Carbon dioxide sequestering composition for bonding and stabilization of aggregate materials

Abstract

A road binder composition includes: a lignosulfonate proportion between 5% and 40% by mass characterized by a molecular mass greater than 2.5 kilodaltons and less than 125 kilodaltons; a carbon-mineralizing proportion between 10% and 35% by mass; and a porous siliceous material proportion between 2% and 15% by mass.

Description

CARBON DIOXIDE SEQUESTERING COMPOSITION FOR BONDING AND STABILIZATION OF AGGREGATE MATERIALSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This Application claims the benefit of Romanian Provisional Application No. 2023 / 00687, filed on 15-NOV-2023, which is incorporated in its entirety by this reference.TECHNICAL FIELD

[0002] This invention relates generally to the field of road construction and, more specifically, to new and useful carbon dioxide sequestering composition for binding and stabilization of aggregate materials in the field of target biomolecule production and purification via chromatography.BACKGROUND

[0003] Compositions based on organic and mineral ingredients are known for use as a binding agent for road foundation aggregates. U.S. Patent No. 5,024,702 describes a stabilizing agent for road foundation aggregates formed by mixing asphalt emulsion, lignosulfonate, and water. The volume ratio between lignosulfonate and asphalt emulsion is in the range from 10:90 to 90:10, and the lignosulfonate is selected from the group consisting of: (a) calcium lignosulfonate; (b) sodium lignosulfonate; (c) ammonium lignosulfonate.

[0004] U.S. Patent No. 7758280 relates to a composition consisting of coal ash and an emulsion based on petroleum resin and a method of applying it to stabilize and bind the aggregates that constitute the foundation of the road. The emulsion contains petroleum resin, 15 to 45 weight percent lignosulfonate, and 6 to 8 weight percent alkylphenol surfactant. Lignosulfonate contains at least ammonium, calcium, or sodium lignosulfonate. The application process involves the use of an emulsion volume ranging from 2.26 to 6.79 liters per square meter (0.5 to 2.5 gallons per square yard), depending on the type of aggregates and the type of coal ash used.

[0005] PCT Application No. 2000 / 049229 relates to a method of making a foundation for roads, which includes the application of a composition that includes a lignin or lignosulfonate-based binding agent, a binding additive selected from cement, lime, fly ash, calcium sulfate or slag and possibly water, and mixing the slurry thus obtained with the soil at the base of the road, and possibly also a filler material.

[0006] Romanian Patent No. 99295 relates to a process for making road layers from stabilized natural aggregates, which consists of the following steps: scarification of the existing covering to a thickness of 12 cm through successive passes with the motor grader; and sprinkling ballast with a binding and stabilizing composition consisting of 2.5% by mass of ammonium lignosulfonate, 50% solution, and 0.4% by mass of potassium or sodium dichromate. The disclosed mixture results from sprinkling natural aggregates with lignosulfonate and dichromate solutions and compacting, through successive passes of the compactor with smooth rollers.

[0007] U.S. Patent No. 4129449 relates to a composition for strengthening road base soil layers consisting of 96.5% Portland cement, 0.2 to 0.8% by mass lignosulfonate with a molecular weight of 400 to 700,000 Daltons, 0.4 to 0.5% by mass sodium tripolyphosphate, 0.2 to 0.3% by mass calcium stearate, 1.5 to 2.0% by mass calcium chloride, and 0.5 to 0.5% by mass 1.0 wt.% high silica slag.

[0008] Generally, road foundations include a significant proportion of potentially toxic elements, including elements with high mobility, such as cadmium or zinc. Coal ash has a significant content of potentially toxic elements, such as arsenic or lead. Slag from the production of cast iron or steel consistently has a content above the permissible limits of arsenic, hexavalent chromium, and manganese, and sometimes of cobalt and lead.

[0009] The compositions described in the prior art increase the risk of potentially toxic elements from the soil in the road foundation due to their coal ash and / or slag content. For example, the composition from Romanian Patent No. 99295 has a high risk of environmental contamination with hexavalent chromium ions.

[0010] Thus, there remains a need for a composition that sequesters carbon dioxide and limits the circulation of potentially toxic elements.BRIEF DESCRIPTION OF THE FIGURES

[0011] FIGURE 1 is a schematic representation of one variant of the road binder composition;

[0012] FIGURE 2 is a schematic representation of one variant of the road binder composition.

[0013] FIGURE 3 is a schematic representation of one variant of the road composition that includes one variant of the road binder composition.

[0014] FIGURE 4 is a schematic representation of one variant of the road composition that includes one variant of the road binder composition.

[0015] FIGURE 5 is a chart representation of a grading curve for 0 / 4 millimeter crushed rock utilized for unconfined compressive strength testing of variants of the road composition.

[0016] FIGURE 6 is a chart representation of the unconfined compressive strengths of variants of the road composition including variants of the road binder composition.DESCRIPTION OF THE EMBODIMENTS

[0017] The following description of embodiments of the invention is not intended to Emit the invention to these embodiments but rather to enable a person skilled in the art to make and use this invention. Variations, configurations, implementations, example implementations, and examples described herein are optional and are not exclusive to the variations, configurations, implementations, example implementations, and examples they describe. The invention described herein can include any and all permutations of these variations, configurations, implementations, example implementations, and examples.

