Compositions and methods of making carbon neutral cementitious composites

Abstract

Functionalized biochar compositions are provided, which can be used in cementitious materials to provide carbon-neutral cementitious composites, while preserving the strength of the composite. The functionalized biochar compositions include an effective amount of functionalization agents such as polydopamine (PDA), polyacrylic acid (PAA) and / or polyvinyl alcohol. The functionalized biochar is included in a binder, in an effective amount to ensure cementitious composites made therefrom are carbon-neutral and show improved compressive strength.

Description

[0001] ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0002] COMPOSITIONS AND METHODS OF MAKING CARBON NEUTRAL CEMENTITIOUS COMPOSITES CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims benefit of U.S. Provisional Application No. 63 / 730,126, filed December 10, 2024, the entire content of which is hereby incorporated by reference for all purposes in its entirety.

[0004] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0005] This invention was made with government support under 2028462 and 2318123 awarded by the National Science Foundation. The government has certain rights in the invention.

[0006] FIELD OF THE INVENTION

[0007] The disclosed invention is generally in the field of carbon neutral cementitious composites and specifically in the area of functionalized biochar compositions for reducing binder carbon footprint while retaining compressive strength of composites made therefrom.

[0008] BACKGROUND OF THE INVENTION

[0009] CO2 emissions increased by 53% worldwide from 1990 to 2020, adversely impacting the climate and the ecosystem [1], Currently, many countries (e.g., the European Union and USA) are trying to achieve carbon neutrality by 2050 [2], [3], More than 1000 cities and educational institutes, over 9000 companies, and around 600 financial institutes have joined ‘Race to Zero’ to take immediate action to halve global emissions by 2030 [4], Ordinary Portland Cement (OPC) is the second most consumed material in the world after water [5], which is produced at a rate of 4 billion metric tons per year [6], The cement and concrete industry is also responsible for nearly 8% of global CO2 emissions [7], This industry is considered one of the ‘hard to decarbonize’ sectors and requires new innovations to achieve the net zero goal. While supplementary cementitious materials (SCM) such as fly ash, slag, and silica fume can be good alternatives to OPC for reducing the CO2 footprint of concrete, producing carbon- neutral / negative cementitious materials using SCM is challenging due to their limited carbon sequestration capacity.

[0010] To achieve carbon neutrality of concrete, a significant amount of carbon sequestration is required, which can be achieved by using biochar [5], [8]—

[0011] , Biochar is produced from the pyrolysis of biomass. Biomass, like forest residue, sequesters CO2 from the atmosphere as its growing mechanism, which can be easily released into the atmosphere while getting decomposed by microorganisms

[0012] . Onsite incineration of this residue can adversely affect soil productivity by modifying microbial populations, eradicating seeds, and creating bare soil

[0013] , Therefore, pyrolysis, which is a thermomechanical process earned out in an oxygen-limited environment,

[0011] 45808306.1 1 ATTORNEY DOCKET NO. UTSB 24-27 PCT was introduced as a feasible option for converting the organic carbon in biomass into solid (biochar), liquid (bio-oil), and gaseous (syngas) carbonaceous products

[0014] ,

[0015] , The net energy production from the pyrolysis of wood waste for biochar generation is 38% less than incineration, making it a preferred approach to processing wood waste

[0016] , Of the two pyrolysis processes, slow pyrolysis yields higher amounts of biochar, whereas fast pyrolysis enhances biooil production

[0017] ,

[0018] ,

[0012] By controlling factors such as feedstock type, moisture content, and ash content, the addition of biochar offers a pathway to achieve a lower carbon footprint compared to other biobased building materials like hemp fiber

[0019]

[0020] . According to Zampori et al., the global warming potential (GWP) of hemp fiber, with a yield of 15%, is -1.73 kg CO2 eq / kg

[0019] , Similarly, biochar produced from wood residue with a comparable yield efficiency of 16% has a GWP ranging from -1.6 to -2.1 kg CO2 cq / kg

[0019]

[0020] , Although the stability of biochar is strongly influenced by the feedstock type and the conditions of pyrolysis, stable polycyclic aromatic carbon (SPAC) formation can be achieved through high-temperature pyrolysis

[0021] This SPAC remains stable in biochar over a centennial timescale, thus ensuring carbon sequestration in biochar composites for hundreds to thousands of years

[0021] ,

[0022] , Such long-term carbon sequestration is not achievable using other bio-based or wood-based composites, as their decay liberates carbon in the form of carbon dioxide or methane in the atmosphere

[0023] .

[0013] Studies have been conducted on the use of biochar in cement-based composites, primarily due to their internal curing capacity

[0024] —

[0028] . However, the challenge is the negative effect of biochar on the mechanical performance of the composites. Though the use of biochar is one of the most promising pathways to produce carbon-neutral concrete, the corresponding reduction in strength makes it less convincing for the end users, causing a blockade toward net zero movement. Therefore, identifying potential pathways to utilize biochar for carbon sequestration, which also enhances the performance of the composite compared to the traditional composites (concrete without biochar), is a crucial research need.

[0014] There remains a need for improved methods of using high biochar doses to improve the overall performance of carbon-neutral cementitious composites.

[0015] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

[0016] 45808306.1 2 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0017] BRIEF SUMMARY OF THE INVENTION

[0018] Functionalized biochar compositions are provided, which can be used in cementitious materials to provide carbon-neutral cementitious composites, while preserving the strength of the composite.

