Multi-fold carbon-negative organic alternative cement

Abstract

A carbon-neutral, or even carbon-negative, cement is provided. The hardening of these novel cements is based on acid-base reactions, and the cements are formulated with CO2- or biomass-derived organic acids, organic acid salts (e.g., NaHC2O4), or mixtufres thereof, and geographically abundant mineral bases, with or without small-dose functional admixtures or additives.

Description

MULTI-FOLD CARBON-NEGATIVE ORGANIC ALTERNATIVE CEMENTCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the priority benefit of U.S. Provisional Patent Application Serial No. 63 / 515,251, filed July 24, 2023, entitled CARBON-NEGATIVE ORGANIC ALTERNATIVE CEMENT, the entirety of which is incorporated by reference herein.BACKGROUNDField

[0002] The present disclosure broadly relates to alternative cements and methods of making those cements that are at least carbon-neutral, and preferably carbon-negative.Description of Related Art

[0003] The annual global production of cement is currently >4.5 billion metric tons to meet the development of infrastructure. However, cement production is an industry associated with high carbon emissions and high energy consumption. It is generally agreed that the production of 1 ton of cement releases approximately 1 ton of carbon dioxide (FIG. 1). Therefore, this industry has been contributing nearly 9% of global anthropogenic CO2 emissions. The cement industry is now required to achieve zero emissions by 2050. Thus, there is a need for novel carbon-neutral, and even carbon-negative, alternative cements that are fundamentally different from conventional portland cement.SUMMARY

[0004] In one embodiment, the present disclosure is concerned with a method of forming an alternative cement comprising mixing a mineral base and an acidic component chosen from one or both of organic acids or organic acidic salts to form said cement.

[0005] In another embodiment, a method of forming a cement is provided wherein the method comprises mixing an acidic component and olivine to form the cement. The acidic component is chosen from oxalic acid, salts of oxalic acid, or mixtures thereof.

[0006] The disclosure also provides a method of forming a cement comprising mixing an acidic component and a mineral base to form the cement. The acidic component is chosen from oxalic acid, acetic acid, citric acid, malic acid, malonic acid, succinic acid, glutaric acid, adipic acid, aconitic acid, tartaric acid, fumaric acid, propane- 1, 2, 3-tricarboxylic acid, glutaconic acid, mesaconic acid, tartronic acid, aspartic acid, suberic acid, or mixtures thereof. The mineral base is chosen from: non-carbonate rocks chosen from basalt, peridotite, or mixtures thereof;non-carbonate minerals are chosen from plagioclase, olivine, pyroxenes, amphiboles, glauconite, serpentine, dunite, hematite, or mixtures thereof; wastes chosen from metal smelting slags, combustion ashes, recycled concrete, mine tailings, or mixtures thereof; or combinations of the foregoing.

[0007] The disclosure is also concerned with systems for carrying out any of the foregoing methods and products formed by any of the foregoing methods.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure (Fig.) 1 schematically depicts the conventional manufacturing process of one metric ton of portland cement;

[0009] Fig. 2 schematically depicts the manufacturing process of one metric ton of the carbonnegative organic cement as described herein;

[0010] Fig. 3 is a graph showing compressive strengths for a hydrated blend comprising 22.2% oxalic acid and 77.8% olivine (Example 1);

[0011] Fig. 4 provides an X-ray diffractogram for olivine, oxalic acid, and a hydrated blend comprising 22.2% oxalic acid and 77.8% olivine (Example 1);

[0012] Fig. 5 provides backscattered electron images and elementary mappings for a hydrated blend comprising 22.2% oxalic acid and 77.8% olivine (Example 1);

[0013] Fig. 6 provides an X-ray diffractogram for steel slag, oxalic acid, and a hydrated blend comprising 33.3% oxalic acid and 66.7% steel slag (Example 2);

[0014] Fig. 7 provides a thermogram for a hydrated blend comprising 33.3% oxalic acid and 66.7% steel slag (Example 2);

[0015] Fig. 8 provides an X-ray diffractogram for steel slag, olivine, oxalic acid, and a hydrated blend comprising 20% oxalic acid, 40% steel slag, and 40% olivine (Example 5);

[0016] Fig. 9 is a graph depicting compressive strengths of hydrated blends comprising 20% citric acid and 80% copper slag (Example 8);

[0017] Fig. 10 provides an X-ray diffractogram for citric acid, copper slag, and a hydrated paste comprising 20% citric acid and 80% copper slag (Example 8); and

[0018] Fig. 11 is a photograph of blocks formed using the alternative cement formulations and processes described herein (Example 12).DETAILED DESCRIPTION

[0019] The present disclosure is concerned with methods of making an alternative cement product that is carbon-neutral or even carbon-negative. The methods broadly comprise mixing a mineral base with an acidic component to form the cement.COMPONENTS FOR MAKING CEMENT1. Acidic Component

[0020] The acidic component can be obtained from any source or methods, but is preferably chemically, electrochemically, or biologically derived from CO2, CO2-containing flue gases, and / or biomass (growth of which removes CO2 photosynthetically from air). Preferably, the acidic components are energy-efficiently derived from carbon and can readily react with mineral bases with tunable kinetics to form thermodynamically stable and non-dissoluble organic salt (hydrates) products that yield sufficient strength and durability for safety and / or longevity of cement-based materials and / or structures, and preferably also provide permanent carbon storage.

[0021] Suitable acidic components include organic acids, organic acid salts, or mixtures thereof. Typical acidic components for use herein have a molecular weight of about 500 g / mol or lower, more preferably about 300 g / mol or lower, even more preferably about 200 g / mol or lower, and most preferably about 50 g / mol to about 200 g / mol.

[0022] In some embodiments, the acidic component is a non- aromatic organic acid, a non- aromatic organic acid salt, or mixtures thereof. Preferred acidic components include carboxylic acids (including mono-, di-, and / or tricarboxylic acids), carboxylic acid salts, or mixtures thereof.

[0023] Examples of suitable organic acids include oxalic acid, acetic acid, citric acid, malic acid, malonic acid, succinic acid, glutaric acid, adipic acid, aconitic acid, tartaric acid, fumaric acid, propane- 1, 2, 3 -tricarboxylic acid, glutaconic acid, mesaconic acid, tartronic acid, aspartic acid, suberic acid, or mixtures thereof.

