Synthetic cementitious materials, methods, and system for concrete applications

Abstract

A synthetic supplementary cementitious material (SCM) includes a milled mixture (324) of two or more oxides (310, 312, 314, 316), wherein a first of the two or more oxides is silicon oxide (310), and a second of the two or more oxides is aluminum oxide (314). A structure of the milled mixture (324) was amorphized so that x-ray diffraction performed on the milled mixture (324) shows about 30 to 100 % of atom peaks being smaller than corresponding peaks of a non-amorphized structure of the two or more oxides.

Description

Attorney Docket No. 0339-003-WOSYNTHETIC CEMENTITIOUS MATERIALS, METHODS, AND SYSTEM FOR CONCRETE APPLICATIONSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 695,412, filed on September 17, 2024, entitled “SYNTHETIC CEMENTITIOUS MATERIALS VIA CONTROLLED REACTIONS WITH SAND, CLAY AND LIMESTONE,” the disclosure of which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTIONTECHNICAL FIELD

[0002] Embodiments of the subject matter disclosed herein generally relate to a system, compositions, and methods for manufacturing synthetic supplementary cementitious materials with less energy than the traditional cementitious materials, and more particularly, using one or more of silicon oxides, aluminum oxides, iron oxides, and alkaline and alkaline-earth oxides as precursors of the synthetic supplementary cementitious materials.DISCUSSION OF THE BACKGROUND

[0003] Cementitious materials, such as Portland cement, are foundational components in the construction industry. The Portland cement is widely used for producing concrete, mortar, and other building materials. However, the production ofconventional Portland cement is an energy-intensive process, which pollutes the environment and uses a large amount of resources.

[0004] The production of Portland cement is a complex, multi-stage process that transforms raw materials into a fine powder with specific hydraulic properties. The process is energy-intensive and involves high-temperature reactions (up to 1400 °C). The primary raw materials for cement production are limestone and a secondary material like clay or shale. These materials provide the essential chemical components of the Portland cement, e.g., calcium carbonate (CaCOa) from limestone, and silica (SiC ), alumina (AI2O3), and iron oxide (FeaOa) from the clay or shale. The raw materials are typically extracted from quarries. Large rocks are crushed into smaller pieces, then ground into a fine powder called “raw meal.” This step is important for ensuring a uniform chemical composition and efficient reactions in the next stage. However, this step already require a large amount of energy.

[0005] Next, the raw meal is fed into a large, rotating kiln, which is a cylindrical furnace tilted at a slight angle. As the kiln rotates, the material slowly moves towards the lower, hotter end. In the kiln, the raw meal is first dried to remove moisture. As the temperature rises, the limestone undergoes a process called calcination (around 900°C), where the calcium carbonate breaks down into calcium oxide (lime) and carbon dioxide (CO2). This step releases the majority of the cement industry's CO2 emissions. At the hottest part of the kiln (up to 1450°C), the materials partially melt and react to form new compounds. The calcium oxide reacts with the silica, alumina, and iron oxide to form clinker, which are dark, round pellets about the size of marbles. Some of the formed compounds are tricalcium silicate, dicalcium silicate,tricalcium aluminate, and tetracalcium aluminoferrite, which are responsible for cement's strength and setting properties.

[0006] Then, the hot clinker is cooled and moved to a grinding mill. The clinker is pulverized into an extremely fine powder. During this grinding process, a small amount of gypsum may be added. Gypsum plays a role in controlling the setting time of the cement. Without it, the cement would hydrate and harden almost instantly upon contact with water, making it unusable. The final product is the gray powder known as Portland cement.

[0007] The process discussed above is not only damaging for the environment because of the release of the CO2, but is also a power-hungry process, which means that producing the energy necessary for the hot kiln is further contributing to the global warming and also consuming scarce resources.

[0008] In response to these energy and environmental concerns, alternative or supplementary cementitious materials (SCMs) have been developed and utilized. The goal in making these materials is to partially replace the amount of Portland cement that is used for making the concrete, mortar, and other building materials. The most common SCM materials include industrial byproducts like ground granulated blast furnace slag (GGBFS) and fly ash. The GGBFS is a by-product from the iron industry. After collecting the quenched GGBFS particles, they are generally dried and ground to increase their reactive surface area and degree of amorphization. The fly ash is collected from flue gases in combustion processes and is mostly glassy aluminosilicate. Another SCM is kaolinitic clay, which is thermally treated at around 600-1000 °C to produce metakaolin (a well-established and highlyreactive SCM). Thermal treatment of clays or natural pozzolans contributes, at some degree, to CO2 emissions.

[0009] While the use of such SCMs may reduce the overall carbon footprint of the resulting concrete, their availability and consistency may be problematic. The supply of these materials is directly tied to the output of other industries or mining sites (e.g., for natural pozzolans and clays), which may be declining or geographically constrained. Furthermore, the chemical and physical properties of these products vary significantly depending on their source, which can introduce unpredictability into the performance of the final cementitious product.

