COMPOSITIONS COMPRISING A MECHANICALLY CARBOXYLATED MINERAL FILLER AND A CEMENT AND / OR ASPHALT BINDER

Abstract

The present invention relates to compositions comprising a mechanically carboxylated mineral filler and a binder, wherein the binder is cement and / or asphalt and wherein the filler can be obtained by mechanically carboxylating a silicate mineral. The invention further relates to a method for preparing the compositions. The invention also relates to a method for preparing concrete from these compositions and to the concrete obtainable by the method for preparing concrete. The invention also relates to the uses of the mechanically carboxylated mineral filler, for example, as a filler in asphalt or cement.

Description

COMPOSITIONS COMPRISING A MECHANICALLY CARBOXYLATED MINERAL FILLER AND A CEMENT AND / OR ASPHALT BINDER FIELD OF INVENTION The present invention relates to compositions comprising a mechanically carboxylated mineral filler and a binder, wherein the binder is cement and / or asphalt. The invention further relates to a method for preparing the compositions. The invention also relates to a method for preparing concrete from these compositions and to the concrete obtainable from the method for preparing concrete. The invention also relates to the uses of the mechanically carboxylated mineral filler, for example, as a filler in asphalt or cement. BACKGROUND OF THE INVENTION Concrete is a composite material, comprising an aggregate matrix (typically rock) and a binder (typically Portland cement or asphalt) that holds the matrix together. Concrete is one of the most frequently used construction materials and is said to be the second most widely used material on Earth, after water. To reduce the cost of concrete and the CO2 emissions generated by global cement production, much research effort has been devoted to identifying an inexpensive material that can be used as a filler to replace the binding component without adversely affecting the properties of concrete. An example of a widely used cementitious filler is limestone. A comprehensive overview of fillers in cementitious materials can be found in John Vanderley M., et al. “Fillers in cementitious materials — Experience, recent advances and future potential”. Cement and Concrete Research 114 (2018): 65-78. Portland cement production contributes approximately 10% of carbon dioxide emissions. According to Vanderley et al., traditional mitigation strategies for CO2 emissions in the cement industry are insufficient to ensure the necessary mitigation in a scenario of increasing cement demand. Therefore, the adoption of carbon capture and storage (CCS), while expensive and environmentally risky, has been considered an unavoidable solution by cement industry leaders. Consequently, there remains a need to develop an affordable filler technology that can combine both the CO2 emission reduction achieved by reduced cement production and the CO2 emission reduction achieved by carbon capture technology, and that does not adversely affect the properties of concrete. An objective of the present invention is to provide improved fillers for cement or asphalt binder. A further objective of the present invention is to provide improved fillers for cement or asphalt binder that are inexpensive to produce. A further objective of the present invention is to provide improved fillers for cement or asphalt binder that are produced using CO2 storage technology. A further objective of the present invention is to provide improved fillers for cement or asphalt binder that enhance the properties of the resulting concrete, such as compressive strength. BRIEF DESCRIPTION OF THE INVENTION The inventors hereof have surprisingly found that one or more of these objectives can be met by using, as a filler for cement and / or asphalt, a mechanically and chemically carboxylated mineral filler, obtainable by a method comprising the following steps: a) provide a solid raw material comprising a silicate mineral; b) provide an oxidizing gas comprising CO2; c) introduce the solid raw material and the oxidizing gas into a mechanical stirring unit; d) subjecting the solid raw material in the presence of the oxidizing gas and optionally in the presence of a catalyst to a mechanical stirring operation in the mechanical stirring unit at an oxidizing gas pressure of more than 1 atm to obtain the mechanochemically carboxylated ore-filled mineral; where the solid raw material is a particulate material which has a BET surface area of ​​more than 0.01 m2 / g and a D50 within the range of 0.1-5000 pm; and the CO2 content of the mechanically carboxylated mineral packing is greater than 1% by