[0018] Generally, the term “set,” as utilized herein, can include a single instance or multiple instances of an associated object. Descriptors such as “first,” “second,” “third,” etc., as utilized herein, do not imply a sequence or order unless otherwise specified but do imply separate instances of the associated object.

[0019] Generally, various components of the road composition are described herein as percentages or proportions of the whole road composition. In these circumstances, the terms “percentage” or “proportion” or the symbol “%” refer to mass percentages or proportions unless otherwise specified.

[0020] Generally, the term “road composition,” as utilized herein, refers to a heterogenous and compacted mixture of road materials that form one or more of a set of road layers, including a sub-base, a base course, a binder course, and / or a surface course. Therefore, characteristics, properties, or attributes of the road composition described herein refer to bulk characteristics, properties, or attributes of the road composition on the resolution of the square meter or cubic meter scale and may vary locally within smaller samples of the road composition.1. Road Binder Composition

[0021] As shown in FIGURE 1, the road binder composition 100 includes a functionalized lignin proportion 110 between 5% and 40% by mass; a carbon-mineralizing proportion 120 between 10% and 35% by mass; and a porous siliceous material proportion 130 between 2% and 15% by mass.

[0022] In one variant, a road binder composition 100 includes: a lignosulfonate proportion 112 between 5% and 40% by mass characterized by a molecular mass greater than 2.5 kilodaltonsand less than 125 kilodaltons; a carbon-mineralizing proportion 120 between 10% and 35% by mass; and a porous siliceous material proportion 130 between 2% and 15% by mass.

[0023] In another variant, the road binder composition 100 includes: a carboxylated Kraft lignin proportion between 5% and 40% by mass characterized by a molecular mass greater than 50 kilodaltons and less than 400 kilodaltons; a carbon-mineralizing proportion 120 between 10% and 35% by mass; and a porous siliceous material proportion 130 between 2% and 15% by mass.

[0024] As shown in FIGURE 2, one variant of the road binder composition 100 includes: a lignosulfonate proportion 112 between 20% and 30% by mass and characterized by a molecular mass between 2.5 kDa and 125 kDa; a diatomite proportion 132 between 5% and 10% by mass; and a binding additive proportion 122 between 50% and 55% by mass.2. Road Composition

[0025] As shown in FIGURE 3, a road composition 200 includes: an aggregate proportion 210 greater than 90% by mass; and a road binder proportion 220 less than 10% by mass and greater than 1% by mass. The road binder proportion 220 further includes: a functionalized lignin proportion 110 between 5% and 40% by mass characterized; a carbon-mineralizing proportion 120 between 10% and 35% by mass; and a porous siliceous material proportion 130 between 5% and 15% by mass.

[0026] As shown in FIGURE 4, a road composition 200 includes: an aggregate proportion 210 greater than 90% by mass; and a road binder proportion 220 less than 10% by mass. The road binder proportion 220 further includes: a lignosulfonate proportion 112 between 5% and 40% by mass characterized by a molecular mass greater than 2.5 kilodaltons and less than 125 kilodaltons; a carbon-mineralizing proportion 120 between 10% and 35% by mass; and a porous siliceous material proportion 130 between 5% and 15% by mass.3. Applications

[0027] Generally, a carbon-sequestering road binder composition 100 (hereinafter “the road binder composition 100”) for binding aggregate materials during road construction includes a combination of ingredients that function together to: increase the mass of carbon dioxide absorbed and sequestered by roads integrating the road binder composition 100 for a given mass of road material; reduce the unbound concentration of toxic elements or compounds within roads integrating the road binder composition 100; and improve the material properties (e.g., compressive strength) of roads integrating the road binder composition 100. More specifically,the road binder composition 100 includes a functionalized lignin proportion 110 (e.g., lignosulfonate, carboxylated Kraft lignin) acting as a naturally derived binding agent and surfactant; a carbon-mineralizing proportion 120 functioning as a carbonating agent; and a porous siliceous material proportion 130 functioning as a sorptive agent for potentially toxic elements or compounds present in other components of the road binder composition 100 and as a carbon dioxide concentrator. Thus, the road binder composition 100 surpasses traditional road binders in carbon sequestration capacity and environmental safety while maintaining or exceeding mechanical benchmarks for effective road construction based on the synergistic effects of the constituent proportions of the road binder.

[0028] The road binder composition 100 is utilized as an alternative to carbon-intensive binders, such as bitumen or Portland cement that are responsible for a net increase in carbon dioxide in the atmosphere, and instead sequesters significant proportions of carbon dioxide without sacrificing target mechanical properties of the road. Additionally, the road binder composition 100 can be utilized in road construction to prevent leaching of toxic elements or compounds from the road composition via on the inclusion of the porous siliceous material proportion 130 within the road binder composition 100. Furthermore, the road binder composition 100 can define self-healing properties based on the breakdown of particles of the carbon-mineralizing proportion, which releases alkaline earth metal species (e.g., calcium ions, magnesium ions, calcium hydroxide) into the functionalized lignin proportion 110, causing carbon mineralization and strengthening of the material. Thus, the road binder composition 100 is useful for multiple purposes in the field of road construction.