[0010] Other approaches for reducing the amount of the Portland cement have focused on developing alternative binder systems. For example, alkali- activated materials, also known as geopolymers, utilize aluminosilicate source materials that are reacted with an alkaline solution to form a binding matrix. While these systems can offer certain performance characteristics, they present their own set of challenges. The highly alkaline activators used in these systems can be caustic and may require specialized handling procedures. Additionally, the setting times and strength development of geopolymer systems can be sensitive to curing temperatures and the specific chemical composition of the source materials, making their widespread adoption in various field conditions difficult.

[0011] Currently, the SCMs and associated methods discussed above are not enough for reducing the CO2 emissions and also for reducing the energy consumption associated with the manufacturing of the SCMs as their manufacturing processes are still energy intensive.SUMMARY OF THE INVENTION

[0012] According to an embodiment, there is a synthetic supplementary cementitious material (SCM) that includes a milled mixture of two or more oxides, where a first of the two or more oxides is silicon oxide, and a second of the two or more oxides is aluminum oxide. A structure of the milled mixture was amorphized so that x-ray diffraction performed on the milled mixture shows about 30 to 100 % of atom peaks being smaller than corresponding peaks of a non-amorphized structure of the two or more oxides.

[0013] According to another embodiment, there is a method for making a synthetic SCM, and the method includes providing two or more oxides, where a first of the two or more oxides is silicon oxide, and a second of the two or more oxides is aluminum oxide, forming a milled mixture by inducing amorphization through mechanochemistry to break a crystalline structure of the two or more oxides, wherein a structure of the milled mixture is amorphized so that x-ray diffraction performed on the milled mixture shows about 30 to 100 % of atom peaks being smaller than corresponding peaks of a non-amorphized structure of the two or more oxides, and heating the milled mixture to a temperature not higher than 850 °C to form the SCM.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0015] FIG. 1 is a table that illustrates existing SCM materials and their limitations;

[0016] FIG. 2 schematically illustrates chemical compositions of various SCM materials;

[0017] FIG. 3 schematically illustrates a reactor for imparting energy to a mixture of one or more oxides for making an SCM;

[0018] FIG. 4 schematically illustrates x-ray diffraction peaks for various SCM materials indicating various degrees of amorphization;

[0019] FIG. 5 is a table that illustrates various chemical compositions for energy efficient SCM materials;

[0020] FIG. 6 is a table that illustrates the possible concentrations for the two or more oxides in the SCM material of FIG. 5;

[0021] FIG. 7 is a table that illustrates the possible particle distributions for the two or more oxides in the SCM material of FIG. 5;

[0022] FIG. 8 is a graph that illustrates the particle size distributions for an energy efficient SCM material and existing SCM materials;

[0023] FIG. 9 illustrates the reactivity of various SCM materials compared with the SCM material made in FIG. 3; and

[0024] FIG. 10 is a flow chart of a method for manufacturing an SCM material as discussed in FIG. 3.DETAILED DESCRIPTION OF THE INVENTION

[0025] The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to SCM materials that include a combination of up to four materials. However, the embodiments to be discussed next are not limited to these four materials, but may be applied to other materials.

[0026] Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0027] According to an embodiment, a method and system for manufacturing SCMs at lower temperatures (lower than the current SCMs) includes mixing two or more precursors (e.g., silicon oxides, alkaline and alkaline-earth containing minerals, aluminum oxides, and iron oxides) and one solvent (for example, water) to form a mixture. The mixture is then processed, for example, by mechanochemistry, toinduce amorphization of the structure of the mixture. The amorphized structure is then the subject of a heating process (at temperatures lower than those used in the process of making the Portland cement) to enhance property materials of the mixture and to remove any possible solvent, which was used in the previous step. The product resulting from these steps is then milled to obtain a fine powder at the desired particle size distribution. This product is then used to replace a certain amount of the Portland cement in concrete related applications, e.g., between 10 and 40% of the original amount of Portland cement. In this way, less CO2 is generated and less energy is consumed. The method and system used for producing these advantageous SCSs are now discussed in more detail.

[0028] The inventors have realized that SCMs that generate less pollution and use less energy need to use techniques that are not typically used for the traditional SCMs. Also, these SCMs need to have high reactivity to react with the Portland cement and / or other materials when forming concrete or concrete related mixtures. To increase the reactivity of a substance, the crystalline structure of a precursor material needs to be broken, i.e., the structure of the precursor material needs to be amorphized.

[0029] In the context of these amorphized or disordered structures, understanding the roles of bridging oxygen (BO) atoms and non-bridging oxygen (NBO) atoms is necessary for explaining the differences in reactivity among various pozzolanic materials, such as silica fume, fly ash, and metakaolin. The relative proportions of BO and NBO atoms may be quantified using advanced analytical techniques like X-ray Photoelectron Spectroscopy (XPS), Nuclear MagneticResonance (NMR), Raman spectroscopy, and Fourier-Transform Infrared (FTIR) spectroscopy.