weight (in total weight of the mechanically carboxylated mineral packing), where the CO2 content is determined as the mass loss above 120°C measured by TGA-MS using a temperature path where the temperature was increased from ambient temperature to 800°C at a rate of 10°C / min and then decreased to ambient temperature at a rate of 15°C / min. As will be shown in the accompanying examples, it was found that when this mechanochemically carboxylated mineral filler is used as a filler in a binder (such as cement), the compressive strength of the resulting concrete increases significantly beyond the values ​​obtained when using pure cement. Furthermore, the time required for strength development decreases. Moreover, a much larger quantity of this mechanochemically carboxylated mineral filler can be used as a filler in a binder (such as cement) while still yielding acceptable concrete properties. Additionally, the production of the mechanochemically carboxylated mineral filler relies on a cheap CO2 conversion technology platform, so as to provide a filler that can be produced in an economically viable way and that combines both the CO2 emission reduction achieved by the reduced cement production and the CO2 emission reduction achieved by the carbon capture technology. Furthermore, the durability of concrete produced using the mechanochemically treated fly ash filler was found to be significantly increased. Without wishing to be limited by any single theory, the inventors of this material believe this is due to improved micro- and subscale hydration, reduced chloride permeability, and / or reduced porosity of the concrete. Finally, the increased oxygen content compared to untreated raw materials may result in better dispersion in polar solvents and improved compatibility with materials containing epoxy and carboxyl functional groups. An overview of the mechanochemical carboxylation method can be found in WO2019 / 012474. Accordingly, in a first aspect, the invention provides a composition comprising a mechanically carboxylated mineral filler and a binder; wherein the binder is selected from the group consisting of cement, asphalt, and combinations thereof; and wherein the mechanically carboxylated mineral filler is obtainable by a method comprising the following steps: a) provide a solid raw material comprising a silicate mineral, wherein the solid raw material is a particulate material which has a BET surface area of ​​no more than 0.01 m2 / g and a D50 within the range of 0.1-5000 pm; b) provide an oxidizing gas comprising CO2; c) introduce the solid raw material and the oxidizing gas into a mechanical stirring unit; and d) subjecting the solid raw material in the presence of the oxidizing gas and optionally in the presence of a catalyst to a mechanical stirring operation in the mechanical stirring unit at an oxidizing gas pressure of more than 1 atm to obtain the mechanochemically carboxylated mineral filler; where the CO2 content of the mechanically carboxylated mineral packing is greater than 1% by weight (in total weight of the mechanically carboxylated mineral packing), where the CO2 content is determined as the mass loss above 120°C measured by TGA-MS using a temperature path where the temperature was increased from ambient temperature to 800°C at a rate of 10°C / min and then decreased to ambient temperature at a rate of 15°C / min. In another aspect, the invention provides a method for preparing a composition as described herein, the method comprising the following steps: (i) provide a mechanochemically carboxylated mineral filler as described herein; (i) provide a binder selected from cement, asphalt and combinations thereof as described herein; (ii) combine the mechanochemically carboxylated mineral filler from step (i) with the binder from step (i). In another aspect, the invention provides a method for preparing concrete, the method comprising the following steps: (i) provide a composition as described herein; (i) provide a construction aggregate; (iii) bring into contact, preferably mix, the composition of step (i) with the building aggregate of step (ii). In another aspect, the invention provides concrete obtainable by the method for preparing concrete described herein. In another aspect, the invention provides for the use of a mechanochemically carboxylated mineral filler as described herein: • as a filler in a binder as described herein; • as a partial replacement for a binder as described herein; • to increase the compressive strength of concrete; • to improve the durability of concrete; or • to improve the durability of concrete by reducing chloride permeability and / or porosity. DETAILED