EP4649068A1 - Methods of preparing concrete precursors and systems thereof - Google Patents

Abstract

Provided herein are method of preparing concrete precursor and systems thereof. The methods and systems include contacting recycled concrete aggregates with an acid to produce said concrete precursors.

Description

ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR METHODS OF PREPARING CONCRETE PRECURSORS AND SYSTEMS THEREOF CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Application No.63/452,107, filed on March 14, 2023, the contents of which is hereby incorporated by reference in its entirety including any drawings. TECHNICAL FIELD [0001] This specification relates generally to a method of preparing concrete precursors from recycled concrete aggregates (RCA). BACKGROUND [0002] Accelerated urbanization and industrialization have resulted in over 3 billion tons annually of construction and demolition (C&D) wastes that mainly is disposed of in landfills. A large portion of this C&D waste is concrete. While the generation of waste concrete raises the environmental burden and handling cost, the unlimited exploitation of natural resources, such as natural aggregates, has created a shortage of new construction materials in highly urbanized areas, such as Hong Kong. Therefore, attempts have been made to use recycled concrete aggregates (RCA), to lower the waste handling cost and also to provide additional materials for new construction. However, concrete made from RCA has significantly poorer performance because of, for example, the high water absorption of the RCA, substantially limiting the use of such materials in a structural capacity. [0003] Further, cement production releases an enormous amount of CO2 into the atmosphere. A key step in cement production is calcination, i.e. CaCO₃→ CaO + CO₂, which directly generates CO2 as a product of the reaction and also requires significant energy expenditure to maintain the necessary temperatures of up to 1,500°C. SUMMARY [0004] Provided herein are methods and systems for producing concrete precursors from RCAs for use in the manufacture of cement and/or concrete. The systems and methods described herein can have several advantages over the conventional methods of making such building materials, including (for example), reducing the use of natural mineral resources, using less energy (e.g., net energy neutral), producing less CO2 (e.g., carbon neutral) or even ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR being net carbon negative (e.g., sequestering CO2), and providing a regenerative process to reuse byproducts of the reaction in the reaction. [0005] In general, this disclosure relates to processes and systems for preparing concrete precursors from recycled concrete aggregates (RCA). [0006] Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting an inorganic solid waste comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; (b) contacting the liquid rich in the one or more metallic ions with a base to produce a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer to regenerate the acid and the base, and (d) repeating each of steps (a)-(b) at least once with the acid and the base from step (c). [0007] Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregate (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; (b) contacting the one or more liquid rich in the one or more metallic ions with a base to produce a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer to regenerate the acid and the base, and (d) repeating each of steps (a)-(b) at least once with the acid and the base from step (c). [0008] Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregate (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; (b) contacting the liquid rich in the one or more metallic ions with a base and carbon dioxide to produce a precipitate comprising one or more metal carbonates from the one or more metallic ions and a liquid deficient in the one or more metallic ions; and (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR to regenerate the acid and the base. [0009] Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregates (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions (b) contacting the liquid rich in the one or more metallic ions with a base comprising a carbonate salt and/or a bicarbonate salt to produce one or more metal carbonates from the one or more metallic ions and a liquid deficient in the one or more metallic ions; and (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer to regenerate the acid and the base, wherein the carbonate salt and/or the bicarbonate salt are produced from admixing carbon dioxide and a metal hydroxide. Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregates (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; and (b) contacting the liquid rich in the one or more metallic ions with an electrolyzer to regenerate the acid and produce a precipitate comprising the one or more metallic ions. [0010] Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregates (RCA) comprising one or more metallic ions with an acid in an electrochemical cell to produce the concrete precursors and a liquid rich in the one or more metallic ions; and (b) contacting the liquid rich in the one or more metallic ions with a base in the electrochemical cell to form a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; wherein the electrochemical cell comprises an anode reservoir comprising an anode and the acid, and a cathode reservoir comprising a cathode and the base, wherein the anode reservoir and the cathode reservoir are separated by a separator. [0011] Some embodiments provide a system for preparing concrete precursors, comprising: an electrochemical cell configured to prepare concrete precursors, wherein the ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR electrochemical cell comprises an anode reservoir comprising an anode and an acid, and a cathode reservoir comprising a cathode and a base, wherein the anode reservoir and the cathode reservoir are separated by a separator; a contactor configured to input recycled concrete aggregates (RCA) comprising the one or more metallic ions into the anode reservoir, wherein the anode reservoir is configured to contact the RCA with the acid to produce the concrete precursors and a liquid rich in the one or more metallic ions, and the cathode reservoir is configured to contact the liquid rich in the one or more metallic ions with the base to form a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; a first filtration system in contact with the anode reservoir configured to filter out the concrete precursors from the anode reservoir; and a second filtration system in contact with the cathode reservoir configured to filter out the precipitate from the cathode. [0012] Other implementations of the above aspects include corresponding systems, apparatus, and computer programs, configured to perform the actions of the methods, encoded on computer storage devices. The details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. [0013] In some embodiments, the methods described herein provide a significant cost reduction relative to current methods of preparing concrete precursors, including methods that use RCAs. In some embodiments, the methods described herein provide a significant reduction in the amount of waste concrete by transforming RCAs into valuable resources. BRIEF DESCRIPTION OF THE DRAWINGS [0014] FIG. 1A depicts an example method of preparing concrete precursors from recycled concrete aggregates disclosed herein. The Ca(OH)₂ or other metal hydroxides can be further treated thermally and mechanically to make cement or supplementary cementitious materials. [0015] FIG.1B, FIG.1C, and FIG.1D each depict an example electrolyzer that can be used in the method of preparing concrete precursors of FIG. 1A disclosed herein. The anion ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR exchange membrane (AEM) and cation exchange membrane (CEM) can be replaced with a bipolar membrane. [0016] FIG. 2. Depicts a bipolar membrane electrolyzer for acid and base generation. Multiple electrodialysis units can be implemented in this cell configuration. For example, as an alternative to having one electrodialysis unit (as shown) written as [Electrode | CEM | BPM | AEM | CEM| Electrode], it can also be [Electrode | CEM | BPM | AEM | CEM | BPM | AEM | CEM| Electrode], [Electrode | CEM | BPM | AEM | CEM | BPM | AEM | CEM | BPM | AEM | CEM| Electrode], or [Electrode | CEM (| BPM | AEM | CEM ) * n | Electrode] which would further reduce the overall cost of electrodialysis. [0017] FIG. 3 depicts an example method of preparing concrete precursors from recycled concrete aggregates and CO2 disclosed herein, wherein the CO2 is added during a base treatment. [0018] FIG. 4 depicts an example method of preparing concrete precursors from recycled concrete aggregates and CO₂ disclosed herein, wherein the CO₂ is added to a base to generate an aqueous carbonate. [0019] FIG. 5A depicts an example method of preparing concrete precursors from recycled concrete aggregates disclosed herein, wherein the calcium salt undergoes direct electrolysis. [0020] FIG.5B, 5C, and 5D each depict an example electrolyzer that can be used in the method of preparing concrete precursors of FIG.5A disclosed herein. [0021] FIG. 6 depicts an example method of preparing concrete precursors from recycled concrete aggregates disclosed herein, wherein the RCA is used directly in an electrolyzer. [0022] FIG. 7 depicts an example of a step of the method of preparing concrete precursors of FIG.3, wherein the electrolysis step is done sequentially via electrodistillation as disclosed herein. [0023] FIG. 8 depicts an example of a step of the method of preparing concrete precursors of FIG.6, wherein the electrolysis step is done sequentially via electrodistillation as disclosed herein. [0024] FIG. 9 depicts an example of a batch process electrolysis method that can be used in a method of preparing concrete precursors disclosed herein. [0025] FIG. 10 depicts an example of a continuous base treatment that can be used in the methods of preparing concrete precursors disclosed herein, e.g., the methods of FIG.1A. [0026] FIG.11 depicts a schematic of packed bed reactor (form factor 1) ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR [0027] FIG.12A and 12B depicts form factor 1 and acid-treated RCA using form factor one as described in Example 2, respectively. RCA is packed into 10 ft tall tube, then acid solution is continuously circulated by peristaltic pump through the packed bed of RCA. The acid treated RCA still has high mortar content. [0028] FIG.13 depicts time course of pH during acid treatment of RCA in rotary drum (form factor 2) in Example 2. [0029] FIG.14A, FIG. 14B, and FIG.14C depict photographs of acid treated RCA in rotary drum (form factor 2) after 1^st portion, 2^nd portion, and 3^rd portion of consecutive acid treatments, respectively in Example 4. Each photograph was after 6h of treatment. These results indicate breaking a single acid treatment into multiple intervals enhanced removal of mortar. The average water absorption of the aggregates after three treatments (18 h total treatment time) was 0.96±0.1. [0030] FIG.15 depicts time course of pH during acid treatment of RCA in rotary drum (form factor 2) in Example 4. First portion is top, second portion is middle, third portion is bottom. [0031] FIG. 16 depicts results of treating RCA with various acids on the water absorption of recovered aggregates. Water absorption dropped by about 80% after acid treatment. HCl was the most effective acid for removing mortar. [0032] FIG.17 depicts the water absorption levels of virgin aggregates, untreated RCA, and RCA treated with HCl. RCA treated with HCl provides recovered aggregates with water absorption values close to virgin aggregate and well within the industry requirement. [0033] FIG. 18 depicts the water absorption of untreated and treated RCA using form factors 1-3, with three multi-batch treatment arms (3-batch and 6-batch rotary drum). The multi-batch experiments used slightly less than stoichiometric amount of acid and less reaction time (18 h vs.24 h). The 10 kg RCA occupied about 20% volume in the drum reactor. [0034] FIG.19A and FIG 19B depict form factor 3, comprising a rotating drum reactor equipped with an inlet and outlet port that enables continuous circulation of HCl solution in the reactor at a level just sufficient to treat the RCA while minimizing the volume of solution. [0035] FIG. 20 depicts base reaction titration, in which NaOH was added to reacted acid (e.g. acid solution that had previously been used to treat RCA) to precipitate Ca(OH)2 and other metal hydroxides and/or carbonates. The extent of precipitation increases with pH. [0036] FIG. 21A and FIG. 21B depict photographs of trays containing cement precursors obtained from treatment of 5 kg RCA with acid followed by treatment with NaOH before and after drying, respectively, on a balance. