Accelerated mineral carbonation and manufacturing of concrete products

Abstract

A process for preparing supplementary cementitious materials (SCMs) involves milling silica-based feedstocks in a carbon dioxide (CO2)-rich environment. In particular, the process includes providing a silica-based feedstock in an aqueous solution within a milling apparatus, and introducing CO2 into the aqueous solution before or during milling. The process transforms the feedstock into a microstructurally activated, passive CO2 sequestering component that can be used as SCMs in cement mixtures.

Description

Atty. Ref. No. 0073605-001123ACCELERATED MINERAL CARBONATION AND MANUFACTURING OF CONCRETE PRODUCTSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 761,389, which was filed on February 21, 2025. The entirety of this application is incorporated by reference herein.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH DEVELOPMENT

[0002] This invention was made with government support under Grant No. 2020-38502-32916 awarded by the United States Department of Agriculture. The Government has certain rights in the inventionFIELD

[0003] The present disclosure pertains to sustainable cementitious materials and carbon capture technologies, particularly to processes that enhance the microstructure and carbon sequestration capacity of silica-based materials, such as those containing calcium and magnesium.BACKGROUND

[0004] The concrete industry is a significant contributor to global carbon dioxide (CO2) emissions, accounting for approximately 7-8% of the total emissions. This substantial environmental impact primarily stems from the production of cement, particularly ordinary Portland cement (OPC), which involves the calcination of limestone (calcium carbonate) into lime (calcium oxide). This process releases a large volume of CO2, making it a critical target for decarbonization efforts. As the world seeks to meet the climate targets set by the ParisAtty. Ref. No. 0073605-001123Agreement, reducing the carbon footprint of cement production has become an urgent challenge for the construction and materials industries.

[0005] One promising approach to mitigating these emissions involves the use of supplementary cementitious materials (SCMs), which can partially replace OPC in concrete formulations. SCMs such as fly ash and steel slag are currently the most widely used, owing to their pozzolanic or hydraulic reactivity, which enables them to contribute to the strength and durability of concrete while reducing the amount of OPC required. Pozzolanic reactivity involves the reaction of reactive silica or alumina with calcium hydroxide (portlandite) produced during cement hydration, forming calcium silicate hydrate (C-S-H) gels that contribute to concrete strength. Hydraulic reactivity, on the other hand, involves SCMs that can react directly with water to produce similar binder gels. However, the supply of traditional SCMs like fly ash and steel slag is diminishing, prompting the need for alternative materials that can fulfill similar roles.

[0006] To qualify as low-CCh SCMs, these alternative materials must not emit significant CO2 during their production, particularly avoiding high-temperature processes, such as thermal activation above 900°C, which can cause calcination of calcium carbonate and release CO2. Additionally, in the United States, SCMs used in concrete must meet standards set by ASTM standards, such as ASTM Cl 945.SUMMARY

[0007] We have developed a new approach for integrating CO2 capture and mineralization within SCMs to address the dual challenges of reducing greenhouse gas emissions and supplementing SCM supply in the concrete industry. Specifically, we have explored the use of high-energy milling of silica-based materials within a CCh-rich environment (i.e., “mechanocarbonation”) to produce highly reactive, low-CCh SCMs capable of sequestering CO2 whileAtty. Ref. No. 0073605-001123enhancing concrete performance. The process can also leverage abundant resources, such as silicate rocks or industrial waste products, as sustainable precursors for both mineral carbonation and SCM production.

[0008] A key result of the mechano-carbonation process is the transformation of inert silica into a more reactive form, facilitating the use of the product material as an SCM. Additionally, the process induces carbon mineralization reactions, promoting the formation of carbonates and enhancing pozzolanic reactivity. Ultimately, the simultaneous transformation of silica into reactive forms and the formation of carbonates make the process innovative and enable environmentally friendly SCM production.

[0009] Ultimately, this approach may not only take advantage of readily available resources but also aligns with global decarbonization efforts by providing a scalable, mineral-based method for CO2 removal and sustainable cementitious material production.

[0010] In an exemplary embodiment, a process for forming a supplementary cementitious material includes providing a silica-based feedstock in an aqueous solution within a milling apparatus; milling the silica-based feedstock; and injecting CO2 gas into the aqueous solution before or during milling to form the supplementary cementitious material.

[0011] In some embodiments, the CO2 gas is injected via a bottom injection port of the milling apparatus.

[0012] In some embodiments, the silica-based feedstock is selected from the group consisting of a mafic rock, an ultramafic rock, an industrial waste product, and a metallurgical slag.

[0013] In some embodiments, the silica-based feedstock is basalt.

[0014] In some embodiments, the silica-based feedstock includes calcium and magnesium.Atty. Ref. No. 0073605-001123

[0015] In some embodiments, a ratio of milling media within the milling apparatus and the silica-based feedstock is between 5:1 and 400:1.

[0016] In some embodiments, the milling apparatus operates at a rotational speed less than 500 rpm.

[0017] In some embodiments, the process further includes filtering the supplementary cementitious material to separate the milling media.

[0018] In some embodiments, the process further includes drying the filtered supplementary cementitious material.

[0019] In some embodiments, the supplementary cementitious material has a higher surface area than the silica-based feedstock.

[0020] In some embodiments, the supplementary cementitious material has a higher porosity than the silica-based feedstock.

[0021] In some embodiments, the milling apparatus is a vertical attrition mill.

[0022] In an exemplary embodiment, a supplementary cementitious material is formed from the method described above.

[0023] In some embodiments, the silica-based feedstock is selected from the group consisting of a mafic rock, an ultramafic rock, a concrete waste product, and a metallurgical slag.

[0024] In some embodiments, the silica-based feedstock is basalt.

[0025] In some embodiments, the silica-based feedstock includes calcium and magnesium.

[0026] In an exemplary embodiment, a concrete mixture includes the supplementary cementitious material described above.

[0027] In some embodiments, the concrete mixture further includes ordinary Portland cement.Atty. Ref. No. 0073605-001123

[0028] Further features, aspects, objects, advantages, and possible applications of the present disclosure will become apparent from a study of the exemplary embodiments and examples described below, in combination with the Figures, and the appended claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, aspects, features, advantages, and possible applications of the present innovation will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings. Like reference numbers used in the drawings may identify like components.

[0030] FIG. 1 is a flowchart demonstrating an exemplary method of producing SCMs.

[0031] FIG. 2 is a diagram of an exemplary milling apparatus used to mill feedstock in a CO2-rich environment.