[0024] Examples of suitable organic acid salts include oxalic acid salts, acetic acid salts, citric acid salts, malic acid salts, malonic acid salts, succinic acid salts, glutaric acid salts, adipic acid salts, aconitic acid salts, tartaric acid salts, fumaric acid salts, propane- 1, 2, 3-tricarboxy lie acid salts, glutaconic acid salts, mesaconic acid salts, tartronic acid salts, aspartic acid salts, suberic acid salts, or mixtures thereof. In some embodiments, the organic acid salt is an alkali metal (e.g., potassium, sodium) of one or more of the foregoing, with examples of such salts including potassium hydrogen oxalate, sodium hydrogen oxalate, potassium oxalate, sodium oxalate, or mixtures thereof.

[0025] In one or more embodiments, the acidic component is converted or derived from CO2. For example, captured (or low-concentration point source, e.g., flue-gas-borne) CO2 can be converted to oxalic acid or a salt thereof via four main pathways:(a) through direct conversion of CO2 to an alkali oxalate;(b) through a metal formate intermediate, which can be obtained from the electrocatalytic or photocatalytic reduction of CO2;(c) via CO and the dialkyl oxalate process; or(d) via ethylene glycol and subsequent oxidation.

[0026] There are also biological pathways that are feasible and highly-scalable to convert biomass (growth of which removes CO2 from the atmosphere) into oxalic acid. One example is through fermentation using the fungus Aspergillus niger. Additionally, there are thermo-catalytic pathways that are also feasible and highly scalable to convert either CO2 or biomass into oxalic acid. Such pathways may also be assisted by plasma to further improve their energy efficiency

[0027] Thus, the acidic component can be produced by one or more of:CO2 captured from air;CO2 captured from point sources; low-concentration CO2 from point sources directly; and / or biomass whose growth removed CO2 from air.2. Mineral Base

[0028] Suitable mineral bases comprise a target mineral that can be provided directly to the process and / or added by way of a source of the target mineral. Sources of the target mineral include, for example, rocks comprising the target mineral, solid wastes comprising the target minerals, solid wastes comprising rocks that include the target mineral, or mixtures thereof.

[0029] Preferred mineral bases for use in the disclosed methods include non-carbonate rocks, noncarbonate minerals, or mixtures thereof. In other embodiments, carbonate minerals and / or rocks comprising carbonate minerals can be used, such as in applications where “air-filled” concrete blocks are desired.

[0030] Carbonate minerals are minerals comprising significant levels of metal carbonates, e.g., calcite, aragonite, gaspeite, magnesite, otavite, rhodochrosite, siderite, smithsonite, spherocobaltite, etc. Carbonate rocks comprise a significant level of carbonate mineral(s). Non-carbonate minerals and non-carbonate rocks comprise less than about 40% by weight metal carbonates, preferably less than about 30% by weight metal carbonates, more preferably less than about 20% by weight metal carbonates, even more preferably less than about 10% by weight metal carbonates, and most preferablyabout 0% by weight metal carbonates, based on the weight of the mineral base or rock comprising the mineral base.

[0031] In some embodiments, preferred non-carbonate minerals comprise alkaline earth metals (e.g., Ca, Mg) and / or transition metals (e.g., Fe and Cu). In one embodiment, non-carbonate minerals comprise silicates and / or aluminosilicates of alkali metals, alkaline earth metals, and / or transition metals. Oxides of one or more of the foregoing metals are particularly suitable minerals for contacting with the acidic component. In one or more embodiments, the mineral bases comprise at least about at least about 60% by weight, preferably at least about 70% by weight, more preferably about least about 80% by weight, even more preferably at least about 90% by weight, and most preferably about 100% by weight silicates, aluminosilicates, and / or oxides of alkali metals, alkaline earth metals, and / or transition metals, based on the weight of the mineral base or rock comprising the mineral base.

[0032] Suitable mineral bases can comprise at least about 30% by weight, preferably at least about 35% by weight, more preferably at least about 40% by weight, and even more preferably at least about 45% by weight total oxides of one or more of the foregoing metals, based on the weight of the mineral to be treated with oxalic acid. In a preferred embodiment, the foregoing levels are achieved by the combination of magnesium oxide, calcium oxide, and iron oxide present in the mineral base. In another embodiment, the foregoing levels are achieved by the combination of magnesium oxide and iron oxide present in the mineral base.

[0033] In one or more embodiments, the mineral base comprises at least about 20% by weight MgO, preferably at least about 30% by weight MgO, more preferably at least about 40% by weight MgO, even more preferably at least about 60% by weight MgO, and most preferably at least about 80% by weight MgO, based on the total mineral base weight. In some embodiments, the mineral base comprises about 25% to about 65% by weight MgO, preferably about 30% to about 60% by weight MgO, more preferably about 35% to about 55% by weight MgO, and even more preferably about 40% to about 50% by weight MgO, based on the total mineral base weight.

[0034] In one or more embodiments, the mineral base comprises at least about 20% by weight CaO, preferably at least about 30% by weight CaO, more preferably at least about 40% by weight CaO, even more preferably at least about 60% by weight CaO, and most preferably at least about 80% by weight CaO, based on the total mineral base weight. In some embodiments, the mineral base comprises about 25% to about 65% by weight CaO, preferably about 30% to about 60% by weight CaO, more preferably about 35% to about 55% by weight CaO, and even more preferably about 40% to about 50% by weight CaO, based on the total mineral base weight.

[0035] In the same or alternative embodiments, the mineral base comprises at least about 8% by weight iron oxide, preferably at least about 12% by weight iron oxide, and more preferably at least about 15% by weight iron oxide, based on the total mineral base weight.

[0036] In one or more embodiments, the mineral base comprises at least about 20% by weight FeO, preferably at least about 30% by weight FeO, more preferably at least about 40% by weight FeO, even more preferably at least about 60% by weight FeO, and most preferably at least about 80% by weight FeO, based on the total mineral base weight. In some embodiments, the mineral base comprises about 25% to about 65% by weight FeO, preferably about 30% to about 60% by weight FeO, more preferably about 35% to about 55% by weight FeO, and even more preferably about 40% to about 50% by weight FeO, based on the total mineral base weight.

