Compositions Comprising Mechanochemically Carboxylated Inorganic Fillers and Cement and / or Asphalt Binders

Abstract

The present invention relates to compositions comprising a mechanochemically carboxylated inorganic filler and a binder, wherein the binder is cement and / or asphalt, and the filler is obtained from a mechanochemically carboxylated silicate mineral. The present invention also relates to methods for making such compositions. The present invention further relates to methods for making concrete from these compositions, and to the concrete obtained from such methods. The present invention also relates to methods for using the mechanochemically carboxylated inorganic filler, for example, as a filler in asphalt or cement.

Description

[Technical Field]

[0001] The present invention relates to compositions comprising a mechanochemically carboxylated inorganic filler and a binder, wherein the binder is cement and / or asphalt. The present invention also relates to methods for making such compositions. The present invention further relates to methods for making concrete from these compositions and the concrete obtained from such methods. The present invention also relates to methods for using the mechanochemically carboxylated inorganic filler, for example, as a filler in asphalt or cement. [Background technology]

[0002] Concrete is a composite material containing a matrix of aggregate (usually rock-based) and a binder (usually Portland cement or asphalt) that binds the matrix. Concrete is one of the most frequently used building materials and is said to be the second most widely used substance on Earth after water.

[0003] In order to reduce the cost of concrete and the CO2 emissions generated by cement production worldwide, much research effort is being put into identifying inexpensive materials that can be used as fillers to replace the binder components without (harmfully) affecting the properties of concrete.

[0004] An example of a widely adopted cement filler is limestone. A comprehensive overview of fillers in cement-based materials can be found in [1].

[0005] Portland cement production accounts for approximately 10% of global carbon dioxide emissions. According to Vanderley et al., traditional strategies for reducing CO2 emissions in the cement industry are insufficient to ensure the necessary reductions in the face of growing cement demand. Therefore, the adoption of carbon capture and storage (CCS), which is expensive and carries significant environmental risks, has been considered a compelling solution by cement industry leaders. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] John,Vanderley M.,et al.'Fillers in cementitious materials-Experience, recent advances and future potential.'Cement and Concrete Research 114(2018):65-78 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, there is a need to develop an inexpensive filler technology that can reduce CO2 emissions by reducing cement production and CO2 emissions through carbon capture technology, without impairing the properties of concrete.

[0008] It is an object of the present invention to provide an improved filler for use in cement or asphalt binders.

[0009] It is a further object of the present invention to provide an improved filler for use in cement or asphalt binders that is inexpensive to produce.

[0010] It is a further object of the present invention to provide an improved filler for use in binders for cement or asphalt produced using CO2 storage technology.

[0011] It is a further object of the present invention to provide an improved filler for use in cement or asphalt binders which improves properties, such as compressive strength, of the resulting concrete. [Means for solving the problem]

[0012] The inventors have surprisingly found that one or more of these objectives can be achieved by employing as filler in cement and / or asphalt a mechanochemically carboxylated inorganic filler obtained by a process comprising the steps of: a) providing a solid raw material containing silicate minerals; b) providing an oxidizing gas comprising CO2; c) feeding the solid source material and the oxidizing gas into a mechanical stirring device; 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 and an optional catalyst to obtain a mechanochemically carboxylated inorganic filler; The solid raw material has a BET surface area of ​​0.01 m 2 / g and a D50 in the range of 0.1 to 5000 μm; and The mechanochemically carboxylated inorganic filler has a CO2 content of greater than 1 wt. % (based on the total weight of the mechanochemically carboxylated inorganic filler), the CO2 content being determined from the mass loss above 120°C measured by TGA-MS following a temperature curve from room temperature to 800°C at 10°C / min and then cooling to room temperature at 15°C / min.

[0013] As shown in the examples below, the use of such mechanochemically carboxylated inorganic fillers as fillers in binders such as cement has been found to surprisingly increase the compressive strength of the resulting concrete over that achieved with pure cement. Furthermore, the time required for strength development is reduced. Furthermore, the mechanochemically carboxylated inorganic fillers can be used in very large amounts as dispersing agents in binders such as cement, while still achieving acceptable concrete properties.

[0014] Furthermore, the production of the mechanochemically carboxylated inorganic fillers relies on an inexpensive CO2 conversion technology platform, providing a filler that can be produced in an economically sustainable manner and combines the CO2 emissions reductions of reduced cement production with those of carbon capture technology.