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR [0037] FIG. 22 depicts an overview of the combination of the acid treatment, base reaction, filtration, drying, cooking and blending to obtain cement precursor suitable for use in cement manufacture. [0038] FIG. 23 depicts photographs of RCA cement precursor in various states: FIG. 23A shows uncooked RCA cement precursor. FIG. 23B shows cooked RCA cement without any additives. FIG. 23C shows cooked RCA cement blend (10g dry recovered solids + 4.8 g CaO + 1 g SiO2). [0039] FIG.24 depicts results of compression tests on cement cylinders prepared from RCA cement blend relative to standard cements type I, II, and V. [0040] FIG.25 depicts cement phase composition of cement prepared from recovered cement precursors obtained by treatment of pristine unreacted cement treated with HCl, then NaOH, then cooked at 1450 ° C, then blended with 4% gypsum. Results indicate that the overall process can achieve good mineralogy replication. [0041] FIG. 26A and FIG. 26B depict cement cylinders of types I – V cement along with recovered cement and RCA cement derived cylinders, and the results of compression testing select cylinders, respectively. Each cement sample (1 part) was mixed with 3 parts silica sand and 0.5 parts water to make mortar paste, which is then placed into cylinder molds. The cylinders were then released after curing 3 days. The compression strength of the cylinders were evaluated with a custom made testing instrument, shown in FIG 26A. The cement with 30% recovered cement showed equivalent strength to type I cement. The RCA derived cement (30% RCA recovered cement with 4% gypsum) was weaker. “HL”: indicates solids treated with acid. [0042] FIG. 27 depicts the compressive strength of concrete test cylinders prepared with RCA and recycled concrete aggregates obtained through the treatment of RCA with HCl as disclosed herein. Concrete cylinders were 10% stronger after curing for 7 and 14 days. Cylinders prepared using treated RCA (recycled concrete aggregate, inset) showed significantly higher compression strength than concrete cylinders prepared from untreated RCA. [0043] FIG. 28 depicts H-cell electrolyzer using anion exchange membrane FAA-3- PK-74 with 1 cm² carbon cloth electrode doped with 1 cm² Pt, and a voltage at about 10V at 50 mA and about 5V at 10 mA; the cathode reservoir was observed to turn purple because of base formation, and the anode reservoir was observed to turn clear (pH=2) after 60 minutes. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR [0044] FIG.29 depicts galvanostatic (constant current) voltage performance of H-cell configured with different electrodes (1 cm² area, 5 mA/cm² current density). The two carbon electrodes showed increased voltage, while the Pt electron remained at a constant voltage. [0045] FIG.30A and FIG.30B depict fouled carbon electrode and fully functioning Pt electrode covered by Ca(OH)2 shell, respectively. [0046] FIG. 31 depicts the effect of hydrogen flow rate on current in the hydrogen looping cell of Example 10. The voltage was 1.3 V constant. Hydrogen flow rates were 10, 20, 30, and 50 mL/min (transition points marked with vertical lines). [0047] FIG. 32 depicts the effect of hydrogen flow rate on current in the hydrogen looping cell of Example 10.100 mV/s, 0 to 2.5 volts. Hydrogen flow of top line is 30 mL/min, hydrogen flow of lower line is 0 mL/min (no hydrogen). [0048] FIG.33 depicts the voltage stability of the hydrogen looping cell with Ni mesh cathode and 4 mg/cm² Pt black on carbon cloth W1S1011 anode, with AEM (FAB-PK-130 membrane). Hydrogen flow rate is 30 mL/min, 100 mV/s, between 0.8V and 1.2 V, 1.4, 1.6, 1.8, and 2V (21 cycles each). [0049] FIG.34 depicts the voltage stability of the hydrogen looping cell with Ni mesh cathode and Pt-Ti mesh anode, with AEM (FAB-PK-130 membrane). Hydrogen flow rate is 30 mL/min, 100 mV/s, between 0.8V and 1.2 V, 1.4, 1.6, 1.8, and 2V (11 cycles each). The current of the Pt-Ti mesh was 10-fold lower than the Pt-carbon cloth anode. [0050] FIG. 35 depicts constant voltage run (1.4 V) for 536.028 mAh in hydrogen looping cell with Ni mesh cathode and 4 mg/cm² Pt black on carbon cloth W1S1011 anode, with AEM (FAB-PK-130 membrane) and hydrogen flow of 30 mL/min. This run was equivalent to 0.2 M NaOH production. Current decreased over time, which indicates instability. NaOH faradaic efficiency = 82%, with 1.14 kWh/kg NaOH; average 53 mA/cm² at 1.4 V. [0051] FIG. 36 depicts constant voltage run (1.4 V) in hydrogen looping cell with Ni mesh cathode and 2 mg/cm² Pt black on carbon cloth W1S1011 anode, with AEM (FAB-PK- 130 membrane) and hydrogen flow of 30 mL/min. The Pt loading was half as much as FIG. 35, and the current was 10-fold lower. These results indicate that Pt-loading has a large impact on hydrogen oxidation reaction rate. [0052] FIG.37 depicts the energy cost of producing NaOH using the in-house chloro- alkali cell of Example 11. [0053] FIG. 38 depicts current sweep experiments using the chloro-alkali cell of Example 11. Currents were run at 1, 10, 20, 40, 60, 80, and 100 mA/cm². Sweeping to high current densities resulted in cell instability. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR [0054] FIG. 39A, FIG. 39B, and FIG. 39C depict a comparison between hydrogen- looping and chloro-alkali cell for NaOH faradaic efficiency, energy cost of NaOH, and cell volage, respectively. Hydrogen looping can likely achieve a 1 kWh/kg NaOH output, but the current density remains uncertain. DETAILED DESCRIPTION [0055] To facilitate understanding of the disclosure set forth herein, a number of additional terms are defined below. Generally, the nomenclature and procedures described herein are those well-known and commonly employed in the art. Unless defined otherwise, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Each of the patents, applications, published applications, and other publications that are mentioned throughout the specification and the attached appendices are incorporated herein by reference in their entireties. [0056] The term “about” when referring to a number or a numerical range means that the number or numerical range referred to is an approximation, for example, within experimental variability and/or statistical experimental error, and thus the number or numerical range may vary up to ±10% of the stated number or numerical range. [0057] The term “regeneration” as used herein refers to a step in a process for using the product of a particular step in the process as a reactant or starting material in another step in the process. For example, if compound A is formed from reacting compounds C and X, one of the products of the reaction A+B ^ C+D, compound C, can be further reacted with X to provide A, the starting material A+B reaction. [0058] The term “electrochemical cell” as used here refers to devices and/or device components that perform electrochemistry. Electrochemical cells have two or more electrodes (e.g., a cathode and an anode) and one or more electrolytes and can be configured with or without separators, as described herein. [0059] The term “cement” as used herein refers to hydraulic and non-hydraulic cement, and combination thereof. Exemplary cements include, but are not limited to Ordinary Portland Cement (OPC), Portland Pozzolana Cement (PPC), Rapid Hardening Cement, Extra Rapid Hardening Cement, Low Heat Cement, and Quick Setting Cement. Such cement can be mixed with other materials such as coarse or fine aggregates to make mortar and/or concrete materials. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR [0060] The term “separator” as defined herein, refers to the material between the cathode and anode reservoirs in an electrochemical cell. Representative separators include, but are not limited to cation exchange membranes and anion exchange membranes. [0061] The terms “electro-distillation” and “electrodistillation” are used interchangeably herein and refer to the electrochemical process that separates different materials in space over may linked cells, or one cell in time via differences cell pH and/or cell voltage, analogous to a traditional distillation column that separates materials by boiling point. In a constant-current electrolysis (i.e., continuous electro-distillation), voltage plateaus when one species is precipitating out and then rapidly increases until another species begins to precipitate. [0062] The term “concrete precursor” refers to cement and natural aggregates including, but not limited to, stone, gravel, sand, silt, clay, or the like that have been filtered from inorganic waste (e.g., recycled concrete aggregates) and/or produced by the methods disclosed herein. The cement is made from the precipitates from the base reaction as disclosed herein. [0063] The terms “liquid rich in” an ingredient(s) as provided throughout the disclosure is intended to mean that the liquid contains a concentration of at least 0.1 M of said ingredient(s). For example, the terms “liquid rich in one or more metallic ions” refers to a liquid having a one or more metallic ion concentration of at least 0.1 M (e.g., 0.1 M to 5 M). [0064] The terms “liquid deficient in” an ingredient(s) as provided throughout the disclosure is intended to mean that the liquid contains a concentration of less than 0.1 M of said ingredient(s). For example, the terms “liquid deficient in one or more metallic ions” refers to a liquid having a one or more metallic ion concentration of less than 0.1 M (e.g., in a range of 0.0001-0.09 M). [0065] Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting an inorganic solid waste comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; (b) contacting the liquid rich in one or more metallic ions with a base to produce a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer to regenerate the acid and the base, and (d) repeating each of steps (a)-(b) at least once with the acid and the base from step (c). ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR In some embodiments, the inorganic solid waste comprises one or more of a group of recycled concrete aggregate (RCA), smelting slag, blast furnace slag, incinerator bottom ash, and electronics waste (e.g., batteries, solar cells, and other electronics). In some embodiments, the inorganic solid waste comprises recycled concrete aggregate (RCA). In some embodiments, the inorganic solid waste comprises smelting slag. In some embodiments, the inorganic solid waste comprises blast furnace slag. In some embodiments, the inorganic solid waste comprises incinerator bottom ash. In some embodiments, the inorganic solid waste comprises batteries (e.g., recycled and/or shredded batteries). In some embodiments, the inorganic solid waste comprises solar cells (e.g., recycled and/or shredded solar cells). In some embodiments, the inorganic solid waste comprises electronics (e.g., recycled and/or shredded electronics). In some embodiments, the inorganic solid waste comprises a combination of recycled concrete aggregate (RCA), smelting slag, blast furnace slag, incinerator bottom ash, batteries, solar cells, and electronics. [0066] In some embodiments, the RCA comprises about 1% to about 25% w/w CaO, e.g., about 2% to about 20%, about 3% to about 15%, about 4% to about 10%, about 5% to about 9%, about 6% to about 8%, about 7% to about 8%, about 1% to about 10%, about 2% to about 15%, about 3% to about 12%, about 4% to about 10%, about 5% to about 10%, about 6% to about 10%, bout 7% to about 10%, about 8% to about 10%, about 8% to about 9%. [0067] Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregate (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; (b) contacting the liquid rich in the one or more metallic ions with a base to produce a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer to regenerate the acid and the base, and (d) repeating each of steps (a)-(b) at least once with the acid and the base from step (c). In some embodiments, the electrolyzer is a single-membrane electrolyzer, two- membrane salt splitting electrolyzer, a multi-membrane salt-splitting electrolyzer, a chlor- alkali electrolyzer, a bipolar membrane electrodialysis electrolyzer, or a combination of any of the foregoing. Some embodiments provide a method of preparing concrete precursors, the method ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR comprising: (a) contacting recycled concrete aggregate (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; (b) contacting the liquid rich in one or more metallic ions with a base and carbon dioxide to produce a precipitate comprising one or more metal carbonates from the one or more metallic ions and a liquid deficient in the one or more metallic ions; and (c) contacting the liquid deficient in one or more metallic ions with an electrolyzer to regenerate the acid and the base. [0068] In some embodiments, step (b) comprises sequentially contacting the liquid rich in one or more metallic ions with two or more independently selected bases. In some embodiments, the bases are the same. In some embodiments, the bases are different. In some embodiments, the bases each comprise an independently selected metal hydroxide. [0069] In some embodiments, the carbon dioxide is provided as a composition, wherein the composition comprises carbon dioxide and at least one additional gas, as described herein. For example, some embodiments described herein utilize carbon dioxide, for example, to produce a metal carbonate or bicarbonate from a metal hydroxide. In some embodiments, the carbon dioxide composition comprises a concentrated carbon dioxide source (e.g., flue gas from, for example, a power station). In some embodiments, the carbon dioxide composition comprises a dilute carbon dioxide source (e.g., atmospheric carbon dioxide). In other words, some embodiments described herein comprise carbon dioxide removal and sequestration. [0070] In some embodiments, the composition comprises carbon dioxide in an amount of about 0.01 wt% to about 99.9 wt%, or about 0.01 wt% to about 1.5 wt%, or about 1 wt% to about 20 wt%, or about 5 wt% to about 20 wt%, or about 50 wt% to about 90 wt%. In some embodiments, the composition comprises carbon dioxide in an amount of about 0.01 wt% to about 99.9 wt%. In some embodiments, the composition comprises carbon dioxide in an amount of about 0.01 wt% to about 1.5 wt%. In some embodiments, the composition comprises carbon dioxide in an amount of about 1 wt% to about 10 wt%. In some embodiments, the composition comprises carbon dioxide in an amount of about 50 wt% to about 90 wt%. [0071] In some embodiments, the carbonate salt and/or the bicarbonate salt is selected from sodium, potassium, lithium, and combinations of any of the foregoing. In some embodiments, the salt is sodium carbonate, potassium carbonate, lithium carbonate, or a combination of any of the foregoing. In some embodiments, the salt is sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, or a combination of any of the foregoing. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR [0072] Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregates (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in one or more metallic ions; and (b) contacting the liquid rich in one or more metallic ions with an electrolyzer to regenerate the acid and produce a precipitate comprising the one or more metallic ions. [0073] In some embodiments, the sequential electrolysis occurs via continuous electro- distillation. In some embodiments, the sequential electrolysis comprises continuous electro- distillation. In some embodiments, the sequential electrolysis is continuous electro-distillation. [0074] Some embodiments provide a method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregates (RCA) comprising one or more metallic ions with an acid in an electrochemical cell to produce the concrete precursors and a liquid rich in one or more metallic ions; and (b) contacting the liquid rich in one or more metallic ions with a base in the electrochemical cell to form a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; wherein the electrochemical cell comprises an anode reservoir comprising an anode and the acid, and a cathode reservoir comprising a cathode and the base, wherein the anode reservoir and the cathode reservoir are separated by a separator. [0075] In some embodiments, the separator is an anion exchange membrane or a cation exchange membrane. In some embodiments, the separator is an anion exchange membrane. In some embodiments, the separator is a cation exchange membrane. [0076] In some embodiments, the sequential electrolysis occurs via continuous electro- distillation. In some embodiments, the sequential electrolysis comprises continuous electro- distillation. In some embodiments, the sequential electrolysis is continuous electro-distillation. [0077] In some embodiments, the electrochemical cell comprises an anode reservoir comprising an anode and an acid, and a cathode reservoir comprising a cathode and a base, wherein the anode reservoir and the cathode reservoir are separated by a separator; a contactor configured to input recycled concrete aggregates (RCA) comprising one or more metallic ions into the anode reservoir, wherein the anode reservoir is configured to contact the RCA with the acid to produce the concrete precursors and a liquid rich in one or more metallic ions, and the cathode reservoir is configured to contact the liquid rich in one or more ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR metallic ions with the base to form a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; a first filtration system in contact with the anode reservoir configured to filter out the concrete precursors from the anode reservoir; and a second filtration system in contact with the cathode reservoir configured to filter out the precipitate from the cathode. [0078] In some embodiments, the first filtration system is additionally configured to filter the liquid, rich in one or more metallic ions, from the concrete precursors and input the liquid rich in one or more metallic ions into the cathode reservoir. [0079] In some embodiments, the separator is an anion exchange membrane or a cation exchange membrane. In some embodiments, the separator is an anion exchange membrane. In some embodiments, the separator is a cation exchange membrane. [0080] In some embodiments, the one or more metallic ions are selected from ions of lithium, sodium, potassium, beryllium, magnesium, calcium, strontium, barium, radium, aluminum, gallium, indium, tin, thallium, lead, bismuth, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, and mercury. In some embodiments, the one or more metallic ions are ionic pairs with one or more hydroxide anion to form metal hydroxides (e.g., Ca(OH)₂). [0081] In some embodiments, the one or more metallic ions are selected from ions of sodium, potassium, magnesium, calcium, tin, lead, iron, cobalt, nickel, copper, zinc, palladium, silver, cadmium, platinum, and gold. [0082] In some embodiments, the one or more metallic ions are selected from ions of sodium, potassium, magnesium, and calcium. [0083] In some embodiments, the metal hydroxides (e.g., Ca(OH)₂) are further treated thermally and mechanically to with additional cementitious materials to form cement. [0084] Some embodiments further comprise: (a) mixing the precipitate with one or more silicates to form a mixture; (b) grinding the mixture to form a particulate; and (c) heating the particulate to about 1,000°C to about 1,500°C for a period of time, to provide cement. [0085] In some embodiments, the one or more metal hydroxides described herein (e.g., calcium hydroxide) are mixed with materials obtained from one of the filtration steps described herein (referred to herein as filtration products). In some embodiments, these filtration products ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR comprise silica and/or silicates. In some embodiments, the silica and/or silicates are ground or milled (for example, to form nano-silica) prior to mixing with the one or more metal hydroxides. In some embodiments, the mixture of the filtration products and the one or more metal hydroxides is milled or ground to produce nanoparticulate material. [0086] In some embodiments, the one or more metal hydroxides described herein (e.g., calcium hydroxide) are mixed with CaO and/or SiO₂. In some embodiments, additional materials are mixed with the hydroxide precipitates, including but not limited to Al2O3, CaCO3, MgO, MgCO₃, Fe₂O₃, or Li₂CO₃. [0087] In some embodiments, the nanoparticulate material is then subjected to cooking temperatures of about 500°C and about 1,450°C (i.e., clinkerization). In some embodiments, the cooking temperature is about 500°C and about 1,200°C or about 500°C and about 1,000°C. In some embodiments, the cooking temperature is from about 1000°C to about 1500°C, e.g., from about 1200°C to about 1500°C, 1250°C to about 1450°C. [0088] In some embodiments, the nanoparticulate material is subjected to the cooking temperature for about 20 minutes to about 5 h, e.g., from about 30 min to about 4 h, from about 45 min to about 3 h, from about 1 h to about 2 h, from about 1 h to about 1.5 h, from about 45 min to about 1.5 h. In some embodiments, the nanoparticulate material is subjected to the cooking temperature for about 1 h. [0089] In some embodiments, the nanoparticulate material is subjected to the cooking temperature in increments, e.g., starting at about 100 °C and ending at the highest temperature over a set period of time. In some embodiments, the time course the cooking of nanoparticulate material occurs in manner substantially similar as shown in Table 6 in Example 9. [0090] In some embodiments, the energy for the grinding or milling is provided via green electricity. [0091] In some embodiments, performance of the methods and operation of the systems described herein is carbon neutral. [0092] In some embodiments, the nanoparticulate material after being subjected to cooking (i.e., clinkerized/sintered) is blended with gypsum. In some embodiments, the amount of gypsum is about 1 to about 10% w/w, e.g., about 2% to about 8%, about 3% to about 6%, about 4% to about 5%. [0093] The methods disclosed herein can include (a) contacting recycled concrete aggregate (RCA) comprising calcium with an acid to produce the concrete precursors and a calcium-rich liquid; (b) contacting the calcium-rich liquid with a base to produce a calcium precipitate (e.g., calcium hydroxide) and a calcium-deficient liquid; (c) contacting the calcium- ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR deficient liquid with an electrolyzer to regenerate the acid and the base. In some embodiments, the methods can include a step (d), wherein step (d) includes repeating each of steps (a)-(b) at least once with the acid and the base from step (c). The methods disclosed herein can include (a) contacting recycled concrete aggregate (RCA) comprising calcium with an acid to produce the concrete precursors and a calcium-rich liquid; (b) contacting the calcium-rich liquid with a base and carbon dioxide to produce calcium carbonate and a calcium-deficient liquid; and (c) contacting the calcium-deficient liquid with an electrolyzer to regenerate the acid and the base. The methods disclosed herein can include (a) contacting recycled concrete aggregates (RCA) comprising calcium with an acid to produce the concrete precursors and a calcium-rich liquid; (b) contacting the calcium-rich liquid with a base comprising a carbonate salt and/or a bicarbonate salt to produce calcium carbonate and a calcium-deficient liquid; and (c) contacting the calcium-deficient liquid with an electrolyzer to regenerate the acid and the base; wherein the carbonate salt and/or the bicarbonate salt are produced from admixing carbon dioxide and a metal hydroxide. The methods disclosed herein can include (a) contacting recycled concrete aggregates (RCA) comprising calcium with an acid to produce the concrete precursors and a calcium-rich liquid; and (b) contacting the calcium-rich liquid with an electrolyzer to regenerate the acid and produce a calcium precipitate. The methods disclosed herein can include (a) contacting recycled concrete aggregates (RCA) comprising calcium with an acid in an electrochemical cell to produce the concrete precursors and a calcium-rich liquid; and (b) contacting the calcium-rich liquid with a base in the electrochemical cell to form a calcium precipitate and a calcium-deficient liquid; wherein the electrochemical cell comprises an anode reservoir comprising an anode and the acid, and a cathode reservoir comprising a cathode and the base, wherein the anode reservoir and the cathode reservoir are separated by a separator. [0094] Also provided herein are systems for preparing concrete precursors. In some embodiments, the systems can include an electrochemical cell configured to prepare concrete precursors, wherein the electrochemical cell comprises an anode reservoir comprising an anode and an acid, and a cathode reservoir comprising a cathode and a base, wherein the anode reservoir and the cathode reservoir are separated by a separator; a contactor configured to input recycled concrete aggregates (RCA) comprising calcium into the anode reservoir, wherein the anode reservoir is configured to contact the RCA with the acid to produce the concrete precursors and a calcium-rich liquid, and the cathode reservoir is configured to contact the calcium-rich liquid with the base to form a calcium precipitate and a calcium-deficient liquid; a first filtration system in contact with the anode reservoir configured to filter out the concrete precursors from the anode reservoir; and a second filtration system in contact with the cathode ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR reservoir configured to filter out the calcium precipitate from the cathode. [0095] In some embodiments, cement comprises calcium oxide. In some embodiments, cement comprises calcium hydroxide. [0096] In some embodiments, cement further comprises one or more additional materials including, but not limited to, silicates, silicon dioxide, iron oxide, aluminum oxide, aluminates (e.g., tricalcium aluminate), and other minerals. [0097] FIG. 1 depicts exemplary methods of preparing concrete precursors, e.g., calcium hydroxide, from RCA. The methods can include three steps, (1) acid treatment; (2) base treatment; and (3) electrolyzer for acid and base regeneration. Applicable acids, bases, salts and mortar material includes, but is not limited to, to HCl, NaOH, NaCl and Ca(OH)₂ as shown in FIG.1. [0098] Acid Treatment: The RCA is subject to reaction with an acid under controlled temperature and stirring. The hardened mortar, including metal hydroxides, such as Ca(OH)2, and metal oxides, such as CaO, on the surface of RCA are dissolved by the acid to form a calcium-rich liquid. The natural aggregate, including metal aluminosilicate, remains undissolved to form concrete precursors. After acid treatment, the mixture of the concrete precursors and the calcium-rich liquid is filtered. The precipitates can then be washed and subject to sieving. In some embodiments, the aggregates, e.g., concrete precursors, that remain on a #4 sieves are recovered coarse natural aggregates. [0099] Some embodiments described herein provide methods for removing mortar from RCAs using the methods described herein. [00100] In some embodiments, the concrete precursors have a water absorption coefficient as low as virgin aggregates. In some embodiments, the concrete precursors have a water absorption below about 3% w/w, e.g., below 2.5%, below 2%, below 1.5%, below 1%. In some embodiments, the concrete precursors have a water absorption of about 0.1% w/w to about 2.5% w/w. In some embodiments, the concrete precursors have a water