[0037] The mineral base may also comprise less than about 35% by weight FezOs, preferably less than about 30% by weight FeTh, more preferably less than about 20% by weight FeOc and more preferably less than about 10% by weight FezCh, based on the total mineral base weight.

[0038] In yet another embodiment, the mineral base will comprise magnesium oxide and iron oxide in any combination of the foregoing ranges.

[0039] In some embodiments, the mineral base comprises about 5% to about 45% by weight Mg, preferably about 10% to about 40% by weight Mg, more preferably about 15% to about 35% by weight Mg, and even more preferably about 20% to about 30% by weight Mg, based on the total mineral base weight.

[0040] Additionally or alternatively, the mineral base can comprise less than about 35% by weight Fe, preferably less than about 30% by weight Fe, more preferably less than about 20% by weight Fe, even more preferably less than about 15% by weight Fe, and most preferably less than about 10% by weight Fe, based on the total mineral base weight.

[0041] In one or more embodiments, the mineral base includes less than about 10% by weight copper slag, preferably less than about 5% by weight copper slag, more preferably less than about 2% by weight copper slag, and even more preferably about 0% by weight copper slag, based on the total mineral base weight.

[0042] The mineral base may include less than about 10% by weight phosphates, preferably less than about 5% by weight phosphates, more preferably less than about 2% by weight phosphates, and even more preferably about 0% by weight phosphates, based on the total mineral base weight.

[0043] In some embodiments, the mineral base includes less than about 10% by weight limestone, preferably less than about 5% by weight limestone, more preferably less than about 2% by weight limestone, and even more preferably about 0% by weight limestone, based on the total mineral base weight.

[0044] The mineral base can also include less than about 10% by weight calcium, preferably less than about 5% by weight calcium, more preferably less than about 2% by weight calcium, and even more preferably about 0% by weight calcium, based on the total mineral base weight.

[0045] The mineral base will also typically comprise a metalloid such as Si, typically in oxide form. The total SiC levels are preferably less than about 65% by weight, preferably less than about 60% by weight, and more preferably less than about 55% by weight, based on the total weight of the mineral base.

[0046] It is intended that each of the foregoing ranges for total oxides, silicates, aluminosilicates, magnesium oxide, iron oxides, calcium oxide, magnesium, iron, copper slag, phosphates, limestone, calcium, and / or silicon dioxide levels can be present in any number or combination.

[0047] Examples of suitable non-carbonate mineral bases for use in the methods described herein include those chosen from plagioclase, olivine (e.g., forsterite, fayalite), pyroxenes (e.g., hypersthene), amphiboles, glauconite, serpentine, dunite, hematite, other similar minerals, or mixtures thereof.

[0048] In some embodiments, the rocks (preferably non-carbonate rocks) are chosen from mafic, ultramafic, hybrids thereof, or mixtures of the foregoing. Preferred rocks comprise one or more of the mineral bases described above, preferably in quantities needed to provide the previously described levels of metals, oxides, carbonates, etc. Additionally, the rocks are preferably included at sufficient levels to provide at least about 20% by weight, preferably at least about 25% by weight, and more preferably at least about 30% by weight total oxides of alkaline earth, transition, and / or post-transition metals, based on the total rock weight. In the same or different embodiments, the rock comprises at least about 8% by weight, preferably at least about 10% by weight, more preferably at least about 12% by weight, and even more preferably at least about 15% by weight of oxides of magnesium and iron, based on the total rock weight.

[0049] The total SiO levels in the non-carbonate rocks are generally less than about 60% by weight, preferably less than about 55% by weight, more preferably less than about 50% by weight, and even more preferably less than about 45% by weight, based on the total weight of the rock. Examples of suitable non-carbonate rocks for use in the methods described herein include those chosen from basalt, peridotite, or mixtures thereof.

[0050] In some embodiments, the mineral base can also be supplied by industrial wastes that include the previously described target mineral and / or rocks that include those target minerals. Again, the industrial waste is preferably provided in quantities needed to achieve the previously described levels of metals, oxides, carbonates, etc. Such wastes include metal smelting slags (e.g., copper slag, nickel slag, steel slag), combustion ashes, recycled concrete, mine tailings, or mixtures thereof. As used herein, “mine tailings” refers to the materials remaining after the process of separating thevaluable / target commodity. These materials typically include processed rock, soil, dunite, peridotite, olivine, serpentine, basalt, and / or limestone / dolomite.PROCESS FOR MAKING CEMENT

[0051] The acidic component is mixed with the mineral base to form the cement. In preferred embodiments, one of both of the acidic component and mineral base are in powder form. The acidic component and / or mineral base can be ground prior to mixing, or mixed and simultaneously ground. Tn some embodiments, the average particle size is about 400 microns and smaller, preferably about 300 microns and smaller, preferably about 200 microns and smaller, and even more preferably about 100 microns and smaller. In the same or alternative embodiments, the average particle size is about 10 microns to about 400 microns, and preferably about 100 microns to about 300 microns. Particle size can be determined by passing through a sieve or using a laser diffraction particle size analyzer.

[0052] Regardless of whether the components have been ground prior to mixing, the acidic component is preferably included at a level of about 10% to about 40% by weight, more preferably about 15% to about 30% by weight, even more preferably about 18% to about 25% by weight, and most preferably about 18% to about 23% by weight, based on the total weight of the cement taken as 100% by weight.

[0053] The mineral base will be included at the levels necessary to achieve desired levels of components (e.g., oxides) described previously. This will typically result in the mineral base being included in the cement at a level of about 60% to about 90% by weight, preferably about 65% to about 87% by weight, more preferably about 70% to about 87% by weight, and even more preferably about 73% to about 82% by weight, based on the total weight of the cement taken as 100% by weight.

