Method for producing hydraulic binder

Abstract

A method for producing a hydraulic binder, comprising: introducing an aluminum source into water to form aluminum hydroxide; introducing an ion source in the form of a slug into the water, the ion source configured to emit a plurality of ions into the water; introducing a counterion source into the water, the counterion source configured to release a plurality of counterions into the water; converting at least a portion of the aluminum hydroxide, at least a portion of the plurality of counterions, and / or at least a portion of the plurality of ions to a crystalline AFt phase; converting at least a portion of the crystalline AFt phase to a crystalline AFm phase using at least a portion of the plurality of ions, wherein the crystalline AFm phase and / or the crystalline AFt phase form the hydraulic binder; A method for producing a hydraulic binder, comprising:

Description

[Technical Field]

[0001] The present invention relates to a method for producing a hydraulic binder. In particular, the present invention relates to hydraulic binders produced by an improved cement hydration mechanism. [Background technology]

[0002] Portland cement is the most common type of hydraulic binder commonly used throughout the world as the basic component of concrete, mortar, plaster, and general-purpose grout. Portland cement is widely used, at least in part, due to the low cost and ready availability of the manufacturing materials.

[0003] However, recently, the continued and expanded use of Portland cement has been called into question due to the large amount of energy consumed in the manufacturing process. Furthermore, the production of one tonne of Portland cement clinker produces an average of 843 kg of carbon dioxide, raising concerns about the product's environmental sustainability.

[0004] An essential step in the use of Portland cement is the hydration process. When Portland cement powder is dissolved in water, hydration products in the form of calcium hydroxide (CH) and calcium silicate hydrate (CSH) are produced at a pH of about 13.5. CSH not only changes composition in the same way as calcium hydroxide (CH), but also reacts with carbon dioxide and salts in the environment. This reaction with carbon dioxide and salt has the effect of destabilizing the hydration products, and CSH and CH are no longer stable to the environment. As a result of this reduced stability, hydrated Portland cement can experience a significant loss in performance (due to decomposition) over a relatively short period of time.

[0005] Several attempts have been made to overcome the drawback of high carbon dioxide loading. For example, alternative hydraulic binders such as geopolymer cement (typically a combination of aluminum silicate and chemical activators) have been used as environmentally friendly alternatives to Portland cement. However, geopolymer cement often has poorer mechanical properties than Portland cement, and residues from the geopolymer activation process tend to accelerate degradation mechanisms, resulting in faster degradation rates.

[0006] In light of the above, it would be advantageous to provide an improved hydraulic binder and method for its manufacture that is not only more environmentally friendly than Portland cement, but also produces a product with improved mechanical properties and environmental stability.

[0007] It is to be expressly understood that where a prior art document is referred to in this specification, no admission is made that the document forms part of the common general knowledge in the art in Australia or anywhere else. Summary of the Invention [Problem to be solved by the invention]

[0008] Embodiments of the present invention provide a method for producing a hydraulic binder that may at least partially solve one or more of the problems or drawbacks discussed above, or provide a useful or commercial option to the public. [Means for solving the problem]

[0009] According to a first aspect of the present invention, there is provided a method for producing a hydraulic binder, comprising the steps of: introducing an aluminum source into water to form aluminum hydroxide; introducing an ion source in the form of a slug into the water, the ion source configured to emit a plurality of ions into the water; introducing a counterion source into the water, the counterion source configured to release a plurality of counterions into the water; converting at least a portion of the aluminum hydroxide, at least a portion of the plurality of counterions, and / or at least a portion of the plurality of ions to a crystalline AFt phase; converting at least a portion of the crystalline AFt phase to a crystalline AFm phase using at least a portion of the plurality of ions, wherein the crystalline AFm phase and / or the crystalline AFt phase form the hydraulic binder; A method for producing a hydraulic binder is provided, comprising:

[0010] The term "AFt phase" is an abbreviation for "alumina, iron oxide, tri-counterion" or (Al2O3-Fe2O3-tri). This term refers to the group of calcium sulfoaluminate hydrates. The general formula for the AFt phase is [Ca3(Al,Fe)(OH)6·12H2O]2·X3·nH2O, where X represents a charged anion (X in this case is sulfate). Ettringite is a common member of the AFt group and is the name of the mineralogical supergroup to which all AFt belong.

[0011] The term "AFm phase" is an abbreviation for "alumina, iron oxide, mono counterion" or (Al2O3-Fe2O3-mono). This represents another group of calcium aluminate hydrates with the general formula [Ca2(Al,Fe)(OH)6]2·X·nH2O, where X represents a lone charged anion. X can be one of many anions, common anions include hydroxyl, sulfate, carbonate, and the like.

