, it forms a paste, called wet mortar, which can be applied to various substrates before setting and hardening, finally forming a hardened mortar. Mortars can for example be used as coatings, plasters, flooring compounds, masonry mortars, concrete repair mortar, tile adhesives, grouts, etc. or to produce construction elements by additive manufacturing.

[0003] Concrete repair mortars are used to repair and restore damaged concrete surfaces. They must achieve a high level of bonding with the existing concrete, allowing it to integrate seamlessly into the damaged area and restore the structural integrity of the concrete element. Concrete repair mortar must meet specific requirements to ensure its effectiveness in repairing and restoring damaged concrete.These requirements include high compressive strength (to match or exceed the strength of the existing concrete, so that the repaired area can support the same loads as the surrounding undamaged concrete), good bond strength (to prevent the repaired area from delaminating or failing under stress), workability (to ensure proper filling of cracks, voids, and imperfections), durability (to ensure long-term performance and protection of the repaired concrete), and must be compatible with the existing concrete in terms of composition, strength, and expansion characteristics.

[0004] Concrete repair mortars are used, among other things, for filling and sealing cracks, spalling, and chipped areas in concrete structures, for filling holes, voids, and imperfections in concrete surfaces, restoring a smooth, even surface, for leveling uneven concrete surfaces and resurfacing degraded slabs, floors, and other horizontal concrete members, for repairing and strengthening damaged concrete structural members, such as beams, columns, and foundations, and for protecting concrete surfaces from corrosion caused by chloride ions and chemical attack from sulfates and other aggressive substances.

[0005] Flooring compounds, also known as self-leveling compounds or floor leveling compounds, are designed to create a smooth, flat, and level surface for installing tile, laminate flooring, vinyl flooring, and other floor coverings. They can be used on a variety of subfloors, including concrete, plywood, and backer boards. Flooring compounds must meet a number of requirements, including excellent flowability, allowing it to self-level and spread evenly over the subfloor, filling any voids or imperfections; rapid curing, minimizing downtime and allowing efficient installation of floor coverings; good adhesion to the subfloor, ensuring a strong bond and preventing the floor covering from delaminating or lifting; and high compressive strength, in order to support the weight of the floor covering and any furniture or appliances that will be placed on it.

[0006] One aim of the invention is in particular to provide a mortar that meets these requirements and can therefore be used as concrete repair mortars or flooring compounds. Another aim to be achieved is to lower the carbon footprint of the mortar. The hydraulic binder used in mortars is often cement, in particular Portland cement (PC), aluminous cement (CAC) or sulpho-luminous cement (SAC), the production of which requires significant amounts of energy and releases significant amounts of CO2 into the atmosphere. There is therefore a need to provide mortar compositions having a much lower CO2 footprint while still meeting requirements, for example in terms of workability and mechanical strength.

[0007] For this purpose, the invention relates to a dry mortar composition comprising aggregates and a hydraulic binder, said hydraulic binder comprising 0 to 40% by weight of a source of calcium sulfate (CS), 0 to 50% by weight of Portland cement (PC), and 40 to 90% by weight of a source of aluminum oxide, relative to the weight of hydraulic binder, wherein said source of aluminum oxide comprises treated aluminum salt slag (TASS) and optionally one or more of aluminous cement (CAC) and sulfoaluminous cement (SAC), the weight ratio (TASS:(CAC+SAC)) between the amount of said treated aluminum salt slag and the sum of the amounts of aluminous cement and sulfoaluminous cement being from 10:90 to 100:0.

[0008] The inventors have found that in CAC or CSA based binary binders and ternary binders comprising calcium sulfate and / or Portland cement, CAC and CSA could be at least partially substituted by treated aluminum salt slag, thereby reducing the carbon footprint of the mortar, without sacrificing binder reactivity and required mortar properties and performance, particularly for applications as concrete repair mortars and flooring compounds.

[0009] Aluminum salt slag, also called "salt cake" or "dross" is a by-product of the secondary aluminum industry. Recycling of Aluminum smelting involves melting aluminum scrap under a bath of molten salts (chlorides, especially sodium chloride and potassium chloride, and possibly fluorides, such as cryolite or calcium fluoride). The salt flux protects the molten aluminum bath from oxidation and improves the recovery of metal from the scrap. This generates a by-product called "aluminum salt slag" containing oxides (especially aluminum oxide), metallic aluminum, and halides.