[0030] The BO refers to oxygen atoms that are bonded to two silicon (Si) or aluminum (Al) atoms, forming linkages like Si-O-Si or Si-O-AL These oxygen atoms are integral components of the three-dimensional aluminosilicate network. While they are still present in disordered silicate networks (such as those found in glasses and amorphous silica), their arrangement lacks the repeating crystal lattice characteristic of crystalline materials. Due to their involvement in the network's structural integrity, BO sites are generally less chemically reactive.

[0031] Conversely, the NBO are bonded to only one silicon (Si) or aluminum (Al) atom. These sites are typically charge-balanced by an adjacent metal cation, such as sodium (Na+) or calcium (Ca2+). NBO atoms represent structural defects or “broken bonds” within the silicate network. Their singular bonding makes them more exposed and thus significantly more chemically reactive, playing a positive role in the pozzolanic reactions that contribute to the strength and durability of cementitious materials.

[0032] Thus, the inventors have noted that more NBO atoms result in more reactive sites which in turn results in a faster pozzolanic reaction. To increase the NBO content of a given material or mixture of materials, a network depolymerization is desired, i.e. , due to alkali components, heat, and / or milling. By increasing the amorphous content and surface area of a material or mixture of materials, the dissolution and reactivity of that material is enhanced. Thus, the inventors have discovered methods and mixtures that have increased NBO, and thus, increasedreactivity, so that these NBO enhanced mixtures achieve the same or almost the same strength as the Portland cement in their binding properties, but they may be manufactured with less energy and CO2 emissions.

[0033] Prior to discussing these methods and corresponding SCMs, a brief review of the existing SCMs and their characteristics are indicated in the table 1 shown in FIG. 1 . Silica fume is mostly an amorphous SiO2material with a high fraction of NBO atoms due to the rapid condensation of fumes. It has a high reactivity. The metakaolin (e.g., dehydroxylated kaolinite (AI2Si2O7)), is a disordered aluminosilicate with both BO and some NBO atoms, especially near the Al atoms. It also has high reactivity. The fly ash is mostly glassy aluminosilicate with both BO and NBO atoms, but often more polymerized than the silica fume. If has a lower initial reactivity, unless activated. The GGBS includes a moderate amount of NBO atoms, high Ca content, and has good latent hydraulic. This material needs alkaline activation. The crystalline phases (e.g., quartz) is a fully polymerized material that has only BO atoms. It is essentially an inert material under standard conditions due to its low reactivity.

[0034] However, as discussed in the Background section of this document, the existing SCMs need to be improved. Thus, according to an embodiment, a mechanochemistry process is used to manufacture synthetic SCMs by using abundant natural materials. The term “synthetic” is used in this document to indicate that the composition of the SCM manufactured in this document is not found in the nature, although the components of the SCM may be natural products. The process offers reduced energy consumption and the ability to tailor the properties andreactivity of the SCM via at least one of: induced amorphization, dihydroxylation, creation of NBO atoms, and particle size tuning.

[0035] To ensure that NBO atoms are generated in the SCMs without the use of high temperatures, thus increasing the reactivity of the material, the inventors have relied on mechanochemistry for inducing amorphization in the precursors.Mechanochemistry is a branch of chemistry that uses (only) a mechanical force to initiate and sustain chemical reactions. Instead of relying on traditional methods like heat, light, or solvents, the mechanochemistry process harnesses the mechanical energy, typically through grinding, milling, or shearing, to drive chemical transformations. The applied mechanical energy breaks down the solid reactants (precursors in this case), increasing their surface area, creating defects in their crystalline structures, and generating localized heat, all of which contribute to lowering the activation energy needed for the reaction to occur. Mechanochemistry works by applying forces, such as compressive, shear, and / or tensile stress, to solid reactants (precursors). A possible modern technique for achieving these results is ball milling, where the precursors are placed in a container with hard balls and then shaken or rotated at high speeds. The collisions and friction between the balls and the precursors provide the necessary mechanical energy. This process effectively brings the precursors into very close contact, enabling reactions that might be impossible in a solvent-based system, especially for compounds with low solubility. By manipulating factors like the size of the balls, the milling speed, and the milling duration, it is possible to precisely control the reaction conditions and achievespecific outcomes. Thus, it is possible to control some of the characteristics of the formed mixture.

[0036] An advantage of the mechanochemistry is its “green chemistry” aspect. It significantly reduces or completely eliminates the need for often toxic or expensive solvents, which are a major source of waste in traditional chemical synthesis. This makes the process safer, more environmentally friendly, and more cost-effective. Mechanochemistry also enables faster reaction times, sometimes completing reactions in minutes rather than hours or days. It can facilitate the synthesis of new materials and complex molecules that are difficult to create using conventional methods. The ability to directly manipulate solid-state materials (precursors) without solvents opens up new avenues for synthesis and innovation.