[0019] The functionalized biochar compositions in some forms, include an effective amount of polydopamine (PDA). The functionalized biochar in some forms, includes an effective amount of polyacrylic acid (PAA). The functionalized biochar in some forms, includes an effective amount polycarboxylic acid (PCA), maleic acid, and polymers thereof. The functionalized biochar compositions are included in a binder, in an effective amount to ensure cementitious composites made therefrom are carbon-neutral and show improved compressive strength.

[0020] Methods of making modified biochar compositions which can be included in cementitious materials to provide carbon-neutral cementitious composites, while preserving the strength of the composite are also provided.

[0021] Carbon-neutral cementitious materials are provided, which can be used to make carbon- neutral cementitious composites which have improved compressive strength.

[0022] Additional advantages of the disclosed method and compositions will be set forth in part in the description which follows, and in part will be understood from the description, or can be learned by practice of the disclosed method and compositions. The advantages of the disclosed method and compositions will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings illustrate several embodiments of the disclosed method and compositions and together with the description, serve to explain the principles of the disclosed method and compositions.

[0025] FIG. 1 shows particle size distribution of different batches

[0026] FIG. 2 shows thermogravimetric analysis (TGA) plots of biochar.

[0027] FIG. 3 is a schematic showing the sample preparation and test setup

[0028] FIG. 4A. Moisture absorption and surface area of functionalized biochar, FIG. 4B. Zeta potential of Blended binder and functionalized biochar. FIG. 4C. SEM image of unground biochar and (FIG. 4D) SEM image of ground biochar. Scale bars represent 50 pm.

[0029] 45808306.1 3 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0030] FIG. 5A-5C shows flow table test for different batches (FIG. 5A) flow diameter up to 60 minutes, flow table images: (FIG. 5B) Control (FIG. 5C) Bio_Control_23% (FIG. 5D) Bio_Grn_23%(FIG. 5E)Bio_PDA_23% (FIG. 5F) Bio_PAA_23%.

[0031] FIG. 6 shows density measurement for fresh mortar mixtures containing various types of biochar.

[0032] FIG. 7A. Heat flow and (FIG. 7B) total heat release for the paste mixtures containing functionalized biochar batches.

[0033] FIG. 8. Compressive strength of mortar samples exposed to sealed curing for various durations.

[0034] FIG. 9A-9C. X-ray diffraction (XRD) plots of 28 days sealed cured samples.

[0035] FIG. 10A. Thermogravimetric analysis (TGA) plots of 28 days sealed cured samples and (FIG. 10B) bar chart showing the weight loss (%) in samples from 105°C to 600°C.

[0036] FIG. 11. Compressive strength of mortar samples exposed to carbonation curing for various durations.

[0037] FIG. 12A-12C. X-ray diffraction (XRD) plots for 28 days carbonation cured samples.

[0038] FIG. 13A. Thermogravimetric analysis (TGA) plots of carbonation curing 28 days paste samples, (FIG. 13B) bar chart showing calcium carbonate contents (%) with respect to the total carbonated matrix.

[0039] FIG. 14A. Low-resolution BSE image, (FIG. 14B) low-resolution BSE area mapping, (FIG. 14C) high-resolution BSE image, and (FIG. 14D) high-resolution BSE area mapping of Bio_PDA_23% carbonation curing batch showing carbon distribution in the matrix.

[0040] FIG. 15A-15E. High-resolution BSE image of 28-day carbonation curing Bio_PAA_23% batch: (FIG. ISA) the shape of biochar (aspect ratio), and (FIG. 15B, FIG. 15C, FIG. 15D and FIG. 15E. EDS data points showing C-S-H composition at points 1-4 respectively.

[0041] FIG. 16A-16B. Correlating GWP and compressive strength of biochar-based mortar samples- (16A) carbonation cured, and (16B) sealed cured.

[0042] FIG. 17A-17B show GWP of (17A) carbonation cured and (17B) sealed cured samples considering compressive strength as a parameter of the functional unit.

[0043] FIG. 18A. Low-resolution BSE image, (FIG. 18B) low-resolution BSE area mapping, (FIG. 18C) high-resolution BSE image and (FIG. 18D) high-resolution BSE area mapping of Bio_PAA_23% carbonation curing batch showing carbon distribution in the matrix.

[0044] 45808306.1 4 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0045] FIG. 19A. Low-resolution BSE image, (FIG. 19B) low-resolution BSE area mapping, (FIG. 19C) high-resolution BSE image and (FIG. 19D) high-resolution BSE area mapping of Bio_Grn_23% carbonation curing batch showing carbon distribution in the matrix.

[0046] DETAILED DESCRIPTION OF THE INVENTION

[0047] The disclosed method and compositions can be understood more readily by reference to the following detailed description of particular embodiments and the Example included therein and to the Figures and their previous and following description.

[0048] It is to be understood that the disclosed method and compositions are not limited to specific synthetic methods, specific analytical techniques, or to particular reagents unless otherwise specified, and, as such, can vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0049] I. COMPOSITIONS

[0050] The functionalized biochar compositions in some forms, include an effective amount of polydopamine (PDA). The functionalized biochar in some forms, includes an effective amount of polyacrylic acid (PAA). The functionalized are included in a binder, in an effective amount to ensure cementitious composites made therefrom are carbon-neutral and show improved compressive strength.

[0051] A. Functionalized Biochar

[0052] Biochar is black carbon produced from biomass sources [i.e., wood chips, plant residues, manure or other agricultural waste products] for the purpose of transforming the biomass carbon into a more stable form (carbon sequestration). Black carbon is the name of the range of solid residual products resulting from the chemical and / or thermal conversion of any carbon containing material (e.g., fossil fuels and biomass). Biochar does not refer to a singular product with a given set of chemical and physical characteristics. Rather, biochar spans the sped rum of black carbon forms and it is chemically and physically unique as a function of the feedstock, creation process (pyrolysis unit), cooling, and storage conditions. Biochar is commercially available.