[0029] Additionally, the road binder composition 100 is particularly suited for use in road construction due to the road binder composition’s tendency to form suspensions based on the surfactant properties of lignosulfonates, thereby creating a sufficiently homogenous aqueous mixture of the constituent ingredients. Furthermore, the lignosulfonate provides a thixotropic effect, which enables distribution of the road binder composition 100 over an aggregate material layer via sprinkling instead of direct pouring, thereby facilitating integration into aggregate materials.

[0030] In implementations of the road binder composition 100 including partially decarbonated eggshells, the road binder composition 100 is characterized by self-healing properties, which may be applicable to roads in environments with many freeze-thaw cycles. In this application, the road binder composition 100 can release calcium oxide from the partially decarbonated eggshells in response to the formation of microcracks in the partially decarbonated eggshell particles.Upon release, the calcium oxide may facilitate further cementitious reactions within the binder, thereby “healing” the microcracks in the road composition.

[0031] In summary, the road composition effectively valorizes industrial byproducts, such as lignosulfonate, slag, and partially decarbonated eggshells, to increase the sequestration capacity of road compositions while also preventing seepage of potentially toxic elements and compounds present in these industrial byproducts into the environment.4. Suspension

[0032] Generally, the road binder composition 100 is an aqueous suspension including the functionalized lignin proportion 110, the carbon-mineralizing proportion 120, and the porous siliceous material proportion 130. More specifically, the road binder composition 100 can include a water proportion greater than 40% by mass. In particular, the road binder composition 100 is produced by mixing solid constituents, including the carbon-mineralizing proportion 120 and the porous siliceous material proportion 130, into an aqueous solution of the functionalized lignin proportion 110 and water. The road binder composition 100 can be mixed onsite or offsite via a continuous or batch drum mixer, planetary mixer, twin shaft mixers, ribbon blenders, or any suitable mixing machinery that produces a sufficiently homogenous mixture of the constituents of the road binder composition 100 while preventing over-milling of the solid ingredients below the intended particle size distribution.

[0033] In one implementation, the road binder composition 100 is manufactured from an aqueous solution of functionalized lignin and water characterized by a ratio of functionalized lignin to water between 40:60 and 60:40 by mass. More specifically, the road binder composition 100 can be characterized by a ratio of functionalized lignin to water selected based on a target viscosity for the road binder composition 100 at various expected temperatures during road construction, an average molecular mass of the functionalized lignin proportion 110, a degree of functionalization of the functionalized lignin proportion 110, a humidity and temperature range at a target location of the road, based on target molecular mobility within the road binder composition 100, and / or for any other reason.5. Functionalized Lignin Proportion

[0034] Generally, the road binder composition 100 includes a functionalized lignin proportion 110 consisting of lignin-based polymers functionalized with anionic functional groups such as sulfonic groups or carboxyl groups, thereby increasing the solubility and reactivity of thelignin-based compound and improving the capability of lignin as a binding agent. More specifically, the road binder composition 100 can include a functionalized lignin proportion 110 between 5% and 40% by mass. In particular, the functionalized lignin proportion 110 can include a lignosulfonate proportion 112, a carboxylated Kraft lignin proportion, an organosolv lignin proportion, a sulfonated Kraft lignin proportion, an oxidized lignin proportion, a hydroxyalkylated lignin proportion, and / or a phenolated lignin proportion. A subset of the aforementioned functionalized lignins are described in further detail below.5.1 Lignosulfonate Variant

[0035] In one implementation, the road binder composition 100 includes a lignosulfonate proportion 112 functioning as the primary binding agent and as a surfactant that increases the concentration of carbon dioxide within the road binder composition 100, thereby enabling increased carbon sequestration by the carbon-mineralizing proportion 120. More specifically, the road binder composition 100 includes a lignosulfonate proportion 112 between 5% and 40% by mass. In particular, the road binder can include a lignosulfonate proportion 112 characterized by a molecular mass greater than 2.5 kilodaltons and less than 125 kilodaltons, as this range of molecular masses results in desirable extant physical properties of the road binder composition 100 including suitable solubility of the lignosulfonate proportion 112 in water, suitable viscosity for distribution into aggregate material of a road, and suitable binding strength to provide mechanical support to the aggregate materials of a road. Additionally, when the lignosulfonate proportion 112 is combined with water in an aqueous solution, the lignosulfonate proportion 112 provides a surfactant effect, thereby lowering the surface tension of the aqueous solution and decreasing the solvation energy of carbon dioxide. Furthermore, the lignosulfonate proportion 112, via the aforementioned surfactant characteristics, can lead to micelle formation within the aqueous solution, thereby increasing the concentration of carbon dioxide dissolved in the aqueous solution. Thus, the lignosulfonate proportion 112 supports the target mechanical and chemical properties of the road binder composition 100 via intermolecular interactions between lignosulfonate molecules and by increasing the concentration of dissolved carbon dioxide and bicarbonate ions in the aqueous solution.