[0032] FIG. 3 shows the mineralogy of basaltic fine samples before and after milling, each box representing different milling parameters. Symbols correspond to mineral phases identified as follows: Co - Corundum AI2O3, Cl - Clinochlore Mg2.45Ali.iSii.45O5(OH)4, La - Labradorite Nao.25Cao75Al175Si2.25O8, Q - Quartz SiO2, Di - Diopside Ko.o73Nao.o23Cao.8Mgo.95Cro.o7Feo.o6Alo.o2Si206, C — Calcite Ca(CO3), and M — Muscovite KA12(AlSi3Oio)(F, OH)2.

[0033] FIG. 4 shows an amorphous phase examination of basalt samples before and after milling within the 5 and 2520 range through X-ray diffraction. Corundum peaks are aligned between the 40 to 7029 range, displaying a shift in or decrease in amorphous hump in 40 ball to powder ratio (b:p) samples when compared to 10 b:p samples and unprocessed (plain) basaltic fines.

[0034] FIG. 5 shows inductively coupled plasma mass spectrometry (ICP-MS) of Mg released into the solution throughout high-energy milling of basalt with CO2. Samples were taken atAtty. Ref. No. 0073605-001123minutes 1, 3, 5, 7, 9, 11, 13, 15, 20, 30, 60, 90, and 180, with the extracted sample replaced with DI water to maintain a constant liquid to solid ratio.

[0035] FIG. 6 shows ICP-MS of Si released into the solution throughout high-energy milling of basalt with CO2. Samples were taken at minutes 1, 3, 5, 7, 9, 11, 13, 15, 20, 30, 60, 90, and 180.

[0036] FIG. 7 shows ICP-MS of Ca released into the solution throughout high-energy milling of basalt with CO2. Samples were taken at minutes 1, 3, 5, 7, 9, 11, 13, 15, 20, 30, 60, 90, and 180.

[0037] FIG. 8 shows ICP-MS of Fe released into the solution throughout high-energy milling of basalt with CO2. Samples were taken at minutes 1, 3, 5, 7, 9, 11, 13, 15, 20, 30, 60, 90, and 180.

[0038] FIG. 9 shows the particle size distribution of plain basalt when compared to particle size distribution of mechano-carbonated basalt at different b:p ratios and rpms. Plain basalt had a Dv(50) of 24.5pm and a Dv(90) of 73.8pm, 10 b:p 250 rpm had aDv(50) of 9.51pm and a Dv(90) of 60.3pm, 40 b:p 250 rpm had a Dv(50) of 29.8pm and a Dv(90) of 764pm, 10 b:p 500 rpm had a Dv(50) of 14.8pm and a Dv(90) of 235pm, and 40 b:p 500 rpm had a Dv(50) of 307pm and aDv(90) of 879pm.

[0039] FIG. 10 and FIG. 11 are scanning electron microscopy (SEM) images of basalt after mechano-carbonation at 2500x magnification for size comparison, along with individually focused images to display the surface characteristics of the basalt, noting the increase in surface roughness and bright spots in processed basalt images due to the increase in surface area that requires covering, as the iridium coating remained a consistent depth for all samples. The scale bars in FIG. 10 are 50 pm, and the scale bars in FIG. 11 are 10 pm.

[0040] FIG. 12 shows scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS) of mechano-carbonated basalt, with EDS scans of unprocessed basalt. The particlesAtty. Ref. No. 0073605-001123were scanned for Si, Mg, Fe, C, Ca, and Al, with point EDS analysis on particles that showed potential to be carbonates, or of specific points of interest.

[0041] FIG. 13 shows SEM-EDS of mechano-carbonated basalt, with EDS scans of 250rpm 10 b:p ratio. The particles were scanned for Si, Mg, Fe, C, Ca, and Al, with point EDS analysis on particles that showed potential to be carbonates, or of specific points of interest.

[0042] FIG. 14 shows SEM-EDS of mechano-carbonated basalt, with EDS scans of 250rpm 40 b:p ratio. The particles were scanned for Si, Mg, Fe, C, Ca, and Al, with point EDS analysis on particles that showed potential to be carbonates, or of specific points of interest.

[0043] FIG. 15 shows SEM-EDS of mechano-carbonated basalt, with EDS scans of 500rpm 10 b:p ratio. The particles were scanned for Si, Mg, Fe, C, Ca, and Al, with point EDS analysis on particles that showed potential to be carbonates, or of specific points of interest.

[0044] FIG. 16 shows SEM-EDS of mechano-carbonated basalt, with EDS scans of 500rpm 40 b:p ratio. The particles were scanned for Si, Mg, Fe, C, Ca, and Al, with point EDS analysis on particles that showed potential to be carbonates, or of specific points of interest.

[0045] FIG. 17 shows a thermo-gravimetric analysis of plain basalt with mechano-carbonated basalt, displaying the variation in b:p ratio and how the carbonation extent and thermal decomposition pattern varies between 0-850°C. 40 b:p ratio samples report a -6% decrease in normalized weight at 850°C, with 10 b:p samples reporting a -4.5% decrease in normalized weight at 850°C. Unprocessed basalt reported a decrease of -3.5% in normalized weight at 850°C.

[0046] FIG. 18 shows a thermo-gravimetric analysis and derivative curves of plain basalt compared to 10 b:p, 250 rpm mechano-carbonated basalt, displaying the variation in derivatives and weight loss curves between 25-850°C.Atty. Ref. No. 0073605-001123

[0047] FIG. 19 shows a thermo-gravimetric analysis and derivative curves of plain basalt compared to 40 b:p, 250 rpm mechano-carbonated basalt, displaying the variation in derivatives and weight loss curves between 25-850°C.

[0048] FIG. 20 shows a thermo-gravimetric analysis and derivative curves of plain basalt compared to 10 b:p, 500 rpm mechano-carbonated basalt, displaying the variation in derivatives and weight loss curves between 25-850°C.

[0049] FIG. 21 shows a thermo-gravimetric analysis and derivative curves of plain basalt compared to 40 b:p, 500 rpm mechano-carbonated basalt, displaying the variation in derivatives and weight loss curves between 25-850°C.

[0050] FIG. 22 shows a Fourier-Transform Infrared Spectroscopy (FT-IR) analysis of plain basalt compared to mechano-carbonated basalt, with absorbance matched at 4000cm'1and the silica peak matched at -965cm'1. No significant changes in carbonate content were determined, with the main structural changes occurring at -586cm'1, -629cm'1, -874cm'1, and -965cm'1.