absorption of about 0.5% w/w to about 2.5% w/w. In some embodiments, the concrete precursors have a water absorption of about 0.1% w/w to about 2% w/w. In some embodiments, the concrete precursors have a water absorption of about 0.5% w/w to about 2% w/w. In some embodiments, the concrete precursors have a water absorption of about 0.1% w/w to about 1.5% w/w. In some embodiments, the concrete precursors have a water absorption of about 0.5% w/w to about 1.5% w/w. In some embodiments, the concrete precursors have a water absorption of about 1% w/w to about 2% w/w. [00101] The particles that pass a #4 sieves will be a mixture of fine aggregates ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR and silica gel, which can also be used as raw materials for various purposes. A variety of acids, including but not limited to H₂SO₄, HCl, HNO₃, HBr, HI, acetic acid, H₃PO₄, formic acid, maleic acid, can be used in the acid treatment step for the methods disclosed herein. The concentration of the acids can vary from 0.05 M to 30 M. [00102] In some embodiments, the acid is HCl. In some embodiments, the HCl has a concentration of about 0.2 M to about 5 M, e.g., about 0.3 M to about 4 M, about 0.4 M to about 3 M, about 0.5 M to about 2 M, about 0.5 M to about 1 M. [00103] Any type of stirring/agitation methods may be applied to ensure sufficient reaction. In situ sensing, including but not limited to pH, conductivity, atomic absorption spectroscopy, NMR spectroscopy, ICP-OES, can be implemented in this step and allow real-time monitoring of reaction progress and feedback control. In some embodiments, the acid reaction with RCA occurs in a reactor of form factor 1. In some embodiments, the acid reaction with RCA occurs in a reactor of form factor 2. In some embodiments, the acid reaction with RCA occurs in a reactor of form factor 2, with consecutive treatments of acid. In some embodiments, the consecutive treatments of acid total from 2-10, e.g., 2-8, 2-7, 2-6, 2-5, 2-4, 3-9, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5. In some embodiments, the acid reaction with RCA occurs in a reactor of form factor 3. [00104] In some embodiments, the acid reaction with RCA occurs over a period of about 1 h to about 48 h, e.g., about 2 h to about 46 h, about 3 h to about 42 h, about 4 h to about 40 h about 12 h to about 24 h, about 1 h to about 2 h, about 1 h to about 6 h, about 1 h to about 12 h, about 1 h to about 24 h, about 1 h to about 36 h, about 24 h to about 48 h. [00105] Base Treatment: The calcium-rich liquid the acid treatment and after filtration, e.g., Filtration 1 of FIG.1A, is mixed with a base (e.g., a base solution). The calcium- rich liquid can include a calcium salt (e.g., one or more of CaCl2, CaSO4, and Ca(NO3)2) and one or more of MgCl₂, FeCl₂, FeCl₃, MgSO₄, Ca(NO₃)₂, and Mg(NO₃)₂, formed during the acid treatment. The calcium-rich liquid reacts and turns to calcium precipitate (e.g., calcium hydroxide), including but not limited to Ca(OH)₂, Mg(OH)₂, Fe(OH)₂, Fe(OH)₃, Al(OH)₃, which precipitates out from solution. The calcium precipitate (e.g., metal hydroxides) are filtered out of the solution leaving a calcium-deficient liquid. It has been discovered that different metal hydroxides can precipitate out at different pH. Therefore, implementing in situ sensing can allow better monitoring of reaction progress and enable easier separation of different products. Just like the acid treatment step, a large variety of bases, at different concentrations, may be implemented in this step. [00106] In some embodiments, the concentration of base is from about 0.2 M to ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR about 5 M, e.g., about 0.3 M to about 4 M, about 0.4 M to about 3 M, about 0.5 M to about 2 M, about 0.5 M to about 1 M. [00107] In some embodiments, the base is NaOH. In some embodiments, the concentration of NaOH is from about 0.2 M to about 5 M, e.g., about 0.3 M to about 4 M, about 0.4 M to about 3 M, about 0.5 M to about 2 M, about 0.5 M to about 1 M. [00108] In some embodiments, the pH after treatment of the calcium-rich liquid with base is about 10 to about 14, e.g., about 11 to about 14, about 12 to about 14, about 13 to about 14. [00109] Electrolysis: The calcium-deficient liquid from the filtration after the base treatment, Filtration 2 as shown in Figure 1A, has high salt concentration (such as one or more of LiCl, NaCl, KCl, Li2SO4, Na2SO4, K2SO4, LiNO3, NaNO3, and KNO3). The calcium- deficient liquid is fed into an electrolyzer to generate the acid and base, used in steps 1 and 2, respectively. Several cell structures and electrolysis strategies can be implemented here. Some examples are explained below. [00110] FIG. 1B shows a two-membrane salt-splitting cell that can be used in the methods depicted in FIG. 1A, with water oxidation, i.e. H2O→1/2O2 + 2H⁺+2e-, on the anode side and water reduction, i.e. 2H2O + 2e- → H2 + 2OH-, on the cathode side. The electrolyzer can include an anion exchange membrane (AEM) and a cation exchange membrane (CEM) as depicted in FIG. 1B. In some embodiments, the AEM and CEM can be replaced with a bipolar membrane. The calcium-deficient liquid can be fed into the central reservoir. When a large enough voltage is applied to the electrodes, a water splitting reaction takes place. At the anode, water is oxidized to oxygen, and the anions are pulled from the central reservoir, which results in an acid solution in the anode electrolyte. Meanwhile at the cathode, water is reduced to hydrogen, and cations are pulled from the central reservoir, creating a base electrolyte in the cathode reservoir. The thermodynamic voltage for the reaction is 1.23 V. In addition, a possible auxiliary device to this setup is a H2 + O2 fuel cell, which can cover part of the electricity cost. [00111] FIG. 1C shows a slightly modified version of the two-membrane salt splitting cell that can be used in the methods depicted in FIG.1A. Instead of reduction of water on the cathode side, oxygen reduction, i.e.1/2O2 + 2H2O + 2e- → 2OH-, is utilized, and the O2 gas is circulated in between anode and cathode side. There is a smaller voltage difference between anode and cathode (0 V to ~0.8 V depending on the pH gradient), which can lead to less energetic cost during electrolysis. [00112] FIG.1D shows an additional electrolyzer that can be used in the methods ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR depicted in FIG.1A. Instead of oxidation of water on the anode side, hydrogen oxidation, i.e. H₂ → 2H⁺ + 2e-, is utilized. Hydrogen is circulated internally. There is a smaller voltage difference between anode and cathode which can lead to less energetic cost during electrolysis. [00113] Another possible electrolyzer that can be used in the methods depicted in FIG. 1A is a classic chlor-alkali electrolyzer. A cation membrane separates the anode side from the cathode side. During electrolysis, chloride ions are oxidized to chlorine, i.e. 2Cl- → Cl2 + 2e-, at the anode, and water is reduced to hydrogen at the cathode. A fuel cell is required to convert hydrogen and chlorine into HCl gas. [00114] In some embodiments, the electrolyzer comprises an electrode comprising Pt. In some embodiments, the electrolyzer comprises an electrode comprising Ni. [00115] In some embodiments, the electrolyzer comprises a cathode comprising Pt. In some embodiments, the electrolyzer comprises a cathode comprising Ni. In some embodiments, the electrolyzer comprises an anode comprising Pt. In some embodiments, the electrolyzer comprises an anode comprising Pt on carbon fiber. In some embodiments, the electrolyzer comprises an anode comprising Pt on carbon fiber with a Pt loading of about 2% to about 10 %, e.g., about 3% to about 8 %, about 4% to about 6 %, about 4% to about 5 %. [00116] Further, a bipolar membrane electrodialysis cell (e.g., an electrodialysis cell as described in U.S. Pat. No. 9,586,181) can be used in the methods depicted in FIG.1A. Multiple electrodialysis units can optionally be implemented in this cell configuration. For example, instead of having one electrodialysis unit (as shown in FIG.2) written as [Electrode | CEM | BPM | AEM | CEM| Electrode], it can be [Electrode | CEM | BPM | AEM | CEM | BPM | AEM | CEM| Electrode], [Electrode | CEM | BPM | AEM | CEM | BPM | AEM | CEM | BPM | AEM | CEM| Electrode], or [Electrode | CEM (| BPM | AEM | CEM ) * n | Electrode] to reduce the overall cost of electrodialysis. [00117] FIG. 3 depicts an additional method for preparing concrete precursors disclosed herein. The method depicted in FIG. 3 is similar to the method depicted in FIG. 1A except for the addition of CO₂-rich gas, such as flue gas or air, into the base treatment reservoir, thereby converting Ca(OH)2 to CaCO3. This is to combine carbon capture and sequestration with RCA upgrading. In addition, because of the low solubility of CaCO₃ in water, separation and purification of CaCO3 from the calcium-deficient liquid is much easier compared to Ca(OH)₂. The same idea applies to other metal hydroxides, such as Mg(OH)₂, Fe(OH)₂, etc., and carbonates, e.g., but not limited to, MgCO3, FeCO3, Fe2(CO3)3, etc. By sensing the CO2 concentration and flow rate at the inlet and exit, one can monitor CO₂ capture in real time. [00118] FIG. 4 depicts an additional method for preparing concrete precursors ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR disclosed herein. The base stream coming off from the electrolyzer is exposed to CO2 rich gas, such as flue gas or air, on a contactor, and is converted to aqueous carbonates, such as, but not limited to, Na2CO3, NaHCO3, K2CO3, and KHCO3. The aqueous base stream has higher basicity and concentration of active material compared to the semi-soluble base used in the methods depicted in FIG. 3. Therefore, the CO2 capture rate is expected to be faster and CO2 can be extracted from low concentration streams such as air. The aqueous carbonate stream reacts with the product of acid stream to form carbonate precipitates such as, but not limited to, CaCO₃, MgCO₃, Fe₂(CO₃)₃, or Al₂(CO₃)₃. Different carbonate products will precipitate out at different pH, thus it is possible to obtain pure products through carefully controlling the titration process. [00119] FIG.5A depicts an additional method for preparing concrete precursors disclosed herein. In this approach, the filtrate from the acid treatment is subject to direct electrolysis. Semi-soluble hydroxides are formed in the cathode side of the electrolyzer and can be separated/purified for sale. This way, fewer steps are involved, so fewer reactors are needed. In addition, only one membrane is needed in the electrolyzer, which can decrease costs. Several electrolyzers can be used in the methods depicted in FIG.5A. FIG.5B shows the first design that employs water oxidation at the anode and water reduction at the cathode. Only an AEM is used to separate two reservoirs. Chloride is allowed to pass from the cathode side to the anode side during electrolysis. The filtrate from the acid treatment, containing CaCl₂ or other soluble salts, is passed into the cathode side, and the resulting solution will contain high hydroxide content, both dissolved in water and in a slurry. To increase conductivity, a small amount, from 0.01 M to 1 M, of salt such as NaCl or KCl can be added to the anode side. FIG. 5C shows the second design that is the same design as FIG. 5B except the design of FIG. 5C uses oxygen reduction for the cathode. FIG.5D shows the third design that is the same design as the FIG.5B except the design of FIG.5D uses hydrogen oxidation for the anode. [00120] FIG. 6 depicts an additional method for preparing concrete precursors disclosed herein. In this approach, all the separated steps described in the original approach are combined together. The RCA dissolution step (the acid treatment step of FIG.1A) takes place in the anode reservoir of the electrolysis cell and the hydroxide precipitation step takes place in the cathode side of the cell, just as depicted in FIG. 5A. This system requires the least equipment, hence lower capital expenditures to realize. In addition, as soon as acid is generated at the anode, it is consumed by Ca(OH)2. The hydroxide generated at the cathode reacts with CaCl₂ and form precipitates. Therefore, the pH gradient across the AEM will be small. This is beneficial because undesired ion leakage will be small and the concentration overpotential will ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR also be small, leading to a lower energy cost. The hydroxides can include, but are not limited to, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, iron hydroxide (both iron(II) and iron(III)). [00121] Two chamber single AEM membrane electrolyzers have a component cost and complexity advantage over multi membrane systems, but pose some unique challenges in scaling up. Namely this configuration separates products in time rather than in spaces compared to the 2 membrane 3 chamber electrolyzers. To deal with this particularity, it was found that a batch wise system (FIG.9) and a continuous system (FIG.7, FIG.8, and FIG.10), can be useful. In the batch configuration (e.g., FIG. 9), continuous processing would be achieved by a series of settling tank electrolyzer pairs connected by circulation pumps. In this configuration a given tank would be charged and the solution circulates through the electrolyzer to allow the desired hydroxides to precipitate out of solution and be collected in the connected setting tank (FIG. 9). Continuous production can be achieved by staggered charging and processing of several of these pairs. [00122] In