[0054] Optional additives (e.g., cement set retarder) can be mixed in at this time as well. Examples of suitable cement set retarders include those chosen from lignosulphonates, hydroxycarboxylic acids and salts thereof, phosphonates, sugars (e.g., sucrose), a source of boron (such as borax and / or boric acid), a salt of aluminum (e.g., aluminum sulfate), other inorganic salts (e.g., chloride and nitrate / nitrite salts), organic acid or salts (e.g., glacial acetic acid), salts of Pb, Zn, Cu, As, and / or Sb, silica, or combinations of one or more of the foregoing. In embodiments where a cement set retarder is included, it is typically included at a level of about 0. 1% to about 10% by weight, preferably about 0.5% to about 7% by weight, more preferably about 1% by weight to about 5% by weight, and even more preferably about 1% to about 3% by weight, based on the total weight of the cement taken as 100% by weight.

[0055] In some embodiments, the cement consists essentially of, or consists of, the acidic component and the mineral base. In other embodiments, the cement consists essentially of, or consists of, the acidic component, the mineral base, and the cement set retarder.

[0056] Regardless of whether a cement set retarder is included in the cement, the formed cement can be mixed with water to form a paste that will ultimately harden or set into the desired product. The amount of water utilized can be varied, but typical amounts will be at least about 5% by weight water, at least about 8% by weight water, at least about 10% by weight water, at least about 15% by weight water, at least about 20% by weight water, and / or about 35% by weight or lower water, about 30% by weight or lower water, about 25% by weight or lower water, or about 22% by weight or lower water, wherein the % by weight is based on the weight of the cement.

[0057] In some embodiments, the paste consists essentially of, or consists of, the acidic component, the mineral base, and water. In other embodiments, the paste consists essentially of, or consists of, the acidic component, the mineral base, water, and the cement set retarder.

[0058] In some embodiments, one or more types of concrete aggregate can be mixed with the cement powder, cement paste, or both to form a concrete mix. Suitable aggregate can be fine aggregate, coarse aggregate, or a combination thereof. Examples of coarse aggregate include gravel, crushed stone, rocks, slag, recycled concrete, geosynthetic aggregate, glass, coarse CO -sequestering aggregate, or mixtures thereof. Examples of fine aggregate include sand, silt, clay, or mixtures thereof.

[0059] The aggregate is typically mixed with the cement at a level of about 35% to about 90% by weight, preferably about 40% to about 85% by weight, and more preferably about 45% to about 80% by weight, based on the combined weight of aggregate plus cement, or the combined weight of aggregate plus paste. The cement or paste (depending on which is used) will typically be mixed with the aggregate at a level of about 10% to about 65% by weight, preferably about 15% to about 60% by weight, and more preferably about 20% to about 55% by weight, based on the combined weight of aggregate plus cement, or the combined weight of aggregate plus paste.

[0060] In some embodiments, the concrete mix consists essentially of, or consists of, the acidic component, the mineral base, water, and aggregate. In other embodiments, the concrete mix consists essentially of, or consists of, the acidic component, the mineral base, water, the cement set retarder, and aggregate.

[0061] It is preferred that the above is carried out at temperatures about 0°C or higher and less than about 35°C, more preferably about 15°C to about 25°C, and even more preferably about 20°C to about 25°C.

[0062] Upon contact with water to form the paste (regardless of whether aggregate is present), the acidic component will accelerate dissolution of the rocks and minerals it contacts, releasing metals ions into solution. A reaction between the mineral base and acidic component preferably takes place, thus forming insoluble organic salts (e.g., oxalates and / or oxalate hydrates) of the metal(s) provided by the mineral base. Examples of the reaction products when oxalic acid is used as the acidiccomponent include magnesium oxalate dihydrate, ferrous oxalate dihydrate, calcium oxalate monohydrate, other oxalate hydrates, or mixtures thereof.

[0063] The cementation mechanisms are generally illustrated (using divalent metal and relevant acids as examples, but not limited to divalent) below:M2+SiO3+ H2CxOy+ ZH2O -> M2+CxOy(z+l)H2O + SiO2(aq)(1)M2+2SiO4+ 2H2CxOy + 2zH2O 2M2+CxOy (z+ 1 )H2O + SiO2(aq)(2)M2+O + H2CxOy + ZH2O M2+CxOy (Z+1)H2O (3)Where M2+= Ca2+, Mg2+, Fe2+, etc.; H2CxOydenotes an organic acid meeting the previously described requirements; equals zero or a positive integer; SiO2(aq) can be H4SiO4aqueous silicic acid), any of its acid dissociation products, or precipitated silica minerals or amorphous gels. In reactions (1) and (2), the silicates can also be aluminosilicates or other derivatives, such as those in alkali aluminosilicate solid wastes (e.g., slags, ashes, recycled concrete).

[0064] The cement paste (either with or without aggregate) typically hardens in about 15 minutes to about 60 minutes, and preferably about 15 minutes to about 45 minutes. In some embodiments, the set or hardening time is about 20 minutes or greater, preferably about 30 minutes or greater, more preferably about 45 minutes or greater, and even more preferably about 45 minutes to about 180 minutes, and more preferably about 30 minutes to about 120 minutes. Regardless, the set time is preferably determined by a Vicat apparatus according to the relevant penetration depth in ASTM C191.

[0065] It will be appreciated that the cement has a 3 -day compressive strength of at least about 20 MPa, preferably at least about 25 MPa, and more preferably at least about 30 MPa. Additionally or alternatively, the cement has a 28-day compressive strength of at least about 30 MPa, preferably at least about 35 MPa, and more preferably at least about 40 MPa. Compressive strength is preferably determined using a mechanical compression machine with a maximum load of 100 kN, using the arithmetic mean of three samples as the compressive strength.

[0066] Either way, it will be appreciated that the paste (with or without aggregate) can be formed or shaped into a desired shape (e.g., block) depending on the end use, similar to formation methods carried out with conventional cement and concrete.