[0051] FIG. 23 shows confirmation of CaCCh formation via X-ray diffraction (XRD), with the only two phases detected in each sample being Ca - Calcite Ca(COs) and A - Aragonite Ca(COs). On the right, the growth of CaCOs over time within the basaltic solution and solid is shown. Note that the initial decrease is due to no carbonate formation in the solution, and a decrease in carbonate formation is shown in the thermogravimetric analysis (TGA) curves between carbonate decomposition temperatures.

[0052] FIG. 24 shows the isothermal calorimetry of processed and unprocessed basalt, mixed as an SCM with calcium carbonate and calcium hydroxide in a potassium solution according to ASTM C1897.DETAILED DESCRIPTIONAtty. Ref. No. 0073605-001123

[0053] The following description illustrates exemplary embodiments and methods of use that are presently contemplated for implementing the present invention. This description is not intended to be limiting, but rather to elucidate the general principles and features of various aspects of the invention. The scope of the invention is not restricted by this description.

[0054] Embodiments relate generally to a process for producing supplementary cementitious materials (SCMs) derived from silica-based feedstocks. In particular, the process transforms these feedstocks into microstructurally activated, passive carbon dioxide (CO2) sequestering components that can be used as IOW-CO2 SCMs in cement mixtures. The resulting materials, after a period of passive carbonation, can be characterized by their microstructural refinement, high surface area, and stable mineral carbonate phases, which enable efficient CO2 sequestration and improved reactivity in cementitious systems.

[0055] Unless otherwise specified, all technical and scientific terms used herein have the meanings commonly understood by persons skilled in the art to which this invention pertains.

[0056] As used herein, the terms “silica-based feedstocks” or “silica-based materials” refer broadly to materials that contain silica (SiCh). These materials may vary in mineralogy, particle size, microstructure, etc., but are capable of undergoing mechanical activation and passive carbonation (i.e., “mechano-carbonation”) to produce reactive materials.

[0057] Referring to FIG. 1, the process for preparing SCMs involves milling silica-based feedstocks in a CCh-rich environment. Specifically, the process includes providing a silica-based feedstock in an aqueous solution within a milling apparatus, and introducing CO2 into the aqueous solution before or during milling.

[0058] Referring to FIG. 2, the milling apparatus 102 mills the silica-based feedstocks by imparting mechanical energy to the materials. The milling apparatus 102 can be a high-energyAtty. Ref. No. 0073605-001123device, such as an attrition mill, a planetary ball mill, or a similar device. The milling apparatus 102 can include a chamber 104 with milling media 106, such as milling balls, and an aqueous solution (not shown), contained therein. The milling apparatus can also include a rotating mechanism(s) 108 configured to move and / or agitate the feedstock and milling media 106. The mechanism(s) 108 can include, but are not limited to, one or more rotating arms or fins configured to move the feedstock and milling media 106.

[0059] The chamber 104 can be fitted with an injection port 110, which allows for the introduction of gases such as CO2 directly into the chamber 104 and solution. The position of the injection port 110 is not particularly limited, so long as the injection port 110 is positioned beneath the free surface of the solution within the chamber 104. For example, the injection port 110 can be a bottom injection port (e.g., positioned within the bottom surface of the chamber 104) or a side injection port (e.g., positioned within a side wall of the chamber 104). In particular, a bottom injection port may ensure that the injected gas is uniformly distributed throughout the chamber 104 and solution.

[0060] The chamber 104 can be equipped with temperature control measures to maintain a desired operational temperature range. Controlling the temperature of the chamber may prevent thermal effects that could otherwise influence microstructural evolution and carbonation kinetics.

[0061] The silica-based feedstocks may be any material that includes silica, such as silicate rocks (e.g., mafic rocks, ultramafic rocks, basalt, etc.), industrial waste products (e.g., Portland cement containing products), metallurgical slags, or similar materials. In some embodiments, the silica-based feedstocks advantageously contain calcium and / or magnesium.

[0062] The feedstocks may be added to the milling apparatus in particulate form, such as powders or small granules. The particulate form of the materials may maximize the surface areaAtty. Ref. No. 0073605-001123of the materials and facilitate microstructural activation by providing more surfaces for interaction with the gas.

[0063] Before or during milling, CO2 gas can be introduced into the milling apparatus 102, such as directly into the chamber 104 or aqueous solution, to provide a CCh-rich environment. The pressure at which CO2 is introduced is not limited by chemistry but may be determined by design and / or rating of the milling apparatus. Pressure regulation may be achieved through a controlled, continuous flow of CO2 passing through the chamber 104 via an inlet (e.g., injection port 110) and outlet (not shown) system, including a control valve that can permit outflow of reacted gas, thereby maintaining stable chamber pressure. This approach contrasts with other existing methods that may introduce a fixed quantity of gas prior to milling and rely on passive reaction over time. The continuous, controlled gas flow can allow for real-time adjustment of process conditions, which may enhance the efficiency and stability of mineralization. Moreover, the pressure involved may be lower than those used in other existing methods processes, which can simplify engineering requirements, reduce energy input, and improve safety.

[0064] Throughout the milling process, the CO2 reacts with dissolved calcium and magnesium ions, which were liberated from the feedstock materials as a result of the milling, thus leading to formation of carbonate-rich materials with carbonates such as calcite and aragonite. This mineralization process can occur gradually, enabling passive CO2 sequestration without the need for high-temperature calcination or other energy-intensive steps. Put differently, the potential for carbonate content due to liberated ions may increase with longer milling times and higher milling intensities occurring from passive mineralization.

[0065] We have found that milling parameters can affect the microstructural characteristics of the products. The ratio between the milling media and the silica-based feedstocks provided in theAtty. Ref. No. 0073605-001123chamber 104, referred to herein as the ball-to-powder (b:p) ratio, may be adjustable depending on desired microstructural and carbonation outcomes. For example, larger b:p ratios may enhance particle size reduction and carbonate formation but may also promote particle agglomeration.

[0066] In some embodiments, the b:p ratio may be between 5:1 and 400:1. As nonlimiting examples, the b:p ratio may be at least 5:1, at least 50:1, at least 100:1, at least 200:1, at least 300: 1, at least 350: 1, and / or the like. As further nonlimiting examples, the b:p ratio may be no greater than 400: 1, no greater than 350: 1, no greater than 300: 1, no greater than 200: 1, no greater than 100: 1, no greater than 50:1, and / or the like.

[0067] Further, the milling apparatus may be operated at variable rotational speeds, with higher speeds corresponding to increased energy input into the milling process.. For example, higher energy input into the process may lead to finer particle sizes, increased surface area, increased amorphous content, and enhanced ion release.