[0012] The method for producing the hydraulic binder of the present invention is carried out in the absence of Portland cement.

[0013] The aluminum source may be in any suitable form. For example, the aluminum source may be composed of a single material or two or more materials. Preferably, the aluminum source may be an inorganic material. More preferably, the aluminum source may consist of one or more water-soluble ionic compounds. The aluminum source may be comprised of one or more silicates, oxides, sulfates, sulfides (or other soluble sulfur-containing compounds), hydroxides, carbonates, chlorides, etc., or any suitable combination thereof. Thus, the aluminum source is capable of introducing aluminum cations into the water.

[0014] In the present invention, a calcium source can also be introduced into the water. The calcium source may be in any suitable form. For example, the calcium source may be composed of a single material or two or more materials. Preferably, the aluminum source may be an inorganic material. More preferably, the calcium source may consist of one or more water-soluble ionic compounds. The calcium source may be comprised of one or more silicates, oxides, sulfates, sulfides (or other soluble sulfur-containing compounds), hydroxides, bromides, iodides, chlorides, acetates, etc., or any suitable combination thereof. Thus, the calcium source is capable of introducing calcium cations into the water.

[0015] In the present invention, calcium depletion of the pore solution promotes dissolution of the pozzolanic material. Specifically, the solution is depleted at a relatively low pH compared to traditional Portland cement processes, drawing out ions from the raw materials introduced into the water.

[0016] The aluminum source and calcium source in the present invention may comprise different water-soluble ionic compounds. Alternatively, the aluminum source and the calcium source may be the same water-soluble ionic compound. The water soluble ionic compound may be of any suitable type, including, but not limited to, calcium aluminum silicate, calcium aluminum oxide, calcium aluminum halide, calcium aluminum hydroxide, calcium aluminum chloride, calcium aluminum sulfide, calcium aluminum sulfate, or any suitable combination thereof.

[0017] As previously mentioned, an ion source in the form of a slug is introduced into the water. In certain embodiments, the slag may include slag produced in steel manufacturing processes, such as slag produced in a basic oxygen furnace (BOF). Thus, the slag may be a steel slag.

[0018] It is estimated that between 190 million and 280 million tons of steel slag is generated annually. Steel slag is considered waste, with an estimated 2 billion tonnes of steel slag sitting in landfills worldwide. In some cases, rather than being sent to landfills, steel slag is cast and crushed to be used as roadbed material. However, leaching of metals from steel slag can produce toxic substances, which can cause environmental problems.

[0019] In the present invention, by using this steel slag as an ion source, it is possible to produce an environmentally friendly hydraulic binder (with relatively low energy) using a large amount of waste material from the earth, and when produced in this manner, carbon emissions are significantly reduced compared to the conventional manufacturing process of Portland cement.

[0020] The slag in the present invention may be subjected to a size reduction process before being introduced into the water. Any suitable size reduction technique can be used, including but not limited to crushing, grinding, etc.

[0021] The slug may be reduced to any suitable size. For example, the average size of the slugs after the size reduction step may be less than 100 mm. In another embodiment of the present invention, the average size of the slugs after the size reduction step may be less than 50 mm. In another embodiment of the present invention, the average size of the slugs after the size reduction step may be less than 10 mm.

[0022] This slag may then be mixed with calcium sulfoaluminate cement or calcium aluminate cement before being introduced into the water. The slag may also be subjected to a size reduction step before being introduced into the water and mixed with the calcium sulfoaluminate cement or calcium aluminate cement.

[0023] Additionally, the slag may be mixed with calcium sulfoaluminate cement or calcium aluminate cement in any suitable ratio. For example, when slag is mixed with calcium sulfoaluminate cement or calcium aluminate cement, the proportion of slag may be 1% by weight to 99% by weight. More preferably, when the slag is mixed with calcium sulfoaluminate cement or calcium aluminate cement, the proportion of the slag may be 10% by weight to 90% by weight. More preferably, when the slag is mixed with calcium sulfoaluminate cement or calcium aluminate cement, the proportion of the slag may be 25% by weight to 75% by weight.

[0024] The ion source in the present invention may include an aluminum ion source. More preferably, the ion source may include a source of aluminum ions and a source of calcium ions. More preferably, the ion source may include an aluminum ion source, a calcium ion source, and a silicon ion source. However, the slag may be comprised of ion sources of many other elements, including, but not limited to, gallium, manganese, tungsten, cadmium, chromium, strontium, cobalt, lead, nickel, barium, titanium, molybdenum, vanadium, selenium, arsenic, iodine, bromine, boron, and chlorine. Thus, the slag in the present invention does not constitute a traditional cementing agent, but instead is a "minable" resource, and ions from the slag can be recovered for use in the methods of the present invention. Ions of other elements may also be used in the process of the present invention to aid in the formation of the AFt phase.