DESCRIPTION OF THE INVENTION In a first aspect, the invention provides a composition comprising a mechanically carboxylated mineral filler and a binder; wherein the binder is selected from the group consisting of cement, asphalt, and combinations thereof; and wherein the mechanically carboxylated mineral filler is obtainable by a method comprising the following steps: a) provide a solid raw material comprising a silicate mineral; b) provide an oxidizing gas comprising CO2; c) introduce the solid raw material and the oxidizing gas into a mechanical stirring unit; d) subjecting the solid raw material in the presence of the oxidizing gas and optionally in the presence of a catalyst to a mechanical stirring operation in the mechanical stirring unit at an oxidizing gas pressure of more than 1 atm to obtain the mechanochemically carboxylated mineral filler; where the solid raw material is a particulate material which has a BET surface area of ​​no more than 0.01 m2 / g and a D50 within the range of 0.1-5000 pm; and the CO2 content of the mechanically carboxylated mineral packing is greater than 1% by weight (in total weight of the mechanically carboxylated mineral packing) where the CO2 content is determined as the mass loss above 120°C measured by TGA-MS using a temperature path where the temperature was increased from ambient temperature to 800°C at a rate of 10°C / min and then decreased to ambient temperature at a rate of 15°C / min. It is within the ability of a person skilled in the art, in light of the guidance provided in this description, to adapt the relevant process parameters so that the mechanochemically carboxylated mineral filler obtained has the properties listed herein. According to the invention, the cement can be either hydraulic or non-hydraulic. In preferred embodiments, the cement is hydraulic cement, such as Portland cement. In highly preferred embodiments of the invention, the cement is one of the cements defined in EN 197-1 (2011), preferably Portland cement as defined in EN 197-1 (2011). According to the invention, the surface area of ​​BET is determined at a temperature of 77 K using a sample mass of 0.5-1 g. A preferred analytical method for determining the surface area of ​​BET, the cumulative desorption surface area of ​​BJH from the pores, and the average desorption pore width (4V / A per BET) comprises heating the samples to 400°C for one desorption cycle before surface area analysis. In preferred embodiments of the invention, the BET surface area of ​​the mechanochemically carboxylated mineral filler is at least 110%, preferably at least 120%, more preferably at least 150%, of the BET surface area of ​​the solid raw material. In preferred embodiments of the invention, the Fe2Os content of the mechanochemically carboxylated mineral filler is at least 150%, preferably at least 200%, more preferably at least 250% of the Fe2Os content of the solid raw material. Without wishing to be limited by any theory, the inventors of the present invention believe that the increase in BET surface area observed with the mechanochemical carboxylation of the mineral filler according to the present invention can be largely attributed to an increase in the number of pores, observed by a decrease in the average pore width and an increase in the total pore surface area.Accordingly, in embodiments of the invention, the cumulative BJH desorption surface area of ​​the pores of the mechanically carboxylated mineral packing is at least 110%, preferably at least 120%, more preferably at least 150%, of the cumulative BJH desorption surface area of ​​the pores of the solid raw material, and the average desorption pore width (4V / A per BET) of the mechanically carboxylated mineral packing is not greater than 90%, preferably not greater than 85%, more preferably not greater than 80% of the average desorption pore width (4V / A per BET) of the solid raw material. A preferred method for determining mineral content, such as the Fe2Os or CaO content referred to herein, is by X-ray fluorescence spectroscopy, preferably using a Bruker Tracer 5G. As will be understood by the expert, the Fe2Os and CaO content of both the raw material and the mechanochemically carboxylated fly ash referred to herein is preferably determined using X-ray fluorescence spectroscopy. TGA-MS, as used herein, refers to thermogravimetric analysis coupled with mass spectrometry, a technique known to the skilled trades in the prior art. A preferred TGA-MS apparatus configuration for determining the CO2 content of raw materials and mechanochemically carboxylated materials in the context of the present invention is a Setaram TAG 16 TGA / DSC dual-chamber