[0053] In some forms, the functionalized biochar in some forms, includes an effective amount of polydopamine, obtained following a reaction of dopamine hydrochloride (C8H11NO2-HC1, 99%) and biochar at a dosage between about 0.2 to 10% by weight of biochar, preferably between 0.5 and 5 % by weight of biochar and more preferably between 1 and 3 % by weight of biochar.

[0054] 45808306.1 5 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0055] In some forms, the functionalized biochar includes an effective amount of polyacrylic acid (PAA), obtained by reacting biochar and polyacrylic acid (C3H4O2)n (molecular weight- 2000) at a dosage between about 0.2 to 10% by weight of biochar, preferably between 0.5 and 5 % by weight of biochar and more preferably between 1 and 3 % by weight of biochar.

[0056] PAA is a synthetic high-molecular weight polymer of acrylic acid. PAA is an anionic polymer, that is, PAA side chains are ionized at neutral pH and bear a negative charge. Due to this, PAAs are able to absorb and retain water and swell many times compared to their original volume. In addition to the homopolymers, a variety of copolymers and crosslinked polymers, and partially deprotonated derivatives thereof, are known and of commercial value.

[0057] In some forms, the functionalized biochar includes an effective amount of polyacrylic acid (PAA), obtained by reacting biochar and an effective amount of Poly vinyl alcohol (PVA). Polyvinyl alcohol (PVOH, PVA, or PVA1) is a water-soluble synthetic polymer. It has the idealized formula [CH2CH(OH)]n.

[0058] In some forms, the functionalized biochar includes an effective amount of polydopamine (PDA).

[0059] PDA is a self-polymerized layer formed from dopamine (DA) under alkaline conditions. PDA is characterized by an abundance of catechol and amino group. Due to this, PDA increases surface hydrophilicity, reduces cytotoxic or reactive surface characteristics, and providing functional groups for biomolecule immobilization.

[0060] While polyacrylic acid is demonstrated for functionalizing biochar, it will be understood by those skilled in the art that other compounds possessing multiple carboxyl functional groups may be employed to achieve substantially similar technical effects. The present disclosure contemplates that such modifications can be made without departing from the spirit and scope of the invention, particularly where the procedures described herein and the teachings of the prior art provide sufficient guidance for implementation.

[0061] In some embodiments, the biochar may be functionalized using polycarboxylic acids (PCA) or polymers thereof. These materials are known to introduce carboxyl groups capable of interacting with calcium ions and other hydration products in cementitious systems. A person of ordinary skill in the art, familiar with polymer grafting techniques and surface modification strategies, would recognize that such polymers may be grafted onto biochar surfaces through chemical bonding methods analogous to those described for polyacrylic acid. The resulting functionalized biochar would be expected to exhibit improved hydrophilicity, enhanced dispersion in aqueous cement pastes, and increased chemical affinity for hydration products, thereby contributing to improved mechanical and durability properties.

[0062] 45808306.1 6 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0063] PCA is a polymeric material comprising multiple carboxyl functional groups along its backbone. PCAs are characterized by a high density of ionizable carboxylate groups, which enable strong electrostatic interactions with a wide range of substrates. Due to this, PCAs enhance surface hydrophilicity, promote ionic crosslinking or coordination with metal ions, and provide reactive sites for covalent or noncovalent immobilization of biomolecules or other functional agents.

[0064] In another embodiment, the functionalization agent can be maleic acid, maleic anhydride, or polymers and copolymers derived therefrom. When applied to biochar, such compounds may provide similar benefits to those observed with polyacrylic acid, including improved wettability and interfacial bonding. The selection of maleic-based polymers may also allow for tailored performance characteristics, such as controlled molecular weight or copolymer composition, which can influence the degree of functionalization and the interaction with cement hydrates.

[0065] Maleic acid is a dicarboxylic acid capable of forming poly(maleic acid) or related polymeric structures under appropriate polymerization conditions. Maleic acid-based polymers are characterized by a high density of carboxyl and carboxylate groups along the polymer backbone. Due to this, maleic acid polymers increase surface hydrophilicity, enable ionic or covalent interactions with metal ions or nucleophilic species, and provide reactive functional groups suitable for biomolecule immobilization or further chemical modification.

[0066] A person having ordinary skill in the art, guided by the examples and procedures described herein and informed by the state of the art as of the filing date, would be able to select suitable polycarboxylic acids and adapt the functionalization process to accommodate differences in polymer structure, reactivity, and solubility. Such modifications are considered within the scope of the invention, provided they achieve substantially similar improvements in dispersion, hydration compatibility, and composite performance.

[0067] B. Functionalized Biochar-supplemented Binders

[0068] The disclosed compositions include binders supplemented with functionalized biochar supplemented binder(s). In some forms, the compositions include a blend of binders.

[0069] In some forms, the disclosed compositions includes functionalized biochar at a concentration of at least 15, 20, 25, 30, 35 or up to 50% by weight of the binder.

[0070] Binders are substances which are used to bind inorganic and organic particles and fibers to form strong, hard and / or flexible components. This is generally due to chemical reactions which take place when the binder is heated, mixed with water and / or other materials, or just exposed to air. There are four main groups of binders: mineral binders, bituminous binders, natural binders and synthetic binders. Mineral Binders can be divided into three categories:

[0071] 45808306.1 7 ATTORNEY DOCKET NO. UTSB 24-27 PCT hydraulic binders, which require water to harden and develop strength; non-hydraulic binders, which can only harden in the presence of air; thermoplastic binders, which harden on cooling and become soft when heated.