[0025] Ions of other elements in conventional processes are not typically utilized because they are typically not present in the water at the start of hydration, their reaction rates are inhibited, or they are excluded by more reactive / dominant ions. However, when these ions are introduced into water before normal hydration occurs, a phase reaction occurs and particle size has less effect on the hydration rate compared to the Portland cement application process.

[0026] Slags such as steel slags have low reactivity. However, the reactions that occur in the manufacturing methods of the present invention are typically fast (certainly faster than the hydration reaction of Portland cement) even when the slag is not ground to a relatively small size.

[0027] In particular, the process of the present invention may involve a series of reactions that can utilize one or more products from a previous reaction. Thus, a series of reactions may include a stepwise series of reactions.

[0028] This series of reactions, which reduces the amount of soluble ions in the water, may facilitate (or be manipulated to facilitate) a process by which less desirable ions (in terms of reactivity or crystal-forming properties) are released or removed from the ion source. Thus, less reactive phases of the ion source can be effectively mined from the ion source to produce solutes for forming other members of the solid solution family. JPEG2025526165000002.jpg21170 This is in contrast to the three aluminum sulfate solid solution elements of the more rapidly forming ettringite (C6ASSS) system, which decomposes to calcium carbonate, aluminum hydroxide, and calcium sulfate in the presence of atmospheric carbon dioxide.

[0029] The counterion source may be in any suitable form and may release the counterion into water in any suitable manner, such as by dissolving in water. The source of counter ions may in turn include one or more water-soluble inorganic compounds. The counter ions in this embodiment may be released into water by dissolution of the water-soluble inorganic compound. It will be appreciated that the exact nature of the counterion source will depend on the counterion that is to be released into the water. For example, if the desired positive counterion comprises sodium, the counterion source may comprise a water-soluble sodium compound (such as sodium chloride, sodium oxide, sodium sulfate, sodium carbonate, sodium hydroxide, or any suitable combination thereof). Desired counterions may include sodium, potassium, calcium, iron, aluminum, copper, nickel, strontium, chromium, zinc ions, or any suitable combination thereof. In a most preferred embodiment, the counterion source may comprise a calcium ion source. In this embodiment, a stoichiometric excess of calcium ions may be provided to promote the formation of the crystalline AFt phase.

[0030] The negative counterion provided by the counterion source may be in any suitable form, and the negative counterion may vary depending on the nature of the positive counterion, the nature of the aluminum source (and calcium source, if present), etc. Thus, the negative counterions may include carbonate anions, chloride anions, oxide anions, sulfate anions, hydroxide anions, or any suitable combination thereof.

[0031] The water may be of any suitable type, and the amount and nature of the water will depend on the amount of crystalline AFt phase to be produced. And, the form of water includes pools, vats, tanks, ponds, reservoirs, and the like. The water may be in any suitable form, but it is preferred that the water be relatively free of ions prior to carrying out the manufacturing method of the present invention. The water in the present invention may contain a certain amount of counter ions. The pH of the water can be any suitable pH, but it is preferred that the water be at a relatively neutral pH or a slightly basic pH (ie, a pH between 7 and about 9).

[0032] In the present invention, one or more reactants are added to water. The one or more reactants may be in any suitable form, and one of skill in the art will appreciate that the addition of the one or more reactants (and the amount of the one or more reactants used) will depend, among other things, on the nature and composition of the other components of the process.

[0033] The one or more reactants in the present invention may include one or more of a plasticizer, a retarder, and an accelerator. Any suitable materials can be used as the plasticizer, retarder and accelerator. The plasticizer in the present invention may contain calcium naphthalenesulfonate. The retarder may then comprise an acid, particularly citric acid. The promoter may also include lithium carbonate, especially relatively finely divided lithium carbonate.

[0034] The aluminum hydroxide produced from the aluminum source may be produced in any suitable manner. The aluminum hydroxide may be produced as a precipitate. More specifically, the aluminum hydroxide may be precipitated as an aluminum hydroxide gel. To further explain, the aluminum hydroxide that is formed precipitates from solution as an amorphous, semi-soluble polymer that then combines with calcium to form a hydrated ion pair. This ion pair formation is the reason why the AFt phase grows as elongated needle-like crystals. Typically, the base of the AFt crystal contains an insoluble catalyst, providing a charged surface for AFt to coordinate to. Additionally, calcium aluminum ion pairs are inserted into the base of the crystal, effectively pushing or growing the crystal up from the base.