the continuous system (e.g., continuous electrodistillation via sequential electrolysis or continuous base treatment; FIG. 7 and FIG. 8), several combined electrolyzer settling tank pairs would be combined in series. Different voltages are applied to each electrolyzer unit in order to precipitate out different hydroxide species at lower power consumption. The solution to be processed would flow slowly from one cell to the next producing a gradient or pH (FIG. 10) and precipitation products going down the line FIG. 7 and FIG.8). [00123] Some embodiments provide a mobile apparatus for performing the methods described herein, for example, an apparatus that is configured to be moveable and/or is attached to a mechanism for moving the apparatus from location to location. [00124] For example, an additional aspect of this disclosure provides a mobile processing plant for removing chemical content from waste, comprising: a mobile electrochemical cell 100 configured to reduce chemical content in waste, wherein the electrochemical cell comprises an anode reservoir 101 comprising an anode and an acid, and a cathode reservoir 102 comprising a cathode and a base, wherein the anode reservoir and the cathode reservoir are separated by a separator 103; or a contactor 104 configured to input the waste into the electrochemical cell 100; a filtration system 105 in contact with the anode reservoir; and a filtration system 106 in contact with the cathode reservoir. [00125] In some embodiments, the mobile processing plant is comprised of a ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR railroad car, which is transported by rail to the site where the waste is accessible. In some embodiments, the mobile processing plant is comprised of a trailer, which is transported by road to the site where the waste is accessible. In some embodiments, the mobile processing plant is comprised of a truck, which travels by road to the site where the waste is accessible. In some embodiments, the mobile processing plant is comprised of a barge, which is transported by water to the site where the waste is accessible. In some embodiments, the mobile processing plant is comprised of a ship which travels by water to the site where the waste is accessible. In some embodiments, the mobile processing plant is comprised of an aircraft which travels by air to the site where the waste is accessible. [00126] Particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. EXAMPLES Example 1. Treatment of 2 kg batch RCA with of 0.5 M hydrochloric acid with mild agitation [00127] Hydrochloric acid is a strong acid that can be used to dissolve concrete mortar. Described herein is the use of 0.5 M hydrochloric acid solution to dissolve the mortar off 2 kg batch of recycled concrete aggregate (RCA) in a shaken reactor vessel to obtain recovered natural concrete aggregates. [00128] Procedure: [00129] Into 12.98 L of tap water was slowly added 0.58 L of 37% w/w HCl. The mixture was mechanically stirred to homogeneity. Into a 6 gallon plastic drum equipped with tight sealing lid was added 2 kg RCA (7.5-9% w/w CaO). In a fume hood, 13.7 L of 0.5M HCl solution was slowly added to the RCA in the drum. When effervescence ceased, the lid of the drum was sealed and the drum was placed in an orbital shaker. The slurry was shaken at 80-120 rpm for 3-48 h. The liquid contents of the drum were decanted, and the remaining solids were washed multiple times with tap water until the solution above the solids was clear. [00130] After the solids were washed, they were placed on a #8 sieve and rubbed over the sieve for a couple of minutes to remove leftover fines/mortar. The aggregates were then placed into a container for final rinsing with tap water. The treated aggregates and fines ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR were placed into separate containers and allowed to dry. Example 2. Treatment of RCA with HCl in a packed bed reactor (form factor 1). [00131] Described herein is the use of 0.5 M hydrochloric acid solution to dissolve the mortar off a 10 kg batch of RCA in a packed bed reactor, where the packed bed is made of RCA. This describes use of reactor form factor 1. [00132] Using the solution preparation procedure of Example 1, 62 L of 0.5 M HCl was prepared. Into the 10-ft reactor tube of the packed bed reactor shown in FIG. 11 and FIG.12 was added 10 kg RCA (7.5-9% of CaO). Summary of procedure: 1. Pump tubings were connected and all valves were placed in the correct position. 2. Data collection (conductivity and pH) was enabled. 3. Acid treatment reaction was initiated by pumping the acid into the packed bed reactor tube. 4. Treatment was continued for 3-48 h. 5. The packed bed reactor tube was drained of acid solution and the RCA bed rinsed with water. 6. The treated RCA was removed from the packed bed reactor tube. [00133] The following SOP was used for the above procedure: Section 1. Preparing material for reaction 1. Secure the lid onto the acid tank, making sure to orient the inlet and outlet unions toward the inlet and outlet lines. 2. Slip the peristaltic pump tubing off of the reactor inlet port, and replace it with tubing connected to the sink. Turn on the faucet to fill the reservoir with water to the water fill line marked on the side of the reservoir. DO NOT multitask during this step or leave the reservoir unattended which may cause it to flood. The water fill line marks 60 gallons, which is the minimum volume of liquid level required to ensure the reservoir pH probe is submerged when the stirring impeller is on. 3. Put on the face shield and elbow length rubber gloves. Make an acid solution in the fume hood by mixing the desired volume of concentrated HCl with water in a bucket. For 10 kg RCA and 0.5 molar HCl, this is 2.3 L of 37% HCl diluted in 59 L of H2O. 4. Use tubing and a peristaltic pump to transfer the concentrated acid solution from the bucket within the fume hood to the reservoir filled with water. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR 5. After the acid is transferred, carefully bring the end of the tube that is in the bucket over to the reservoir and submerge it. Then unlatch the tubing from the peristaltic pump, pick up the middle of the tube and lift it above the height of the reservoir to drain any remaining acid in the tube into the reservoir. 6. Connect the tubing used to transfer the acid to the sink and flush it with water. DO not try to pull peristaltic tubing off of the barbed fitting on the sink (you may injure yourself when it finally breaks free), it must be cut off to be removed from the barb. 7. To clean up: return concentrated HCl acid to the acid cabinet. Fill the acid solution bucket with water to rinse. Pour first rinse in the acid waste containment. Any subsequent rinses can go down the sink. 8. Measure out the desired amount of RCA using a tared bucket. Make sure to have a dust collector nearby to handle the dust when transferring RCA to the bucket. Then use a small amount of water to wet the RCA before it is loaded into the reactor to suppress dust. Set aside to be loaded in the tube. Section 2: Loading the reactor for an experiment 1. Press the E-stop before opening the reactor doors. 2. Close the electronic ball valve at the reactor outlet, then disconnect the outlet line at the quick-disconnect union. Closing the valve will prevent leftover liquid in the line from pouring out when the line is disconnected. 3. Use a ladder to close the ball valve at the reactor inlet and then disconnect the inlet line at the quick-disconnect union. 4. Disconnect the overflow line at the top of the reactor using the quick disconnect union, this line should be empty. 5. Slide the tube reactor out of the enclosure by pressing the yellow release lever. 6. Unscrew the reactor lid from the top of the tube and set aside. 7. Use a plastic scoop to load unreacted RCA one scoop at a time. For a well- packed bed, one person should use two heavy tools to tap the sides of the reactor walls while someone else scoops RCA into the top. Tapping reduces the bed voids to 40%. Scooping RCA in without tapping results in an initial bed void of 50%. A lower bed void reduces channeling, while a higher bed void exposes more RCA surfaces for reaction. 8. Screw the lid to the tube reactor back on, making sure to orient the quick disconnect unions in the direction of the tubing. 9. Depress the yellow release lever and slide the tube back into the enclosure until it is locked in place. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR 10. Reconnect the tube inlet line and overflow line to the quick-disconnect unions at the top and the side of the tube lid, respectively. Open the manual ball valve on the tube inlet line. 11. Reconnect the tube outlet to the quick-disconnect union at the top of the reservoir. Set the electronic ball valve at the outlet to 50% open. 12. Lower the conductivity probe down into the sampling port on the reservoir lid, and make sure all cables are plugged into the meter so data can be collected. Section 3. Starting a reaction 1. Make sure the peristaltic pump speed is set to the desired power setting. 2. Turn on the stirrer motor to a reasonable speed so the acid reservoir is well mixed without splashing or breaking the impeller. 3. Place leak detecting sensors evenly throughout the bottom of the enclosure. 4. Log in to the automation code to begin conductivity data collection. 5. Shut the enclosure doors and disengage the E-stop to start the flow of acid. Check that the leak detecting sensors have green LED lights visible so you know they are working. When tripped with acid or other liquid, the lights will be red and will prevent the pumps from receiving power. 6. Follow the calibration procedure for the liquid level sensors and begin automatic ball valve control to maintain the liquid level. Section 4. Monitoring a reaction 1. Use the wyze camera to monitor reaction progress or observe the reaction in person 2. Download the data throughout the reactor or at the end of the reaction 3. A sudden stop of acid flow or draining of the liquid level means there is a leak that was detected and shut off power to the pump. Section 5. Stopping a reaction 1. Press the emergency stop. 2. Open the electronic ball valve to drain the tube. 3. Open the door and stop the stirrer motor. 4. Close the ball valve completely before and then disconnect the outlet line from the reservoir 5. Close the inlet line ball valve and disconnect the inlet line and over flow lines form the top of the tube reactor. 6. Slide the reactor out of the enclosure and place a bucket below the sand trap. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR 7. While wearing full PPE plus a face shield, slowly open the ball valve at the bottom of the sand trap to empty the collected sand and acid that cannot otherwise drain from the tube. If sand is clogging this exit, slide a small piece of peristaltic pump tubing into the ball valve to release the blockage. When it is released, be careful not to let the sand and acid splash you. Pour excess acid liquid into the reservoir to retain only sand in the bucket. 8. Then open the RCA port on the side of the tube reactor to drain out the RCA into the same bucket containing the sand. Rinse the RCA/Sand with water, dump rinse water into the waste container for the first 2 rinses, and then in the sink. 9. Save acid in reservoir until it can be processed in a base reaction. Section 6. Cleaning the reactor 1. Clean the threads of the RCA port on the side of the reactor very well to remove all sand. Put Teflon tape on the threads before screwing the plug back into the port. Tighten the plug to make sure it is leak-proof. 2. Slide tube back into the enclosure, reconnect the tube inlet line and overflow line to the quick-disconnect unions at the top and the side of the tube lid, respectively. Open the manual ball valve on the tube inlet line. 3. Reconnect the tube outlet to the quick-disconnect union at the top of the reservoir. Set the electronic ball valve at the outlet to 50% open. 4. Fill the reservoir with water as described in section 1 step 2. 5. Close the enclosure doors and start the peristaltic pump to recirculate water from the reservoir through the tubing and the reactor tube until acid and fines are removed and collected in the reservoir. 