[0072] A cement is a binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Cementing materials that are widely used for construction are materials that exhibit characteristic properties of setting and hardening when mixed to a paste with water. Cements used in construction are usually inorganic, often lime or calcium silicate based, which can be characterized as non-hydraulic or hydraulic respectively, depending on the ability of the cement to set in the presence of water

[0073] The disclosed compositions and methods in some forms, use non-hydraulic binder materials (for example, wollastonite, y-C2S), semi-hydraulic (for example, slag, Belite cement) binders, and / or a hydraulic (OPC) binders. An exemplary non-hydraulic binder is a calcium silicate mineral material. Tricalcium silicate (C3S), -dicalcium silicate (P-C2S), y-dicalcium silicate (y-C2S), tricalcium disilicate (C3S2) and monocalcium silicate (CS) can react with CO2 and form strong monolithic matrices.

[0074] Wollastonite is naturally occurring low-lime calcium silicate (CaO.SiCh) mineral with a substantially lower carbon footprint compared to the ordinary Portland cement (OPC). . Wollastonite is a group of innosilicate mineral, with a formula, CaSiO3 that may include small amount of magnesium, manganese and iron substituting for calcium. A valuable industrial mineral, wollastonite is white, gray, or pale green in color. It occurs as rare, tabular crystals or massive, coarse-bladed, foliated, or fibrous masses. Its crystals are usually triclinic, although its structure has seven variants, one of which is monoclinic. These variations are however, indistinguishable in hand specimens. Wollastonite forms as a result of the contact metamorphism of limestones and in igneous rocks that are contaminated by carbon-rich inclusions. It can be accompanied by other calcium containing silicates, such as diopside, tremolite, epidote, and grossular garnet. Wollastonite also appears in regionally metamorphosed rocks in schists, slates, and phyllites. It forms when impure limestone or dolomite is subjected to high temperature and pressure, which sometimes occurs in the presence of silica-bearing fluids as in skarns or in contact with metamorphic rocks.

[0075] In another embodiment, the binder material is a semi-hydraulic material such as slag or belite cement. Ground granulated blast furnace slag (hereby referred as slag) have attracted attention due its latent hydraulic properties, its widespread availability and the observation that

[0076] 45808306.1 8 ATTORNEY DOCKET NO. UTSB 24-27 PCT slag based cement composites have shown superior durability as represented by good resistance against chemical attacks, including chloride penetration.

[0077] The functionalized biochar-supplemented binders wherein the composition is in some forms, formed into a solid composite mortar (further comprising sand) and further subjected to carbonation curing or sealed curing. The disclosed functionalized biochar-supplemented binders can be used to make composite materials such as bridge girders, beams, blocks, hardscape components such as pavers, edging blocks, stepping stones, etc. Biochar compositions subjected to carbonation curing exhibited negative carbon footprints, with GWP reductions ranging from 90% to 170% compared to the control compositions (binder not supplemented with functionalized biochar / functionalized with raw biochar) The disclosed mortar compositions (50 mm by 50 mm) have a compressive strength of at least 40 MPA, preferably up to 70 MPa, measured using a Universal Testing Machine with a load rate of 2001b / s-4001b / s according to ASTM C109

[0042] , Data in the present application shows that compared to the raw biochar, the compressive strengths of the mortar samples containing functionalized biochar were drastically improved. At the 23% dosage, the addition of Bio_Gm showed 369% higher strength compared to Bio_Control after 56 days of sealed curing. The compressive strengths of the Bio_PDA containing mortar samples were remarkably enhanced compared to those containing raw biochar (Bio_Control) and ground biochar (Bio_Gm). The addition of 23% Bio_PDA resulted in 28% higher compressive strength compared to the control batch (without biochar) after 28 days of sealed curing. The addition of 23% Bio_PAA in mortar samples resulted in a higher strength compared to the control (without biochar), raw biochar (Bio_Control), and ground biochar (Bio_Gm) containing samples after 28 days of sealed curing.

[0078] II. METHODS OF MAKING AND USING

[0079] Biochar is functionalized as disclosed herein, by reacting milled biochar with dopamine hydrochloride (C8H11NO2-HC1, 99%) and Polyacrylic acid (C3H4O2)n (molecular weight- 2000) at a dosage between about 0.2 to 10% by weight of biochar, preferably between 0.5 and 5 % by weight of biochar and more preferably between 1 and 3 % by weight of biochar.

[0080] First, the biochar is ground for about one hour, then the functionalization agent is added at the disclosed dosages, following which, the combination is grown again for about one hour. The rotation speed of the ball mill ca be set at 2520 rpm for uniform blending.

[0081] Functionalized biochar is combined with binder as disclosed herein to provide cementitious materials that are used to make carbon neutral composites while reducing the compromise in strength of the material that typically would result from combining high concentrations of raw biochar in binders.

[0082] 45808306.1 9 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0083] 'Phis is in contrast to studies using non-functionalized biochar. Most of the past studies used a small dosage (up to 10% of the binder) of biochar and observed no or negligible benefits in enhancing the compressive strength of the composites [8],

[0029]

[0031] . Such biochar dosages are too low to offset the CO2 emitted during cement production and not adequate to achieve carbon neutrality. On the other hand, when a high dosage of biochar (up to 30% by weight of the binder) is used, a drastic reduction in the strength of cementitious composites was observed. For example, Chen et al. replaced the fine aggregate with up to 30% biochar to produce carbon- neutral concrete with 28 days of compressive strength of around 13 MPa [5], Such a range of compressive strength is typically considered too low for structural concrete applications. Li and Shi [9] also developed a carbon-negative concrete using 30 wt.% CCF-weather biochar and 70 wt.% Portland limestone cement with a 28-day compressive strength of 27.6 MPa. In their study, the control batch (without biochar) showed a compressive strength of around 50 MPa at 28 days, indicating a nearly 45 % reduction in strength due to the addition of biochar.