[0067] In some embodiments, the cement, paste, concrete mix, and / or formed product comprise, based on the weight of the cement, paste, concrete mix, or formed product: a) less than about 10% by weight copper slag, preferably less than about 5% by weight copper slag, more preferably less than about 2% by weight copper slag, and even more preferably about 0% by weight copper slag;b) less than about 10% by weight phosphates, preferably less than about 5% by weight phosphates, more preferably less than about 2% by weight phosphates, and even more preferably about 0% by weight phosphates; c) less than about 35% by weight Fe^Ch, preferably less than about 30% by weight Fe^Ch, more preferably less than about 20% by weight Fe^C , and more preferably less than about 10% by weight FezC ; d) less than about 35% by weight Fe, preferably less than about 30% by weight Fe, more preferably less than about 20% by weight Fe, even more preferably less than about 15% by weight Fe, and most preferably less than about 10% by weight Fe; e) about 25% to about 65% by weight MgO, preferably about 30% to about 60% by weight MgO, more preferably about 35% to about 55% by weight MgO, and even more preferably about 40% to about 50% by weight MgO; f) about 5% to about 45% by weight Mg, preferably about 10% to about 40% by weight Mg, more preferably about 15% to about 35% by weight Mg, and even more preferably about 20% to about 30% by weight Mg; g) less than about 10% by weight limestone, preferably less than about 5% by weight limestone, more preferably less than about 2% by weight limestone, and even more preferably about 0% by weight limestone; and / or h) less than about 10% by weight calcium, preferably less than about 5% by weight calcium, more preferably less than about 2% by weight calcium, and even more preferably about 0% by weight calcium.

[0068] One, two, three, four, five, six, seven, or all eight of (a) to (h) can be true, in any combination.

[0069] Advantageously, these cements can be used in the same way as conventional cements for making slurry / grout, mortar, ready-mixed concrete, and / or pre-cast concrete but without the drawbacks or limitations of currently available carbon-negative cements. Since the manufacturing of the cements involves only proportioning and grinding / co-grinding, the overall energy-efficiency of the manufacturing process is extremely high, and the cements can achieve cradle-to-gate and / or cradle-to- grave carbon negativity. This efficiency is increased even further if the organic acidic component(s) are derived from CO2, CCF-containing flue gases, and / or biomass (growth of which removes CO2 photosynthetically from air), as described previously.

[0070] Thus, methods can be carried out, and the various products formed, in carbon-neutral, or even carbon-negative, ways. That is, the formation and / or use of the described cement, paste, concrete mix, and / or formed products is carbon-neutral, or even carbon-negative. As used herein, “carbon-neutral” means the carbon dioxide released into the atmosphere by the particular activity, method, use, etc., is approximately offset by the amount of carbon dioxide absorbed or removed from the atmosphere during the particular activity, method, use, etc. “Carbon-negative” means that the carbon dioxide released into the atmosphere by the particular activity, method, use, etc., is more than offset by the amount of carbon dioxide absorbed or removed from the atmosphere during the particular activity, method, use, etc. In other words, “carbon-negative” results in the activity, method, use, etc., having a net effect of removing carbon dioxide from the atmosphere rather than adding to it.

[0071] Fig. 2 provides a schematic depiction of the manufacturing process of the disclosed carbonnegative organic cements. As compared with that of conventional portland cement (Fig. 1), the disclosed method reduces the CO2 footprint of 1 metric ton portland cement from roughly 0.9 metric ton CO2 to approximately -0.2 metric ton CO2 per metric ton of the organic cement (see Fig. 2). Thus, the net CO2 footprint of this process is about 0 metric ton or lower of CO2 per metric ton of organic cement, preferably about -0.1 metric ton or lower of CO2 per metric ton of organic cement, and more preferably about -0.2 metric ton or lower of CO2 per metric ton of organic cement.

[0072] Additional advantages of the various embodiments will be apparent to those skilled in the art upon review of the disclosure herein and the working examples below. It will be appreciated that the various embodiments described herein are not necessarily mutually exclusive unless otherwise indicated herein. For example, a feature described or depicted in one embodiment may also be included in other embodiments but is not necessarily included. Thus, the present disclosure encompasses a variety of combinations and / or integrations of the specific embodiments described herein.

[0073] As used herein, the phrase "and / or," when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing or excluding components A, B, and / or C, the composition can contain or exclude A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0074] The present description also uses numerical ranges to quantify certain parameters relating to various embodiments. It should be understood that when numerical ranges are provided, such ranges are to be construed as providing literal support for claim limitations that only recite the lower value of the range as well as claim limitations that only recite the upper value of the range. For example, a disclosed numerical range of about 10 to about 100 provides literal support for a claim reciting "greater than about 10" (with no upper bounds) and a claim reciting "less than about 100" (with no lower bounds).EXAMPLES

[0075] The following examples set forth methods in accordance with the disclosure. It is to be understood, however, that these examples are provided by way of illustration, and nothing therein should be taken as a limitation upon the overall scope.

[0076] Table 1 sets forth the weight percentages for carbon-negative organic cement compositions described in examples herein. For each example in Table 1, additional formulations are envisioned, including plus and minus 25 percent, plus and minus 15 percent, and plus and minus 10 percent variation in weight percentage of each ingredient.Table 1. Examples 1-11 FormulationsExamplesMaterials#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11Oxalic acid 22.2 33.3 20.0 16.7 10Citric acid 20.0 20.0 15 20 10Potassium hydrogen oxalate 25.0S odium hydrogen oxalate 33.3Olivine 77.8 40.0 80.0 60 80Steel slag 66.7 75.0 66.7 40.0Copper slag 80.0 60 20Class C fly ash 83.3Silica powder 25Borax 2.0 0.5 0.5

[0077] Table 2 sets forth the X-ray fluorescence (XRF) data of base materials used in examples herein. Commercial organic acids and organic acidic salts were used in examples herein.Table 2. X-Ray Fluorescence DataChemical composition determined by XRF (wt %)MaterialsMgO AI2O3 SiO2 CaO Fe2Os CnOr MnO NiO SiO3 OthersOlivine 48.38 0.25 39.00 0.17 10.66 0.73 0.17 0.52 - 0.12Steel slag 5.65 10.16 14.98 29.44 30.36 2.22 5.58 - 0.41 1.20Copper slag 1.91 9.91 32.29 11.40 40.36 - 0.17 - 0.66 3.30Class C fly ash 3.19 17.96 49.44 17.08 6.96 - - - 1.76 3.61EXAMPLE 1Oxalic Acid + Olivine

[0078] In this Example, carbon-negative organic cement composition was made using a powder blend that was a mixture of 21.8 percent oxalic acid and 76.2 percent olivine, to which 2 percent borax was added. The addition of borax delayed the setting and temperature rise of the paste.