[0068] In some embodiments, the rotational speed may be less than 500 rpm. As nonlimiting examples, the rotational speed may be no greater than 500 rpm, no greater than 450 rpm, no greater than 400 rpm, no greater than 350 rpm, no greater than 300 rpm, no greater than 250 rpm, no greater than 150 rpm, and / or the like.

[0069] In some embodiments, the process may further include filtering or separating the product from the milling media, including for the use of further passive mineralization.

[0070] In some embodiments, the process may further include drying the product. For example, a dried product may be more easily used as an SCM in some applications.

[0071] The final product of the above-described process is a material that is microstructurally refined, amorphized, and mineralized with stable carbonate phases. The material exhibits aAtty. Ref. No. 0073605-001123higher surface area and porosity relative to the feedstock material, which is advantageous for pozzolanic reactions when incorporated into cementitious systems.

[0072] The formation of carbonate phases provides a stable, environmentally durable form of sequestered CO2, while microstructural refinement enhances the material’s reactivity as an SCM. In particular, carbonate-rich materials demonstrate improved pozzolanic reactivity, comparable to or exceeding that of traditional SCMs such as fly ash. The microstructure’s increased amorphous content and surface activity facilitate rapid hydration and strength development in concrete.

[0073] Accordingly, embodiments further relate to cement or concrete mixtures using the products as SCMs. The cement or concrete mixtures can further include, without limitation, ordinary Portland cement, limestone, pozzolanic materials, etc.

[0074] Ultimately, the carbonate phases within the material serve as a durable, stable form of CO2 sequestration, providing an environmental benefit by actively removing greenhouse gases from the atmosphere or industrial emissions in a passive manner. This passive mineralization process, occurring under near-neutral pH conditions, requires no additional energy input beyond the milling process.EXAMPLES

[0075] While the example is described as using basaltic fines as a calcium- and magnesium-containing feedstock, it is understood that other calcium- and magnesium-containing feedstock may similarly be used, and similar results can be expected. The scope of the present disclosure is in no way limited to the specific embodiments described in this example.

[0076] MaterialsAtty. Ref. No. 0073605-001123

[0077] The basaltic fines were obtained from Rock Dust LLC (Vermont, USA). The DI water was sourced on site within the ECoRE engineering building in State College, PA, with a conductivity of 6.6 pS / cm. The 100% CO2 gas was sourced from Fairless Hills, PA, and distributed by ProSpec by Linde. The CaCCh used in the R3 testing was sourced from Thermo Scientific at 99.0% purity, the calcium hydroxide was sourced from Thermo Scientific at 99.0% purity, and the potassium solution was prepared according to ASTM Cl 702 using KOH and K2SO4 from Thermo Scientific, both at 99.0% purity. The quartz control was sourced from Thermo Scientific at 99.9% purity. The corundum used for quantitative XRD was sourced from SkySpring Nanomaterials Inc. and has a D(50) of 3.5-15pm at 99.99% purity. The basaltic fines were initially characterized to determine oxide composition (Table 1), surface area and average pore diameter (Table 1), and particle size distribution (FIG. 9). All methods are described to determine the characterized parameters, which are detailed below.Table 1 : The oxide wt% of the basaltic fines as determined through X-ray fluorescence spectrometry (XRF)Atty. Ref. No. 0073605-001123* = loss on ignition, alongside surface area and average pore diameter determined through Nitrogen Absorption

[0078] Mechano-Carbonation of Basalt

[0079] The basaltic fines underwent mechano-carbonation in a modified Union Process S-l vertical attrition mill, which was water-cooled to maintain a jacket temperature of 20°C. The chamber held a CO2 atmosphere of 9psi for all mechano-carbonation experiments reported, with all reactions occurring in DI water. The CO2 was bubbled from underneath the mill into the milling chamber. The rpm was varied between 250 and 500 in a constant liquid to solid (L: S) ratio of 10. The ball-to-powder ratio (b :p) was 10 and 40 respectively, with zirconium milling balls used at 10mm diameter. Samples were taken for ICP sampling at time intervals 1, 3, 5, 7, 9, 11, 13, 15, 20, 30, 60, 90, and 180 minutes, with 5ml liquid samples extracted via syringe being replaced with 5ml of DI water. The timer was stopped for all sampling and restarted upon the mill being restarted. When sampling occurred, gas injection was stopped, the internal pressure of CO2 was released into the atmosphere, the lid was removed, the sample was taken, the lid was replaced, the mill was repressurized to 9psi, and the mill was restarted for mechano-carbonation.

[0080] Material Property Characterization

[0081] Isothermal Calorimetry . Isothermal Calorimetry was conducted using a TAM Air Isothermal Calorimeter according to ASTM Cl 897. Baseline measurements were taken before and after calorimetry. A 20mL disposable glass ampoule was used, with a 22.5g solid powder used and a 27g potassium solution. Both the ampoule and mixtures were separately heated to 40°C before calorimetry. Samples were mixed for 2 minutes at I600rpm, with 15.005g ± 0.005g of solution being used in the ampoule. Each sample was placed in the calorimeter at 3-4 minuteAtty. Ref. No. 0073605-001123intervals in ports Cl, C3, C6, and C8. This pattern was chosen to prevent cross chatter between substances of unknown reactivity.

[0082] Scanning Electron Microscopy . SEM was conducted using a Nanoscience Phenom ProX equipped with a thermionic Cerium Hexaboride (CeB6) source and a high sensitivity multi-mode backscatter electron (BSE) for microscopical and elemental characterization. The sample was placed in a Phenom Pharos STEM holder on a stage covered in carbon tape and examined under a 5kV electron beam. The sample was sputter-coated with a 5pm iridium coating for 30 seconds before testing. The basaltic rock was placed onto the sample stage by dusting the powder onto adhesive carbon tape, then by removing the excess material. EDS was conducted using the same device with a 15kV electron beam.

[0083] Thermal Gravimetric Analysis: Combined differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) was conducted using a TA Instruments TGA550 auto sampler under a nitrogen atmosphere of 20mL / min. Samples were pre-heated to 105°C for 24 hours before TGA. During TGA, samples were then heated at 10°C / min to l,000°C. Normalized weight loss was calculated using the traditional method of dividing the weight at a given temperature by the initial weight.