[0084] The disclosed compositions and methods can be further understood by way of the following non- limiting examples.

[0085] EXAMPLES

[0086] Aiming to improve the overall performance of carbon-neutral cementitious composites using higher biochar dosage, the present studies evaluated novel chemo-mechanical modifications of biochar using two organic additives. These additives are polydopamine (PDA) and polyacrylic acid (PAA).

[0087] These studies aimed to investigate the effect of PDA and PAA on cementitious material containing higher dosages of biochar with two different curing conditions: (I) sealed curing and (II) CO2 curing. The specific goals were as follows: (I) to produce carbon-negative cementitious composites with superior mechanical performance, (II) to investigate the effect of PDA and PAA on the workability and the hydration of cementitious materials after using a higher dosage of biochar, (III) to investigate the effect of different curing conditions (sealed curing and CO2 curing) and admixtures (PDA and PAA) on the macroscale (compressive strength) and microscale performances of carbon neutral cementitious composites.

[0088] Materials and Methods

[0089] Raw Materials

[0090] The raw materials used in this study were ordinary Portland cement (OPC). slag cement, biochar, and river sand. The chemical composition of OPC and slag cement was measured by X- ray fluorescence (XRF), shown in Table 1. OPC and slag were mixed in a 1 :1 ratio to produce a blended binder. Slag was used to achieve a lower carbon footprint of the blended binder.

[0091] 45808306.1 10 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0092] The materials’ particle size distribution (PSD) was obtained using a laser particle size analyzer (Shown in FIG. 1). Biochar was supplied by a commercial supplier. They used a slow pyrolysis kiln to produce biochar from wood materials by keeping it at 1250°F for up to 10 hours in a vacuum. The TGA and derivative of thermogravimetry (DTG) graph of biochar is shown in Error! Reference source not found..

[0093] Table 2 represents the characteristics of raw biochar as obtained from the supplier. Different dosages of dopamine hydrochloride (CsHnNO2-HCl, 99%) and Polyacrylic acid (C3H4O2)n (molecular weight- 2000) were used to modify the biochar.

[0094] Table 1: Oxide contents of OPC and slag cement used in this study.

[0095] Table 2: Characteristics of raw biochar

[0096] Sample Preparation

[0097] Engineering Biochar Three different functionalized biochar batches were produced in this study: Bio_Grn,

[0098] Bio_PDA, and Bio_PAA. The production of Bio_Grn only involved a mechanical process as it

[0099] 45808306.1 11 ATTORNEY DOCKET NO. UTSB 24-27 PCT was produced by grinding raw biochar in a ball mill for 2 hours. Tor Bio_PDA, the biochar was ground for one hour, then dopamine hydrochloride was added at a dosage of 2% by wt. of biochar, and again ground for one hour. The same procedure was followed to produce Bio_PAA, where PAA was added instead of PDA. The rotation speed of the ball mill was 2520 rpm for uniform blending. Four nylon jars with 8 pieces of zirconia balls of 4 different sizes per jar were used to grind the biochar. The particle size distributions of these functionalized biochar batches compared to that of the binder are shown in Error! Reference source not found.. The schematic showing the sample preparation and test setup is depicted in Error! Reference source not found..

[0100] Test Sample Preparation

[0101] The mixture proportions, as shown in Table 3, were designed to obtain carbon-negative and carbon-neutral batches using different biochar dosages. Paste samples were prepared to observe the cement hydration and microstructural properties. Mortar samples were prepared to evaluate the mechanical properties and carbon footprint. The functionalized biochar was added at 23% and 30% by wt. of binder to obtain carbon-neutral and carbon-negative batches, which was determined by an approximate carbon sequestration capacity of 3.2 kg CO2 eq / kg of biochar considering 87.4% solid carbon content

[0030] , The water-to-binder ratio was 0.55, and the aggregate-to-binder ratio was 2.75.

[0102] For mortar sample preparation, the slag and OPC were mixed in a Hobart mixer for 2 minutes at a slow speed (140+10 rpm). After that, ASTM C305

[0040] was followed to prepare the mortar mix. After mixing the binder, water, and sand according to ASTM C305, biochar was added to the mixture and then first mixed at a medium speed (285±10 rpm) for 60 seconds and finally at a high speed (580+10 rpm) for 30 seconds.

[0103] To prepare paste samples, the biochar was mixed with the binder for one minute (dry mix) to ensure uniform distribution of all materials. Then, water was added to the dry mixture and mixed at 350 rpm for 1.5 minutes. These paste samples were used to determine the microstructural properties using thermogravimetric analysis (TGA), X-ray diffraction (XRD), and backscattered electron (BSE) after both carbonation and sealed curing.

[0104] Two sets of mortar and paste samples were prepared. All the samples were demolded after 24 hours of casting. One set was subjected to sealed curing, and another set was subjected to accelerated carbonation curing. For the accelerated carbonation curing, samples were kept in the carbonation chamber at 20% CO2 concentration, 65% relative humidity, and 25°C temperature until testing.

[0105] 45808306.1 12 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0106] Table 3: Mix design (per lOOgm of binder).