[0037] The methods discussed in this document may use two or more precursors, which are fed to the mechanochemistry process for obtaining a desired SCM. The precursor materials may be a combination of silicon oxides, alkaline and alkaline-earth containing minerals, aluminum oxides, and iron oxides. For example, in one embodiment, the precursors include only silicon oxides and aluminum oxides. In another embodiment, the precursors include only silicon oxides, alkaline and alkaline-earth containing minerals, and aluminum oxides. In yet another embodiment, the precursors include all four materials noted above.

[0038] The “alkaline containing minerals” is a material that incudes alkaline metals from Group 1 of the periodic table, excluding hydrogen. They are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). These metals are extremely reactive because they have only one electron in theiroutermost shell, which they readily give up forming a +1 ion. When they react with water, they form strong alkaline (basic) solutions.

[0039] The “alkaline-earth containing minerals” is a material that includes alkaline-earth metals from Group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). These metals are less reactive than the alkali metals but are still very reactive. They have two electrons in their outermost shell, which they readily give up for forming a +2 ion. Calcium and magnesium are especially common in the Earth's crust.

[0040] Five different compositions (1 to 5) of the final SCM (after mechanochemical treatment and thermal activation) are illustrated within a circle 202 in FIG. 2, which is a 3-phase diagram of (SiO2)-(Al2O3+Fe2O3)-(XO), where X is a combination of alkaline and / or alkaline earth metals. Note that the five different compositions were obtained by controlling the number of precursors, the amount of energy imparted during the milling process, and the thermal activation temperature. Note that by controlling the various parameters of the mechanochemistry and / or the thermal activation processes, and also the type of oxide that is part of the precursors, an SCM may be obtained that fits anywhere in the circle 202. Note that FIG. 2 shows a combination of aluminum oxide and iron oxide, but the iron oxide is weighted by y, which may be 0 or 1 . The figure also indicates current, emerging, and future SCMs.

[0041] The final SCM obtained with the method indicated above may have traces of other elements (up to 2% by weight of the total SCM mass) depending on the location and nature of the starting natural materials used in the manufacturingprocess. The particle size of the precursors may vary between 1 nm to 1 mm, preferred between 5 pm to 500 pm. While FIG. 2 shows the SCMs 1 to 5 being made from all four precursors (silicon oxides, alkaline and alkaline-earth containing minerals, aluminum oxides, and iron oxides), as discussed above, it is possible to use only two or only three of the four precursors for manufacturing the SCM. For this reason, the XO is weighted by z, which may be 0 or 1 .

[0042] A liquid solution may be used to improve the reaction of the precursors. The solvent (that forms the liquid solution with the precursors) may also help to disperse the heat created during the mechanochemistry process. This liquid may have any pH and may be a combination of different liquids. A preferred liquid is H2O. Other liquids may be cyclohexane, ethanol, methanol, or isopropylene.

[0043] The process for obtaining the final SCM may also use a promoter to improve the reactivity of the SCM, its amorphization, and formation of NBO atoms. The promoter material may be one of: sodium hydroxide (NaOH) and sodium silicate (SS); alternative activators as olive stone ash (OBA), rice husk ash (RHA) and silicic acid (SA).

[0044] A reactor 300 for applying the mechanochemistry process for breaking the crystalline bonds of the precursors and inducing amorphization is schematically illustrated in FIG. 3. The reactor 300 includes a housing 302 (for example, a drum) that is configured to rotate along a longitudinal axis X when activated by a motor 304. The housing 302 is configured to hold the precursors, for example, silicon oxides 310, alkaline and alkaline-earth containing minerals 312, aluminum oxides 314, and iron oxides 316. FIG. 3 shows all the four precursors 310 to 316 beingpresent. However, as discussed above, it is possible to have only a subset of these precursors, for example, 310 and 314, or 310, 314, and 312. In one embodiment, a solvent 318 and / or promoter 319 may also be present.

[0045] Grinding media 320 (balls in this case, but other shapes may also be used) is also present inside the housing 302 and its kinetic energy, due to the rotation of the housing, is imparted to the one or more precursors 310 to 316. An objective of the reactor 300 is to transfer as much kinetic energy as possible to the precursors 310 to 316, to induce amorphization and to form enough reactive NBO atoms in the precursors’ structure. One example of the kinetic energy reactor would be a ball-milling reactor. The collisions between the grinding media 320 and the precursors 310-316 enhance the chemical reactivity of the processed materials through dislocations and induced defects.