6. After rinsing, water should be pumped from the reservoir directly to a waste drum. 7. The reactor is now ready to be loaded with fresh RCA and acid. When the tube is removed from the enclosure to be filled with the next batch of RCA, place a bucket below the tube and open the sand trap ball valve to drain the volume of rinse water trapped below the tube, and dispose of it in the waste drum. Results: [00134] Visual inspection (FIG.12B) indicated the RCA had high mortar content when form factor 1 was used as described herein. Example 3. Acid treatment of RCA in rotary drum (form factor 2) [00135] As evidenced by Example 2, dilute HCl (less than 1 molar) alone was ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR insufficient for removing all the mortar from RCA even when more than stoichiometric amount of HCl was used; mechanical abrasion, e.g., tumbling, of the RCA during treatment was investigated as a means of increasing mortar removal. Herein describes a procedure for performing mechanical abrasion in a rotary drum reactor to enhance reaction effectiveness. This protocol describes a use of form factor 2 acid reactor. Procedure: [00136] Into 12.98 L of tap water was slowly added 0.58 L of 37% w/w HCl. The mixture was mechanically stirred to homogeneity. Into a 6 gallon plastic drum equipped with lid with O-ring was added 2 kg RCA (7.5-9% w/w CaO). In a fume hood, 13.7 L of 0.5M HCl solution was slowly added to the RCA in the drum. When effervescence ceased, the lid of the drum was sealed and the drum was placed onto a rotary mixer located in a well-ventilated area. The rotary mixer rotated the sealed drum at 60 rpm. Continuous recording of pH was enabled with an in situ pH probe. The mixer was turned after reacting for 1-48 h. As seen in FIG.13, the pH of the reaction increased with time to reach a steady state of about pH 1.3 after about 10 h reaction time. [00137] After the target reaction time was completed, the liquid contents of the drum were decanted, and the remaining solids were washed multiple times with tap water until the solution above the solids was clear. After the solids were washed, they were placed on a #8 sieve and rubbed over the sieve for a couple of minutes to remove leftover fines/mortar. The aggregates were then placed into a container for final rinsing with tap water. The treated aggregates and fines were placed into separate containers and allowed to dry. [00138] Results: Visual inspection indicated the treated RCA contained significantly less mortar content than seen for packed bed reactor for the same reaction time. Example 4. Acid treatment of RCA in a rotary drum (form factor 2) with consecutive HCl treatments [00139] As evidenced by Example 3, mechanical abrasion, e.g., tumbling, of the RCA during acid treatment enhanced reaction effectiveness. However, using a dilute HCl solution requires a large volume of the acid solution, which reduces the load capacity for RCA and increases the capital expenditure (CapEx). For instance, treating 10 kg of RCA with 0.5 M HCl requires over 60 L of acid, exceeding the capacity of a 22.7 L (6-gallon) bucket. By splitting the acid into six 10 L portions and reacting each portion with the RCA sequentially, the same bucket can accommodate 10 kg of RCA. This approach allows for the treatment of a ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR significantly larger amount of RCA in a reactor with limited size. [00140] Herein describes treatment of a 5 kg batch of RCA with three consecutive treatment runs using 10 L of fresh 0.5 M HCl for each run for a total of about 30 L of 0.5 M HCl treatment. For each batch, the RCA was reacted with the HCl solution at 60 rpm rotation for 6 h with continuous monitoring of pH. This protocol describes use of form factor 2 acid reactor in multi-batch mode. Procedure: [00141] 10 L of 0.5 M HCl solution was prepared as described on example 3. Into a 6 gallon plastic drum equipped with lid with O-ring was added 5 kg RCA (7.5-9% w/w CaO). In a fume hood, the 10 L of 0.5M HCl solution was slowly added to the RCA in the drum. When effervescence ceased, the lid of the drum was sealed and the drum was placed onto a rotary mixer located in a well-ventilated area. The rotary mixer rotated the sealed drum at 60 rpm. Continuous recording of pH was enabled with an in situ pH probe. The mixer was turned at 60 rpm for 6 h. The drum was opened, the liquid contents of the drum were decanted, and 10 L of fresh 0.5 M HCl (see above) was added. The lid of the drum was sealed and rotated at 60 rpm another 6 h. The drum was opened, the liquid contents of the drum were decanted, and 10 L of fresh 0.5 M HCl (see above) was added. The lid of the drum was sealed and rotated at 60 rpm another 6 h. Total acid treatment time for the 5 kg batch of RCA was 18 h. [00142] At the end of the third run, the liquid contents of the drum were decanted, and the remaining solids were washed multiple times with tap water until the solution above the solids was clear. After the solids were washed, they were placed on a #8 sieve and rubbed over the sieve for a couple of minutes to remove leftover fines/mortar. The aggregates were then placed into a container for final rinsing with tap water. The treated aggregates and fines were placed into separate containers and allowed to dry. Results: [00143] Visual inspection after each run (FIG. 14 A, FIG. 14B, and FIG. 14C) indicated the amount of mortar content in treated RCA decreased. The pH time course for each run (FIG. 15) indicated that the base content of the mortar neutralized the acid significantly during the first acid treatment, but the neutralizing effect decreased with additional treatments. The pH and conductivity of each run is also summarized in Table 1 below. Table 1. pH and conductivity of each of three batch runs of treated RCA run initial pH final pH initial final ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR conductivity conductivity [00144] Water absorption for aggregates is an important test in the concrete industry. Lower water absorption in aggregates correlates with higher concrete strength. Herein describes a procedure for determining the water absorption of recycled coarse aggregates. Procedure: [00145] Previously acid treated RCA and untreated (control) RCA (about 500 g of RCA for each sample with 3 samples for each group) were rinsed with tap water for 2 minutes with mild agitation of the filter basket. After draining, each sample was placed in an aluminum tray and placed into the oven at 230 ° C for 24 h. The sample trays were removed, allowed to cool for about 10 minutes then weighed (with samples). The dry weight of RCA was obtained by subtracting the tray mass (note: the tray is weighed after the total weight in order to exclude the tray weight and any residue stuck on it). [00146] After determining the dry weight of each sample, each sample was placed in a container. Each container containing sample was filled with water at least 3 times the volume of RCA and left to soak for 24-72 hours (with treatment time recorded). After 72 hours, each container was drained of water. Each sample was placed on a sheets of paper towel. Additional paper towels were used to dry the rocks with light massaging. Each sample was then allowed to dry for a couple minutes until there was no more visible water on the surface(shininess). The mass of each sample was then recorded. [00147] Water absorption (w.a) as a percentage was calculated as: w.a. % = [(sw - dw)/dw]x100 where sw is saturated weight and dw is dry weight. The controls were used to test the improvement of acid treatment. Results: [00148] Using the method described herein, several RCA treatment groups were analyzed. FIG. 16 shows the results for untreated RCA and RCA treated with various acids. FIG. 17 shows the water absorption levels of virgin aggregates, untreated RCA, and RCA treated with HCl, and where these water absorption levels fall relative to the industry ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR requirement for cement aggregates. FIG.18 shows the water absorption of untreated and treated RCA using form factors 1-3, with three multi-batch treatment arms (3-batch and 6-batch rotary drum). Example 6. Form factor 3 of acid reactor [00149] The use of form factor 2 as described in Examples 3-4 illustrates a few issues in the design: 1) low volume occupation by RCA, 2) high number of reactor units for increased scale, 3) a relatively high CapEx, and 4) relatively high operating expense (OpEx) attributed to moving liquid. A new design was sought, which would reduce the liquid/solid volume or mass ration of the drum while maintaining HCl/RCA stoichiometry. [00150] Herein describes a design for a drum reactor for treatment of RCA with acid that address the issues for form factor 2. This design provides lower liquid/solid volume ratio so that more energy is dedicated to mechanical abrasion, e.g., tumbling, of RCA than just moving liquid. This design, which is form factor 3, maintains HCl/RCA stoichiometry. Form factor 3 (FIG.18) comprises a rotating drum reactor equipped with an inlet and outlet port that allows for continuous circulation of HCl solution in the reactor at a level just sufficient to treat the RCA while minimizing the volume of solution. Example 7. Base reaction and filtration procedure [00151] As provided in the description and claims, the liquid rich in the one or more metallic ions may be contacted with a base to produce a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions. An embodiment that relates to treatment of RCA with acid produces a liquid rich in calcium ions (e.g., one or more of CaCl2, CaSO4, and Ca(NO3)2. When base, e.g., NaOH is contacted with the liquid rich in calcium ions, Ca(OH)₂ (and/or other metal hydroxides, such as Mg(OH)₂, Fe(OH)₂) may form. [00152] Herein describes a procedure for the base reaction. NaOH was added to reacted acid (e.g. acid solution that had previously been used to treat RCA) to precipitate Ca(OH)₂ and other metal hydroxides and/or carbonates. Vacuum filtration was then applied to separate the precipitates from the liquid phase. Subsequent washing with water followed the filtration step to wash off salt contaminants in the precipitates. Base reaction procedure: [00153] Into a 22 gallon base reactor was added reacted acid solution/sludge from treatment of RCA with HCl solution (e.g., from Examples 1-4). The mixer was blended ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR for 2 minutes using a cement mixer, then the pH and conductivity was recorded. An appropriately sized tank was placed in fume hood, then an amount of NaOH needed to achieve desired molarity, e.g., 1-5 M, was added. The base solution was mixed until well blended, then initial pH and conductivity of the base solution was recorded. Using a peristaltic pump and tubing, transfer all of the base solution through the port on the base reactor lid while mixing the base reaction for 10-30 minutes. The pH and conductivity of the precipitate slurry was then recorded. A lab top version of the base titration is shown in FIG. 20, which illustrates precipitation increases with pH. Filtration procedure: [00154] An appropriately sized buchner funnel was prepared having filter fabric and filter paper on top of the filter fabric. Vacuum tubing was to connected to a small vacuum pump to an 11 L filtrate collector (suction canister) and the outlet of the buchner funnel was connected to the filtrate collector with vacuum tubing. The filter paper was wetted with water and then flattened to remove any bubbles in the paper against the fabric. The buchner funnel was connected with the lid, and the vacuum pump was activated to create a good seal with the filter paper. Once the buchner funnel was prepared, the vacuum pump was turned off, and the lid to the funnel was removed to load the precipitate slurry. The base precipitate slurry was slowly poured into the buchner funnel. The lid was placed back on the buchner funnel and the vacuum pump was activated to begin removing filtrate from the precipitates. In parallel with the filtration, 30 L of fresh water was preheated in the cement mixer to 80 °C using the sous vide heater for washing. The filtration process was continued until no more water was removed from the filter cake, and the precipitate consistency appeared as conditioner. The lid was removed periodically during filtration to check the moisture content in the filter cake. If cracks formed in the cake, a scoop was used to compress the cake and fill the cracks, which improved the efficiency of filtration. The pH and conductivity of the filtrate was recorded. The filter cake was washed with the preheated water until the conductivity of the collected rinse water was below 20 mS/cm. Post treatment procedure: [00155] Stainless steel baking sheets with silicone cover (and vented plastic lids if applicable) were weighed, then the wet precipitate was added onto the baking sheets and the weight of each loaded sheet was measured. The precipitates were dried in a thermotron at > 120° C for at least 48 hours, or until the weight was no longer decreasing with time. The drying process was observed to occur much faster without lids. Trays containing cement precursors obtained from treatment of 5 kg RCA with acid followed by treatment with NaOH are shown ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR before and after drying in FIG. 21. Finally, the weight of the dry precipitates on the baking sheets were measured, then the dried precipitates were transferred to a grinder and ground for 2 minutes to form a powder. Ball milling was optionally performed. Example 8. Cement cylinder preparation and compression testing [00156] As provided in the description and claims, the cement precursors obtained through acid treatment followed by base titration as described in Example 7 may be used to prepare cement and cement and cement materials, e.g., concrete. [00157] Herein describes a procedure to make cement mortar test cylinders. This is based on ASTM C129, but significant modifications were made to reduce the test sample size from 2x2x2 inch cubes to cylinders of size 0.9 cm diameter * 2 cm. Materials and equipment [00158] Screening machine (Model TS-4), Compression machine (AC-325), concrete cylinder molds, and slump test set were obtained from Gilson, Lewis Center, OH. Vibrating table was obtained from vibropro. The 5.0 cu. ft. Portable Concrete Mixer was obtained from Ryobi. Cement mortar recipe (7-8 cylinders for each recipe): 1. Recipe 1: standard type I cement a. New sand: 10cy*4g/cy /4.5*3 = 26.67 g b. New cement (Type I): 10cy*4g/cy /4.5 = 8.88 g c. Water: 10cy*4g/cy /4.5*0.5 = 4.44 g 2. Recipe 2: standard type II/V cement a. New sand: 10cy*4g/cy /4.5*3 = 26.67 g b. New cement (Type I): 10cy*4g/cy /4.5 = 8.88 g c. Water: 10cy*4g/cy /4.5*0.5 = 4.44 g 3. Recipe 3: cement containing 30% HL RCA cement a. Sand: 10cy*4g/cy /4.5*3 = 26.67 g b. Recycled cement: 10cy*4g/cy /4.5*0.3 = 2.67 g c. New cement (Type I): 10cy*4g/cy /4.5*0.7 = 6.2 d. Water: 10cy*4g/cy /4.5*0.5 = 4.44 g Casting mortar cylinders: [00159] One hour before casting, mold release was sprayed onto the cylinder molds. Using a paint stick in a 16 oz. mixing jar, the dry sand and cement according to the ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR recipe above was mixed, Water was added to the mix using a micropipette. The slurry was mixed using a paint stick on a working vibrating table (150 hz) for 45 seconds. The mixing jar was removed from the vibrating table and the molds were placed onto the vibrating table. While the molds were vibrated, the wet mix was scooped into the molds, using a spatula to distribute the wet mix into 8 cylinder holes. All the holes were packed with a screw one and a half minutes after pouring the first scoop. Then a spatula was used to move overflowing mix materials into the holes. Vibrating was continued for 3 minutes. After all cylinders were caste, the vibrating table was stopped. Then a sheet of towel was wet and wrapped around one set of molds (seven to eight cylinders). The wrapped molds were then placed into a Ziploc-bag and cured for three days under these conditions. Each cylinder was demolded on day 3 and another wet towel was used to wrap the cylinders. Each cylinder was then placed into a Ziploc bag to cure until crushing. Crushing was performed on day 7 or day 10. [00160] Additional test cylinders were prepared according to formulations provided in Table 2. Cylinder compression testing followed ASTM C39. Slump test followed Slump test: ASTM C143. Table 2. Additional test cylinder formulations RCA(lb.) HCl treated RCA(lb.) Example 9. Evaluation of cement precursor recycling process [00161] An overview of the combination of the acid treatment, base reaction, filtration, drying, cooking and blending to obtain cement precursor suitable for final cement is shown in FIG. 22. Herein describes evaluation of this recycling process as well as the performance of recycled concrete aggregate. Specifically, a comparison between the ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR minerology and performance of pristine portland cement versus cement prepared from the recovered solids obtained through the process disclosed herein is presented. [00162] X-ray fluorescence spectroscopy (XRF) analysis of the recovered solids indicated different ratios of certain minerals than pristine cement. Recovered RCA cement has high Cl and Na content but is deficient in CaO and SiO2 (Table 3). Table 3. Summary of XRF analysis of RCA recovered solids C^{omponent Original After adding} Remove volatile C_{aO and silica} species renormalize [00163] There results indicated a need to augment the recovered solids in order to render them closer in chemical composition to pristine cement. Accordingly, CaO and SiO2 were blended with the recovered solids to give the compositions shown in Table 3 with the mineral ratios shown in Table 4. The approximate ratio of treatment was 10 g recovered solids + 4.8 g CO + 1 g SiO₂. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR Table 4. Mineral ratios of RCA recovered solids after cooking After adding Ratios Original CaO and SiO₂ Recommended value ortions of the four main minerals in cement clinker, which are: 1. Tricalcium silicate (C3S) – Alite 2. Dicalcium Silicate (C2S) - Belite 3. Tricalcium aluminate (C3A) -Aluminate Phase 4. Tetracalcium Aluminoferrite (C4AF)- Ferrite Phase [00165] Table 5. shows the Bogues equation values before and after adding CaO and SiO₂ followed by heating to 1450 °C as described below. Table 5. Composition of cement precursors Bogues Equation calculation Original after adding CaO and SiO2 [00166] The amended recovered solids were blended as described above and heated up to 1450 °C over 60 minutes according to Table 6. The appearance before and heating is shown in FIG.23. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR Table 6. Concrete precursor heating time course Segment Temp (°C) Time (min) 1 0 5 CA recovered solids did not appear to have clinkerized/sintered. Also, there was a faint chloride odor. About 4% gypsum was then added to the cooked recovered cement precursor to provide a composition suitable for preparation of cement. The XRF analysis of the final composition is provided in Table 7. Overall, the amended RCA cement had good CaO/SiO2 ratios, relatively high MgO and Ca2Al2O5 content, and relatively low SO3 content. Table 7. Mineral composition of amended RCA cement Component Conc. Component Conc. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR CaO 64.4 Y2O3 0.003 next evaluated. Using the protocols and procedures disclosed in Example 8, cement cylinders were prepared. The results of compression tests of these cylinders (FIG.24) indicated that RCA cement prepared from 30% recycled mix with 70% type I cement was weaker than type I and type II/V cement. Interestingly, however, RCA cement prepared from 30% recycled mix with 70% type I cement appeared hydrophobic. [00169] By way of comparison, dry type I Portland cement was treated with HCl solution as described in Examples 1-4, and the solution rich in calcium salts from dissolved cement was then treated with NaOH solution as described in Example 7 to obtain recovered solids. [00170] The batches of recovered cement precursor starting with pristine unreacted cement as starting material and having good minerology replication showed better performance, as shown in FIG. 25. The addition of 4% gypsum to the cooked blend provided significant improvement to strength of the cement (FIG.26). [00171] As further evaluation of the cement precursor recycling process described herein, test cylinders were prepared using treated and untreated RCA. The recycled concrete aggregates performed significantly better than untreated RCA (FIG.27). Example 9. H-Cell Electrolysis procedure [00172] As provided in the description and claims, the liquid deficient in the one or more metallic ions may be contacted with an electrolyzer to regenerate the acid and the base. [00173] Herein describes the an H-Cell containing Ca(NO₃)₂ is tested for acid and base generation. Materials and equipment [00174] The electrolyzer was H -Type Electrochemical Cell Sealed 50 mL, obtained from DEK Research, Kowloon, Hong Kong. The carbon cathode was 3 mg/cm² 40% Platinum on Vulcan - Carbon Cloth Electrode (W1S1010), Fuelcell store, Boulder, Colorado. The anode was 99.99% Platinum Plate Electrode Coated with PTFE Insoluble Anode ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR (10mm×10mm×0.1mm). The membrane was umasep FAA-3-PK-75 obtained from Fuelcell store, Boulder, Colorado). The power supplies were BioLogic Potentiostat VSP-3e Potentiostat, Biologic, France. The Ca(NO3)2 was obtained from Sigma-Aldrich. Procedure: 1. Cell Assembly: The anion exchange membrane was placed between the two O- rings. the two cell bodies were then connected to the O-rings. The cell bodies were clamped to secure the membrane's position. A 1 cm² carbon paper or cloth electrode was attached to an electrode holder and fix it to the lid of the anode chamber. Another 1 cm² carbon paper or a platinum plate was attached to an electrode holder and secure it to the lid of the cathode chamber. Both chambers were capped with their respective lids. 2. 100 mL of 0.2 M Ca(NO3)2 solution was prepared by dissolving 3.28 g of Ca(NO₃)₂ powder into 100 mL of DI water.40 mL of each solution was added to each electrode reservoir. 3. The anode extension cord emanating from the potentiostat was attached to the anode, and the same was done with the cathode extension cord and the cathode. 4. A chronopotentiometry experiment was performed by selecting a current (10 mA or 5 mA). 5. The pH change was measured with a pH probe. The pH of the anode reservoir was expected to decrease because of acid (HNO₃) formation and the pH of the cathode reservoir is expected to increase because of base formation (Ca(OH)2). 6. Observe any precipitation, which would be Ca(OH)₂, on the surface of the cathode. Results: [00175] Using anion exchange membrane FAA-3-PK-74 with 1 cm² carbon cloth electrode doped with 1 cm² Pt, and a voltage at about 10V at 50 mA and about 5V at 10 mA, the cathode reservoir was observed to turn purple because of base formation, and the anode reservoir was observed to turn clear (pH=2) after 60 minutes (FIG. 28). A shell of Ca(OH)2 was observed at the cathode (FIG. 30A, 30B), which is consistent with the increased voltage observed for the carbon electrodes causing fouling and malfunction (FIG.29). The Pt electrode remained at a constant voltage despite having a shell of Ca(OH)₂. Example 10. Hydrogen looping for NaOH and HCl generation [00176] Hydrogen looping method is employed to reduce the energy ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR consumption of NaOH production. Hydrogen gas is consumed at the anode and is simultaneously produced at the cathode, so that the thermodynamics cost of HCl and NaOH generation in this cell is 0. All the cost goes to the overpotential. Equipment and Materials: [00177] The CO₂ Electrolyzer, 5 cm² active area (Fuelcell store, Boulder, Colorado). The cathode end plate material was SS304L. The Cathode material was Pure Ni, 40 mesh (Fuel Cell Materials) obtained from McMaster-Carr. The Anode end plate material: graphite with custom machining. Anode material: 4 mg/cm² Pt black on carbon cloth W1S1011(Fuelcell store, Boulder, Colorado). The membrane was AEM (FAB-PK-130) obtained from Fuelcell store, Boulder, Colorado). The power supplies were BioLogic Potentiostat VSP-3e Potentiostat, Biologic, France. ACS grades NaCl was obtained from Sigma-Aldrich. Peristaltic pump was Kamoer DIPump 550 (Kamoer, Shanghai, China). Hydrogen was 99.999%, UHP obtained from Instrument depot, Rochester, NY. The mass flow controller was obtained from Alicat, Tucson, AZ. Procedure: 1. Electrolyte Preparation: For the catholyte, 100 mL of 1 M NaCl solution is used. Simultaneously, 100 mL of 1 M NaCl solution is used for the anolyte. 2. Cell Assembly: The cell components were assembles according to manufacturer’s instructions applying a torque of 30 lb. inch to secure the components 3. Electrode Connection: The cell cathode was attached to the working electrode cable and the anode to the counter electrode cable of the BioLogic potentiostat or Labjack. 4. Hydrogen Gas Setup: The hydrogen gas supply was connected to the designated inlet port of the cell using PTFE tubing and a mass flow controller flow controller. The gas outlet and electrolyte outlet were both attached to the anolyte reservoir since liquid will come out from both tubings. The hydrogen flow rate was set to 20 mL/min on the mass flow controller 5. Cell Setup: The cell was placed inside a preheated water bath (88°C) up to the designated safe level, then the tubing to the cell reservoirs and peristaltic pumps were connected. 6. Electrolyte Circulation: Both catholyte and anolyte solutions were pumped with the peristaltic pumps at 100 rpm. ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR 7. Electrochemical Measurements: Baseline potential was established by allowing the system to equilibrate for 1 minute at open circuit voltage (OCV). Note : BioLogic potentiostat was used, but when large current densities were required a Labjack + power supply was used. 8. Chronopotentiometry Experiments: Various current densities were selected using CP on Biologic or setting the current through Labjack. The desired current was applied for a predetermined time period (e.g., 10-30 minutes) while recording the cell voltage continuously. 9. Determine the concentration of NaOH: This accomplished as described in Example 11. Results: [00178] While hydrogen flow above 20 mL/min had minimal impact (FIG.31), there was some evidence of hydrogen depolarization at higher voltages (FIG. 32). The Pt- carbon anode was stable up to 1.6 V under continuous voltage; the stability was not limited by membrane or Ni cathode (FIG. 33). The Pt-on-Ti mesh did not show sufficient activity. The current of Pt-Ti mesh is 10x lower than Pt-carbon cloth (FIG.34). Without wishing to be bound my theory, this may be due to either (1) lack of catalytic activity of low-defect Pt coating, or (2) insufficient mixing of H2 and electrolyte without gas diffusion layer. For the anode having 4 mg/cm² Pt black on carbon cloth, the current was observed to continually decrease, indicating instability even at 1.4 Volts (FIG. 35). Lowering the Pt level to 2 mg/cm² Pt black on carbon cloth and lowering the current resulted in a more stable configuration (FIG.36), however these results also indicate that Pt-loading has a large impact on hydrogen oxidation reaction rate. Example 11. Chlor-Alkali Electrolysis and auto-titrator procedure [00179] A chlor-alkali cell was run in the lab to provide a baseline energy cost for base (NaOH) generation in kJ/mol. The energy cost in kJ was measured by the potentiostat or the power supply connected to a labjack. The quantity of sodium hydroxide generated was determined by a custom-made auto-titrator. Equipment and Materials: [00180] The CO2 Electrolyzer, 5 cm² active area (Fuelcell store, Boulder, Colorado). The cathode end plate material was SS304L. The Cathode material was Pure Ni, 40 mesh (Fuel Cell Materials) obtained from McMaster-Carr. The Anode end plate material: Titanium machined in house. The anode was Dimensionally Stable Anode (DSA)obtained from TIBROMTACK. The membrane was GI-N417 (PTFE fabric reinforced perfluorosulfonic acid ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR (PFSA)) obtained from Fuelcell store, Boulder, Colorado).The power supplies were BioLogic Potentiostat VSP-3e Potentiostat, Biologic, France, or Labjack T4 (LabJack, lakewood, CO) and a DC Power Supply Variable, Hyelec 30V 10A Adjustable Switching Regulated DC Bench Power Supply. ACS grades NaOH and NaCl, and 1 M HCl standard solution were obtained from Sigma-Aldrich. The pH probe was obtained from Teyleten. Wireless connection was through Arduino UNO WiFi REV2. The syring pumps were KDS Legato™ 270 (Sigma- Aldrich). The stir plate was Hot Plate Stirrer, Multi-position (8 positions) | BT Lab Systems (Saint Louis, MO) Procedure: [00181] 150 mL of 1 M NaOH solution was prepared as catholyte and 150 mL of 5 M NaCl solution was prepared as anolyte. The electrolyzer cell was assembled according to the manufacturer's instructions. The torque applied to join the units was 30 lb. inch. The cell cathode was connected to the working electrode cable and the anode to the counter electrode cable of the BioLogic potentiostat or Labjack. 