[0084] X-Ray Florescence: A Nexus CG Rigaku Nex DE benchtop X-ray Fluorescence spectrometer with a Pd X-ray tube and silicon drift detector were used to measure elemental composition of samples. To ensure sample homogeneity, 3-4 g of powdered sampleswere pelleted using Stryker 25 manual hydraulic press at 18 tons of pressure. Samples were held at this pressure for 30 seconds and then slowly released to minimize cracking to the surface of the pellets. Once formed, pellets were loaded into the XRF and put under a vacuum (<10 Pa) to reduce the background noise. The measurement conditions were set at 50kV voltage and 1 mAAtty. Ref. No. 0073605-001123current and secondary detectors Al, Mo, Cu, RX9 and Si which measurement time for each detector of 200, 100, 100, 100 and 300 seconds, respectively. The total measurement time per sample was about 13-15 min. The fundamental parameters (FP) program utilized LE (light element)-pellet method.

[0085] Surface Area and Particle Size Analysis: BET Surface Absorption Testing was conducted according to ASTM Cl 274 - 12 on a Mastersizer 3000 from Malvern Panalytical. It was conducted using a TriStar II Plus from Micrometrics using a nitrogen absorptive and an analysis bath temperature of 77.350 K. The particle size distribution was determined using laser diffraction according to ASTM E3340-22. The particle size range spanned from 0.01 pm to 3500 pm using a Mie scattering model.

[0086] X-Ray Diffraction: X-ray diffraction (XRD) was conducted using a Malvern Panalytical Empyrean 4 diffractometer, using a Cu radiation source, a PIXcel 3D detector, and a silicon zero background holder. A scan range of 5-70° 29, a step size of 0.026°, and a dwell time of 96 s was used. Phase identification was done in MDI Jade (V8.8) with the PDF-4+ (2024) diffraction database. Particle size controlled corundum was used as an internal standard and thus obtained a consistent peak intensity throughout all standards, allowing for the quantification of varying peak intensities between each sample. 10wt% of corundum was added to each sample and was gently mixed in a pestle and mortar for 20 seconds as to not reduce the particle size of the corundum.

[0087] pH: The pH was measured using a Mettler Toledo InLab Expert Pro Probe connected to a Mettler Toledo Seven Excellence Multiparameter pH unit. The pH was calibrated within ±0.05 of the buffer solutions used at a pH of 4, 7 and 10.

[0088] Inductively Coupled Plasma Mass Spectrometry (ICP-MS): ICP-MS was conducted on a Thermo Scientific iCAP 7400. Solution samples were filtered through a 0.45pm mesh filterAtty. Ref. No. 0073605-001123before analysis. 5ml samples were extracted from the mill via a plastic syringe, and 5ml DI water was added back into the mill after sampling.

[0089] Fourier Transform Infrared Spectroscopy (FT-IR). FT-IR was conducted on a Bruker vertex 80 spectrometer equipped with a liquid nitrogen cooled mercury cadmium telluride (MCT) detector. Experiments were conducted in Kretschmann ATR geometry at 35 degrees incident angle. A total of 400 scans at 6cm1resolution were averaged per spectrum, and absorbance was calculated by referencing to open circuit potential (OCP).

[0090] Extraction of Carbonates from Solution. The carbonates were extracted via metal spatulas from the surface of the liquid slurry and via a small glass beaker. The extracted carbonates and liquid were then centrifuged for 4 minutes at 4000rpm before the excess liquid was removed. The carbonates were placed in a drying oven at 105 °C for 24 hours before being lightly ground by a pestle and mortar before XRD analysis and weighing (matching the method described above). For total carbonate analysis, an Elementar Vario Max Cube CN analyzer (Ronkonkoma, NY) was used to determine the total Carbon in the sample.

[0091] Results and Discussion

[0092] Displayed in FIG. 3, mechano-carbonation of basaltic fines overall displayed a consistent decrease in peak intensity among all phases present in the basalt, with 40 b:p ratio runs showing an overall peak intensity decrease when compared to 10 b:p ratio runs and unprocessed (plain) basaltic fines. This variation in peak intensity is shown with labradorite at -2720, displaying a -80% decrease in peak intensity at 500rpm and 40 b:p ratio compared to plain basalt.Additionally, the diffraction intensity of clinochlore, labradorite, quartz, diopside, calcite, and lizardite minerals are observed to decrease by -50% in 40 b :p ratio runs when compared to plain basalt diffraction intensities. In contrast, at a lower b:p ratio of 10, the diffraction intensities onlyAtty. Ref. No. 0073605-001123decrease by -10-25% among the aforementioned phases; however, phases like clinochlore decreased 30% less than phases such as quartz.

[0093] This is seen within literature as a product of high-energy milling, where in the variation of b:p ratio, there is typically a non-linear relationship between b:p ratio and XRD peak area, with higher b:p ratios causing a greater decrease. As these higher b:p ratios (>20) cause the most significant decrease in diffraction intensities, this may suggest that more cations are present in the solution with higher b:p, based upon the relation between peak intensity decrease and availability of mineral ions in a solution within basalt. These minerals, such as Mg, Fe, and Ca ions, are removed from the basaltic fines and into the DI water solution, and subsequently react with the H2CO3 formed by the CO2 in the DI water to form mineral carbonates in the solution and on the surface of the basalt. However, not all crystalline peak intensities decrease equally as a function of milling intensity, namely the calcite phase, which reduces significantly across all b:p ratios.

[0094] This disproportionate removal of the calcite phase relates to the Mohs hardness of the material and the bond work index (BWi) of each mineral, as they are both lower for calcite than labradorite and quartz. As pure labradorite and quartz have a larger BWi than calcite, this demonstrates why the calcite phase is removed substantially by lower b:p ratios (10 b:p). This suggests that the BWi for milling may predict the effects of milling intensity and reduced diffraction intensities; however, it doesn’t account for the bond strength between different mineral phases in basalt, which may also be a significant factor in removing the calcite phase from basalt.

[0095] For the basalt explored and the subsequent phases identified, the Mohs hardness of each phase is: labradorite (6-6.5), quartz (7), clinochlore (2-2.5), diopside (5.5-6.5), and calcite (3).Atty. Ref. No. 0073605-001123Calcite and clinochlore have the greatest reduction in peak intensity and the lowest Mohs hardness, however, the large reduction in labradorite remains unexplained as it has a larger Mohs hardness compared to the aforementioned phases. This suggests that Mohs hardness and BWi are predictors of this peak intensity decrease, but don’t display the full trends in the peak intensity decrease. This may be in part because this mineral phase interaction can also be categorized by the Van der Waals forces. Additionally, specific mineral bonds (Si-Mg, Si-Ca) may reveal an important trend in the material fracture, but Mohs hardness still seems to present a sufficient generalized predictor of which phases will be removed from the milling process at which time, and thus, which phases will have a peak intensity decrease. With this decrease in peak intensity, additional trends emerge when comparing the amorphous phase of the processed basalt at 10 and 40 b:p when compared to plain basalt.