[0036] In one implementation, the lignosulfonate proportion 112 includes sodium lignosulfonate. Generally, sodium lignosulfonate is characterized by greater solubility in water and greater pH stability than alternative lignosulfonate compounds. Therefore, implementations of the road binder composition 100 including sodium lignosulfonate enable a greater lignosulf onateproportion 112 for a given viscosity. Additionally, implementations of the road binder composition 100 including sodium lignosulfonate exhibit greater pH stability and can therefore be used with more alkaline or acidic constituents of the road binder composition 100s.

[0037] In another implementation, the lignosulfonate proportion 112 includes calcium lignosulfonate. Generally, calcium lignosulfonate exhibits lower solubility in water and a tendency to precipitate as calcium carbonate (especially in alkaline environments) compared to alternative lignosulfonate compounds. Therefore, implementations of the road binder composition 100 including calcium lignosulfonate are applicable when the improved binding characteristics provided by precipitated calcium are useful for increasing road durability and / or compressive strength.

[0038] In yet another implementation, the lignosulfonate proportion 112 includes ammonium lignosulfonate. Generally, ammonium lignosulfonate offers moderate to low-to-moderate viscosity compared to alternative lignosulfonate compositions but is more pH sensitive than sodium lignosulfonate.

[0039] The lignosulf onate proportion 112 can include lignosulfonate compounds including but not limited to magnesium lignosulfonate, potassium lignosulfonate, iron lignosulfonate, zinc lignosulfonate, or aluminum lignosulfonate. Additionally, the lignosulfonate proportion 112 can further include any combination of lignosulfonate compounds.5.2 Carboxylated Kraft Lignin Variant

[0040] In one variant, the road binder composition 100 includes a carboxylated Kraft lignin proportion in addition to or in replacement of the lignosulfonate proportion 112. In this variant, the road binder composition 100 leverages the more robust supply chain of Kraft lignin from the Kraft pulping process to replace the role of lignosulfonate in the road binder composition 100. Generally, carboxylated Kraft lignin proportion fulfills the role of the lignosulfonate proportion 112 while exhibiting slightly lower solubility in acidic solutions due to the presence of less ionized carboxyl groups relative to the more ionized sulfonate groups of lignosulfonates. Thus, in implementations of the road binder composition 100 characterized by higher pH (e.g., implementations including higher concentrations of alkaline earth metal ions), carboxylated Kraft lignin functions as a replacement for lignosulfonate with a more robust supply chain, thereby enabling greater production scaling for the road binder composition 100.

[0041] In one implementation, the carboxylated Kraft lignin proportion is characterized by a degree of carboxylation greater than 1.0 millimole per gram. In some examples of thisimplementation, the carboxylated Kraft lignin proportion is characterized by a degree of carboxylation greater than 2.5 millimoles per gram. Generally, higher degrees of carboxylation increase the solubility of the carboxylated Kraft lignin proportion. Thus, in this implementation, the road binder composition 100 can remain sufficiently water soluble at room temperature to facilitate dispersal into aggregate materials during road construction.

[0042] In another implementation, the carboxylated Kraft lignin proportion is characterized by a degree of carboxylation between 1.5 and 2.5 millimoles per gram. In this implementation, the carboxylated Kraft lignin proportion is limited to 2.5 millimoles per gram to prevent aggregation or self-adhesion of carboxylated Kraft lignin particles due to increased interparticle forces within the interphase at degrees of carboxylation greater than 2.5 millimoles per gram. Thus, in this implementation, the carboxylated Kraft lignin proportion maintains a balance of solubility and dispersion properties that enable the use of carboxylated Kraft lignin as a binder.

[0043] In yet another implementation, the carboxylated Kraft lignin proportion is characterized by a molecular mass between 50 and 400 kilodaltons, which enables an effective balance of solubility and binding characteristics. In one example of this implementation, the carboxylated Kraft lignin proportion is characterized by a molecular mass between 300 and 350 kilodaltons, further refining the target solubility and binding characteristics of the road binder composition 100.However, the carboxylated Kraft lignin proportion can define any combination of carboxylation degree and molecular mass that results in the target solubility, dispersion, and binding properties in the road binder composition 100.6. Carbon-Mineralizing Proportion

[0044] Generally, the road binder composition 100 includes a carbon-mineralizing proportion 120 or a binding additive proportion 122 to facilitate carbonation reactions with carbon dioxide dissolved in the aqueous solution of the functionalized lignin proportion 110 and water. More specifically, the road binder composition 100 can include a carbon-mineralizing proportion 120 between 10% and 35% by mass. In particular, the carbon-mineralizing proportion 120 can include a set of sources of alkaline earth metal species such that each of the set of alkaline earth metal species contributes to improving structural and carbon sequestering properties of road compositions 200 including the road binder composition 100. The carbon mineralizing proportion 120 can include carbon-mineralizing materials derived from industrial byproducts, such as partially decarbonated eggshells and slag, or from natural sources, such as alkaline earthmetal silicates. The carbon-mineralizing proportion 120 reacts with carbon dioxide dissolved in the solution of the functionalized lignin and water according to the following generalized reaction:where a, b, c, d, e, f, g, and h are stoichiometric constants that vary based on the carbon-mineralizing material, M represents an alkaline earth metal, A represents an anionic species, B represents a precipitant of the reaction, and n represents the balanced charges of aM and bA. Intermediate species and byproducts, such as H2CO3(carbonic acid), HCO^ (bicarbonate ions), ionic forms of A, H+(protons), and OH , are not shown but may be present to facilitate forward progression of the generalized reaction.