[0035] Any suitable reaction may be used to precipitate the aluminum hydroxide from the solution. A specific example of an aluminum hydroxide precipitation reaction (including aluminum chloride, sodium carbonate, and water) is shown below: 2AlCl3+3Na2CO3+3H2O→2Al(OH)3+3CO2+6NaCl

[0036] Typically, the conversion of aluminum cations to aluminum hydroxide gel is a relatively fast process. Furthermore, precipitation of aluminum hydroxide gel occurs at a pH of about 8, compared to the formation of CSH during the conventional Portland cement hydration process (which occurs at a pH of 13.5).

[0037] As previously mentioned, at least a portion of the aluminum hydroxide, at least a portion of the ions, and at least a portion of the plurality of counterions are converted to a crystalline AFt phase. At least a portion of the aluminum hydroxide, at least a portion of the ions, and at least a portion of the plurality of counterions may be converted to any suitable crystalline AFt phase, but in a preferred embodiment of the present invention, at least a portion of the aluminum hydroxide, at least a portion of the ions, and at least a portion of the plurality of counterions may be converted to ettringite. Compounds in this embodiment may be of the general form: (CaO)6(Al2O3)(SO3)3·32H2O or (CaO)3(Al2O3)(CaSO4)3·32H2O.

[0038] The aluminum hydroxide, at least a portion of the ions, and at least a portion of the plurality of counterions may be converted to a crystalline AFt phase using any suitable technique. These aluminum hydroxides, at least a portion of the ions, and at least a portion of the counterions are then converted to a crystalline AFt phase via a hydration mechanism. The crystalline AFt phase may absorb a relatively large amount of moisture from the water, resulting in a relatively high moisture content of the crystalline AFt phase.

[0039] The crystalline AFt phase may have any suitable crystal structure. For example, the crystalline AFt phase may have a triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, or cubic crystal structure, or any suitable combination thereof. And, the crystalline AFt phase may have a relatively elongated (or needle-like) morphology. Preferably, the crystalline AFt phase has a relatively high water content.

[0040] As previously mentioned, at least a portion of the crystalline AFt phase is converted to a crystalline AFm phase. This conversion may be done using any suitable technique. In the present invention, the transformation of the crystalline AFt phase to the crystalline AFm phase is driven, at least in part, by dehydration during the formation of the crystalline AFt phase. More specifically, when water is consumed during the formation of the crystalline AFt phase, the reduction in available water promotes the transformation of the crystalline AFt phase to the crystalline AFm phase.

[0041] As previously mentioned, the transformation of the crystalline AFt phase to the crystalline AFm phase is carried out in the presence of an ion source. In the present invention, an ion source may be provided to promote the formation of the crystalline AFt and / or crystalline AFm phases.

[0042] In conventional processes, environmental substances (such as salts, carbon dioxide, etc.) can be attracted to the process and react to degrade or decompose the reaction products. However, in the present invention, not only do the reaction products (crystalline AFt phase and crystalline AFm phase) not substantially react with environmental substances, but environmental substances may react to promote the formation of the crystalline AFt phase and / or the crystalline AFm phase. Thus, environmental substances not only do not adversely affect the present invention, but may also increase the formation of crystalline AFt and / or crystalline AFm phases.

[0043] The crystalline AFm phase may be in any suitable form. In the present invention, the crystalline AFm phase may be composed of a combination of monocarbonate, monosulfate and gehlenite hydrate (C2ASH8).

[0044] The crystalline AFt phase may be a rapidly forming, thermodynamically unstable crystalline hydrate. The crystalline AFt phase may include elongated morphologies and have a high water content. This crystalline AFt phase may then form a dispersed, non-continuous support structure that defines the initial dimensions of the cement product, particularly the cement product after hardening.

[0045] Thus, the crystalline AFt phase may form a framework or scaffold upon which the crystalline AFm phase may form.

[0046] As mentioned above, the formation of the crystalline AFt phase consumes a large amount of water. Thus, hydration of the crystalline AFt phase promotes at least partial conversion of the crystalline AFt phase by removing unbound pore water until the formation of the crystalline AFt phase slows or stops due to the unavailability of water, thereby converting the reaction to the formation of the crystalline AFm phase. The mechanism of formation of the crystalline AFm phase may involve successive substitutions of elements within the crystalline AFt phase and / or counterions.