[0079] The powder blend was made by two methods. In the first one, olivine and granular oxalic acid were separately ground and subsequently mixed and homogenized in the proportion previously described. In the second one, olivine sand and granular oxalic acid were co-ground in the same proportion to obtain the homogenous powder blend.

[0080] The powder blend was slowly added to 16 percent water and thoroughly mixed to form a homogenous paste. Setting time and compressive strength of the blend prepared using separate grinding and co-grinding were tested. FIG. 3 depicts the compressive strength in both cases. The blend prepared using the separate grinding method was set in 28 minutes from the addition of water, and its strength was found to increase from 16.8 MPa at 3 days to 27.3 MPa at 7 days and to 36.3 MPa at 28 days. The use of co-grinding method slightly shortened setting time and reduced compressive strength when compared to the use of separate grinding.

[0081] X-ray diffraction analysis (FIG. 4) revealed that the hydrated paste consisted of unreacted olivine and the sole carbon-bearing reaction product - glushinskite (MgC2O4 2H2O). No peaks of the oxalic acid were noted, indicating its complete reaction. Backscattered electron (SEM) images and elementary mappings (in terms of Mg, Si, Fe, C, and Al) of the paste are shown in FIG. 5. The resultingpaste was observed to be dense, non-porous, and homogenous. The unreacted olivine particles can be clearly seen in the Fig. 5 images and confirmed by the Mg, Si, and Fe mappings. The reaction products surrounding the unreacted olivine particles were composed of C (21%), Mg (14%), Si (13%), Fe (2.6%), O (48%), and others (1.4%), in which the elements’ respective percentages were determined by energy dispersive spectroscopy (EDS). The incorporation of carbon from oxalic acid in the products manifests the occurrence of chemical reactions between olivine and oxalic acid, and the elemental ratio strongly suggests the formation of oxalates.EXAMPLE 2Oxalic Acid + Steel Slag

[0082] In this Example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 33.3 percent oxalic acid and 66.7 percent steel slag. The powder blend was slowly added to 22 percent water and thoroughly mixed to form a homogenous paste. Table 3 shows the results of setting time and compressive strength of the paste made in this Example (as well as Examples 3-4, discussed below). The pastes solidified into a hard matrix within 18 minutes. A strength gain of over 25 MPa at 3 days may be achieved. Ultimate strength at 28 days was approximately 40 MPa.Table 3. Setting Times and Compressive StrengthsCompressive strength, MPa (psi) ttillg Lllll -, 1111113 days 7 days 28 days#2 18 25.2 (3655) 28.7 (4160) 39.7 (5755)#3 19 24.3 (3525) 32.4 (4670) 40.1 (5815)#4 25 16.4 (2380) 25.1 (3640) 31.2 (4525)

[0083] X-ray diffraction (FIG. 6) and thermogravimetric analyses (FIG. 7) revealed that the main reaction products of the hydrated paste were carbon-bearing hydrates including whewellite (CaC2O4 H2O), weddellite (CaC2O4 2H2O), and humboldtine (FeC2O4 2H2O). The paste lacked any peaks corresponding to the oxalic acid, indicating that it all reacted.EXAMPLE 3Potassium Hydrogen Oxalate + Steel Slag

[0084] In this example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 25 percent potassium hydrogen oxalate and 75 percent steel slag. The powder blend was slowly added to 20 percent water and thoroughly mixed to form a homogenous paste. Data on setting time and compressive strength of the paste made in this Example are shown in Table 3 above. The paste was observed to set into a hard matrix in about 19 min. Compressive strength was found to increase from 24.3 MPa at 3 days to 32.4 MPa at 7 days and 40.1 MPa at 28 days.EXAMPLE 4Sodium Hydrogen Oxalate + Steel Slag

[0085] In this example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 33.3 percent sodium hydrogen oxalate and 66.7 percent steel slag. The powder blend was slowly added to 22 percent water and thoroughly mixed to form a homogenous paste. Data on setting time and compressive strength of the paste made in this Example are shown in Table 3 above. The paste set in about 25 min. Compressive strength was found to increase from 16.4 MPa at 3 days to 25.1 MPa at 7 days and to 31.2 MPa at 28 days. A comparison of the results shown in Table 3 with those of Examples #2 and #4 indicates the setting time was slightly prolonged and the strength was decreased when replacing oxalic acid with its acidic salt - sodium hydrogen oxalate.EXAMPLE 5Oxalic Acid + Steel Slag + Olivine

[0086] In this Example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 20 percent oxalic acid, 40 percent olivine and 40 percent steel slag. The powder blends were slowly added to 22 percent water and thoroughly mixed to form a homogenous paste. Data on setting time and compressive strength of a series of pastes made in this Example are shown in Table 4. The pastes solidified into a hard matrix within 55 minutes. Compressive strength was found to increase from 14.2 MPa in 3 days to 20.9 MPa in 7 days and 32.1 MPa in 28 days. X-ray diffraction analysis (FIG. 8) revealed the co-existence of multiple carbon-bearing hydrates including glushinskite (MgC2O4 2H2O), whewellite (CaC2O4 H2O), weddellite (CaC2O4 2H2O), and humboldtine (FeC2O4 2H2O) within the hydrated paste.Table 4. Setting Times and Compressive StrengthsCompressive strength, MPa (psi)Examples Setting time, min -3 days 7 days 28 days#5 55 14.2 (2060) 20.9 (3030) 32.1 (4655)EXAMPLE 6 Oxalic Acid + Class C Fly Ash

[0087] In this Example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 16.7 percent oxalic acid and 83.3 percent Class C fly ash. The powder blend was slowly added to 18 percent water and thoroughly mixed to form a homogenous paste. The paste set in 12 minutes and attained compressive strengths of 10.2 MPa at 3 days, 18.8 MPa at 7 days, and 34.9 MPa at 28 days.EXAMPLE 7Citric Acid + Olivine

[0088] In this Example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 20 percent citric acid and 80 percent olivine. The powder blend was slowly added to 12 percent water and thoroughly mixed to form a homogenous paste. The paste was observed to set into a hard matrix between 6 and 10 hours. The compressive strength of hydrated paste was found to increase from 1.1 MPa at 3 days to 5.4 MPa at 7 days and to 31.1 MPa at 28 days.EXAMPLE 8Citric acid + Copper slag