balance coupled to an Ametek Dycor Proline MS using a 0.1-2 mg sample. In preferred embodiments of the invention, the CO2 content of the mechanically carboxylated mineral packing is greater than 2% by weight (in the total weight of the mechanically carboxylated mineral packing), preferably greater than 5% by weight, more preferably greater than 7% by weight, wherein the CO2 content is determined as the mass loss above 120°C measured by TGA-MS using a temperature path where the temperature was increased from ambient temperature to 800°C at a rate of 10°C / min and then decreased to ambient temperature at a rate of 15°C / min. In highly preferred embodiments of the invention, the CO2 content of the solid raw material is less than 0.5% by weight (of the total weight of the solid raw material), preferably less than 0.2% by weight, more preferably less than 0.1% by weight, wherein the CO2 content is determined as the mass loss above 120°C measured by TGA-MS using a temperature path where the temperature was increased from ambient temperature to 800°C at a rate of 10°C / min and then decreased to ambient temperature at a rate of 15°C / min. In embodiments of the invention, the solid raw material comprises a material selected from the group consisting of pyroxenes, hydrated magnesium silicates, talc, serpentines, olivine, fly ash, bottom ash, and combinations thereof, preferably fly ash. In embodiments of the invention, more than 50% by weight, preferably more than 80% by weight, of the solid raw material comprises a material selected from the group consisting of pyroxenes, hydrated magnesium silicates, talc, serpentines, olivine, fly ash, bottom ash, and combinations thereof, preferably fly ash. In preferred embodiments, the solid raw material of the invention consists of a material selected from the group consisting of pyroxenes, hydrated magnesium silicates, talc, serpentines, olivine, fly ash, bottom ash, and combinations thereof, preferably fly ash. Without wishing to be limited by any theory, the inventors of the present invention have found that improved performance can be obtained when the solid raw material is low in carbonaceous material. In embodiments of the invention, the solid raw material has a carbon content of less than 20% by weight (of the total weight of the solid raw material), preferably less than 10% by weight, and more preferably 5% by weight. In embodiments of the invention, the solid raw material has a silicon content of more than 10% by weight (of the total weight of the solid raw material), preferably greater than 15% by weight, and more preferably greater than 20% by weight. The term “fly ash,” as used herein, refers to any type of fly ash, including coal fly ash and petroleum fly ash. Without wishing to be limited to any particular theory, the inventors hereof have found that improved performance can be obtained when the solid feedstock is low in carbonaceous fly ash. Carbonaceous fly ash is a particularly characteristic type of fly ash that constitutes a large portion of petroleum fly ash (along with SiO2, Al2O3, Fe2O3, and other minerals). Accordingly, in preferred embodiments, the fly ash is coal fly ash, such as lignite fly ash, subbituminous coal fly ash, anthracite coal fly ash, bituminous coal fly ash, and combinations thereof. In highly preferred embodiments of the invention, the solid raw material comprises or consists of fly ash that meets the requirements of ASTM C618 (2019), preferably fly ash that meets the requirements of Class C of ASTM C618 (2019). Without wishing to be limited by any theory, the inventors of the present invention have found that better mechanochemical carboxylation results and filler performance are obtained when the raw material comprises at least some CaO. Accordingly, in embodiments of the invention, the solid raw material comprises more than 0.5% by weight (of the total weight of the solid raw material), preferably more than 1% by weight, and more preferably more than 3% by weight of CaO. In preferred embodiments of the invention, the solid raw material comprises more than 5% by weight (of the total weight of the solid raw material) or more than 8% by weight of CaO. In embodiments of the invention, the particle size distribution of the solid raw material has one, two, three or all, preferably all, of the following characteristics: • a D10 within the range 0.1-50 pm, preferably 0.5-20 pm, most preferably 1-10 pm; • a D50 within the range of 1-200 pm, preferably 5-100 pm, most preferably 10-50 pm; • a D90 within the range of 50-700 pm, preferably 50-500 pm, more preferably 60-400 pm; • a D(4:3) within the interval 10-200 pm, preferably 20-130 pm.