[0047] The formation of the crystalline AFm phase may also occur within or on the basis of the framework of the crystalline AFt phase. Once a continuous crystalline matrix is formed within the AFt framework, the AFt framework becomes dehydrated. As a result, the AFt framework becomes unstable, allowing the AFt crystals to decompose into their elemental raw materials, which are then consumed by the ongoing AFm hydration process.

[0048] Furthermore, the crystalline AFm phase may have any suitable crystal structure. For example, the crystalline AFm phase may have a triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, or cubic crystal structure, or any suitable combination thereof.

[0049] The present invention utilizes the AFt-AFm transition system to effectively mine the components of the hydrated mixture (i.e., water and the ion source located therein), enabling the formation of stable, rapidly increasing strength hydrates using non-reactive materials, even in the environment.

[0050] As previously mentioned, the hydraulic binder comprises a crystalline AFm phase and / or a crystalline AFt phase. The hydraulic binder may contain both a crystalline AFm phase and a crystalline AFt phase. In other embodiments, the hydraulic binder may comprise only the crystalline AFm phase.

[0051] The crystalline AFt phase and the crystalline AFm phase may contain only a single crystal form of the AFt phase and the AFm phase. In other embodiments of the present invention, the crystalline AFt phase and / or the crystalline AFm phase may include multiple crystalline forms of the AFt phase and the AFm phase. The different crystalline forms of the AFt and AFm phases may have different crystal structures, different chemical compositions, and / or different stoichiometries from each other.

[0052] In the present invention, the hydraulic binder may further comprise one or more anhydrite deposits. More specifically, the hydraulic binder may further comprise one or more botryoid anhydrite deposits.

[0053] In a second aspect, the invention broadly relates to a hydraulic binder formed by the manufacturing method of the first aspect.

[0054] The present invention does not require that the materials used be cementitious or hydraulic. Instead, the present invention requires only that there be a mechanism for the formation of AFt hydrate, particularly AFt hydrate crystals, and that the materials used be at least somewhat soluble.

[0055] The manufacturing method of the present invention offers the additional advantage that the initial pH value of the present invention is lowered compared to conventional manufacturing methods, and that environmental substances (such as carbon dioxide, salts, etc.) that are attracted to the manufacturing method of the present invention are consumed as counterions rather than causing decomposition or degradation or hydration products.

[0056] Another advantage of the present invention is that the crystalline structure of the hydraulic binder reduces or eliminates shrinkage of the hydraulic binder. Additionally, the ability to produce hydraulic binders at a relatively mildly basic pH not only makes the process safer, but also reduces the amount of reagents required to produce the highly basic pH associated with the production of conventional Portland cement.

[0057] Furthermore, the reaction rate at which strength is achieved with the hydraulic binder of the present invention is faster compared to Portland cement. The rapid reaction rate to form the hydraulic binder means that at least 25% of the total 28-day strength of concrete formed using the hydraulic binder is achieved within about 4 hours of initial set, and 60% to 70% of the total 28-day strength is achieved within 24 hours. Then, between 7 and 14 days after initial hardening, the hydration reaction increases rapidly. This surge in further hydration is associated with silicates in the hydraulic binder.

[0058] Furthermore, the 28-day total strength of the hydraulic binder produced according to the manufacturing method of the present invention is significantly higher (approximately 2 to 2.5 times higher) than the 28-day total strength of conventional concrete formed using Portland cement.

[0059] The fact that the hydraulic binder of the present invention achieves most of its total 28-day strength in a short period of time allows it to be used in applications where traditional Portland cement would have to be allowed to set and harden for an extended period of time before use. For example, when a structure (such as a house) is 3D printed, traditionally a first layer of cement product is printed, which then requires a relatively long period of curing to achieve a sufficient percentage of the total strength of 28 days before a second layer is printed on top of the first layer.

[0060] In contrast, the hydraulic binder of the present invention sets quickly, allowing a second layer to be printed on top of the first layer in a relatively short time after the first layer is printed. Thus, the overall speed of construction is increased, reducing the time it takes to erect a structure compared to conventional cement products.

[0061] Any feature described herein may be combined in any manner with one or more other features described herein within the scope of the present invention.

[0062] The reference to prior art herein is not, and should not be taken as, an acknowledgment or in any way suggestion that the prior art forms part of the common general knowledge. [Example]

[0063] Two samples of Australian BOF steelmaking slag (S500 and S502) were used to determine the efficiency of non-supersaturated reactions using steelmaking slag in a stepwise hydration mechanism. Specifically, this preparation method was designed to demonstrate the stepwise reaction mechanism of the present invention and to utilize the conversion of water from AFt hydrate to AFm hydrate by manipulating water availability during the hydration reaction. Using this manufacturing method, the hydrated product could be converted into a more environmentally stable natural compound.