[0045] A subset of potential carbon-mineralizing materials for the road binder composition 100 is further described below.6.1 Calcium Oxide or Burnt Lime

[0046] In one implementation, the carbon-mineralizing proportion 120 includes a calcium oxide (i.e., burnt lime) source proportion. More specifically, the calcium oxide source proportion can include partially decarbonated eggshells, partially decarbonated seashells, agricultural lime waste, recycled building materials, responsibly sourced coral sand, and / or any other source of calcium oxide. Additionally, the road binder composition 100 can include a calcium oxide content between 1% and 15% by mass, despite a larger mass proportion of the calcium oxide source in the road binder composition 100. The carbon-mineralizing proportion 120 can include higher mass percentages of calcium oxide in applications involving softer aggregate materials to increase the stability of the resulting road composition 200. In particular, the calcium oxide source proportion facilitates further dissolution of carbon dioxide in the road binder composition 100, the carbonation reaction of calcium ions, and the precipitation of calcium carbonate within the road binder composition 100, further solidifying road compositions 200 to which the road binder composition 100 is applied.

[0047] Generally, the carbonation reaction of calcium oxide is a specific instance of equation (1) above where M is calcium, A is oxygen, B is not present, a = 1, b = 1, c = 1, d = 1, e = 1, f = 0, g = 0, and h = 1.

[0048] In one example, the calcium oxide source proportion includes partially decarbonated eggshells. In one example of this implementation, the carbon-mineralizing proportion caninclude partially decarbonated eggshells characterized by an average particle size between 1 millimeter and 2 millimeters, thereby ensuring that the partially decarbonated eggshells can fill voids within the aggregate material of the road composition. Additionally or alternatively, the carbon-mineralizing proportion can include partially decarbonated eggshells characterized by a calcium oxide concentration of greater than 18% by mass, which enables the partially decarbonated eggshells to sufficiently react with dissolved carbon dioxide within the road binder composition 100.

[0049] In this implementation, the partially decarbonated eggshells define mechanical properties that enable the release of additional calcium oxide in response to microcracks within individual partially decarbonated eggshell particles. Therefore, in this implementation, the road binder composition 100 can lend self-healing properties to road compositions 200 including the road binder composition 100, as cracks propagating through the road composition 200 release additional calcium oxide causing further carbonation within the road composition.

[0050] In one example of this implementation, the road binder composition 100 includes a partially decarbonated eggshell proportion between 5% and 10% by mass. In another example of this implementation, the road binder composition 100 includes a partially decarbonated eggshell proportion between 10% and 35% by mass. Thus, the road binder composition 100 can include a carbon-mineralizing proportion 120 consisting partially or entirely of partially decarbonated eggshells.6.2 Slag

[0051] In another implementation, the carbon-mineralizing proportion includes slag, such as blast furnace slag, steel slag, ladle slag, and / or silicon green stone slag (hereinafter “SiGS”). More specifically, slag can include high concentrations of alkaline earth metal silicates, calcium oxide, and magnesium oxide, each of which can donate alkaline earth metal species to the road binder composition 100 and / or increase the pH of the road binder composition 100, thereby aiding the carbonation reaction. In one example of this implementation, the slag is characterized by an average particle size between 1 millimeter and 3 millimeters, thereby enabling slag particles to fill voids in the aggregate materials of the road composition. Thus the road binder composition 100 can include one or more types of slag to improve the material properties of the road binder composition 100 and the carbon sequestration potential of the road binder composition 100.

[0052] Generally, slag includes large proportions of calcium oxide that reacts as described above, thereby causing cementitious carbonation reactions that strengthen the road composition and sequester carbon dioxide. Additionally, certain slags can include calcium and magnesium silicates in amounts depending on the source process of the slag, thereby increasing the carbon sequestering capacity of the slag. In one example of this implementation, the road binder composition 100 includes a slag proportion characterized by a calcium oxide content greater than 15% by mass to ensure the slag proportion provides the intended carbonation effect on the road composition.

[0053] In one example of this implementation, the road composition includes a slag proportion up to 20% of the overall mass of the road composition including road aggregate materials to leverage the favorable compressive strength and hardness of certain slags (e.g., SiGS, blast furnace slag). Due to the favorable mechanical properties of certain slags (e.g., high compressive strength and high hardness), slag can be incorporated into the road composition in higher quantities than other carbon-mineralizing materials. Thus, the road composition can include additional amounts of slag mixed into the aggregate materials separately from the aqueous suspension of the road binder composition 100. This example implementation is particularly effective in improving the compressive strength and durability of road compositions including soft aggregate materials such as soil or brittle minerals.6.3 Alkaline Earth Metal Silicates

[0054] In yet another implementation, the carbon-mineralizing proportion 120 can include alkaline earth metal silicates, such as wollastonite (CaSiO^). serpentiniteolivine (Mg SiO ~), or any other alkaline earth metal silicate. Generally, the road binder composition 100 can include an earth metal silicate proportion between 2% and 25% by mass. Thus, the road binder composition 100 can leverage the carbon sequestering effects of alkaline earth metal silicates to further increase the total carbon sequestering potential of the road binder composition 100.