[0038] In embodiments of the invention, the particle size distribution of the mechanochemically carboxylated mineral filler has one, two, three or all, preferably all, of the following characteristics: • a D10 within the range 0.005-5 pm, preferably 0.01-1 pm, most preferably 0.1-0.5 pm; • a D50 within the range 0.5-50 pm, preferably 1-25 pm, most preferably 1-10 pm; • a D90 within the range 5-200 pm, preferably 20-100 pm, most preferably 30-50 pm; • a D(4:3) within the interval 1-100 pm, preferably 10-25 pm. According to the invention, particle size distribution characteristics such as D10, D50, D90, and D(4:3) are determined by measuring with a laser light diffraction particle size analyzer using Fraunhofer light diffraction theory, such as the Fritsch Analysette 22 Nanotec or another instrument of equal or better sensitivity, and reporting the data using an equivalent-volume sphere model. As is known to the expert, D50 is the median bulk diameter, i.e., the diameter at which 50% of a sample mass is comprised of smaller particles. Similarly, D10 and D90 represent the diameter at which 10% or 90% of a sample mass is comprised of smaller particles, respectively. As is known to the expert, D(4:3) is the volume mean diameter. In embodiments of the invention, the oxidizing gas provided in step (b) comprises more than 90 mol% CO2, preferably more than 95 mol% CO2. In preferred embodiments of the invention, the oxidizing gas provided in step (b) comprises more than 90 mol% CO2, preferably more than 95 mol% CO2 and less than 1000 ppm (v / v) H2O, preferably less than 100 ppm (v / v) H2O. In embodiments of the invention, step (d) is carried out at a pressure of more than 3 atm, preferably more than 6 atm. In embodiments of the invention, step (d) is carried out at a temperature of less than 100°C, preferably less than 60°C, more preferably less than 30°C. In embodiments of the invention, step (d) is carried out for at least 1 hour, preferably for at least 4 hours, more preferably at least 8 hours. In preferred embodiments of the invention, step (d) is carried out at a pressure of more than 3 atm, preferably more than 6 atm; at a temperature of less than 100°C, preferably less than 60°C, more preferably less than 30°C; and for at least 1 hour, preferably for at least 4 hours, more preferably at least 8 hours. The inventors hereof have further found that the mechanochemical carboxylation methods described herein can be advantageously carried out without employing additional oxidizing agents such as acids. Accordingly, the mechanochemical carboxylation methods described herein are preferably carried out without employing a strong acid, and preferably without employing any additional oxidizing agent other than the oxidizing gas provided in step (b). In preferred embodiments of the invention, the mechanochemical stirring operation of step (d) comprises crushing, grinding, mixing, stirring (low-speed or high-speed stirring), shearing (high-torque shearing), stirring, mixing, a fluidized bed, or ultrasonication, preferably crushing, grinding, mixing, stirring (low-speed or high-speed stirring), shearing (high-torque shearing), and ultrasonication. The inventors hereof have found that the mechanochemical carboxylation process is facilitated if the mechanochemical stirring operation of step (d) is carried out in the presence of inert crushing or grinding media, preferably inert balls or beads. A preferred inert material is stainless steel. In preferred embodiments of the invention, step (d) is carried out in the presence of a catalyst, preferably a transition metal oxide catalyst, more preferably a transition metal dioxide catalyst, more preferably a transition metal dioxide catalyst selected from the group consisting of iron oxides, cobalt oxides, ruthenium oxides, titanium oxides and combinations thereof. Accordingly, as will be understood from the foregoing, in highly preferred embodiments of the invention, step (d) comprises a mechanical stirring operation, preferably crushing, grinding, mixing, stirring (low-speed or high-speed stirring), shearing or cutting (high-torque shearing), stirring, mixing, a fluidized bed, or ultrasonication, in the presence of inert crushing or grinding media and a transition metal oxide catalyst. The inventors hereof have found it advantageous with a view to the efficiency of the mechanochemical carboxylation (e.g., reaction time, CO2 absorption, and particle size reduction) to employ inert media as described herein before coating with the transition metal oxide catalyst. In embodiments of the invention, the composition comprises more than 0.1% by weight (of the total weight of the composition), preferably more than 1% by weight, more preferably more than 5% by weight of the mechanochemically carboxylated mineral filler and / or more than 0.1% by weight (of the total weight of the composition), preferably more than 1% by weight, more preferably more than 