[0010] The raw material used in the present invention, called "treated aluminum salt slag" or TASS, is the result of further processing of the salt slag to reduce the metallic aluminum and halide content. The processing usually involves crushing, grinding, screening and washing steps. The crushing, grinding and screening steps separate the metallic aluminum, while the washing (or leaching) steps, usually with water at room temperature or around 100°C, recover the salt stream. The processing may also involve drying and / or calcination steps. The resulting product, called "treated aluminum salt slag", is a mineral powder comprising at least 50% by weight of aluminum oxide (A12O3).As explained above, this mineral powder is obtained by processing aluminum salt slag involving crushing, grinding, screening and washing steps. Such mineral powders are for example sold under the trade names Pavai, Serox, Valoxy, Oxiton or Oxidur.

[0011] The treated aluminum salt slag preferably comprises 50 to 80% by weight, especially 60 to 70% by weight, of Al2O3, 2 to 15% by weight, especially 5 to 10% by weight, of SiO2, 3 to 12% by weight, especially 5 to 10% by weight, of MgO, and 0 to 5% by weight, especially 0.5 to 4% by weight, of F + Cl. It may also comprise 0 to 5% by weight, especially 1 to 4% by weight, of CaO and 0 to 4% by weight, especially 1 to 3% by weight, of Fe2O3 (total iron).

[0012] The amount of metallic aluminum is preferably less than 3% by weight, or even less than 2% by weight or less than 1% by weight. The presence of metallic aluminum can indeed cause swelling of the mortar due to chemical reactions generating hydrogen gas. Metallic aluminum can be removed by grinding and screening the treated aluminum saline slag. Hydrogen generation can also be prevented or reduced by adding to the mortar composition a compound chosen from nitrates (in particular lithium nitrate, potassium nitrate, sodium nitrate, ceric ammonium nitrate), sulfates (in particular lithium sulfate), carbonates (in particular lithium carbonates), permanganates (in particular potassium permanganate), methylthionium chloride. The amount of such a compound is preferably from 0.1 to 5.0% by weight. weight relative to the weight of mortar composition.

[0013] In terms of mineralogy, the treated aluminum salt slag preferably comprises corundum and spinel (MgAl2O4) phases. The spinel content is preferably 10 to 35% by weight, especially 12 to 30% by weight. The corundum content is preferably 5 to 35% by weight, especially 7 to 20% by weight. The treated aluminum salt slag may further comprise boehmite, gibbsite, norstrandite and / or bayerite phases, especially in a total content of 8 to 30% by weight. The crystalline phase content is preferably at least 40% by weight, even at least 50% by weight, for example 60 to 80% by weight. This chemical and mineralogical composition advantageously leads to high reactivity in binary and ternary binder systems comprising calcium sulfate and / or PC.

[0014] To improve their reactivity and their ability to replace CAC and / or CSA, the treated aluminum salt slag preferably has a particle size distribution (based on a volume distribution) such that the D50 is 3 to 50 pm, especially 5 to 30 pm, or even 8 to 25 pm. The D90 is preferably 200 pm or less, or even 100 pm or less. The particle size distribution can be determined by laser particle size analysis.

[0015] The aluminum oxide source comprises a mixture of TASS and (optionally) CAC and / or CSA. It preferably consists of TASS and one or more of CAC and CSA. Alternatively, the aluminum oxide source may comprise other sources.

[0016] CAC and CSA are optional, because in the embodiment where the weight ratio TASS:(CAC+CSA) is 100:0, the amount of CAC and CSA is zero. The source of aluminum oxide is then preferably made up of TASS.

[0017] The TASS:(CAC+CSA) weight ratio is preferably 15:85 to 85:15, especially 20:80 to 80:20, even 25:75 to 75:25, or 30:70 to 60:40. In one embodiment, the binder comprises CAC but no CSA. In such a case, the TASS:CAC weight ratio is preferably 15:85 to 85:15, especially 20:80 to 80:20, even 25:75 to 75:25, or 30:70 to 60:40. In another embodiment, the binder comprises CSA but no CAC. In such a case, the TASS:CSA weight ratio is preferably 15:85 to 85:15, especially 20:80 to 80:20, or even 25:75 to 75:25, or 30:70 to 60:40.

[0018] The source of calcium sulfate (CS) is preferably selected from gypsum, anhydrite, hemihydrate, phosphogypsum and mixtures thereof. Mixtures of anhydrite and hemihydrate are particularly preferred. The amount of the source of calcium sulfate is preferably 15 to 40% by weight, more preferably 20 to 35% by weight, relative to the weight of hydraulic binder.