[0055] In one example of this implementation, the carbon-mineralizing proportion 120 can include an olivine proportion. In this example, the olivine proportion reacts according to equation (1) above where M is magnesium, A and B areg = 0, and h = 0.

[0056] In another example of this implementation, the carbon-mineralizing proportion 120 can include a serpentinite proportion. In this example, the serpentinite proportion reacts according to equation (1) where M is magnesium,e = 3, f = 4, g = 0, and h = 0.

[0057] In yet another example of this implementation, the carbon-mineralizing proportion 120 can include a wollastonite proportion. In this example, the wollastonite proportion reacts according to equation (1) where M is calcium, A is SiO^, B is SiO^, 1, b = 1, c = 1, d = 2, e = 1, f = 4, g = 0, and h = 2.6.4 Combinations

[0058] In some implementations, the carbon-mineralizing proportion 120 can include combinations of the components described above. More specifically, the carbon-mineralizing proportion 120 can include: partially decarbonated eggshells; slag; alkaline earth metal silicates; a mixture of partially decarbonated eggshells, slag, and alkaline earth metal silicates; a mixture of partially decarbonated eggshells and slag; a mixture of partially decarbonated eggshells and alkaline earth metal silicates; or a mixture of slag and alkaline earth metal silicates. The mechanical properties of each mixture depend on the proportion of each constituent material. Some examples of these mixtures are described in further detail below with respect to specific examples.7. Porous Siliceous Material Proportion

[0059] Generally, the road binder composition 100 includes a porous siliceous material proportion 130 to absorb potentially toxic compounds or elements from the alkaline metal source proportion (e.g., olivine or metal slag) while also sequestering additional carbon dioxide dissolved within the functionalized lignin proportion 110. More specifically, the road binder composition 100 can include a siliceous material proportion between 2% and 15% by mass. In one implementation, the porous siliceous material includes a diatomite proportion 132. The porous siliceous material proportion 130 favors the formation of carbonic acid, which increases the rate of carbonation reactions. Additionally, the porous siliceous material can concentrate carbonic acid within pores of the porous siliceous material, thereby increasing local carbonation reaction rates. Thus, the porous siliceous material proportion 130 is synergistic with the carbon-mineralizing proportion 120 in increasing the reaction rate of the carbonation reactionwhile also minimizing any toxic leaching from any road composition including the road binder composition 100.

[0060] In one implementation, the porous siliceous material proportion 130 includes a diatomite proportion 132 derived from frustules of freshwater diatoms of the genera aulacoseira and actinocyclus, as these genera offer greater Brunauer-Emmett- Teller (hereinafter “BET”) surface area than diatomite derived from other diatoms. In one example of this implementation, the diatomite proportion 132 is characterized by a BET surface area of at least 25 square meters per gram. Thus, the porous siliceous material proportion 130 can be characterized by a high BET surface area, thereby amplifying the ability of the road binder composition 100 to capture toxins and promote carbonization.8. Road Composition

[0061] Generally, the road binder composition 100 is integrated into a road composition 200 to bind aggregate materials in situ, and introduce additional binding additives including the carbon-mineralizing proportion 120 and the porous siliceous material proportion 130, to increase the amount of carbon dioxide sequestered by the road composition 200. More specifically, the road composition 200 includes an aggregate material proportion greater than 90% by mass and a road binder proportion 220 less than 10% by mass. Some implementations of the road composition 200 include an aggregate proportion 210 greater than or equal to 98% by mass and a road binder proportion 220 less than or equal to 2% by mass. In other implementations including high solid-to-liquid ratios, the road composition 200 can include a road binder proportion 220 of up to 40%. Thus, a range of proportions of the road binder composition 100 may be added to aggregate materials in situ to bind the aggregate materials for various environments and applications, thereby increasing the compressive strength and carbon sequestering capacity of the road composition 200.9. Road Composition Characterization and Examples

[0062] Generally, the road binder composition 100 can be implemented according to a number of precise proportions that fall within the general ranges defined above. A non-exhaustive fist of examples is described below, accompanied by data describing the characteristics of each example when used to bind a standardized aggregate material mixture.

[0063] In example 1, a road binder composition 100 including a functionalized lignin proportion 110 of 25% by mass including sodium lignosulfonate; a carbon-mineralizing proportion 120 of20% by mass including blast furnace slag; and a porous siliceous material proportion 130 of 5% including diatomite. The remaining 50% of example 1 consists of water.

[0064] In example 2, a road binder composition 100 includes a functionalized lignin proportion 110 of 25% by mass including calcium lignosulfonate; a carbon-mineralizing proportion 120 of 20% by mass including blast furnace slag; and a porous siliceous material proportion 130 of 5% including diatomite. The remaining 50% of example 2 of the road binder composition 100 consists of water.

[0065] In example 3, the road binder composition 100 includes a functionalized lignin proportion 110 of 25% by mass including ammonium lignosulfonate; a carbon-mineralizing proportion 120 of 20% by mass including blast furnace slag; and a porous siliceous material proportion 130 of 5% including diatomite. The remaining 50% of example 3 consists of water.