[0064] Steel slag S500 is of controlled composition, taken from the top of the molten steel in the crucible. Steel slag S502 is the residue of the formed slag, which contains material ejected from the crucible during steel production. Steel slag S502 has a high proportion of steel particles and iron oxide.

[0065] Grouts containing each slag and a grout with a controlled composition that did not contain slag (i.e., conventional CSA cement grout) were prepared. The composition of the grout is shown in Table 1. [Table 1]

[0066] Each grout was then treated to produce a hydraulic binder that was then air cured (the slag grout was treated according to the method of the present invention). The compressive strength of the hydraulic binder was tested over a period of 28 days. The measured compressive strength (MPa) is shown in Table 2. [Table 2]

[0067] The results shown in Table 2 indicate that both hydraulic binders produced by the manufacturing method of the present invention (i.e., produced from slag) have significantly higher compressive strength than conventional Portland cement hydraulic binders.

[0068] Analysis of the hydraulic binder produced from the slag revealed that it had a hydrate matrix consisting of needle-like crystals forming a network. The needle-like crystals were ettringite crystals composed of calcium, aluminum, and sulfate counterions. As hydration proceeded, the ettringite crystals were replaced by solid solution elements of the ettringite system with mixed counterions.

[0069] At later stages of the reaction, AFm hydrates and needle-shaped AFt crystals are present, and in some cases, one or more anhydrite deposits (especially botryoidal anhydrite deposits) are also present.

[0070] Analysis of the needle-like AFt crystals revealed that Ca3(Al n Fe 1-n The composition is shown to be )(OH)6(SO4,SiO4)xH2O, which is similar to that of thaumasite.

[0071] In summary, in the method of the present invention, initial hydration produces AFt hydrate based on a calcium-aluminum framework with sulfate as the counterion. The formation of ettringite rapidly depletes both ions and water from the pore solution, causing the AFt phase to capture ions (from the ion source or other sources including slag). Some of the crystalline AFt phases formed (in the form of ettringite) contain counterions other than sulfate, leading to the formation of more stable AFt solid solution elements such as woodfordite.

[0072] Subsequently, the limited availability of water led to a change in mechanism, with the crystalline AFt phase being sequentially decomposed and reformed. AFm hydrate was initially formed with calcium, aluminum, and sulfate as counterions. However, as the more stable crystalline AFt phase containing ions other than sulfate decomposed, various AFm solid solution elements began to form. At the same time, the anhydrous phases of the original component ion source (ie, slag) and counterion source continuously introduced ions into solution. [Brief explanation of the drawings]

[0073] The present invention can be understood from the following detailed description of the invention. The detailed description of the invention does not limit the scope of the invention as described above. In the detailed description of the invention, reference is made to the following drawings:

[0074] [Figure 1] 1 is a diagram showing a method for manufacturing a hydraulic binder according to an embodiment of the present invention. FIG.

[0075] [Figure 2] 1 is a schematic diagram of a method for producing a hydraulic binder according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0076] FIG. 1 shows a method 10 for producing a hydraulic binder according to one embodiment of the present invention. In this embodiment, an aluminum source 11 is introduced into water 12 . The aluminum source 11 is also a calcium source and may include any suitable soluble aluminum calcium inorganic compound. In an embodiment of the present invention, the aluminum source 11 comprises calcium sulfate aluminate.

[0077] The inorganic compound containing the aluminum source 11 dissolves in the water 12, causing a reaction between the aluminum ions and the water 12 to form an aluminum hydroxide gel 13. The aluminum hydroxide gel 13 is produced at a pH of about 8, which is a significantly lower alkaline pH than that experienced in producing CSH gels in conventional Portland cement hydration processes.

[0078] A source of counter ions 14 is also introduced into the water 12 . The counterion source 14 shown in FIG. 1 is a soluble inorganic calcium compound such as calcium nitrate, calcium sulfate, calcium acetate, calcium hydroxide, calcium chloride, calcium bromide, calcium iodide, or any combination thereof. The inorganic compound of the counterion source 14 dissolves, introducing calcium cations and anions into the water 12 .

[0079] An ion source 16 in the form of BOF steel slag is also added to the water 12 .