[0096] Shown through closer examination of the 5 and 2520 range in FIG. 4, there is a potential shift in or decrease within the amorphous hump of 40 b:p samples when compared to 10 b:p samples and unprocessed (plain) basalt. This is combined with a decrease in peak intensity shown previously amongst 40 b:p ratios; however, 500rpm 40 b:p shows an upwards shift in peak intensity amongst the whole spectrum. With this shift, all samples retain the same crystalline peak patterns and minimal shift in peaks compared to plain basalt. This shift or change in amorphous hump has been seen by Priyono within high-energy milled basalt in a Spex-8000 ball mill reactor, determined as an increase and widening of the wave pattern from 0-720 to 0-1029 after 120 minutes.

[0097] Throughout the high-energy milling process, the Si and Ca ions released into the solution tend to decrease or remain consistent in the solution beyond 60 minutes, with high b:p ratio samples releasing the greatest total (combined Mg, Si, Ca, and Fe) ppm of ions into the solutionsAtty. Ref. No. 0073605-001123overall. Shown in FIGS. 5-8, this stabilization is seen in Fe after 90 minutes, where the Fe ions released remain constant within the upper and lower bounds of 180 minutes and 60 minutes. However, the Fe release may be affected by contamination from milling media and from the mill wall lining (both Fe alloys), which may explain the increased variability in Fe ion release. This trend is not seen, however, in Mg ions, which continually increase over time within the solution. This is particularly present in the Mg release of 500rpm 40 b:p, where the Mg content in the solution almost doubles between 60 and 180 minutes compared to the first 60 minutes. This potentially originates from the bond strength of agglomeration that can occur in basalt, as Mg typically requires greater energy to bond to other elements compared to Ca, Fe, and Si.

[0098] The decrease in Ca, Fe, and Si mineral ion content between 60-90 may be due to agglomeration, an effect seen within high-energy milling literature and present in studies examining basaltic fines undergoing mechano-chemical effects. Additionally, regarding milling parameters, 250rpm 40 b:p releases a greater total (combined Mg, Si, Ca, and Fe) ppm of ions compared to 250rpm 10 b:p, but becomes difficult to differentiate if it releases more ions compared to 500rpm 10 b:p with Si and Ca. This may also be due to the agglomeration of ions back into the particles. This agglomeration can be revealed further through SEM analysis and particle size analysis, where changes in the particle through different milling parameters may further indicate these trends.Table 2: Brunauer-Emmett-Teller (BET) surface area, Langmuir surface area, and average pore size diameter, determined through nitrogen absorption. Note the Barrett-Joyner-Halenda (BJH) method for average pore size.Atty. Ref. No. 0073605-001123

[0099] As the b:p ratio increases, displayed in Table 2, the BET surface area also increases by 2-fold when comparing 10 b:p to 40 b:p, potentially due to the agglomeration of particles, yet the average pore size diameter remains inconsistent with the b:p ratio. However, the average pore size decreases with the presence of ball media in mechano-carbonation, which may indicate important nanoscale processes occurring during mechano-carbonation. This increase in BET surface area is also consistent with other high-energy basaltic fines milling over 1 hour. This variation of b:p ratio is also an important mechanical property as it can vary the efficiency of energy input to the efficiency of grinding output, which results in a non-linear relationship between milling time and increasing CO2 sequestration potential. To verify the agglomeration of particles affecting the BET surface area, further particle morphology and size analysis was conducted.Atty. Ref. No. 0073605-001123

[0100] Shown graphically in FIG. 9, increasing the b :p ratio to 40 contributes to the formation of particles with a Dv(90) of ~800pm compared to an initial Dv(90) of 73.8pm, suggesting the agglomeration of particles occurs as milling energy transfer increases. This variation is seen in the Dv(50) at 500rpm and 40 b:p ratio which increases compared to plain basalt to 307pm, in comparison to 500rpm and 10 b:p ratio where the Dv(50) decreases to 14.8pm.

[0101] It has been suggested that this agglomeration occurs due to mechano-chemical interactions forming bonds due to the high energy milling attrition process between dissolved mineral phases, but the author present that no satisfactory evidence of the specific nature of agglomerates was found within the literature. As the majority of this basalt’s oxide composition is silica (51%), this agglomeration through mechano-chemical activation may due to the formation of silica gels from the dissolution of silicates. This example’s XRD analysis in FIG. 3 shows the same decrease in peak intensity of silicate phases such as labradorite, clinochlore, quartz, and albite, suggesting the dissolution of silicates is also occurring. Through this continual removal of Si from the basaltic fines via mechano-carbonation, this could agglomerate into silica gels in the DI water milling solution. To further characterize these agglomerates, SEM and SEM-EDS analysis was conducted on the resulting agglomerates to determine if silica gels may have formed on the surface of the basalt, in addition to exploring the surface morphology of basalt and the formation of mineral carbonates.

[0102] SEM images in FIGS. 10 and 11 display the change in surface texture and the agglomeration of a multitude of smaller particles combined through high-energy milling, reflecting similar trends seen through the high-energy milling of ultramafic rocks. They also display the increase in BET surface area seen in Table 2. Additionally, these SEM imagesAtty. Ref. No. 0073605-001123indicate that the fracture and reforming process is occurring through the forced diffusion process occurring due to mechano-chemical interactions.

[0103] As displayed in FIGS. 12-16, the SEM-EDS results present the random distribution of mineral ions within the basaltic agglomerates, which varies with milling intensity and b:p ratio, while also displaying the potential presence of micro-carbonates formed on the surface of the agglomerates. For all samples, including plain basalt, the agglomerate examined remains a randomly dispersed mixture of mostly Si, Fe, and Mg, with ‘sunspots’ of elements of high intensity where a specific oxide has formed. Ca, however, was only observed on plain basalt, 500rpm 40 b:p and 250rpm 10 b:p, but not on the other samples. This may be due to an error in SEM-EDS not being able to differentiate between the similarly detectable wavelengths of different elements, and thus may not indicate a trend. Carbon, however, was weakly observed to be evenly distributed throughout all mechano-carbonated samples and not within plain basalt.