[0107] *Raw Biochar; OPC: Ordinary Portland Cement, PDA: Polydopamine, PAA: Polyacrylic Acid; ** The measurement was in the form of dopamine hydrochloride. However, due to the alkaline environment of cement, dopamine hydrochloride will convert to PDA when added in the system

[0108] Experimental Methods

[0109] Zeta Potential of functionalized Biochar

[0110] The zeta potential of the blended binder and different functionalized biochar was measured using the nanoPartica SZ- 100 from Horiba Scientific. The suspensions were prepared using deionized water and contained 0.003% samples. Sonics Vibra Cell VCX 750 Ultrasonic Liquid Processor was used to disperse the suspension for 80 seconds before measuring the zeta potential.

[0111] Workability Measurements According to ASTM C1437

[0041] flow table test was performed to determine the workability of different dosages of biochar with PDA and PAA.

[0112] Strength Measurements

[0113] The compressive strengths of 50 mm by 50 mm mortar cubes were measured using a Universal Testing Machine with a load rate of 2001b / s-4001b / s according to ASTM C109

[0042] ,

[0114] 45808306.1 13 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0115] The compressive strength of mortar samples was measured after 7 days, 28 days, and 56 days of carbonation and sealed curing.

[0116] Effects on Cement Hydration Rate and Product

[0117] A calorimeter test was performed to evaluate the hydration kinetics of paste samples. An isothermal calorimeter (TAM AIR, TA Instrument) with admixture ampoules was used to measure the total heat release and heat flow from the paste samples up to 7 days at an ambient temperature of 25 °C. First, dry mixtures of OPC, slag, and biochar were prepared for different batches according to Table 3. Then, approximately 5g of the dry sample was put in a glass ampoule and placed in the isothermal calorimeter chambers. After putting the samples inside the calorimeter chambers, it took around 45 minutes to stabilize the heat flow signals. After the signals were stabilized, distilled water was added to the dry mix using syringes. The measurement of the heat of reaction started immediately after adding water and continued for up to 7 days. The isothermal calorimeter test was conducted twice to ensure the reliability and repeatability of the results.

[0118] Density

[0119] The fresh density was measured for all the batches by using a cylindrical plastic container. First, the weight of the empty container was measured, and then it was filled with water to determine its volume. Finally, the container was filled with mortar samples in three layers of approximately equal volumes. After filling each layer, it was rodded 25 times with a temping rod according to ASTM C138

[0043] , The side of the container was also tapped gently to release any trapped air bubbles inside the mortar sample. Finally, the weight of the samples was taken to determine the density. The fresh density of the mortar was calculated by dividing the mortar weight by the volume of the container.

[0120] Therrnogravimetric Analysis (TGA)

[0121] Paste samples were used for therrnogravimetric analysis (TGA). Isopropanol was used to stop hydration after 7 days, 28 days, and 56 days of curing following the solvent exchange method. The paste samples were then dried in a desiccator for 3 days to avoid atmospheric carbonation. The thermal analysis was performed using a commercially available instrument (TA instrument, TGA 550). Approximately 35-40 mg of ground paste sample was prepared for TGA measurement using a mortar and pestle. The powdered samples were loaded into a platinum pan and kept under isothermal conditions at around 25°C for 3 minutes, and then the temperature was raised continuously at a rate of 15°C per minute up to 980°C. Nitrogen was used as a purging gas during the test to maintain an inert environment. Mass losses in the 550-900°C range were used to calculate the carbonated samples’ calcium carbonate (CaCO ) mass fraction.

[0122] 45808306.1 14 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0123] The calculation of carbonate content is done according to the reference [ 441. At 23% and 30% dosage, the CaCXT calculation will be significantly affected due to the mass loss of biochar in the same temperature range. The TGA and derivative of thermogravimetry (DTG) graph of biochar is shown in Error! Reference source not found.. Equation 1 is used to determine the CaCth content without biochar adjustment, which means biochar decomposition was not considered in this calculation. However, Equation 2 is used to determine the CaCCh content with biochar adjustment. In Equation 2, the weight loss of biochar in 550-900 °C is determined by using Equation 3. In Equation 3, the weight loss of biochar obtained from Error! Reference source not found, is multiplied by the amount of biochar in 100 g of paste sample. This multiplication provided the total weight loss of biochar in 550-900 °C temperature range. The chemically bound water was calculated by subtracting the mass losses due to the decomposition of CaCCh (550-900°C) and free water (mass loss below 100°C) from the total mass loss up to 980°C

[0045] ,

[0124] Scanning Electron Microscope ( SEM)

[0125] The microstructure of biochar batches was analyzed with a high-resolution scanning electron microscope (HITACHI 3000N SEM). The samples were embedded by epoxy coating for the SEM-EDS analysis according to the supplier’s (Ted Pella) instructions. The aspect ratio of the needle-shaped biochar particles was measured using Microsoft PowerPoint.

[0126] X-Ray Diffraction (XRD)

[0127] X-ray diffraction (XRD) analysis of paste samples was conducted on a Broker D-8 spectrometer using Cu Ka radiation (40kV, 40mA). The diffraction patterns were obtained over 5°-60° (20) ranges with a step size of 0.03 per second.

[0128] Life Cycle Assessment (LCA)

[0129] Goal and scope definition

[0130] The global warming potential (GWP) for most of the raw materials was acquired from the Ecoinvcnt 3 dataset, assessed by TRACI (The Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts), and the analysis was conducted using SimaPro 45808306.1 15 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0131] 9.0.0.38. However, the environmental impact of biochar production varies based on factors such as feedstock types, biomass collection methods, diverse production locations, and various power sources utilized in the production process

[0046] ; furthermore, the physiochemical properties of biochar, specifically carbon content, fluctuate depending on feedstock type and pyrolysis temperature

[0047] . Consequently, the GWP data for biochar was compiled from various sources and employed to evaluate its impact on the variability of the ultimate carbon footprint associated with mortar. Moreover, a set of the samples was carbonation-cured to observe its effect on the mechanical and microstructural properties of mortar, which resulted in additional CO2 sequestration in the form of calcium carbonates: this CO2 content was determined from TGA analysis by calculating the weight reduction of paste samples within the temperature range 550 °C to 980 °C.