20% by weight of the binder. In embodiments of the invention, the composition comprises less than 60% by weight (of the total weight of the composition), preferably less than 50% by weight, more preferably less than 45% by weight of the mechanochemically carboxylated mineral filler and / or less than 95% by weight (of the total weight of the composition), preferably less than 90% by weight, more preferably less than 80% by weight of the binder. In embodiments of the invention, the composition provided herein in the weight:weight ratio of mechanically carboxylated mineral filler to binder is within the range of 1:9 to 2:1, preferably within the range of 1:8 to 1:1, most preferably within the range of 1:6 to 5:6. In embodiments of the invention, the composition comprises 5-70% by weight (of the total weight of the composition), preferably 10-60% by weight, more preferably 20-50% by weight of the mechanochemically carboxylated mineral filler and 30-95% by weight (of the total weight of the composition), preferably 40-90% by weight, preferably 50-80% by weight of the binder. In embodiments of the invention, the composition comprises less than 5% by weight (of the total weight of the composition) of water, preferably less than 1% by weight, more preferably less than 0.1% by weight. The amount of water can be suitably determined as the mass loss up to 120°C measured by TGA-MS using a temperature path where the temperature was increased from ambient temperature to 800°C at a rate of 10°C / min. In embodiments of the invention, the composition consists of the mechanochemically carboxylated mineral filler and the binder. In one further aspect, the present invention provides a method for preparing a composition as described herein, the method comprising the following steps: (i) provide a mechanochemically carboxylated mineral filler as described herein; (i) provide a binder selected from cement, asphalt, and combinations thereof as described herein; and (ii) combine the mechanochemically carboxylated mineral filler of step (i) with the binder of step (ii). In one further aspect, the present invention provides a method for preparing concrete, the method comprising the following steps: (i) provide a composition as described herein; (i) provide a construction aggregate; and (ii) bring into contact, preferably mix the composition of step (i) with the construction aggregate of step (ii). In embodiments of the invention, the construction aggregate is selected from the group consisting of sand, gravel, crushed stone, slag, recycled concrete, clay, pumice, perlite, vermiculite, and combinations thereof. In preferred embodiments, the construction aggregate is one of the aggregates defined in EN 13043 (2002), EN 13383 (2019), EN 12620 (2013), or EN 13242 (2013), preferably the construction aggregate is one of the aggregates defined in EN 12620 (2013). In preferred embodiments of the invention, step (iii) further comprises contacting, preferably mixing, the composition of step (i) with the building aggregate of step (ii) and water. According to the invention, the composition of step (i), the building aggregate of step (ii), and water can be contacted, preferably mixed substantially, simultaneously or in a staggered manner, where the composition of step (i) is contacted first, preferably mixed with water, before being contacted, preferably mixed, with the building aggregate of step (ii). In another aspect of the invention, a concrete obtainable by the method for preparing concrete described herein is provided. In another aspect of the invention, the use of a mechanochemically carboxylated mineral filler is provided as described herein: • as a filler in a binder as described herein; • as a partial replacement of a binder as described herein in concrete; • to increase the compressive strength of concrete; • to improve the durability of concrete; or • to improve the durability of concrete by reducing chloride permeability and / or porosity. The expert will understand that the embodiments of the invention described herein in the context of the composition, especially with regard to the characteristics of the mechanochemically carboxylated mineral filler or with regard to the characteristics of the binder, are equally applicable to the method for preparing the composition described herein and the uses of the mechanochemically carboxylated mineral filler described herein. In one further aspect, the present invention provides a method for producing a mechanochemically carboxylated mineral filler comprising the following steps: a) providing a solid raw material comprising a silicate mineral as described herein, wherein the solid raw material is a particulate material which has a BET surface area of ​​more than 0.01 m2 / g and a D50 within the range of 0.1-5000 pm; b) provide an oxidizing gas comprising CO2 as described herein; c) introduce the solid raw material and the oxidizing gas into a mechanical