[0066] In example 4, the road binder composition 100 includes a functionalized lignin proportion 110 of 30% by mass including sodium lignosulfonate; a carbon-mineralizing proportion 120 of 15% by mass including a blast furnace slag proportion of 10% and a partially decarbonated egg shell proportion of 5%; and a porous siliceous material proportion 130 of 5% including diatomite. The remaining 50% of example 4 consists of water.

[0067] In example 5, the road binder composition 100 includes a functionalized lignin proportion 110 of 25% by mass including sodium lignosulfonate; a carbon-mineralizing proportion 120 of 15% by mass including a blast furnace slag proportion of 10% and a partially decarbonated egg shell proportion of 5%; and a porous siliceous material proportion 130 of 5% including diatomite. The remaining 55% of example 5 consists of water.

[0068] In example 6, the road binder composition 100 includes a functionalized lignin proportion 110 of 25% by mass including sodium lignosulfonate; a carbon-mineralizing proportion 120 of 15% by mass including a blast furnace slag proportion of 15%; and a porous siliceous material proportion 130 of 10% including diatomite. The remaining 50% of example 6 consists of water.

[0069] In example 7, the road binder composition 100 includes a functionalized lignin proportion 110 of 25% by mass including sodium lignosulfonate; a carbon-mineralizing proportion 120 of 20% by mass including an olivine proportion of 20%; and a porous siliceous material proportion 130 of 5% including diatomite. The remaining 50% of example 7 consists of water.

[0070] In example 8, the road binder composition 100 includes a functionalized lignin proportion 110 of 20% by mass including sodium lignosulfonate; a carbon-mineralizing proportion 120 of 25% by mass including an olivine proportion of 25%; and a porous siliceous material proportion 130 of 10% including diatomite. The remaining 45% of example 8 consists of water.

[0071] The data presented below are derived from tests made by using the road binder composition 100 to bind a 50%:50% mixture of clayey soil and siliceous aggregates with the following characteristics, shown in TABLE 1 and TABLE 2 below.TABLE 1: Characteristics of clayey soilTABLE 2: Characteristics of siliceous aggregates

[0072] The data presented in TABLE 3 below, with respect to example 1, were collected according to ISO 17892-12, determination of fluidity and plasticity Emits, and ASTM D4318-17,standard test methods for the liquid limit, plastic limit, and plasticity index of soils. The other example road compositions 200 exhibited similar, though not identical characteristics. Each example of the road binder composition 100 is mixed with the dried aggregate materials (including clayey soil and siliceous aggregates) at a ratio of 2%:98%. In addition to example 1, two controls were tested including: control 1, a 100% clayey soil and siliceous aggregate mixture; and control 2, a mixture of 1% of a 50%:50% lignosulfonate and water solution and 99% of the clayey soil and siliceous aggregate mixture.TABLE 3: Atterberg limits for controls and example 1

[0073] TABLE 4 below summarizes data characterizing the quantity of carbon dioxide sequestered and the content of potentially hazardous elements cadmium and nickel within various examples of the road composition 200. The test protocol utilized to derive the carbon sequestering capacity of each example includes inserting the road composition 200 into a laboratory reactor in a high-pressure carbon dioxide-rich environment to accelerate the carbonation reaction in the road composition 200, and recording the drop in pressure of the carbon dioxide-rich environment over time. Cadmium and nickel levels were calculated in the supernatant solution according to DIN EN 16171:2017, determination of elements by inductively coupled plasma mass spectrometry.TABLE 4: Amount of carbon dioxide sequestered, cadmium content, and nickel content for various examples of the road composition 200

[0074] In addition to the examples tested above, three additional examples were created for the purpose of testing unconfined compressive strength (hereinafter “UCS”).

[0075] In example 9, the road binder composition 100 includes a functionalized lignin proportion 110 of 20% by mass; a carbon-mineralizing proportion 120 of 50% by mass including a steel slag proportion of 20% by mass, an olivine proportion of 20% by mass, and a calcium oxide proportion of 10% by mass; and a porous siliceous material proportion 130 of 10% including diatomite. The remaining 20% of example 9 of the road binder composition 100 consists of water.

[0076] In example 10, the road binder composition 100 includes a functionalized lignin proportion 110 of 4% by mass; a carbon-mineralizing proportion 120 of 82% by mass including a steel slag proportion of 76% by mass, an olivine proportion of 4% by mass, and a calcium oxide proportion of 2% by mass; and a porous siliceous material proportion 130 of 10% including diatomite. The remaining 4% of example 10 of the road binder composition 100 consists of water.

[0077] In example 11, the road binder composition 100 includes a functionalized lignin proportion 110 of 3% by mass; a carbon-mineralizing proportion 120 of 86% by mass including a SiGS proportion of 81% by mass, an olivine proportion of 3% by mass, and a calcium oxide proportion of 2% by mass; and a porous siliceous material proportion 130 of 8% including diatomite. The remaining 3% of example 11 of the road binder composition 100 consists of water.