[0019] Portland cement (PC) is preferably of the CEM I or CEM IL type. In this In the latter case it may then contain fly ash, silica fumes, pozzolans or ground granulated blast furnace slag in addition to the clinker.

[0020] In a first preferred embodiment, the hydraulic binder is based on a binary binder, in which CAC and / or CSA are at least partially substituted by TASS. In this embodiment, the hydraulic binder preferably comprises (and more preferably consists of) 10 to 40% by weight, in particular 15 to 35% by weight, or more preferably 20 to 30% by weight, of a source of calcium sulfate (CS) and 60 to 90% by weight, in particular 65 to 85% by weight or more preferably 70 to 80% by weight, of a source of aluminum oxide, relative to the weight of hydraulic binder. In this embodiment, the aluminum oxide source preferably consists of TASS and CSA, and the TASS:CSA weight ratio is preferably 15:85 to 85:15, especially 20:80 to 80:20, or even 25:75 to 75:25, or 30:70 to 60:40.

[0021] In a second preferred embodiment, the hydraulic binder is based on a ternary binder, in which CSA and / or CAC is at least partially substituted by TASS.

[0022] In a first variant of this second embodiment, the hydraulic binder comprises 15 to 40% by weight, in particular 20 to 35% by weight, of a source of calcium sulfate (CS), 10 to 35% by weight, in particular 15 to 30% by weight, of Portland cement (PC) and 40 to 65% by weight, in particular 45 to 60% by weight, of a source of aluminum oxide, relative to the weight of hydraulic binder. In this first variant, the source of aluminum oxide preferably consists of TASS and CAC, and the TASS:CAC weight ratio is preferably 15:85 to 85:15, in particular 20:80 to 80:20, or even 25:75 to 75:25, or 30:70 to 60:40.

[0023] In a second variant of this second embodiment, the hydraulic binder comprises 0 to 40% by weight, in particular 10 to 30% by weight, of a source of calcium sulfate (CS), 10 to 50% by weight, in particular 20 to 40% by weight, of Portland cement (PC) and 50 to 90% by weight, in particular 60 to 80% by weight, of a source of aluminum oxide, relative to the weight of hydraulic binder. In this second variant, the source of aluminum oxide preferably consists of TASS and CSA, and the TASS:CSA weight ratio is preferably 15:85 to 85:15, in particular 20:80 to 80:20, or even 25:75 to 75:25, or 30:70 to 60:40.

[0024] In the hydraulic binder, the total amount of CS, PC, CAC, CSA and TASS is preferably at least 80% by weight, or even at least 90% by weight, relative to the weight of hydraulic binder. The hydraulic binder may also comprise lime. Preferably, the hydraulic binder consists of CS, PC, CAC, CSA and TASS.

[0025] The aggregate content is preferably 40 to 70% by weight, or even 45 to 60% by weight, relative to the weight of the dry mortar composition.

[0026] The aggregates are preferably chosen from siliceous, calcareous aggregates, Dolomitic aggregates and mixtures thereof. Examples are limestone fillers, dolomite fillers and silica sand. The aggregates preferably comprise sands (size 0 to 6 mm) and / or fillers (size 0 to 0.1 mm). Alternatively or cumulatively, the aggregates may comprise lightweight aggregates, i.e. aggregates having a bulk density of not more than 600 kg / m3 such as hydrophobic expanded perlite, thermosetting polymer powder (e.g. micronized rubber powder), hollow silicate particles (e.g. expanded glass beads and / or cenospheres) and mixtures thereof. The aggregates may also comprise fibers.

[0027] The hydraulic binder content is preferably 25 to 60% by weight, or even 30 to 55% by weight, relative to the weight of the dry mortar composition.

[0028] The dry mortar composition may further comprise one or more additive(s), in particular chosen from redispersible polymer powders, pigments, defoamers, stabilizers, thickeners, water retention agents, shrinkage reducing agents, hydrophobic agents, retarders, accelerators, plasticizers and superplasticizers. The total amount of such additives, relative to the weight of dry mortar composition, is preferably from 0.1 to 8.0% by weight, in particular from 0.5 to 3.0% by weight. The thickeners and water retention agents are, for example, cellulose ethers and / or starch ethers.The redispersible polymer powder preferably comprises at least one polymer based on one or more monomers selected from the group comprising vinyl esters (especially vinyl esters of unbranched or branched alkylcarboxylic acids having from 1 to 15 carbon atoms), methacrylates and acrylates (especially (meth)acrylates of alcohols having from 1 to 10 carbon atoms), methacrylic acid, acrylic acid, vinyl aromatics, olefins (such as ethylene or propylene), dienes and vinyl halides. Accelerators and retarders are advantageously used in combination to regulate the setting and hardening of the wet mortar. The accelerator is for example a lithium salt, such as lithium carbonate, while the retarder is for example a polycarboxylic acid or a salt thereof, such as tartaric acid or citric acid.