[0089] In this Example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 20 percent citric acid and 80 percent copper slag, to which 0.5 percent borax was added. The powder blend was slowly added to 8-12 percent water and thoroughly mixed to form homogenous pastes. The pastes with various amounts of water solidified into a hard matrix within 15-47 minutes. Results of the compressive strength of a series of pastes with various amounts of water made in this Example are shown in FIG. 9. As the water amount decreased from 12 percent to 8 percent, the compressive strength increased significantly. Based on these data, ultimate strength at 28 days may reach approximately 90 MPa when a lower water percent is included. X-ray diffraction analysis (FIG. 10) revealed the depletion of citric acid and the formation of a carbon-bearing phase - ferric citrate (FeCeOsH).EXAMPLE 9Citric Acid + Copper Slag + Silica Powder

[0090] In this Example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 15 percent citric acid and 60 percent copper slag, 25 percent silica powder, to which 0.5 percent borax was added. The powder blend was slowly added to 12 percent water and thoroughly mixed to form homogenous pastes. The paste set in 22 minutes. The use of silica powder as a filler can retard the setting time. Compressive strength of hydrated paste was found to increase from 8.9 MPa at 3 days to 25.7 MPa at 7 days and to 32.6 MPa at 28 days.EXAMPLE 10Citric Acid + Olivine + Copper Slag

[0091] In this Example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 20 percent citric acid, 60 percent olivine and 20 percent copper slag. The powder blend was slowly added to 12 percent water and thoroughly mixed to form a homogenous paste. The paste set in 28 minutes and attained compressive strengths of 5.5 MPa at 3 days, 13.3 MPa at 7 days, and 44.1 MPa at 28 days.EXAMPLE 11Oxalic Acid + Citric Acid + Olivine

[0092] In this Example, a carbon-negative organic cement composition was made using a powder blend that was a mixture of 5 percent oxalic acid, 15 percent citric acid and 80 percent olivine. The powder blend was slowly added to 12 percent water and thoroughly mixed to form a homogenous paste. The paste was observed to set in 54 min. The compressive strength of hydrated paste was found to increase from 10.5 MPa at 3 days to 22.8 MPa at 7 days and to 32.7 MPa at 28 days.EXAMPLE 12 Sample BlocksCements were made following procedures similar to those described above, with each sample being placed in a mold to form the block. Those blocks are shown in FIG. 11 , with the blocks being, from left to right: oxalic acid + electric arc furnace steel slag, oxalic acid + olivine, oxalic acid + class F coal fly ash, oxalic acid + class C coal fly ash, oxalic acid + electric arc furnace steel slag + olivine, oxalic acid + ladle metallurgy furnace steel slag, oxalic acid + ladle metallurgy furnace steel slag + olivine, citric acid + copper slag, citric acid + olivine.

[0093] The experimental data shows that carbon-negative organic cements can be formed successfully. These cements feature fast hardening and low water demand (i.e., they can achieve comparable flowability to portland cement at much lower water-to-cement mass ratios). It is worth noting that the low water demands result in low porosity after hardening, and, thus, superior durability. The cements can achieve the standard requirements for hydraulic cements (ASTM Cl 157), including workability (e.g., setting time is not less than about 45 minutes) and compressive strength (e.g., the 28-day compressive strength is not less than about 28 MPa).

Claims

CLAIMS1. A method of forming an alternative cement comprising mixing a mineral base and an acidic component chosen from one or both of organic acids or organic acidic salts to form said cement.

2. The method of claim 1, wherein said acidic component is chosen from oxalic acid, acetic acid salts of oxalic acid, salts of acetic acid, or mixtures thereof.

3. The method of claim 2, wherein said salts of oxalic acid are chosen from alkali metal hydrogen salts of oxalic acid, alkali metal salts of oxalic acid, or mixtures thereof.

4. The method of any of the foregoing claims, wherein said mineral base comprises noncarbonate rocks, non-carbonate minerals, alkali (alumino)silicate solid wastes, or mixtures thereof.

5. The method of any claim 4, wherein: said non-carbonate rocks are chosen from basalt, peridotite, or mixtures thereof; and said non-carbonate minerals are chosen from plagioclase, olivine, pyroxenes, amphiboles, glauconite, serpentine, dunite, hematite, or mixtures thereof.

6. The method of any of the foregoing claims, wherein said mineral base comprises olivine.

7. The method of any of the foregoing claims, wherein said mineral base comprises carbonate rocks, carbonate minerals, or mixtures thereof.

8. The method of any of the foregoing claims, wherein the acidic component is present in said cement at a level of about 10% to about 40% by weight, based on the total weight of the cement taken as 100% by weight.

9. The method of any of the foregoing claims, wherein said mineral base is present in said cement at a level of about 60% to about 90% by weight, based on the total weight of the cement taken as 100% by weight.

10. The method of any of the foregoing claims, wherein one or both of said mineral baseor said acidic component are in the form of a powder.

11. The method of any of the foregoing claims, further comprising the steps of grinding one or both of said mineral base or said acidic component to form a powder of said mineral base and / or acidic component.

12. The method of any of the foregoing claims, wherein said mineral base and acidic component are mixed with water to form a paste, said paste being formed by a reaction between the mineral base and acidic component.

13. The method of claim 12, wherein said paste forms a hardened material in about 15 minutes to about 60 minutes.

14. The method of claim 12, wherein said paste forms a hardened material in about 20 minutes or greater.

15. The method of any of the foregoing claims, further comprising mixing a cement set retarder with said mineral base and acidic component.

16. The method of claim 15, wherein said cement set retarder is present in said cement at a level of about 0.1% to about 10% by weight, based on the total weight of the cement taken as 100% by weight.

17. The method of claim 15 or 16, wherein said cement set retarder is chosen from lignosulphonates, hydroxycarboxylic acids, hydroxycarboxylic acids salts, glacial acetic acid, phosphonates, sugars, a source of boron, aluminum salts, chloride salts, nitrate salts, nitrite salts, a salt of lead salts, zinc salts, copper salts, arsenic salts, antimony salts, silica powder, or mixtures thereof.