[0132] Data inventory

[0133] The source of GWP for biochar is discussed in the Results section. Data on GWP for the remaining raw materials were gathered from the Ecoinvent 3 dataset. The selected material categories from this database, along with their corresponding GWP values, are presented in Table 4. The production of OPC results in the emission of approximately 1 kg of CO2 per kg due to the high temperature needed for clinkerization and calcination of limestone. In contrast, slag is an industrial byproduct that undergoes a purification process involving quenching with water, dewatering, crushing, grinding, and storage in a pile. Consequently, substituting 50% of OPC with slag leads to a reduction in the overall GWP of the binder. Polydopamine and polyacrylic acid were employed to enhance the overall performance of the biochar-based cementitious material. Based on SimaPro analysis, polyacrylic acid demonstrated a GWP of 2.13 kg CO2 eq / kg, while no specific data was available for polydopamine. Consequently, the GWP value for polydopamine was assumed to be similar to that of polyacrylic acid.

[0134] Table 4: Raw material categories from the Ecoinvent 3 dataset.

[0135] 45808306.1 16 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0136] Results and Discussion

[0137] Error! Reference source not found.A shows the moisture content mass depending on the relative humidity condition and surface area of different functionalized biochar. Bio_PDA and Bio_PAA have higher moisture absorption capacity in 97.5% relative humidity due to higher surface area compared to the Bio_Grn. High surface area of different admixture contributes to hydration and development of mechanical properties of cementitious composites

[0031] ,

[0048] ,

[0138] Error! Reference source not found.B shows the zeta potential measurements. The functional groups of PDA (Catechol groups and Amine groups) and PAA (carboxylic acid groups) contribute to the higher surface charge. A higher negative surface charge results in increased electrostatic repulsion between individual particles, which prevents particles from agglomeration, promoting better dispersion.

[0139] Error! Reference source not found.C and Error! Reference source not found.D represent the morphology of unground and ground biochar, respectively. The unground biochar has a highly porous structure with large macropores, which are inherited from the parent feedstock. Grinding the biochar helps to break down the porous particles into a finer size and smooth surface. As a result, the overall porosity got reduced after grinding the biochar

[0049] ,

[0140] Effects on Early-age Properties

[0141] Density and Workability of Fresh Mortar Mixtures

[0142] FIG. 5 represents the flow table measurements of the control and different biocharcontaining mortar mixtures. The flowability test was continued for 60 minutes at intervals of 15 minutes. The initial flow diameter values of the Bio_Control 23% and 30% were 188.5 mm and 193.75 mm, respectively. Although the flow diameter of the Bio_Control batches is higher than other biochar batches, it was not a workable batch after adding the water since they are completely disaggregated, which can be observed from FIG.5C. That’s why the flowability test was not continued at other time intervals for the Bio_Control batches. The drastic reduction in the workability of the mortar mixture containing Bio_Control (i.e., raw biochar) compared to the control batch is due to the high-water retention capacity of the porous raw biochar

[0050]

[0051] and the angular shape of biochar that tries to restrain the movement of cement particles

[0052] , The structure of carbon in biochar particles has a high cation exchange capacity, indicating that it can

[0143] 45808306.1 17 ATTORNEY DOCKET NO. UTSB 24-27 PCT bind to cations in solution by ion exchange. As a result, biochar can rapidly absorb part of the mixing water by hydrogen bonding during sample preparation, reducing the mix’s flowability

[0051] , Most of the previous research used a lower biochar dosage because of the drastic reduction in flowability

[0029] ,

[0030] ,

[0050] , This further indicates that it is not possible to produce workable and carbon-negative / neutral cementitious composite using only raw biochar. As shown in this work, after adding the PDA or PAA modified biochar, the workability is significantly increased compared to Bio_Control and Bio_Gm batches. In high pH pore solution, dopamine hydrochloride spontaneously self-polymerizes by oxidation and subsequent cross-linking of the catechol structure to form polydopamine (PDA) film

[0037] . Formation of such PDA film on biochar reduces their water absorption and thus enhances the workability of mortar mixtures. The impact of PAA on flowability was more significant than PDA. This is because PAA’s greater zeta potential and stcric hindrance resulted in a stronger dispersion of mortar samples

[0038] ,

[0144] The fresh density of the mortar batches is shown in FIG. 6. As shown in this figure, the density of the mortar was reduced by 23.5% and 30% after adding 23% and 30% raw biochar, respectively, compared to the control batch. The reduction in density was expected due to the porous structure of raw biochar particles

[0029] , The density of the mortar mixtures containing functionalized biochar was increased compared to the sample containing raw biochar. The fresh densities of mortar containing 23% Bio_Grn, Bio_PDA, and Bio_PAA were 96%, 99.4%, and 100.5% of the control batch, respectively. The superior workability of the mortar mixtures containing Bio_PDA and Bio_PAA resulted in higher densities of the mortar mixtures containing these additives compared to the Bio_Grn batches at the same biochar dosage.