[0015] Furthermore, the inventors have found that the durability of concrete obtained using the mechanochemical fly ash filler is significantly improved. While not wishing to be bound by any particular theory, they believe this is due to accelerated hydration at the micro- and sub-microscale, resulting in reduced chloride permeability and / or reduced concrete porosity. Finally, the increased oxygen content compared to the untreated raw material is believed to improve dispersibility in polar solvents and compatibility with materials containing epoxy and carboxyl groups.

[0016] A general description of mechanochemical carboxylation is given in WO 2019 / 012474.

[0017] Accordingly, in a first aspect, the present invention provides a composition comprising a mechanochemically carboxylated inorganic filler and a binder, wherein the binder is selected from the group consisting of cement, asphalt and mixtures thereof, and the mechanochemically carboxylated inorganic filler is obtainable by a process comprising the steps of: a) providing a solid raw material containing a silicate mineral, the solid raw material having a BET surface area of ​​0.01 m 2 / g and particulate matter with a D50 in the range of 0.1 to 5000 μm; b) providing an oxidizing gas comprising CO2; c) feeding the solid raw material and the oxidizing gas into a mechanical stirring device; 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 and an optional catalyst to obtain a mechanochemically carboxylated inorganic filler; The mechanochemically carboxylated inorganic filler has a CO2 content of greater than 1 wt. % (based on the total weight of the mechanochemically carboxylated inorganic filler), determined from the mass loss at or above 120°C measured by TGA-MS following a temperature curve from room temperature to 800°C at 10°C / min, then cooling to room temperature at 15°C / min.

[0018] Another aspect of the present invention provides a method for making the compositions described herein, the method comprising the steps of: (i) providing a mechanochemically carboxylated inorganic filler as described herein; (ii) providing a binder as described herein, selected from cement, asphalt, and combinations thereof; and (iii) combining the mechanochemically carboxylated inorganic filler of step (i) above with the binder of step (ii) above.

[0019] Another aspect of the present invention provides a method for producing concrete, the method comprising the steps of: (i) providing a composition described herein; (ii) preparing construction aggregate; and (iii) contacting, preferably mixing, the composition of step (i) with the construction aggregate of step (ii)

[0020] Another aspect of the present invention provides a concrete obtainable by the method for making concrete described herein.

[0021] Another aspect of the present invention is the use of the mechanochemically carboxylated inorganic fillers described herein, Use as a filler in the binders described herein; Use as a partial replacement of the binders described herein in concrete; Use for increasing the compressive strength of concrete, Use to improve the durability of concrete, or Use to improve the durability of concrete by reducing chloride permeability and / or porosity. DETAILED DESCRIPTION OF THE INVENTION

[0022] A first aspect of the present invention provides a composition comprising a mechanochemically carboxylated inorganic filler and a binder, wherein the binder is selected from the group consisting of cement, asphalt, and mixtures thereof, and the mechanochemically carboxylated inorganic filler is obtainable by a process comprising the steps of: a) providing a solid raw material containing silicate minerals; b) providing an oxidizing gas comprising CO2; c) feeding the solid raw material and the oxidizing gas into a mechanical stirring device; 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 and an optional catalyst to obtain a mechanochemically carboxylated inorganic filler; The solid raw material has a BET surface area of ​​0.01 m 2 / g and a D50 in the range of 0.1 to 5000 μm; and The mechanochemically carboxylated inorganic filler has a CO2 content of greater than 1 wt. % (based on the total weight of the mechanochemically carboxylated inorganic filler), determined from the mass loss above 120°C measured by TGA-MS following a temperature curve from room temperature to 800°C at 10°C / min, then cooling to room temperature at 15°C / min.

[0023] In light of the guidance provided in this disclosure, it is within the ability of one skilled in the art to appropriately modify the relevant process parameters to obtain mechanochemically carboxylated inorganic fillers having the properties described herein.

[0024] According to the present invention, the cement may be a hydraulic cement or a non-hydraulic cement. In a preferred embodiment, the cement is a hydraulic cement such as Portland cement. In a more preferred embodiment of this embodiment, the cement is one of the cements defined in EN 197-1 (2011), and even more preferably, Portland cement as defined in EN 197-1 (2011).

[0025] According to the present invention, BET surface area is determined using a sample having a mass of 0.5 to 1 g at a temperature of 77 K. A preferred analytical method for determining BET surface area, BJH desorption cumulative pore surface area, and desorption average pore diameter (4V / A by BET) involves heating the sample to 400° C. during the desorption cycle prior to performing the surface area analysis.