[0029] The invention also relates to a hardened mortar manufactured by mixing the dry mortar composition according to the invention with water to produce a wet mortar and allowing said wet mortar to harden.

[0030] The ratio of water to dry mortar composition ("water ratio") preferably ranges from 0.10 to 0.50 by weight, in order to obtain the correct consistency of the paste (wet mortar). This corresponds to a water dosage of 10 to 50% (added to 100% dry mortar).

[0031] The hardened mortar is in particular a flooring compound or a concrete repair mortar.

[0032] The invention also relates to a method of repairing damaged concrete, comprising mixing the dry mortar composition with water to make a wet mortar and applying said wet mortar to damaged areas of said concrete. The wet mortar may be applied to the prepared concrete surface using a trowel or other suitable tool. The wet mortar is carefully worked into cracks, voids and imperfections, ensuring complete filling and coverage. After curing, the mortar is finished to match the surrounding concrete surface. This may include smoothing, texturizing, or applying a protective coating if necessary.

[0033] Floor covering compounds include self-leveling floors and screeds.

[0034] The invention also relates to a method of applying a flooring compound to a subfloor, comprising mixing the dry mortar composition with water to make a wet mortar and applying said wet mortar to said subfloor. The application may be carried out by a trowel or, preferably, by means of a self-leveling mechanism.

[0035] The dry mortar composition can also be used for other applications, for example as coatings, plasters, tile adhesives, masonry mortars, grouts, etc. or for manufacturing building elements by additive manufacturing.

[0036] The following examples illustrate the invention in a non-limiting manner.

[0037] First series of examples

[0038] Dry mortar compositions for use as concrete repair mortars were obtained by mixing 59% by weight of aggregates (limestone fillers and silica sand) with 39.5% by weight of a hydraulic binder and 1.5% by weight of additives (including redispersible polymers, retarders, starch ethers, cellulose ethers and defoamers). The water ratio was 19%.

[0039] In a comparative example, the hydraulic binder comprised 20% by weight of PC (CEM II AL 42.5 R), 52% by weight of CAC (Ciment Fondu®) and 28% by weight of calcium sulfate (mixture of anhydrite and hemihydrate). The initial and final setting times were 33 and 48 minutes. After 24 hours, the flexural strength was 5.6 MPa, and the compressive strength was 29 MPa. After 28 days, the shrinkage (in mm / m) was 0.66 mm / m, the flexural strength was 7.8 MPa, and the compressive strength was 42 MPa.

[0040] In a first example of the invention, CAC is partially substituted by TASS (Pavai, Befesa), so that the TASS:CAC weight ratio was 25:75.

[0041] The initial and final setting times were 23 and 25 minutes. After 24 hours, the flexural strength was 4.6 MPa, and the compressive strength was 27 MPa. After 28 days, the shrinkage (in mm / m) was 0.39 mm / m, the flexural strength was 7.1 MPa, and the compressive strength was 46 MPa.

[0042] In a second example of the invention, the TASS:CAC weight ratio was 50:50.

[0043] The initial and final setting times were 26 and 34 minutes. After 24 hours, the flexural strength was 3.8 MPa, and the compressive strength was 19 MPa. After 28 days, the shrinkage (in mm / m) was 0.19 mm / m, the flexural strength was 5.4 MPa, and the compressive strength was 42 MPa.

[0044] The example shows that the substitution of CAC by TASS improves the reactivity, compressive strength, and shrinkage of repair mortars.

[0045] Second series of examples

[0046] Dry mortar compositions for self-leveling screeds were obtained by mixing 49.7% by weight of aggregates (limestone fillers) with 49.7% by weight of a hydraulic binder and 0.5% by weight of additives (including 0.01% by weight of lithium carbonate and 0.41% by weight of tartaric acid). The water ratio was 41%.

[0047] In a comparative example, the hydraulic binder comprised 25 wt% PC (CEM I), 50 wt% CAC and 25 wt% of a calcium sulfate source (anhydrite and hemihydrate). The compressive strength was 21 MPa after 2 days, 22 MPa after 7 days and 29 MPa after 28 days.