stirring unit; and d) subjecting the solid raw material in the presence of the oxidizing gas, inert media and a transition metal oxide catalyst to a mechanical stirring operation as described herein, in the mechanical stirring unit at an oxidizing gas pressure of more than 1 atm to obtain the mechanochemically carboxylated mineral packing; wherein the CO2 content of the mechanochemically carboxylated mineral packing is greater than 1% by weight (of the total weight of the mechanochemically carboxylated mineral packing), wherein the CO2 content is determined as the mass loss above 120°C measured by TGA-MS using a temperature path where the temperature was increased from ambient temperature to 800°C at a rate of 10°C / min and then decreased to room temperature at a rate of 15°C / min. In preferred embodiments, the inert media, preferably inert crushing or grinding media, are coated with the transition metal oxide catalyst. Examples The BET surface area, the cumulative BJH desorption surface area of ​​the pores, and the average desorption pore width (4V / A per BET) were determined at a temperature of 77K using a sample mass of 0.5-1 g where the samples were heated to 400°C for one desorption cycle before the surface area analysis. Particle Size Distribution measurements were carried out on a Fritsch Analysette 22 Nanotec using Fraunhofer diffraction theory. The mineral content (SiO2, Al2O3, Fe2Oa and CaO) was determined by X-ray fluorescence spectroscopy using a Bruker Tracer 5G. The CO2 content was determined as the mass loss above 120°C measured by TGAMS using a temperature path, where the temperature was increased from room temperature to 800°C at a rate of 10°C / min and then decreased to room temperature at a rate of 15°C / min using a Setaram TAG 16 TGA / DSC dual chamber balance coupled to an Ametek Dycor Proline MS and a 0.1-2 mg sample. Compressive strength was tested in accordance with ISO 1920:2005, part 4. Example 1 Mechanochemically carboxylated fly ash was produced by inserting a 10 g sample of fly ash into a pressure cell containing 500 g of inert media (stainless steel balls) coated with titanium dioxide. The cell was pressurized to 1 MPa (9.87 atm), placed in a high-energy ball mill, and rotated at 5000 RPM for 48 hours. The reaction was initiated at room temperature, and no heating or cooling was applied. Example 2 Two fly ash samples, A and B, were mechanochemically carboxylated (“treated”) using a process according to Example 1, where the mechanical agitation and CO2 pressure were adjusted to obtain a product with the characteristics shown in the table below. Raw sample A was obtained from the Gennessee Coal Plant, Alberta, Canada, and meets the requirements of ASTM C618 (2019) Class F. Raw sample B was obtained from the Civita Vecchia Coal Plant, Italy. Raw sample C was obtained from the Cordemais Coal Plant, France. The raw fly ash from samples B and C is generally considered lower-grade fly ash, which is suitable for use as a concrete filler at concentrations above 10% by weight. A - raw A - treated B - raw B - treated C - raw C - treated Density (g / cm3) 2.09 3.06 2.36 2.79 2.25 2.33 CO2 (% by weight) <0.1 9 <0.1 6 0.1 4 S1O2 (% by weight) 56.39 39.45 54.71 45.92 53.76 45.95 Al2O3 (% by weight) 23.71 16.31 22.42 18.91 25.23 21.37 Fe2Os (% by weight) 3.55 24.74 6.59 14.63 5.58 15.08 CaO (% by weight) 9.3 6.4 5.11 4.28 3.58 3.08 D10 (pm) 3.8 0.2 2.6 0.2 6.5 0.1 D50 (pm) 29.6 8.4 14.9 7 39.2 5.5 D90 (pm) 143.3 46.9 68 37.8 358 35.2 D(4;3) (pm) 56.51 20.38 26.87 13.8 114.83 15.11 BET surface area (m7g) 16.1858 32.2091 2.95 5.55 5.5 9.8 Average desorption pore width (4V / A per BET) 12.3 8.6 ndndndnd Cumulative BJH desorption surface area of ​​pores (m2 / g) 24.1221 43.9139 ndndndnd nd = not determined Mechanochemically carboxylated fly ash A and B were used as filler by mixing with Portland cement at a weight:weight ratio of 1:5 (filler:cement). The mixtures obtained from the mechanically carboxylated fly ash and Portland cement were each mixed with fine gravel and water (using identical ratios for each sample) to obtain a concrete slurry. The compressive strength of the resulting concrete was monitored after 2, 7, and 28 days. For comparison, similar concrete slurry was prepared using samples A and B of raw fly ash and pure Portland cement. Compressive strength (MPa) 2 days 7 days 28 days A - Raw 26.6 39.9 53.0 B - Raw 26.3 39.3 54.6 C - Raw 24.9 36.2 49 A - Treated 32.2 42.6 64.1 B - Treated 32.7 42.7 66.2 C - Treated 30.3 45.4 62.8 Portland cement 34.1 48.1 60.9 As can be seen from the compressive strength measurements, the mechanochemically carboxylated mineral fillers of the present invention provide an unexpectedly large increase in performance compared to raw materials (such as fly ash). Furthermore, it was surprisingly found that the mechanochemically carboxylated mineral fillers of the present invention outperform even pure cement mixtures.