[0026] In a preferred embodiment of the present invention, the BET surface area of ​​the mechanochemically carboxylated inorganic filler is at least 110%, preferably at least 120%, more preferably at least 150% of the BET surface area of ​​the solid raw material.

[0027] In a preferred embodiment of the present invention, the Fe2O3 content of the mechanochemically carboxylated inorganic filler is at least 150%, preferably at least 200%, and most preferably at least 250%, relative to the Fe2O3 content of the solid raw material.

[0028] While not wishing to be bound by any particular theory, the inventors believe that the increase in BET surface area observed upon mechanochemical carboxylation of an inorganic filler is largely due to the decrease in the average pore size and the increase in the number of pores resulting from the increase in the total pore surface area. Accordingly, in this embodiment, the BJH desorption integrated surface area of ​​the pores of the mechanochemically carboxylated inorganic filler is at least 110%, preferably at least 120%, and more preferably at least 150% of the BJH desorption integrated surface area of ​​the pores of the solid feedstock. Furthermore, the desorption average pore size (BET 4V / A) of the mechanochemically carboxylated inorganic filler is 90% or less, preferably 85% or less, and more preferably 80% or less of the desorption average pore size (BET 4V / A) of the solid feedstock.

[0029] The preferred method for determining the inorganic content, such as Fe2O3 and CaO content, herein is by X-ray fluorescence spectroscopy, preferably using a Bruker Tracer 5G. As will be appreciated by those skilled in the art, the Fe2O3 and CaO content of both the raw material and the mechanochemically carboxylated fly ash herein are preferably determined by X-ray fluorescence spectroscopy.

[0030] As used herein, TGA-MS refers to the coupling of a thermogravimetric analyzer with a mass spectrometer, a technique known to those skilled in the art. In the context of the present invention, a preferred TGA-MS setup for determining the CO content of raw and mechanochemically carboxylated materials is a Setaram TAG 16 dual chamber TGA / DSC instrument coupled to an Ametek Dycor Proline MS, using 0.1-2 mg samples.

[0031] In a preferred embodiment of the present invention, the CO content of the mechanochemically carboxylated inorganic filler is greater than 2 wt. %, preferably greater than 5 wt. %, and most preferably greater than 7 wt. % (based on the total weight of the mechanochemically carboxylated inorganic filler), as determined from the mass loss above 120° C. measured by TGA-MS following a temperature curve from room temperature to 800° C. at 10° C. / min, followed by a temperature drop to room temperature at 15° C. / min.

[0032] In an even more preferred embodiment of the invention, the CO content of the solid feedstock is less than 0.5 wt. % (based on the total weight of the solid feedstock), preferably less than 0.2 wt. %, and most preferably less than 0.1 wt. %, as determined from the mass loss above 120° C. measured by TGA-MS following a temperature curve ramping from room temperature to 800° C. at 10° C. / min, then ramping down to room temperature at 15° C. / min.

[0033] In this embodiment, the solid raw material comprises a material selected from the group consisting of pyroxene, hydrous magnesium silicate, talc, serpentine, olivine, fly ash, bottom ash, and combinations thereof, preferably fly ash. In this embodiment, more than 50 wt. %, preferably more than 80 wt. %, of the solid raw material is a material selected from the group consisting of pyroxene, hydrous magnesium silicate, talc, serpentine, olivine, fly ash, bottom ash, and combinations thereof, preferably fly ash. In a preferred embodiment, the solid raw material in a preferred aspect of the present invention consists of a material selected from the group consisting of pyroxene, hydrous magnesium silicate, talc, serpentine, olivine, fly ash, bottom ash, and combinations thereof, preferably fly ash.

[0034] Without wishing to be bound by any particular theory, the inventors have found that performance is improved when the solid feedstock has insufficient carbonaceous material. In an embodiment of the invention, the solid feedstock has a C content of less than 20 wt.%, preferably less than 10 wt.%, and most preferably less than 5 wt.% (based on the total weight of the solid feedstock). In an embodiment of the invention, the solid feedstock has a Si content of more than 10 wt.%, preferably more than 15 wt.%, and most preferably more than 20 wt.% (based on the total weight of the solid feedstock).