[0048] In another comparative example, half of the CAC was substituted with a limestone filler. In this case, the compressive strength was 5 MPa after 2 days, 4 MPa after 7 days and 9 MPa after 28 days.

[0049] In the examples of the invention, CAC was partially substituted with TASS such that the TASS:CAC ratio was 50:50.

[0050] Several commercial TASS were tested. When the TASS was from Serox, the compressive strength was 17 MPa after 2 days, 21 MPa after 7 days and 24 MPa after 28 days. When the TASS was Pavai (Befesa), the compressive strength was 18 MPa after 2 days, 19 MPa after 7 days and 26 MPa after 28 days.

[0051] These results show that replacing CAC with TASS allows obtaining flooring compounds with comparable mechanical properties. In addition, the spread of the mortars was similar.

Claims

Claims

1. 1 A dry mortar composition comprising aggregates and a hydraulic binder, said hydraulic binder comprising 0 to 40% by weight of a calcium sulfate (CS) source, 0 to 50% by weight of Portland cement (PC), and 40 to 90% by weight of an aluminum oxide source, based on the weight of hydraulic binder, wherein said aluminum oxide source comprises treated aluminum salt slag (TASS) and optionally one or more of aluminous cement (CAC) and sulfoaluminous cement (SAC), the weight ratio (TASS:(CAC+SAC)) between the amount of said treated aluminum salt slag and the sum of the amounts of aluminous cement and sulfoaluminous cement being from 10:90 to 100:

0.

2. 2 A dry mortar composition according to claim 1, wherein the treated aluminum salt slag comprises 50 to 80 wt% Al2O3, 2 to 15 wt% SiO2, 3 to 12 wt% MgO and 0 to 5 wt% F+Cl.

3. 3 A dry mortar composition according to any preceding claim, wherein the treated aluminum salt slag comprises corundum and spinel (MgAl2O4) phases.

4. 4 A dry mortar composition according to any preceding claim, wherein the treated aluminum salt slag has a particle size distribution, based on a volume distribution, such that the D50 ranges from 3 to 50 pm, especially from 5 to 30 pm.

5. 5 A dry mortar composition according to any preceding claim, wherein the source of aluminum oxide consists of treated aluminum salt slag (TASS) and one or more of alumina cement (CAC) and sulfoalumina cement (SAC).

6. 6 Dry mortar composition according to any one of the preceding claims, in which the weight ratio TASS:(CAC+CSA) is from 15:85 to 85:15, in particular from 20:80 to 80:

20.

7. 7 A dry mortar composition according to any one of the preceding claims, wherein the hydraulic binder comprises 15 to 40% by weight of a source of calcium sulfate (CS), 10 to 35% by weight of Portland cement (PC), and 40 to 65% by weight of a source of aluminum oxide, based on the weight of hydraulic binder.

8. 8 A dry mortar composition according to claim 7, wherein the source of aluminum oxide consists of treated aluminum salt slag and aluminous cement.

9. 9 A dry mortar composition according to any one of claims 1 to 6, wherein the hydraulic binder comprises 10 to 40% by weight of a source of calcium sulfate (CS) and 60 to 90% by weight of a source of aluminum oxide, relative to the weight of hydraulic binder.

10. 10 A dry mortar composition according to any one of claims 1 to 6, wherein the hydraulic binder comprises 0 to 40% by weight of a source of calcium sulfate (CS), 10 to 50% by weight of Portland cement (PC), and 50 to 90% by weight of a source of aluminum oxide, based on the weight of hydraulic binder.

11. 11 A dry mortar composition according to any one of claims 9 or 10, wherein the source of aluminum oxide consists of treated aluminum salt slag and a sulfoaluminous cement.

12. 12 A dry mortar composition according to any one of the preceding claims, wherein the hydraulic binder also comprises lime.

13. 13 A dry mortar composition according to any one of the preceding claims, wherein the aggregate content is 40 to 70% by weight, or even 45 to 60% by weight, relative to the weight of the dry mortar composition.

14. 14 A cured mortar, especially a flooring compound or concrete repair mortar, made by mixing the dry mortar composition according to claims 1 to 13 with water to make a wet mortar, and allowing said wet mortar to harden.

15. 15 A method of repairing damaged concrete comprising mixing the dry mortar composition according to any one of claims 1 to 13 with water to make a wet mortar and applying said wet mortar to damaged areas of said concrete.

16. 16 A method of applying a flooring compound to a subfloor, comprising mixing the dry mortar composition of any one of claims 1 to 13 with water to make a wet mortar and applying said wet mortar to said subfloor.