[0046] The kinetic energy transfer may be carried out in different milling machines, for example a planetary ball-mill. In ball-milling, there may be any number of elements of grinding media (>0). The grinding media 320 may have any shape (a sphere is shown in FIG. 3) and size and may be made of any material, preferably steel or ZrO2. Variables like the milling time (from 1 second to 1 day) and rotations per minute (from 1 -10,000 rpm) of the housing 302 may be controlled by a processor 306 to optimize a surface area and particle size distribution (PSD) of the final mixture 324. In one embodiment, preferred percentiles for the PSD of the final mixture 324 may be as follow: D10 of 1-7 pm, D50 of 7-30 pm, and D90 of 30-100 pm, where D10 of 1-7 pm means that 10% of all the particles of the final mixture have a diameter smaller than a size between 1 and 7 pm (same definitions for D50 and D90except for the particle size diameter). Note that the PSD is typically represented by a cumulative curve, which means that D50 includes the D10 particles.

[0047] FIG. 3 shows all the precursors 310 to 316 being simultaneously milled inside the housing 302. However, one skilled in the art would understand that it is possible to mill each precursor in a corresponding reactor or sequentially in the same reactor, i.e., independent of the other precursors to impart more or less energy. In one embodiment, it is possible to simultaneously mill subsets of the four precursors in the same reactor 300.

[0048] The reactor 300 may optionally include a heater 322, which is shown in FIG. 3 being located outside the housing 302. However, the heater 322 may also be located inside the housing 302, as schematically illustrated by the figure. The heater 322 may be controlled by the processor 306. In another embodiment, the milled mixture 324 is extracted from the housing 302 and placed in a dedicated heater 330, as also illustrated in the figure. The heater 330 may be controlled by the processor 306 or another controller. In one embodiment, a temperature sensor 334 is placed inside a housing 332 of the heater 330 for measuring the heat inside the housing. In one embodiment, the heater may be an open flame that directly acts on the mixture 324. In another embodiment, the heater may be an electrical element that radiates heat (no open flame).

[0049] An objective of the heating process is to further enhance, through dehydroxilation and further amorphization, one or more properties of the produced milled mixture 324 and to remove any possible solvent used during the reaction process, to obtain the SCM 340. Note that a difference between the milled mixture324 and the SCM 340 is that the milled mixture 324 may still include the solvent. For example, a high-temperature kiln may achieve drying the material and enhancing property materials, selectively removing surface OH groups (dehydroxilation).

[0050] Heating the milled mixture 324 may be carried out during any amount of time and under any gaseous atmosphere (e.g., N2, O2, Air, H2, CO2, etc.) or combination of gases. Most of the CO2 emissions in the cement industry come from the heating process, which takes place at about 1450°C as discussed above. By performing this heating step at low temperatures (preferably 500-700 °C, but not higher than 850 °C), emissions are drastically reduced for the SCM manufacturing process. In one embodiment, electrical heating is performed. The milled mixture 324 obtained from the kinetic reactor may be heated up with a ramp (e.g., 1 -50 °C / min) or introduced directly in the heater. The SCM 340 obtained after the heating time may be cooled rapidly by air or cooling baths, which may improve material properties.

[0051] The final product (i.e., SCM 340) may be further milled to obtain a finer powder at a desired particle size distribution. In one embodiment, the PSD is D10 of about 1-7 pm, D50 of about 7-30 pm, and D90 of about 25-100 pm. Other PSD may be obtained depending on the application.

[0052] The inventors found that the obtained SCM 340 presents an amorphous nature that can be identified through X-ray diffraction (XRD) characterization (an amorphous content between 30 and 100% is preferred). Note that XRD is a primary method for determining the amorphous nature of a material because it directly measures the crystalline nature of the material. Crystallinematerials produce sharp, well-defined peaks in an XRD pattern due to the constructive interference of X-rays scattering from their ordered crystal planes. For example, FIG. 4 illustrates a sample 400 having crisp peaks 402. An amorphous material, lacking this long-range order, produce a broad, diffuse “amorphous hump” or halo. FIG. 4 shows the obtained SCM 340 having a corresponding peak 404 that is diffused when compared to peak 402. Other peaks in the figure show the same behavior for the SCM 340 when compared to the crystalline sample 400. The chemical composition of the sample 400 and the SCM 340 is also illustrated in the figure. In one embodiment, the formation of wairakite and / or analcime is present in the SCM 340, which is not present in the sample 400. The figure also shows the peaks for the GGBS, which are even more amorphous than the SCM 340. The X axis in the figure indicates the refraction angle used for the measurements. In one embodiment, the amorphous content between 30 and 100% is understood to mean that a structure of the SCM 340 (i.e., two or more oxides) was amorphized (by ballmilling in the reactor 300) so that XRD performed on the SCM 340 shows about 30 to 100 % of atom peaks being smaller than corresponding peaks of a non- amorphized structure (i.e., the same chemical composition that was not milled).