[0035] As used herein, the term "fly ash" refers to any type of fly ash, including coal fly ash and petroleum fly ash. Without wishing to be bound by any particular theory, the inventors have discovered that performance improves when the solid feedstock is low in carbonaceous fly ash. Carbonaceous fly ash is a particularly distinctive type of fly ash that makes up the majority of petroleum fly ash (after minerals such as SiO, AlO, and FeO).

[0036] Thus, in preferred embodiments, the fly ash is coal fly ash, such as lignite fly ash, subbituminous coal fly ash, anthracite fly ash, bituminous coal fly ash, and combinations thereof. In highly preferred embodiments of the present invention, the solid feedstock comprises or consists of fly ash that meets the requirements of ASTM C618(2019), preferably Class C of ASTM C618(2019).

[0037] Without wishing to be bound by any particular theory, the inventors have found that improved mechanochemical carboxylation and filler performance results when the feedstock contains at least some CaO. Thus, in this embodiment, the solid feedstock contains more than 0.5 wt. %, preferably more than 1 wt. %, and more preferably more than 3 wt. % CaO (based on the total weight of the solid feedstock). In more preferred embodiments of the invention, the solid feedstock contains more than 5 wt. % or more than 8 wt. % CaO (based on the total weight of the solid feedstock).

[0038] In an embodiment of the present invention, the particle size distribution of the solid feedstock has one, two, three or all, preferably all, of the following characteristics: the D10 value is in the range of 0.1 to 50 μm, preferably 0.5 to 20 μm, most preferably 1 to 10 μm; the D50 value is in the range of 1 to 200 μm, preferably 5 to 100 μm, most preferably 10 to 50 μm; the D90 value is in the range of 50 to 700 μm, preferably 5 to 500 μm, most preferably 60 to 400 μm; The value of D(4:3) is in the range of 10 to 200 μm, preferably 20 to 130 μm.

[0039] In an embodiment of the present invention, the particle size distribution of the mechanochemically carboxylated inorganic filler has one, two, three or all, preferably all, of the following characteristics: the value of D10 is in the range of 0.005 to 5 μm, preferably 0.01 to 1 μm, most preferably 0.1 to 0.5 μm; the D50 value is in the range of 0.5 to 50 μm, preferably 1 to 25 μm, most preferably 1 to 10 μm; the D90 value is in the range of 5 to 200 μm, preferably 20 to 100 μm, most preferably 30 to 50 μm; The value of D(4:3) is in the range of 1 to 100 μm, preferably 10 to 25 μm.

[0040] According to the present invention, particle size distribution characteristics such as D10, D50, D90, and D(4:3) are determined by measuring with a laser light scattering particle size analyzer utilizing the Fraunhofer theory of light scattering, such as a Fritsch Analysette 22 Nanotec or other instruments of comparable or greater sensitivity, and recording the data using a volume-equivalent sphere model. As known to those skilled in the art, D50 represents the mass median diameter, i.e., the diameter at which 50% of the sample's mass is made up of smaller particles. Similarly, D10 and D90 represent the diameters at which 10% and 90% of the sample's mass is made up of smaller particles. As known to those skilled in the art, D(4:3) is the volume mean diameter.

[0041] In an embodiment of the invention, the oxidizing gas provided in step (b) comprises more than 90 mol% CO, preferably more than 95 mol% CO. In a preferred embodiment of the invention, the oxidizing gas provided in step (b) comprises more than 90 mol% CO, preferably more than 95 mol% CO, and less than 1000 ppm (v / v) HO, preferably less than 100 ppm (v / v) HO.

[0042] In an embodiment of the present invention, step (d) is carried out at a pressure greater than 3 atm, preferably greater than 6 atm. In an embodiment of the present invention, step (d) is carried out at a temperature less than 100°C, preferably less than 60°C, more preferably less than 30°C. In an embodiment of the present invention, step (d) is carried out for at least 1 hour, preferably at least 4 hours, more preferably at least 8 hours. In a preferred embodiment of the present invention, step (d) is carried out at a pressure greater than 3 atm, preferably greater than 6 atm; at a temperature less than 100°C, preferably less than 60°C, more preferably less than 30°C; and for at least 1 hour, preferably at least 4 hours, more preferably at least 8 hours.

[0043] The inventors have further found that the mechanochemical carboxylation processes described herein can be carried out without providing an additional oxidizing agent, such as an acid. Thus, the mechanochemical carboxylation processes described herein are preferably carried out without the use of a strong acid, and preferably without the use of any additional oxidizing agent other than the oxidizing gas provided in step (b).