[0078] UCS tests were conducted according to ASTM D2166 / D2166M-16, standard test method for unconfined compressive strength of cohesive soils, adapted for granular material stabilizedwith binders. For these UCS tests, granular 0 / 4 millimeter crushed rock sand was utilized as the aggregate material of the road composition 200. FIGURE 5 shows the grading curve of the 0 / 4 millimeter crushed rock. For example 9, 5 grams of the road binder composition 100 were added per 100 grams of 0 / 4 millimeter crushed rock. For example 10, 26 grams of the road binder composition 100 were added per 100 grams of the 0 / 4 millimeter crushed rock. For example 11, 31 grams of the road binder composition 100 were added per 100 grams of the 0 / 4 millimeter crushed rock.

[0079] As shown in FIGURE 6, the UCS of each sample is highly dependent on the curing time of the sample. All examples of the road composition 200 improved upon the untreated aggregate materials. One sample of example 9 achieved a UCS of 3.27 newtons per square millimeter after 29 days of curing. One sample of example 10, achieved a peak UCS of 2.34 newtons per square millimeter over 28 days of curing. One sample of example 11 achieved a UCS of 2.52 newtons per square millimeter over 7 days of curing. Data on the performance of example 11 after more than 7 days of curing are not currently available. However, based on the strength development patterns of other examples, example 11 is projected to exhibit the greatest UCS among these samples. Thus, instances of the road composition 200 can exhibit UCS in excess of 3.27 newtons per square millimeter.

[0080] As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the embodiments of the invention without departing from the scope of this invention as defined in the following claims.

Claims

CLAIMSWe Claim:

1. A road binder composition comprising an aqueous mixture comprising:• a functionalized lignin proportion between 5% and 40% by mass characterized by a molecular mass greater than 2.5 kilodaltons and less than 125 kilodaltons;• a carbon-mineralizing proportion between 10% and 35% by mass; and• a porous siliceous material proportion between 2% and 15% by mass.

2. The road binder composition of Claim 1, wherein the aqueous mixture further comprises a water proportion greater than 40% by mass.

3. The road binder composition of Claim 1, wherein the functionalized lignin proportion is selected from a group consisting of:• sodium lignosulfonate;• ammonium lignosulfonate;• calcium lignosulfonate; and• carboxylated Kraft lignin.

4. The road binder composition of Claim 1, wherein the carbon-mineralizing proportion comprises partially decarbonated eggshells.

5. The road binder composition of Claim 4, wherein the partially decarbonated eggshells are characterized by an average size between 1 millimeter and 2 millimeters.

6. The road binder composition of Claim 4, wherein the partially decarbonated eggshells are characterized by a calcium oxide content greater than 18% by mass.

7. The road binder composition of Claim 1, wherein the carbon-mineralizing proportion comprises slag.

8. The road binder composition of Claim 7, wherein the slag is characterized by an average size between 1 millimeter and 3 millimeters.

9. The road binder composition of Claim 7, wherein the slag is characterized by a calcium oxide content greater than 40% by mass.

10. The road binder composition of Claim 1, wherein the carbon-mineralizing proportion comprises olivine.

11. The road binder composition of Claim 1, wherein the porous siliceous material proportion comprises diatomite.

12. The road binder composition of Claim 11, wherein the diatomite is derived from frustules of freshwater diatoms of the genera aulacoseira and actinocyclus.

13. The road binder composition of Claim 11, wherein the diatomite is characterized by a BET surface area of at least 25 square meters per gram.

14. A road composition comprising:• an aggregate proportion greater than 90% by mass; and• a road binder proportion less than 10% by mass comprising: o a functionalized lignin proportion between 5% and 40% by mass characterized by a molecular mass greater than 2.5 kilodaltons; o a carbon-mineralizing proportion between 10% and 35% by mass; and o a porous siliceous material proportion between 2% and 15% by mass.

15. The road composition of Claim 14, wherein the carbon-mineralizing proportion is selected from a group consisting of:• partially decarbonated eggshells;• slag;• olivine;• a mixture of partially decarbonated eggshells, slag, and olivine;• a mixture of partially decarbonated eggshells and slag;• a mixture of partially decarbonated eggshells and olivine; and• a mixture of slag and olivine.

16. The road composition of Claim 14, wherein the road composition further comprises:• the aggregate proportion of greater than or equal to 98% by mass; and• the road binder proportion of less than or equal to 2% by mass.

17. A road binder composition comprising:• a lignosulfonate proportion between 20% and 30% by mass and characterized by a molecular mass between 2.5 kDa and 125 kDa;• a diatomite proportion between 5% and 10% by mass; and• a binding additive proportion between 50% and 55% by mass.

18. The road composition of Claim 17, wherein the binding additive proportion further comprises:• a slag proportion between 10% and 20% by mass of the binding additive proportion;• a partially decarbonated eggshell proportion between 5% and 10% by mass of the binding additive proportion; and• an olivine proportion between 10% and 25% by mass of the binding additive proportion.

19. The road composition of Claim 18, wherein the eggshell proportion are characterized by:• an average particle size between 1 millimeter and 2 millimeters; and• a calcium oxide concentration of greater than 18% by mass.

20. The road composition of Claim 18, wherein the slag proportion is characterized by an average size between 1 and 3 mm and a calcium oxide content of at least 15% by mass.

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