[0104] Through TGA shown in FIG. 17, an increased b:p ratio leads to significant structural changes, namely, an increase of structural water (1O5-3OO°C) through mechanocarbonation, along with the variation of MgCCh between 500-630°C and CaCCh between 600-850°C. These decomposition temperatures are modeled based upon Chiang and Pan’s ‘Modified TG-DTG Interpretation’ for thermo-gravimetric analysis. The carbonates observed are mainly MgCCh and CaCCh, yet the presence of FeCCh may be observed (300-350°C). Based upon weight % loss between the aforementioned MgCCh and CaCCh temperatures, ~0.5g per 250g basalt of CaCCh was removed from the basalt through the high-energy milling process. This removal of CaCCh was shown in previous XRD analysis, and supports that the calcite phase was liberated during mechano-carbonation. This, however, does not rule out the formation of carbonates, which are seen to form in the water solution over time. However, with furtherAtty. Ref. No. 0073605-001123exploration of carbonates required, there is a significant change in the formation of early-stage weight loss (<300°C) within the samples.

[0105] This change can be seen with comparison to ultra-mafic mechano-carbonation, but additionally within the analysis of the amorphous phase shift in XRD data in FIG. 3. While the wt% of plain basalt below 300°C minimally changes, the initial wt% dramatically changes for 40 b:p mechano-carbonated basalt, suggesting structural water is stored within basalt. This structural water change may be seen within XRD analysis in FIG. 4, showing a shifting of the amorphous phase in 40 b:p samples, compared to a consistent amorphous phase between plain basalt and 10 b:p samples. This could be further reflected in the TGA data, with a reduced binding of structural water in 10 b:p ratio samples when compared to 40 b:p ratio samples. This binding of structural water may not be optimal for certain applications, but could contribute to the material’s pozzolanic reactivity, and demonstrates the importance of controlling the b:p ratio for different desirable outcomes of SCMs produced. However, this early change could be through the formation of silica gels, which may be forming due to the agglomeration of Si within the samples shown via ICP (FIGS. 5-8). These results suggest the formation of structurally bound water or the creation of silica gels, and displays the importance of mechanical optimization of the milling process, as optimizing for CO2 sequestered may result in undesirable properties from mechano-carbonation. Thus, further study, through the analysis of derivative wt%, may indicate clearer trends in data.

[0106] Shown in FIGS. 18-21, the rate of change of weight % is greater (decreases at a greater rate) for 40 b :p samples when compared to 10 b:p samples through 400°C, and aligns with the release of mineral ions shown in ICP when relating to carbonate formation. This is seen up until 400°C, where the derivative curves align in all samples until 450°C, and then 40 b:pAtty. Ref. No. 0073605-001123samples do not follow the same peak decrease at around 500°C seen in plain basalt. This may be due to the removal of any MgCOs between 500-630°C or any trace phases of Mg at this temperature. This aligns with Mg release seen through ICP in FIG. 9, with high b:p ratios exhibiting the greatest release in Mg compared to low b:p ratios. Overall, it suggests that mineral carbonates (CaCOs and MgCOs) may have been liberated from the basaltic fines and are now present within the solution.

[0107] Following this derivative change of weight %, the initial peak change at 50-100°C is inconclusive, as although samples were dried at 105 °C for 24 hours, some water may be absorbed through the air in transfer to the TGA device. However, 40 b:p samples have a noticeably lower derivative weight % between 105 °C and 400°C, with a prominent peak at ~180°C for 40 b:p, 500 rpm. It is unclear through the literature what this peak may represent, but a similar peak at ~180°C has been investigating the pozzolanic characteristics of silica recovered from olivine. This may correspond to an amorphous silica phase formed or potentially a bound water phase, but no further explanation is given by the author. To investigate this further and to determine which phases are changing that display the structural changes shown in TGA, FT-IR was used.

[0108] Overall, the basalt before and after mechano-carbonation display similar wave patterns (shown in FIG. 22), and the overall pattern of this basalt resembles previously studied basaltic rock wave patterns with insignificant changes in where CO2 could be mineralized as CaCOs. Some changes, however, were displayed in the basalt in the ‘Fingerprint zone’, which is characterized in IR spectrometry at the low-frequency region of wave numbers from 1500 to 500 cm1. This zone is hard to characterize specific changes due to the precision of FT-IR at low wave numbers. The main molecular bond expressed in this region is the Si-0 molecular bond inAtty. Ref. No. 0073605-001123and around the 1000 cm1zone. This significant absorption in the 1000 cm1region may be associated with the formation of organo-silicate compounds -C-O-Si- (wave number 1072 cm ' ). Additionally, this can be associated with Si-O-Metal bonds present in basalt between 900 and 1000 cm or the Si-O-Si bond between 900 and 1250 cm'1. This peak is seen to decrease in width with milling, due to a decrease in silica content seen before / after milling through ICP of Si in the DI water solution. However, below 1000 cm'1, the main changes are seen with the increased peaks at -586 and -629 cm'1.

[0109] These changes may be associated with Al-based bonds due to this basalt’s high Al content at -15% shown through XRF. This may be seen at 570-590cm_1, with literature reporting short-range ordered aluminosilicates with varying Al: Si ratios, specific absorption bands within basalt at these wavelengths. This is associated with A1-0H bending vibrations that decrease with increasing Si content, suggesting 40 b:p 500rpm has a decreased Si content compared to other runs, shown through Si release in the solution in ICP (FIGS. 5-8). There is also evidence that this Al absorption peak may extend to -690cm'1, as throughout the literature it is difficult to differentiate the root cause of the -629cm'1peak displayed in FIG. 23. Overall, it is difficult to differentiate between specific peaks; however, the slight reduction in Si content due to ion dissolution alters the Si-Al bond, which may be observed in FT-IR analysis. Additionally, there may also be evidence of Si-0 bonded frameworks within the basalt, which may indicate an increase in reactivity due to the formation of silica gels. With this, minimal evidence of CO2 is observed to be sequestered within the basalt as CaCOa, however, CaCOa was observed heavily within the solution.