[0044] In a preferred embodiment of the present invention, the mechanochemical stirring operation in step (d) comprises grinding, milling, mixing, stirring (low or high speed stirring), shearing (high torque shear), shaking, blending, fluidized bed, or ultrasonic treatment, and is preferably grinding, milling, mixing, stirring (low or high speed stirring), shearing (high torque shear), or ultrasonic treatment. The inventors have found that the mechanochemical carboxylation process is facilitated when the mechanochemical stirring operation in step (d) is carried out in the presence of an inert grinding or milling medium, preferably inert balls or beads. A preferred inert material is stainless steel.

[0045] In a preferred embodiment of the present 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, most preferably a transition metal dioxide catalyst selected from the group consisting of iron oxide, cobalt oxide, ruthenium oxide, titanium oxide, and combinations thereof.

[0046] Thus, as can be seen from the above, in a highly preferred embodiment of the present invention, step (d) comprises a mechanical agitation operation, preferably grinding, milling, mixing, stirring (low or high speed), shearing (high torque shear), shaking, blending, fluidized bed, or ultrasonic treatment, in the presence of an inert grinding or milling medium and a transition metal oxide catalyst. The inventors have found that the use of an inert medium as described herein prior to coating with the transition metal oxide catalyst is beneficial in terms of the efficiency of the mechanochemical carboxylation (e.g., reaction time, CO2 uptake, and particle size reduction).

[0047] In an embodiment of the invention, the composition comprises more than 0.1 wt. %, preferably more than 1 wt. %, more preferably more than 5 wt. % of mechanochemically carboxylated inorganic filler (relative to the total weight of the composition), and / or more than 0.1 wt. %, preferably more than 1 wt. %, more preferably more than 20 wt. % of binder (relative to the total weight of the composition).

[0048] In an embodiment of the invention, the composition comprises less than 60 wt. %, preferably less than 50 wt. %, more preferably less than 45 wt. % of mechanochemically carboxylated inorganic filler (based on the total weight of the composition), and / or less than 95 wt. %, preferably less than 90 wt. %, more preferably less than 80 wt. % of binder (based on the total weight of the composition).

[0049] In an embodiment of the present invention, there is provided a composition in which the ratio of mechanochemically carboxylated inorganic filler to binder, expressed in weight:weight, is in the range of 1:9 to 2:1, preferably 1:8 to 1:1, more preferably 1:6 to 5:6.

[0050] In an embodiment of the present invention, the composition comprises 5 to 70 wt. %, preferably 10 to 60 wt. %, more preferably 20 to 50 wt. % of a mechanochemically carboxylated inorganic filler (based on the total weight of the composition), and 30 to 95 wt. %, preferably 40 to 90 wt. %, more preferably 50 to 80 wt. % of a binder (based on the total weight of the composition).

[0051] In an embodiment of the invention, the composition contains less than 5 wt. % water (based on the total weight of the composition), preferably less than 1 wt. %, more preferably less than 0.1 wt. %. The water content is suitably determined from the mass loss up to 120°C measured by TGA-MS following a temperature curve from room temperature to 800°C at 10°C / min.

[0052] In an embodiment of the present invention, the composition comprises a mechanochemically carboxylated inorganic filler and a binder.

[0053] In a further aspect, the present invention provides a method for obtaining the compositions described herein, such method comprising the steps of: (i) providing a mechanochemically carboxylated inorganic filler as described herein; (ii) providing a binder selected from cement, asphalt, and combinations thereof, as described herein; and (iii) combining the mechanochemically carboxylated inorganic filler of step (i) above with the binder of step (ii) above.

[0054] In a further aspect, the present invention provides a method for obtaining concrete, said method comprising the steps of: (i) providing a composition described herein; (ii) preparing construction aggregate; and (iii) contacting, preferably mixing, the composition of step (i) above with the construction aggregate of step (ii) above.

[0055] In an embodiment of the present 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 a preferred embodiment, the construction aggregate is an aggregate defined in EN 13043 (2002), EN 13383 (2019), EN 12620 (2013), or EN 13242 (2013), preferably an aggregate defined in EN 12620 (2013).

[0056] In a preferred embodiment of the present invention, step (iii) further comprises contacting, preferably mixing, the composition of step (i) with the construction aggregate of step (ii) and water. According to the present invention, the composition of step (i), the construction aggregate of step (ii), and the water may be contacted, preferably mixed, substantially simultaneously, or may be contacted, preferably mixed, in stages, with the composition of step (i) first contacted, preferably mixed, with the water and then contacted, preferably mixed, with the construction aggregate of step (ii).