[0080] Thereafter, at least a portion of the aluminum hydroxide gel 13, at least a portion of the counterions generated from the counterion source 14, and at least a portion of the ions generated from the ion source 16 are converted to a crystalline AFt phase. The crystalline AFt phase shown in FIG. 1 is a form of the crystalline AFt phase 15 of ettringite. The composition of ettringite is (CaO)3(Al2O3)(CaSO4)3·32H2O.

[0081] The crystalline AFt phase 15 of ettringite is formed by hydration of the aluminum hydroxide gel 13, ions from the ion source 16, and counterions from the counterion source 14 via a hydration mechanism. The crystalline AFt phase 15 absorbs a large amount of moisture from the water 12, resulting in a high moisture content of the crystalline AFt phase 15. The crystalline AFt phase 15 of ettringite has an elongated or needle-like crystal structure.

[0082] Ions (particularly calcium, aluminum, and silicon ions) are extracted from an ion source 16 to promote the formation of the AFt phase 15 of ettringite. Thus, the slag used as the ion source 16 is effectively a "minable" resource, as certain components can be extracted from it for use in the manufacturing method of the present invention.

[0083] Environmental factors such as carbon dioxide 17 are generally detrimental to the hydration process of conventional Portland cement. However, in the manufacturing method of the present invention, atmospheric carbon dioxide 17 provides the ions used to convert aluminum hydroxide 13 into the crystalline AFt phase 15 of ettringite.

[0084] The absorption of water 12 during the hydration process to form the crystalline AFt phase 15 of ettringite reduces the available water 12 and promotes the conversion of the crystalline AFt phase 15 to the crystalline AFm phase 18. This crystalline AFm phase 18 may then comprise, at least in part, gehlenite hydrate having the formula C2ASH8.

[0085] In FIG. 1, the mechanism of formation of the crystalline AFm phase 18 involves successive substitution of elements and / or counterions 14 and / or ions 16 within the crystalline AFt phase 15 .

[0086] The crystalline AFm phase 18 forms within or on top of the framework of the crystalline AFt phase 15 . Once a continuous crystalline matrix is formed within the AFt framework, the AFt framework becomes dehydrated. As a result, the AFt framework becomes unstable and the crystalline AFt phase 15 decomposes into its basic raw materials, which become consumed in the ongoing AFm hydration process.

[0087] The AFm crystals 18 are advantageously environmentally stable, meaning that the carbon dioxide 17 and salts 19 that are attracted to the hydration process do not react with the crystalline AFm phase 18, and therefore no decomposition or degradation of the AFm phase 18 occurs (unlike the hydration process of Portland cement in this respect).

[0088] Thus, the hydrated products of the present invention are not only environmentally stable, but the crystalline structure of the crystalline AFm phase 18 reduces or eliminates shrinkage of the crystalline AFm phase 18, resulting in a dimensionally stable product.

[0089] Furthermore, the manufacturing method 10 of the present invention is not only faster than the hydration process of conventional Portland cement, but also increases the strength of the hydraulic binder (crystalline AFm phase 18 and / or residual crystalline AFt phase 15) much more quickly than conventional Portland cement. Furthermore, the compressive strength of the hydraulic binder produced according to the manufacturing method of the present invention is higher than the compressive strength of conventional hydraulic binders produced using Portland cement. Specifically, the 28-day compressive strength of the hydraulic binder produced according to the production method of the present invention is 2 to 2.5 times higher than the 28-day compressive strength of a conventional hydraulic binder produced using Portland cement.

[0090] FIG. 2 shows a schematic diagram of a method 10 for producing a hydraulic binder 20 according to an embodiment of the present invention. In this figure, counterions 14 generated from a counterion source 14 and ions generated from a slag 16 react with an aluminum hydroxide gel 13 formed in water 12 to form a crystalline AFt phase 15. During the course of the reaction time (indicated by arrow 21), conversion of counterions 14 generated from counterion source 14, ions generated from slag 16, and aluminum hydroxide gel 13 continues. This reaction reduces the free water 12 (indicated by arrow 22 ) in the system, which in turn promotes the conversion of the crystalline AFt phase 15 to the crystalline AFm phase 18 . The transformation of the crystalline AFt phase 15 to the crystalline AFm phase 18 is also promoted by ions obtained from the slag 16 and carbon dioxide 17 (such as atmospheric carbon dioxide 17).

[0091] The hydraulic binder 20 includes multiple forms of the crystalline AFm phase 18 . The hydraulic binder 20 comprises AFm in its most chemically stable form.

[0092] In the embodiment of the invention shown in FIG. 2, the hydraulic binder 20 comprises a chemically stable form of an AFt phase 20a and one or more dough-like anhydrite deposits 20b.