Claims

1. A composition characterized in that it comprises a mechanically carboxylated mineral filler and a binder; the binder being selected from the group consisting of cement, asphalt and combinations thereof; and wherein the mechanically carboxylated mineral filler is obtainable by a method comprising the following steps: a) providing a solid raw material comprising a silicate mineral, wherein the solid raw material is a particulate material which has a BET surface area of ​​more than 0.01 m2 / g and a D50 within the range of 0.1 to 5000 pm; b) providing an oxidizing gas comprising CO2; c) introducing the solid raw material and the oxidizing gas into a mechanical stirring unit; and d) subjecting the solid raw material to a mechanical stirring operation in the presence of the oxidizing gas at an oxidizing gas pressure of more than 1 atm to obtain the mechanochemically carboxylated mineral packing; wherein the CO2 content of the mechanochemically carboxylated mineral packing is greater than 1% by weight (in total weight of the mechanochemically carboxylated mineral packing) wherein the CO2 content is determined as the mass loss above 120°C measured by TGA-MS using a temperature path wherein the temperature was increased from ambient temperature to 800°C at a rate of 10°C / min and then decreased to ambient temperature at a rate of 15°C / min.

2. The composition according to claim 1, further characterized in that the solid raw material comprises or consists of a material selected from the group consisting of pyroxenes, hydrated magnesium silicates, talc, serpentines, olivine, fly ash, bottom ash and combinations thereof, preferably fly ash.

3. The composition according to claim 2, further characterized in that the solid raw material comprises or consists of fly ash, preferably fly ash which meets the requirements of ASTM C618 (2019), more preferably fly ash which meets the requirements of class C of ASTM C618 (2019).

4. The composition according to any of claims 1 to 3, further characterized in that the mechanochemically carboxylated mineral filler has a D50 within the range of 0.5 to 50 pm, preferably 1 to 25 pm, more preferably 1 to 10 pm.

5. The composition according to any of claims 1 to 4, further characterized in that the oxidizing gas comprises more than 90 mol% CO2, preferably more than 95 mol% CO2.

6. The composition according to any of claims 1 to 5, further characterized in that step (d) is carried out • at a pressure of more than 3 atm, preferably more than 6 atm; • at a temperature of less than 100°C, preferably less than 60°C, more preferably less than 30°C; and / or for at least 1 hour, preferably for at least 4 hours, more preferably for at least 8 hours.

7. The composition according to any of claims 1 to 6, further characterized in that the mechanochemical stirring operation of step (d) comprises mixing, stirring (low speed stirring or high speed stirring), shearing or cutting (high torque shearing), stirring, mixing, a fluidized bed or ultrasonication, preferably mixing, stirring (low speed stirring or high speed stirring), shearing or cutting (high torque shearing) or ultrasonication.

8. The composition according to any of claims 1 to 7, further characterized in that step (d) is carried out in the presence of a catalyst, preferably a transition metal oxide catalyst, more preferably a transition metal dioxide catalyst, more preferably a transition metal dioxide catalyst selected from the group consisting of iron oxides, cobalt oxides, ruthenium oxides, titanium oxides and combinations thereof.

9. The composition according to any of claims 1 to 8, further characterized in that the binder is a cement, preferably a hydraulic cement, more preferably Portland cement.

10. The composition according to any one of claims 1 to 9, further characterized in that it comprises more than 0.1% by weight (of the total weight of the composition), preferably more than 1% by weight, more preferably more than 5% by weight of the mechanochemically carboxylated mineral filler; and more than 0.1% by weight (of the total weight of the composition), preferably more than 1% by weight, preferably more than 20% by weight of the binder.

11. The composition according to any of claims 1 to 10, further characterized in that it comprises 5 to 70% by weight (of the total weight of the composition), preferably 10 to 60% by weight, more preferably 20 to 50% by weight of the mechanochemically carboxylated mineral filler and 30 to 95% by weight (of the total weight of the composition), preferably 40 to 90% by weight, preferably 50 to 80% by weight of the binder.

12. A method for preparing a composition according to any one of claims 1 to 11, characterized in that it comprises the following steps: (i) providing a mechanically carboxylated mineral filler according to any one of claims 1 to 8; (ii) providing a binder selected from cement, asphalt and combinations thereof, preferably a cement, more preferably a hydraulic cement, more preferably Portland cement; and (ii) combining the mechanically carboxylated mineral filler of step (i) with the binder of step (ii).

13. A method for preparing concrete, the method being characterized in that it comprises the following steps: (i) providing a composition in accordance with any of claims 1 to 11; (ii) providing a construction aggregate; and (iii) contacting, preferably mixing, the composition of step (i) with the construction aggregate of step (ii).

14. A concrete characterized in that it is obtainable by the method according to claim 13. 5 15. Use of a mechanochemically carboxylated mineral filler according to any of claims 1 to 8: • as a filler in a binder selected from the group consisting of cement, asphalt and combinations thereof; • as a partial replacement of a binder in concrete; wherein the binder is selected from the group consisting of cement, asphalt and combinations thereof; • to increase the compressive strength of the concrete; • to improve the durability of the concrete; or • to improve the durability of the concrete by reducing chloride permeability and / or porosity.