[0057] In another aspect of the present invention there is provided a concrete obtainable by the method for obtaining a concrete described herein.

[0058] In another aspect of the present invention, there is provided the use of the mechanochemically carboxylated inorganic fillers described herein. Use as a filler in the binders described herein; Use as a partial replacement of the binders described herein in concrete; · Use to increase the compressive strength of concrete; Use to improve the durability of concrete; or ·Use to improve the durability of concrete by reducing chloride permeability and / or porosity.

[0059] It will be understood by those skilled in the art that the embodiments of the invention described herein, with respect to the characteristics of the composition, in particular the mechanochemically carboxylated inorganic filler, or with respect to the characteristics of the binder, are applicable to the methods of obtaining said compositions described herein and to the uses of the mechanochemically carboxylated inorganic fillers described herein.

[0060] In a further aspect, the present invention provides a method for obtaining a mechanochemically carboxylated inorganic filler, said method comprising the steps of: a) providing a solid feedstock comprising a silicate mineral as described herein, said solid feedstock having a BET surface area of ​​0.01 m 2 / g and particulate matter with a D50 in the range of 0.1 to 5000 μm; b) providing an oxidizing gas comprising CO2 as described herein; c) feeding the solid raw material and the oxidizing gas into a mechanical stirring device; and d) subjecting said solid feedstock material to the mechanical stirring operation described herein in said mechanical stirrer unit in the presence of said oxidizing gas, inert medium, and transition metal oxide catalyst at an oxidizing gas pressure of greater than 1 atm to obtain a mechanochemically carboxylated inorganic filler; wherein the CO content of the mechanochemically carboxylated inorganic filler is greater than 1 wt. % (based on the total weight of the mechanochemically carboxylated inorganic filler), as determined from the mass loss at or above 120°C measured by TGA-MS following a temperature curve from room temperature to 800°C at 10°C / min and then cooling to room temperature at 15°C / min. In a preferred embodiment, the inert media, preferably inert grinding or milling media, is coated with the transition metal oxide catalyst. [Example]

[0061] The BET surface area, BJH desorption cumulative pore surface area, and desorption average pore diameter (4V / A by BET) were determined at a temperature of 77 K using samples weighing 0.5–1 g that had been heated to 400 °C during the desorption cycle prior to surface area analysis.

[0062] Particle size distribution measurements were performed using a Fritsch Analysette 22 Nanotec using the Fraunhofer theory.

[0063] The inorganic (SiO2, Al2O3, Fe2O3 and CaO) contents were determined by X-ray fluorescence spectroscopy using a Bruker Tracer 5G.

[0064] The CO2 content was determined from the mass loss above 120°C measured by TGA-MS using a Setaram TAG 16 TGA / DSC dual chamber balance coupled with an Ametek Dycor Proline MS. Samples of 0.1–2 g were heated from room temperature to 800°C at 10°C / min, then cooled to room temperature at 15°C / min.

[0065] Compressive strength was tested in accordance with ISO1920:2005 Part 4.

[0066] Example 1 Mechanochemically carboxylated fly ash was prepared by placing a 10 g sample of fly ash in a pressure cell along with 500 g of titanium dioxide-coated inert media (stainless steel balls). The cell was pressurized to 1 MPa (9.87 atm) and placed in a high-energy ball mill, rotating at 5000 rpm for 48 hours. The reaction was initiated at room temperature and was not heated or cooled.

[0067] Example 2 Two raw fly ash samples, Samples A and B, were mechanochemically carboxylated (treated) as in Example 1, with variations in mechanical agitation and CO pressure to yield products with the properties shown in the table below. Raw Sample A was obtained from a coal plant in Genesee, Alberta (Canada) and meets the requirements of Class F of ASTM C618 (2019). Raw Sample B was obtained from a coal plant in Civitavecchia (Italy). Raw Sample C was obtained from a coal plant in Cordomé (France). The raw fly ash samples B and C are generally poor quality fly ash and are unsuitable for use as concrete fillers at concentrations greater than 10% by weight.

[0068] [Table 1]

[0069] Mechanochemically carboxylated fly ash A and B were mixed with Portland cement in a weight:weight ratio of 1:5 (filler:cement) and used as fillers.