[0053] The BOs and NBO atoms in the SCM may be quantified, where the latter represents the actives sites of the material. These bonds may be quantified through XPS, FTIR, and NMR. The obtained SCM 340 was measured to have between 5-100% of NBOs from the total BOs and NBOs. In one embodiment, the oxide composition of the SCM 340 was analyzed by x-ray fluorescence (XRF) and the proportions corresponding to circle 202 in FIG. 2 were obtained.

[0054] The inventors generated the SCM 340 from various precursor compositions, at different heating temperatures, having various particle size distributions, and different activity indexes, as illustrated in table 2 of FIG. 5. While table 2 shows various SCMs 340 including all four precursors 310 to 316, table 3 in FIG. 6 shows an SCM 340 that includes only two precursors, e.g., silicon oxide and aluminum oxide. Table 3 shows that the lowest concentration, in percentage by weight, of the total amount of precursors used for making the SCM 340 is 25% for the silicon oxide and 3% for the aluminum oxide. The same figure shows the maximum concentration for the two precursors. One skilled in the art would understand that for this specific SCM configuration, the silicon oxide may be present in any percentage by weight between 25 and 85 and the aluminum oxide may be in any percentage by weight between 3 and 50 with a total percentage of about 100%. Note that some impurities may be present, which may prevent the SCM 340 from having a 100% composition of the two precursors.

[0055] For the SCM 340 having the composition shown in table 2 in FIG. 5 or in table 3 in FIG. 6, the particle size distribution is desired to be as illustrated in table 4 in FIG. 7. FIG. 8 graphically illustrates the particle size distribution 802 for the sample 400 of FIG. 4, the distribution 804 for the SCM 340, and the distribution 806 for the GGBS. The figure also indicates the percentile values for the SCM and GGBS.

[0056] The activity index illustrated in table 2 of FIG. 5 is a measure of the pozzolanic and / or hydraulic reactivity of an SCM, expressed as the ratio of the compressive strength of a mortar containing the SCM to that of a reference mortarmade with 100% ordinary Portland cement (OPC). Compressive strength tests, conducted according to ASTM C109, showed that replacing 20% of OPC with the five different synthetic SCMs of table 2 (materials 1 to 5 in the table) resulted in 28- day strengths ranging from 80% to 99% of the OPC control mortar. The reactivity of material number 3 was evaluated via the ASTM C1897-20 “standard test methods for measuring the reactivity of supplementary cementitious materials by isothermal calorimetry and bound water measurements”.

[0057] The reactivity of the SCM 340 may have pozzolanic and / or latent hydraulic characteristics. Pozzolanic materials, e.g., fly ash, silica fume, metakaolin, are not cementitious on their own. They require a chemical reaction with calcium hydroxide (a byproduct of Portland cement hydration) to form a cementitious compound called calcium silicate hydrate (C-S-H). This reaction, known as the pozzolanic reaction, is typically slower but contributes to strength gain at later ages and enhances durability. The latent hydraulic materials, e.g., ground granulated blast-furnace slag, have cementitious properties but require an activator to react with water. In concrete, the calcium hydroxide and alkalis from the Portland cement act as activators, stimulating a reaction that forms C-S-H. This reaction is similar to the one that occurs in Portland cement, and it contributes to the concrete's strength. In FIG. 9, the synthetic SCM 340 (number 3 in table 2 in FIG. 5) shows latent hydraulic reactivity when compared with other SCMs.

[0058] Based on the above embodiments and observations, a method 1000 for manufacturing the SCM 340 has been introduced by the inventors and this method is now discussed with regard to FIG. 10. The method 1000 starts with a step1002 of providing two or more precursors, e.g., silicon oxides, alkaline and alkaline- earth containing minerals, aluminum oxides, and iron oxides. In one embodiment, the two or more precursors are the silicon oxides and aluminum oxides. In another embodiment, the two or more precursors are the silicon oxides, alkaline and alkaline- earth containing minerals, and aluminum oxides. In yet another embodiment, the two or more precursors are all of the above noted four oxides.

[0059] Next, the two or more precursors are treated in step 1004, in a kinetic reactor to impart energy, to break their crystalline structure to induce amorphization. This step may also use a solvent 318 and / or a promoter 319. The imparted energy enhances the chemical mixing and reactivity of the processed materials via amorphization and creating enough NBO atoms, which gives cementitious properties to the final mixture 324. The size of the grinding media 320, the time spent by the precursors 310 to 316 inside the reactor 300, and the rotation speed of the housing 302 of the reactor 300 are selected so that the surface area and / or particle size distribution of the mixture 324 falls in desired ranges, as discussed above, to maximize the reactivity of the final SCM 340.

[0060] In one embodiment, step 1004 is performed until a structure of the two or more oxides was amorphized so that x-ray diffraction performed on the mixture 324 of the two or more oxides shows about 30 to 100 % of the atom peaks being smaller than corresponding peaks of a non-amorphized structure of the two or more oxides 310 to 316. In a different embodiment, step 1004 is performed until a particle size distribution of the mixture 324 of the two or more oxides includes about 10% of all particles having a diameter smaller than a first size between 1 and 7 pm, about50% of all particles having the diameter smaller than a second size between 7 and 30 pm, and about 90% of all particles having the diameter smaller than a third size between 25 and 100 pm.