1. Cell Setup: The cell was place in a preheated water bath (88°C) to the designated safe level, then the tubing to the cell compartments and peristaltic pumps were connected. 2. Electrolyte Circulation: The peristaltic pumps were started at 100 rpm to pump both catholyte and anolyte solutions to their respective reservoir. 3. Electrochemical Measurements: Baseline potential was established by allowing the system to equilibrate for 1 minute at open circuit voltage (OCV). Note : BioLogic potentiostat was used, but when large current densities were required a Labjack + power supply was used. 4. Chronopotentiometry Experiments: The experiments were conducted at various current densities by choosing CP on Biologic or setting the current through Labjack, applying the desired current for a predetermined time period (e.g., 10-30 minutes) while recording the cell voltage continuously. 5. Sample Collection and Auto-Titration: After each chronopotentiometry experiment, two 10 mL aliquots of the catholyte, where NaOH was generated were collected using a syringe. Each sample was then transferred to a beaker containing a magnetic stir bar and pre-positioned pH probe. The two beakers containing the aliquots of NaOH were stirred on the multi-channel stir plate. Two 30 mL syringes were charged with 30 mL of 1 M HCl standard and loaded onto the syringe pump, with the plastic syringe tip in the titrant to ensure ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR efficient titration. The auto-titration program was configured and run and ensure that the endpoint was beyond the equivalence point of NaOH-HCl titration by having more-than- stoichiometric amount of HCl. The titration was monitored, and data (volume of titrant required to achieve neutrality). Results: [00182] Repeated runs at 200 mA/cm² over several days showed that the stability and reproducibility was good (Table 8). The energy cost to produce NaOH under various currents ranged from as low as 2.10 ± 0.01 as high as 4.02 ± 0.03 kWh/kg. These energy costs are above industrial electrolyzers (FIG. 37). One cause, which was that sweeping to high current densities leads to cell instability (see FIG.38). Without wishing to be bound by theory, the cell instability may be due to carbon paper oxidation at higher potential. Table 8. Summary of in-house chloro-alkali test results Run Current voltage (V) Caustic NaOH energy cost (kWh / kg) A/ ² ffi i % [00183] A comparison between the hydrogen looping method (Example 10) with the Chloro-alkali method indicates the hydrogen looping will achieve better efficiency (FIG. 39A, 39B, and 39C). Hydrogen looping can likely achieve a 1 kWh/kg NaOH output, but the current density remains uncertain.

Claims

ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR CLAIMS 1. A method of preparing concrete precursors, the method comprising: (a) contacting an inorganic solid waste comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; (b) contacting the liquid rich in the one or more metallic ions with a base to produce a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer to regenerate the acid and the base, and (d) repeating each of steps (a)-(b) at least once with the acid and the base from step (c). 2. The method of claim 1, wherein the inorganic solid waste comprises one or more of a group of recycled concrete aggregate (RCA), smelting slag, blast furnace slag, incinerator bottom ash, and electronics waste. 3. A method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregate (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; (b) contacting the liquid rich in the one or more metallic ions with a base to produce a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer to regenerate the acid and the base, and (d) repeating each of steps (a)-(b) at least once with the acid and the base from step (c). 4. The method of any one of claims 1-3, wherein the electrolyzer is a single-membrane electrolyzer, two-membrane salt splitting electrolyzer, a multi-membrane salt-splitting electrolyzer, a chlor-alkali electrolyzer, a bipolar membrane electrodialysis electrolyzer, or a combination of any of the foregoing. 5. A method of preparing concrete precursors, the method comprising: ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR (a) contacting recycled concrete aggregate (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; (b) contacting the liquid rich in one or more metallic ions with a base and carbon dioxide to produce one or more metal carbonates from the one or more metallic ions and a liquid deficient in the one or more metallic ions; and (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer to regenerate the acid and the base. 6. The method of any one of claims 1-5, wherein step (b) comprises sequentially contacting the liquid rich in the one or more metallic ions with two or more independently selected bases. 7. The method of any one of claims 1-6, further comprising separating the precipitate and the liquid deficient in the one or more metallic ions of step (b) prior to step (c). 8. A method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregates (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions (b) contacting the liquid rich in the one or more metallic ions with a base comprising a carbonate salt and/or a bicarbonate salt to produce one or more metal carbonates from the one or more metallic ions and a liquid deficient in the one or more metallic ions; and (c) contacting the liquid deficient in the one or more metallic ions with an electrolyzer to regenerate the acid and the base, wherein the carbonate salt and/or the bicarbonate salt are produced from admixing carbon dioxide and a metal hydroxide. 9. The method of any one of claims 5-8, wherein the carbon dioxide is provided as a composition, wherein the composition comprises carbon dioxide and at least one additional gas. 10. The method of claim 9, wherein the composition comprises carbon dioxide in an amount of about 0.01 wt% to about 99.9 wt%, or about 0.01 wt% to about 1.5 wt%, or about 1 ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR wt% to about 10 wt%, or about 50 wt% to about 90 wt%. 11. The method of any one of claim 5-8, further comprising repeating each of steps (a)- (b) at least once with the acid and the base from step (c). 12. The method of claim any one of claims 8-11, wherein the carbonate salt and/or the bicarbonate salt is selected from sodium, potassium, lithium, and combinations of any of the foregoing. 13. A method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregates (RCA) comprising one or more metallic ions with an acid to produce the concrete precursors and a liquid rich in the one or more metallic ions; and (b) contacting the liquid rich in the one or more metallic ions with an electrolyzer to regenerate the acid and produce a precipitate comprising the one or more metallic ions. 14. The method of claim 13, further comprising separating the concrete precursors from the liquid rich in the one or more metallic ions of step (a) prior to step (b). 15. The method of claim 13 or 14, further comprising separating the precipitate and the acid of step (b). 16. The method of any one of claims 13-15, further comprising repeating step (a) at least once with the acid from step (b). 17. The method of any one of claims 13-16, further comprising separating the precipitate and the liquid deficient in the one or more metallic ions of step (b). 18. The method of any one of claims 13-17, wherein the sequential electrolysis occurs via continuous electro-distillation. 19. A method of preparing concrete precursors, the method comprising: (a) contacting recycled concrete aggregates (RCA) comprising one or more metallic ions with an acid in an electrochemical cell to produce the concrete precursors and a liquid ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR rich in the one or more metallic ions; and (b) contacting the liquid rich in the one or more metallic ions with a base in the electrochemical cell to form a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; wherein the electrochemical cell comprises an anode reservoir comprising an anode and the acid, and a cathode reservoir comprising a cathode and the base, wherein the anode reservoir and the cathode reservoir are separated by a separator. 20. The method of claim 19, wherein the separator is an anion exchange membrane. 21. The method of claim 19, wherein the separator is a cation exchange membrane. 22. The method of any one of claims 19-21, further comprising regenerating the acid and the base in the electrochemical cell. 23. The method of claim 13 or 19, further comprising separating the concrete precursors from the liquid rich in the one or more metallic ions of step (a) prior to step (b). 24. The method of claim 13 or 19, further comprising repeating each of steps (a)-(b) at least once using sequential electrolysis. 25. The method of claim 24, wherein the sequential electrolysis occurs via continuous electro-distillation. 26. The method of any one of claims 1-25, further comprising separating the concrete precursors and the liquid rich in the one or more metallic ions of step (a) prior to step (b). 27. The method of any one of claims 1-26, further comprising heating the precipitate to produce a cement material. 28. A system for preparing concrete precursors, comprising: an electrochemical cell configured to prepare concrete precursors, wherein the electrochemical cell comprises an anode reservoir comprising an anode and an acid, and a cathode reservoir comprising a cathode and a base, wherein the anode reservoir and the ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR cathode reservoir are separated by a separator; a contactor configured to input recycled concrete aggregates (RCA) comprising one or more metallic ions into the anode reservoir, wherein the anode reservoir is configured to contact the RCA with the acid to produce the concrete precursors and a liquid rich in the one or more metallic ions, and the cathode reservoir is configured to contact the liquid rich in the one or more metallic ions with the base to form a precipitate comprising the one or more metallic ions and a liquid deficient in the one or more metallic ions; a first filtration system in contact with the anode reservoir configured to filter out the concrete precursors from the anode reservoir; and a second filtration system in contact with the cathode reservoir configured to filter out the precipitate comprising the one or more metallic ions from the cathode. 29. The system of claim 28, further comprising a tube connecting from the anode reservoir to the cathode reservoir configured to output hydrogen gas from the cathode reservoir and input hydrogen gas into the anode reservoir. 30. The system of claim 28 or 29, further comprising a conducting material connecting the anode to the cathode configure to output electrons from the anode and input the electrons to the cathode. 31. The system of any one of claims 28-30, further comprising a valve configured to input water into the anode reservoir. 32. The system of any one of claims 28-31, wherein the first filtration system is additionally configured to filter the liquid rich in the one or more metallic ions from the concrete precursors and input the liquid rich in the one or more metallic ions into the cathode reservoir. 33. The system of any one of claims 28-32, wherein the separator is an anion exchange membrane or a cation exchange membrane. 34. The method of any one of claims 1-27 or the system of any one of claims 28-33, wherein the one or more metallic ions are selected from ions of lithium, sodium, potassium, beryllium, magnesium, calcium, strontium, barium, radium, aluminum, gallium, indium, tin, thallium, ATTORNEY DOCKET NO. 43374-0739WO1 / X-52718-00-PR lead, bismuth, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, and mercury. 35. The method or system of any one of claims 1-34, wherein the one or more metallic ions are selected from ions of sodium, potassium, magnesium, calcium, tin, lead, iron, cobalt, nickel, copper, zinc, palladium, silver, cadmium, platinum, and gold. 36. The method or system of any one of claims 1-35, wherein the one or more metallic ions are selected from ions of sodium, potassium, magnesium, and calcium. 37. The method or system of any one of claims 1-36, further comprising (a) mixing the precipitate with one or more silicates to form a mixture; (b) grinding the mixture to form a particulate; and (c) heating the particulate to about 1,000°C to about 1,500°C for a period of time, to provide cement.