18. The method of any of the foregoing claims, wherein said acidic component comprises an organic acid, organic acid salt, hydrogen salts, or mixtures thereof produced by at least one of:CO2 captured from air;CO2 captured from point sources; low-concentration CO2 from point sources directly; or biomass whose growth removed CO2 from air.

19. The method of any of the foregoing claims, wherein said cement has a 3-day compressive strength of at least about 20 MPa, as determined using a mechanical compression machine with a maximum load of 100 kN, using the arithmetic mean of three samples as the compressive strength.

20. The method of any of the foregoing claims, wherein said cement has a 28-day compressive strength of at least about 30 MPa, as determined using a mechanical compression machine with a maximum load of 100 kN, using the arithmetic mean of three samples as the compressive strength.

21. The method of any of the foregoing claims, wherein said mineral base comprises: a) less than about 10% by weight copper slag; b) less than about 10% by weight phosphates; c) less than about 35% by weight Fe^Op d) less than about 35% by weight Fe; e) about 25% to about 65% by weight MgO; f) about 5% to about 45% by weight Mg; g) less than about 10% by weight limestone; and / or h) less than about 10% by weight calcium.

22. The method of claim 21, where one, two, three, four, five, six, seven, or all eight of (a) to (h) are true, in any combination.

23. The method of any of the foregoing claims, wherein said cement comprises: a) less than about 10% by weight copper slag; b) less than about 10% by weight phosphates; c) less than about 35% by weight Fe^Ch; d) less than about 35% by weight Fe; e) about 25% to about 65% by weight MgO; f) about 5% to about 45% by weight Mg; g) less than about 10% by weight limestone; and / or h) less than about 10% by weight calcium.

24. The method of claim 23, where one, two, three, four, five, six, seven, or all eight of (a) to (h) are true, in any combination.

25. The method of any of claims 12 to 24, wherein said paste comprises: a) less than about 10% by weight copper slag; b) less than about 10% by weight phosphates; c) less than about 35% by weight Fe^Ch; d) less than about 35% by weight Fe; e) about 25% to about 65% by weight MgO; f) about 5% to about 45% by weight Mg; g) less than about 10% by weight limestone; and / or h) less than about 10% by weight calcium.

26. The method of claim 25, where one, two, three, four, five, six, seven, or all eight of (a) to (h) are true, in any combination.

27. The method of any of the foregoing claims, wherein the formation and / or use of said cement is carbon-neutral or carbon-negative.

28. The method of any of claims 12 to 24, wherein the formation and / or use of said paste is carbon-neutral or carbon-negative.

29. The method of any of the foregoing claims, further comprising:(1) mixing an aggregate with said cement to form a concrete mix;(2) mixing an aggregate with said paste to form a concrete mix; or(3) both (1) and (2).

30. The method of claim 29, wherein said aggregate comprises fine aggregate, coarse aggregate, or a combination thereof.

31. The method of claim 30, wherein said coarse aggregate is chosen from gravel, crushed stone, rocks, slag, recycled concrete, geosynthetic aggregate, glass, coarse CC -sequestering aggregate, or combinations thereof.

32. The method of claim 30, wherein said fine aggregate is chosen from sand, silt, clay, or combinations thereof.

33. The method of any of claims 29 to 32, wherein said aggregate is mixed at a level of about 35% to about 90% by weight, based on the combined weight of aggregate plus cement, or the combined weight of aggregate plus paste.

34. The method of any of claims 29 to 32, wherein said aggregate is mixed so that the level of cement or paste is about 10% to about 65% by weight, based on the combined weight of aggregate plus cement, or the combined weight of aggregate plus paste.

35. The method of any of the foregoing claims, wherein said cement consists essentially of said acidic component and said mineral base.

36. The method of any of claims 1 to 34, wherein said cement consists essentially of said acidic component, said mineral base, and a cement set retarder.

37. The method of any of claims 12 to 34, wherein said paste consists essentially of said acidic component, said mineral base, and water.

38. The method of any of claims 12 to 34, wherein said paste consists essentially of said acidic component, said mineral base, water, and a cement set retarder.

39. The method of any of claims 29 to 34, wherein said concrete mix consists essentially of said acidic component, said mineral base, and water.

40. The method of any of claims 29 to 34, wherein said concrete mix consists essentially of said acidic component, said mineral base, water, and a cement set retarder.

41. The method of any of claims 29 to 34, wherein the formation and / or use of said concrete mix is carbon-neutral or carbon-negative.

42. A method of forming a cement comprising mixing an acidic component and olivine toform said cement, wherein said acidic component is chosen from oxalic acid, salts of oxalic acid, or mixtures thereof.

43. The method of claim 42, wherein said acidic component is present in said cement at a level of about 10% to about 40% by weight, based on the total weight of the cement taken as 100% by weight.

44. The method of claim 42 or 43, wherein said olivine is present in said cement at a level of about 60% to about 90% by weight, based on the total weight of the cement taken as 100% by weight.

45. A method of forming a cement comprising mixing an acidic component and a mineral base to form said cement, wherein: said acidic component is chosen from oxalic acid, acetic acid, citric acid, malic acid, malonic acid, succinic acid, glutaric acid, adipic acid, aconitic acid, tartaric acid, fumaric acid, propane- 1, 2, 3 -tricarboxylic acid, glutaconic acid, mesaconic acid, tartronic acid, aspartic acid, suberic acid, or mixtures thereof; and said mineral base is chosen from: non-carbonate rocks chosen from basalt, peridotite, or mixtures thereof; non-carbonate minerals chosen from plagioclase, olivine, pyroxenes, amphiboles, glauconite, serpentine, dunite, hematite, or mixtures thereof; wastes chosen from metal smelting slags, combustion ashes, recycled concrete, mine tailings, or mixtures thereof; or combinations of the foregoing.

46. The method of claim 45, further comprising mixing said cement with water to form a paste.

47. The method of claim 46, further comprising mixing aggregate with said paste to form a concrete mix.

48. The method of claim 45, further comprising mixing said cement with water and aggregate to form a concrete mix.

49. A concrete product formed according to any of the foregoing claims.

50. The concrete product of claim 49, wherein the formation thereof is carbon-neutral or carbon-negative.

51. A system for carrying out any of the methods of claims 1 to 48.

52. The system of claim 51 , wherein the use thereof is carbon-neutral or carbon-negative.

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