[0061] In yet another embodiment, step 1004 is performed on the mixture 324 of the two or more oxides (which include BO atoms and NBO atoms as discussed above) until the NBO atoms represent between 5 and 100% of all of the bridging and non-bridging oxygen atoms. In one embodiment, step 1004 is performed until a combination (two or more) of the above conditions are achieved, e.g., until (1) 30 to 100% of the atom peaks have been reduced, and / or (2) the above noted particle size distribution has been achieved, and / or (3) the NBO atoms represent 5 to 100 % of the total BO and NBO atoms.

[0062] The milled mixture 324 resulting from step 1004 is then processed by heat during a heating step 1006, to enhance the material properties and form the SCP 340. In one embodiment, the temperature applied during the heating step 1006 is between 500 to 700 °C. In another embodiment, the temperature is between 500 and 800 °C. In yet another embodiment, the temperature is between 700 and 800 °C. In still another embodiment, the temperature is about 700 °C or about 800 °C. In one embodiment, the temperature is between 400 (or 500) and 850 °C. In still another embodiment, the temperature does not exceed 850 °C. The heating (i.e. , dehydroxylating) step 1006 enhances amorphization and improves the material’s surface. The reactivity of the SCM 340 obtained by this method may have latent hydraulic and / or pozzolanic properties. The degree of such reactivity depends on the chosen conditions. In one embodiment, the SCM 340 shown at 28 days, when usedin mortars with 20% OPC replacement, 80-99% of the strength of the OPC control sample.

[0063] The controlled activation of the selected precursors (which are earth abundant natural materials) via chemical modification (through e.g., mechanochemistry) and heat treatment, induces amorphization, creates enough NBO atoms and surface area to react efficiently in concrete applications, effectively substituting the Portland cement. In contrast to common practices for the existing SCMs, where high temperature processes produce supplementary cementitious materials in a bulk manner (already existing processes like the iron industry or combustion processes), the approach in method 1000 focuses in tailoring the material, using less energy, and / or generating less CO2.

[0064] The SCM 340 is then mixed in step 1008 with Portland cement and one or more aggregates (e.g., sand, gravel, etc.) to form concrete or other concrete related materials. The silica (SiC>2) present in the SCM 340, especially non-bridging oxygens, reacts with free lime released during the hydration of cement and forms calcium silicate hydrate (C-S-H) as new hydration products (this is responsible for the pozzolanic reactivity), which improve the mechanical strength of the cement mortar and concrete. This is also applicable to aluminum, which forms C-A-H and C- A-S-H (calcium aluminum hydrate and calcium aluminum silicate hydrate). Calcium aluminum silicates present in SCMs may also react with water, improving the concrete mechanical strength (latent hydraulic reactivity).

[0065] The term “about” is used in this application to mean a variation of up to 20% of the parameter characterized by this term. It will be understood that, althoughthe terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first object or step could be termed a second object or step, and, similarly, a second object or step could be termed a first object or step, without departing from the scope of the present disclosure. The first object or step, and the second object or step, are both, objects or steps, respectively, but they are not to be considered the same object or step.

[0066] The terminology used in the description herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used in this description and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any possible combinations of one or more of the associated listed items. It will be further understood that the terms "includes," "including," "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Further, as used herein, the term "if" may be construed to mean "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context.

[0067] The disclosed embodiments provide a method, system, and SCM composition that may substitute part of the Portland cement in concrete products. It should be understood that this description is not intended to limit the invention. Onthe contrary, the embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

[0068] Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.

[0069] This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.ReferencesThe entire content of all the publications listed herein is incorporated by reference in this patent application.[1] Tole, I., Habermehl-Cwirzen, K., Cwirzen, A. (2019). Mechanochemical activation of natural clay minerals: an alternative to produce sustainable cementitious binders - review. Miner Petrol 113, 449-462.[2] Spellings, R., Suraneni, P., & Skibsted, J. (2023). Future and emerging supplementary cementitious materials. Cement and concrete research, 171 , 107199.[3] Serbource, T., Courtial, M., de Noirfontaine, M. N., Tusseau-Nenez, S., Sandt, C., & Izoret, L. (2024). The glassy structure of reactive supplementary cementitious materials (SCMs) and recycled glass: Contribution of XRD and Raman spectroscopy to their characterization. Cement and Concrete Research, 179, 107468.[4] Zhong, Y., Qiu, X., Gao, J., & Guo, Z. (2019). Chemical structure of Si-0 in silica fume from ferrosilicon production and its reactivity in alkali dissolution. Isij International, 59(6), 1098-1104.[5] Dalby, K. N., Nesbitt, H. W., Zakaznova-Herzog, V. P., & King, P. L. (2007). Resolution of bridging oxygen signals from O 1 s spectra of silicate glasses using XPS: Implications for O and Si speciation. Geochimica et Cosmochimica Acta, 71 (17), 4297-4313.[6] Noor-ul-Amin, N. U. A. (2012). Use of clay as a cement replacement in mortar and its chemical activation to reduce the cost and emission of greenhouse gases. Constr Build Mater 34, 381 -384.