[0110] The formation of CaCOa over time in the solution (identified by XRD and manual extraction in FIG. 23) seems to occur through the degassing process, with the initial decrease inAtty. Ref. No. 0073605-001123CaCOs content in the basalt overtaken by the growth of CaCOs crystals in the solution. Current studies have yet to utilize basaltic fines with a CaCOs present before mechano-carbonation, however, within olivine, carbonate precipitation via exchange reaction and possibly a Sabatiertype CO2 hydrogenation has been displayed, forming under mechano-carbonation. The initial decrease in CaCOs content was determined through TGA in the basalt, which is reported in the supplementary information alongside total carbon analysis, where a 0.5g decrease in CaCOs was initially seen. However, leaving the basalt slurry in a lightly covered bucket over time, CaCCh crystals grew on the surface of the water, with 40 b:p ratio runs achieving a 1.75-2g increase in CaCOs content after 8 weeks. This CaCOs was determined through XRD after being skimmed from the surface and dried, which was determined to be a mix of calcite and aragonite. This growth was only seen in the liquid portion of the slurry, with the basalt sinking to the bottom of the covered bucket, with either FT-IR or TGA determining no growth of CaCOs within the basalt. This was additionally confirmed with total carbonate analysis in the supplementary information, showing an initial decrease in carbon content. However, due to the dissolved Ca2+in the water, along with the formation of carbonic acid (H2CO3) that dissociates into carbonate (CO32) and bicarbonate (HCO3 ), the assumed reaction is a degassing reaction. This general equation for calcium carbonate degassing and precipitation is Ca2++ 2 HCOsCaCOs + H2O + CO 2(aq). This follows the steps that 1. CO2 is dissolved in water (H2O) to form carbonic acid (H2CO3). 2. carbonic acid (H2CO3) dissociates into carbonate (CO32) and bicarbonate (HCO3 ), and 3. carbonate ions (CO32) interact with calcium (Ca2+) to precipitate calcium carbonate (CaCOs). Due to this mechanism of formation, the release of ions seems to correlate with the formation of CaCOs, however, the release of Mg ions may be prohibiting full CaCOs formation.Atty. Ref. No. 0073605-001123

[0111] With an increase in the b:p ratio, and with the subsequent increase in surface area, mechano-carbonated basalt displayed a 4-fold increase in reactivity when compared to unprocessed (plain) basalt, achieving a pozzolanic reactivity similar to that of fly ash, but markedly lower than steel slag. This is seen in FIG. 24, with 40 b:p ratio samples achieving ~160J / gSCM in heat released, compared to ~100J / gSCM with 10 b:p ratio, ~30J / gSCM with plain basalt, and ~25 J / gSCM quartz control, which is consistent with other R3 quartz references. The change in reactivity from b :p ratio may relate to the BET surface area, as with SCMs, increasing the BET surface area of pozzolanic materials improves the resulting pozzolanic reactivity. However, this reactivity increase may also be impacted through amorphized nanosized particles, such as silica gels and carbonates, that agglomerate on the surface of the basalt. However, it is clear throughout the data presented that mechanical parameters such as b:p ratio and rpm have dramatic contributions - both positive and negative - on factors affecting suitability to make a reactive yet carbon negative SCM.

[0112] Ultimately, this example shows the process of high-energy media milling in a CO2 pressurized environment to accelerate the formation of mineral carbonates can form CaCCfi while outputting reactive basaltic fines, improving pozzolanic reactivity as an SCM to that similar to fly ash. This CO2 mineralization was quantified to an estimated -50% increase in the formation of CaCCh within the basalt slurry, along with a 4-fold increase in reactivity determined through R3 isothermal calorimetry. This formation of mineral carbonates was confirmed by XRD, and results through the degassing of CO2 through the precipitation of Ca2+ions. This CaCOs was present as calcite and aragonite and was formed on the surface of the basalt slurry and not within the basalt. The mineral phases that contributed to this formation of mineral carbonates are displayed in XRD analysis to originate from Ca-bearing crystalline phases such asAtty. Ref. No. 0073605-001123labradorite and diopside, which showed decreases in peak intensity and were dissolved into the DI water milling solution. As these phases were removed, they agglomerated together due to the potential formation of silica gels or structurally bound water, seen through TGA and FT-IR.

[0113] It should be understood that modifications to the embodiments disclosed herein can be made to meet a particular set of design criteria. For instance, the number of or configuration of components or parameters may be used to meet a particular objective.

[0114] It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternative embodiments may include some or all of the features of the various embodiments disclosed herein. For instance, it is contemplated that a particular feature described, either individually or as part of an embodiment, can be combined with other individually described features, or parts of other embodiments. The elements and acts of the various embodiments described herein can therefore be combined to provide further embodiments.

[0115] It is the intent to cover all such modifications and alternative embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof.Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range, including the end points. Thus, while certain exemplary embodiments of the device and methods of making and using the same have been discussed and illustrated herein, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

Claims

Atty. Ref. No. 0073605-001123WHAT IS CLAIMED IS:

1. A process for forming a supplementary cementitious material, the process comprising:providing a silica-based feedstock in an aqueous solution within a milling apparatus; milling the silica-based feedstock; andinjecting CO2 gas into the aqueous solution before or during milling to form the supplementary cementitious material.

2. The process of claim 1, wherein the CO2 gas is injected via a bottom injection port of the milling apparatus.

3. The process of claim 1, wherein the silica-based feedstock is selected from the group consisting of a mafic rock, an ultramafic rock, an industrial waste product, and a metallurgical slag.

4. The process of claim 1, wherein the silica-based feedstock is basalt.

5. The process of claim 1, wherein the silica-based feedstock comprises calcium and magnesium.

6. The process of claim 1, wherein a ratio of milling media within the milling apparatus and the silica-based feedstock is between 5:1 and 400: 1.Atty. Ref. No. 0073605-0011237. The process of claim 1, the milling apparatus is operated at a rotational speed less than 500 rpm.

8. The process of claim 1, further comprising:filtering the supplementary cementitious material to separate the milling media.

9. The process of claim 8, further comprising:drying the fdtered supplementary cementitious material.

10. The process of claim 1, wherein the supplementary cementitious material has a higher surface area than the silica-based feedstock.

11. The process of claim 1, wherein the supplementary cementitious material has a higher porosity than the silica-based feedstock.

12. The process of claim 1, wherein the milling apparatus is a vertical attrition mill.

13. A supplementary cementitious material formed from the method of claim 1.

14. The supplementary cementitious material of claim 13, wherein the silica-based feedstock is selected from the group consisting of a mafic rock, an ultramafic rock, a concrete waste product, and a metallurgical slag.Atty. Ref. No. 0073605-00112315. The supplementary cementitious material of claim 13, wherein the silica-based feedstock is basalt.

16. The supplementary cementitious material of claim 13, wherein the silica-based feedstock comprises calcium and magnesium.

17. A concrete mixture comprising the supplementary cementitious material of claim 13.

18. The concrete mixture of claim 17, further comprising ordinary Portland cement.

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