[0093] In this specification and (where applicable) in the claims, the term "comprises" includes each integer listed but does not exclude the inclusion of additional integers.

[0094] Throughout this specification, when a reference is made to "one embodiment," it means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrase "in one embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more combinations.

[0095] In accordance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the means described herein include preferred forms for carrying out the invention, and therefore the invention is not limited to the specific features shown or described. The invention is therefore claimed in any of its forms or modifications within the proper scope of the appended claims (if any) as appropriately interpreted by those skilled in the art.

Claims

1. A method for producing a hydraulic binder, comprising: introducing an aluminum source into water to form aluminum hydroxide; introducing an ion source in the form of a slug into the water, the ion source being configured to release a plurality of ions into the water; introducing a counterion source into the water, the counterion source configured to release a plurality of counterions into the water; converting at least a portion of the aluminum hydroxide, at least a portion of the counterions, and / or at least a portion of the ions to a crystalline AFt phase; converting at least a portion of the crystalline AFt phase to a crystalline AFm phase using at least a portion of the plurality of ions, wherein the crystalline AFm phase and / or the crystalline AFt phase forms the hydraulic binder; A method for producing a hydraulic binder, comprising:

2. 10. The method of claim 1, wherein a calcium source is also introduced into the water.

3. 3. The method for producing a hydraulic binder according to claim 1 or claim 2, wherein the aluminum source and the calcium source comprise one or more water-soluble ionic compounds.

4. 4. The method of claim 3, wherein the one or more water-soluble ionic compounds comprise calcium aluminum silicate, calcium aluminum oxide, calcium aluminum halide, calcium aluminum hydroxide, calcium aluminum chloride, calcium aluminum sulfide, calcium aluminum sulfate, or a combination thereof.

5. 5. The method for producing a hydraulic binder according to claim 1, wherein the source of counter ions comprises one or more water-soluble inorganic compounds.

6. 6. A method for producing a hydraulic binder according to any one of claims 1 to 5, wherein the source of counter ions is a source of sodium, potassium, calcium, iron, aluminum, copper, nickel, strontium, chromium and / or zinc ions.

7. The method for producing a hydraulic binder according to any one of claims 1 to 6, wherein the pH of the water is 7 to 9.

8. 8. A method for producing a hydraulic binder according to any one of claims 1 to 7, wherein the aluminium hydroxide is produced as a precipitate of an aluminium hydroxide gel.

9. 9. A method for producing a hydraulic binder according to any one of claims 1 to 8, wherein the at least a portion of the aluminum hydroxide and the at least a portion of the plurality of counterions are converted to the crystalline AFt phase via a hydration mechanism.

10. 10. A method for producing a hydraulic binder according to any one of claims 1 to 9, wherein the crystalline AFt phase has an acicular morphology.

11. 11. A method for producing a hydraulic binder according to any one of claims 1 to 10, wherein the crystalline AFt phase is in the form of the AFt phase of ettringite.

12. The method for producing a hydraulic binder according to any one of claims 1 to 11, wherein the slag comprises iron and steel slag.

13. The method for producing a hydraulic binder according to claim 12, wherein the steel slag comprises BOF slag.

14. 14. A method for producing a hydraulic binder according to any one of claims 1 to 13, wherein the slag is subjected to a size reduction treatment before being introduced into the water.

15. 15. A method for producing a hydraulic binder according to any one of claims 1 to 14, wherein the slag is mixed with calcium sulfoaluminate cement or calcium aluminate cement before being introduced into the water.

16. 16. A method for producing a hydraulic binder according to any one of claims 1 to 15, wherein the crystalline AFm phase comprises a combination of monocarbonate, monosulfate and gehlenite hydrate.

17. 17. A method for producing a hydraulic binder according to any one of claims 1 to 16, wherein the crystalline AFm phase is formed by successive substitution of elements and / or counterions in the crystalline AFt phase.

18. 18. A method for producing a hydraulic binder according to any one of claims 1 to 17, wherein the crystalline AFt phase forms a framework or base on which the crystalline AFm phase is formed.

19. 18. A method for producing a hydraulic binder according to claim 17, wherein the formation of the crystalline AFm phase occurs within the framework or on the base, whereby the framework or the base becomes dehydrated, causing the crystalline AFm phase to decompose into base materials which are consumed in the formation of the crystalline AFm phase.

20. 20. The method of claim 1, wherein the hydraulic binder further comprises one or more anhydrite deposits.

21. A hydraulic binder formed by the method for producing a hydraulic binder according to any one of claims 1 to 20.

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