Claims

WHAT IS CLAIMED IS:1 . A synthetic supplementary cementitious material (SCM) comprising: a milled mixture (324) of two or more oxides (310, 312, 314, 316), wherein a first of the two or more oxides is silicon oxide (310), and a second of the two or more oxides is aluminum oxide (314), wherein a structure of the milled mixture (324) was amorphized so that x-ray diffraction performed on the milled mixture (324) shows about 30 to 100 % of atom peaks being smaller than corresponding peaks of a non-amorphized structure of the two or more oxides.

2. The synthetic SCM of Claim 1 , wherein a particle size distribution of the milled structure includes about 10% of all particles having a diameter smaller than a first size between 1 and 7 pm, about 50% of all particles having the diameter smaller than a second size between 7 and 30 pm, and about 90% of all particles having the diameter smaller than a third size between 25 and 100 pm.

3. The synthetic SCM of Claim 1 , wherein the milled mixture includes a bridging oxygen atom and a non-bridging oxygen atom, where the bridging oxygen atom is bonded to two Si or Al atoms and the non-bridging oxygen atom is bonded to a single Si or Al atom and a metal cation.

4. The synthetic SCM of Claim 1 , wherein non-bridging oxygen atoms represent between 5 and 100% of all of bridging and non-bridging oxygen atoms.

5. The synthetic SCM of Claim 1 , wherein the two or more oxides include at least one of alkaline and alkaline-earth containing atoms.

6. The synthetic SCM of Claim 5, wherein the two or more oxides further include iron oxides.

7. The synthetic SCM of Claim 1 , wherein the milled mixture has an activity index larger than 76 after 7 days.

8. The synthetic SCM of Claim 1 , wherein a lowest concentration of the silicon oxide is 25% by weight of the milled mixture, and a lowest concentration of the aluminum oxide is 3% by weight of the milled mixture.

9. The synthetic SCM of Claim 8, wherein a highest concentration of the silicon oxide is 85% by weight and a highest concentration of the aluminum oxide is 50% by weight.

10. A method (1000) for making a synthetic supplementary cementitious material (SCM), the method comprising:providing (1002) two or more oxides (310, 312, 314, 316), wherein a first of the two or more oxides is silicon oxide (310), and a second of the two or more oxides is aluminum oxide (314); forming (1004) a milled mixture (324) by inducing amorphization through mechanochemistry to break a crystalline structure of the two or more oxides, wherein a structure of the milled mixture is amorphized so that x-ray diffraction performed on the milled mixture shows about 30 to 100 % of atom peaks being smaller than corresponding peaks of a non-amorphized structure of the two or more oxides; and heating (1006) the milled mixture (324) to a temperature not higher than 850 °C to form the SCM (340).11 . The method Claim 10, wherein a particle size distribution of the milled mixture includes about 10% of all particles having a diameter smaller than a first size between 1 and 7 pm, about 50% of all particles having the diameter smaller than a second size between 7 and 30 pm, and about 90% of all particles having the diameter smaller than a third size between 25 and 100 pm.

12. The method of Claim 10, wherein the milled mixture includes a bridging oxygen atom and a non-bridging oxygen atom, where the bridging oxygen atom is bonded to two Si or Al atoms and the non-bridging oxygen atom is bonded to a single Si or Al atom and a metal cation.

13. The method of Claim 12, wherein non-bridging oxygen atoms represent between 5 and 100% of all of the bridging and non-bridging oxygen atoms.

14. The method of Claim 12, wherein the two or more oxides include at least one of alkaline and alkaline-earth containing atoms.

15. The method of Claim 14, wherein the two or more oxides further include iron oxides.

16. The method of Claim 10, wherein the milled mixture has an activity index larger than 76 after 7 days.

17. The method of Claim 10, wherein a lowest concentration of the silicon oxide is 25% by weight of the two or more oxides, and a lowest concentration of the aluminum oxide is 3% by weight of the two or more oxides.

18. The method of Claim 17, wherein a highest concentration of the silicon oxide is 85% by weight and a highest concentration of the aluminum oxide is 50% by weight.

19. The method of Claim 10, wherein the two or more oxides further include at least one of alkaline and alkaline-earth containing atoms and iron oxide.

20. The method of Claim 10, further comprising: forming concrete by mixing the SCM with cement and aggregates, wherein an amount of cement required for a given concrete application is partially replaced by the SCM.

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