[0070] The resulting mixture of mechanochemically carboxylated fly ash and Portland cement was mixed with fine gravel and water (the same ratio was used for all samples) to obtain concrete slurries. The compressive strength of the resulting concrete was measured after 2, 7, and 28 days.

[0071] For comparison, similar concrete slurries were prepared using raw fly ash samples A and B and pure Portland cement.

[0072] [Table 2]

[0073] As can be seen from compressive strength measurements, the mechanochemically carboxylated inorganic fillers of the present invention provide unexpectedly large performance improvements compared to untreated materials (such as fly ash). Even more surprisingly, the mechanochemically carboxylated inorganic fillers of the present invention have been found to even outperform pure cement blends.

Claims

1. A composition comprising a mechanochemically carboxylated inorganic filler and a binder selected from the group consisting of cement, asphalt, and combinations thereof, The mechanochemically carboxylated inorganic filler can be prepared by the following steps: a) providing a solid raw material containing silicate minerals, the solid raw material having a BET surface area of ​​0.01 m ２ / g and a particulate material with a D50 in the range of 0.1 to 5000 μm; b) CO ２ providing an oxidizing gas comprising: c) feeding the solid source material and the oxidizing gas into a mechanical stirring device; 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 a mechanochemically carboxylated inorganic filler; The mechanochemically carboxylated inorganic filler CO ２ a content of more than 1% by weight (based on the total weight of the mechanochemically carboxylated inorganic fillers), The CO ２ The content is determined from the mass loss above 120°C measured by TGA-MS following a temperature curve ramping from room temperature to 800°C at 10°C / min, then ramping down to room temperature at 15°C / min; the mechanical agitation operation in step d) comprises grinding or milling; The mechanochemically carboxylated inorganic filler has a D90 in the range of 20 to 100 μm and / or a D50 in the range of 0.5 to 50 μm.

2. 2. The composition of claim 1, wherein the solid raw material comprises or consists of one material, preferably fly ash, selected from the group consisting of pyroxene, hydrous magnesium silicate, talc, serpentine, olivine, fly ash, bottom ash, and combinations thereof.

3. 3. The composition of claim 2, wherein the solid feedstock comprises or consists of fly ash.

4. The composition according to any one of claims 1 to 3, wherein the mechanochemically carboxylated inorganic filler has a D50 in the range of 1 to 25 μm.

5. 5. The composition of any one of claims 1 to 4, wherein the acidifying gas comprises greater than 90 mole % CO2.

6. The step d) It is carried out at a pressure of more than 3 atm, carried out at a temperature below 100°C, and / or The composition of any one of claims 1 to 5, wherein the composition is heated for at least 1 hour.

7. The composition of claim 6, wherein step d) is carried out for at least 1 hour.

8. The composition of claim 7, wherein step d) is carried out for at least 8 hours.

9. The composition of any one of claims 1 to 8, wherein the binder is cement.

10. 10. The composition of any one of claims 1 to 9, comprising: more than 5 wt.% of said mechanochemically carboxylated inorganic filler (relative to the total weight of the composition); and more than 20 wt.% of said binder (relative to the total weight of the composition).

11. 11. The composition of any one of claims 1 to 10, comprising 10 to 50 wt% of said mechanochemically carboxylated inorganic filler (based on the total weight of the composition) and 40 to 90 wt% of said binder (based on the total weight of the composition).

12. A method for producing the composition of any one of claims 1 to 11, comprising the steps of: (i) providing a mechanochemically carboxylated inorganic filler according to any one of claims 1 to 8; (ii) providing a binder selected from cement, asphalt, and combinations thereof; and (iii) combining the mechanochemically carboxylated inorganic filler of step (i) with the binder of step (ii).

13. A method for producing concrete, comprising the steps of: (i) providing a composition according to any one of claims 1 to 11; (ii) preparing a construction aggregate; and (iii) mixing the composition of step (i) with the construction aggregate and water of step (ii).

14. Concrete obtainable by the method according to claim 13.

15. Use of the mechanochemically carboxylated inorganic filler according to any one of claims 1 to 8, Use as a filler in a binder selected from the group consisting of cement, asphalt, and combinations thereof; Use as a partial replacement of a binder in concrete, said binder being selected from the group consisting of cement, asphalt, and combinations thereof; Use to increase the compressive strength of concrete; Use to improve the durability of concrete; or Use to improve the durability of concrete by reducing chloride permeability and / or porosity.

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