[0145] Cement Hydration Kinetics

[0146] The effects of various biochar batches on the binder’s heat of hydration are shown in Error! Reference source not found. A and Error! Reference source not found.B, From the heat flow plot, it is observed that the primary peak associated with the hydration product formation was shifted to the left due to the addition of Bio_Gm compared to the control batch indicating the hydration acceleration effect of this additive. Such an acceleration effect of Bio_Gm is attributed to the filler effect

[0050] —

[0053] , that is, the Bio_Gm provided an additional surface area for hydration products to nucleate, causing a faster product formation. FIG. 1 shows that grinding biochar in the ball mill produced finer particles, which played an important role in producing more hydration products at the early stage and reducing the dormant period. Similar findings were also observed in previous studies where they found increased hydration kinetics and a shorter dormant period after adding biochar as a micro filler

[0029] ,

[0031] ,

[0057] , The Bio_Gm

[0147] 45808306.1 18 ATTORNEY DOCKET NO. UTSB 24-27 PCT containing samples also showed a higher total heat release compared to the control batch after 168 hours of hydration (Error! Reference source not found.B). This indicates that a higher amount of cement reacted in the Bio_Grn batch, offering a more efficient cement use compared to the control batch.

[0148] Unlike the Bio_Grn batch, the addition of Bio_PDA or Bio_PAA has negative effects on the early-age cement hydration (Error! Reference source not founcLA). Specifically for the Bio_PDA containing samples, the primary heat flow peak was at the same location as Bio_Grn (left to the control batch), but the intensity was reduced. Therefore, the addition of Bio_PDA accelerated the cement hydration due to its surface area, but a lesser amount of cement reacted compared to the control. Such lesser hydration compared is attributed to the presence of polydopamine (PDA) in this sample. PDA has strong adhesion and affinitive interaction with Ca2+because of their catechol groups

[0058] , The Ca2+ions, available in the cement mixture, were reduced by the presence of PDA through chelating, which slowed down the formation of hydration products. Moreover, due to the binding of Ca2+, PDA can get adsorbed on cement particles and reduce the available surface area for cement hydration, which further suppressed the hydration. However, as observed from Error! Reference source not found.B, such negative effects of Bio_PDA were only apparent at an early age, and after 168 hours of hydration, the Bio_PDA containing samples showed either the same or higher heat release than the control batch.

[0149] The addition of Bio_PAA had significant negative effects on cement hydration (Error! Reference source not found.A-7B), There was no identifiable heat flow peak for these batches, and the total heat release after 168 hours was reduced by 20 to 30% compared to the control batch. This negative effect on cement hydration is due to the ability of PAA to adsorb cement particles, which reduces the available surface area for cement hydration

[0059] ,

[0060] .

[0150] Effects of Functionalized Biochar in Sealed Curing System Role in Compressive Strength

[0151] The compressive strengths of the mortars containing various biochar samples after sealed curing are shown in FIG. 8. The addition of raw biochar drastically reduces the compressive strength of the mortar batches compared to the control samples. Specifically, the 56 days compressive strengths of mortars containing 23% and 30% Bio_Control both dropped by 82%, compared to the control batch (i.e., without biochar). After 56 days of sealed curing, these batches achieved only around 8 MPa compared to the 45 MPa compressive strength of the control batch. This drastic reduction in strength is expected due to the high void ratio of raw biochar. Therefore, the addition of raw biochar to achieve carbon neutrality of cementitious

[0152] 45808306.1 19 ATTORNEY DOCKET NO. UTSB 24-27 PCT composites is impractical due to such inefficient binder use in addition to the lack of workability of the mixture (as observed in FIG. 5C).

[0153] Compared to the raw biochar, the compressive strengths of the mortar samples containing functionalized biochar were drastically improved. At the 23% dosage, the addition of Bio_Grn showed 369% higher strength compared to Bio_Control after 56 days of sealed curing. The addition of ground biochar (i.e., Bio_Gm) instead of the raw biochar (i.e., Bio_Control) results in a denser matrix due to the reduced voids of biochar particles, and therefore resulted in a superior compressive strength. However, the strength of Bio_Grn containing samples remained less than the control batch. The 56 days compressive strength for Bio_Gm 23% and 30% is 86% and 74%, respectively, of the control batch for sealed curing condition. The compressive strength of the mortar containing 30% Bio_Grn was less than that of the 23% Bio_Gm batch. Such a reduction in strength with increasing dosage of biochar is expected due to the dilution effect, i.e., reducing the amounts of cement with less reactive biochar in the unit volume of mortar.

[0154] The compressive strengths of the Bio_PDA containing mortar samples were remarkably enhanced compared to those containing raw biochar (Bio_Control) and ground biochar (Bio_Gm). The addition of 23% Bio_PDA resulted in 28% higher compressive strength compared to the control batch (without biochar) after 28 days of sealed curing. Such drastic enhancement of strength due to the addition of Bio_PDA was attributed to the high adhesive properties of PDA that adhered to the surface of the biochar

[0035] and achieved a better adhesion between the surface of biochar and cement particles resulting in a densification of the cement matrix. Additionally, our previous study showed that PDA can form composites with calcium silicate hydrate (C-S-H, primary cement hydration product), which enhances the mechanical properties of C-S-H

[0061] . The formation of this C-S-H-PDA also contributed to the superior compressive strength of the mortar containing Bio_PDA. The addition of 30% Bio_PDA resulted in 2% lesser strength than the control batch (without biochar) and 32% higher strength than the Bio_Gm after 56 days. The lower strength of 30% Bio_PDA samples compared to the 23% Bio_PDA is due to the dilution effects as well as potential agglomeration of PDA.

[0155] The addition of 23% Bio_PAA in mortar samples resulted in a higher strength compared to the control (without biochar), raw biochar (Bio_Control), and ground biochar (Bio_Gm) containing samples after 28 days of sealed curing. The strength improvement of Bio_PAA after long-term curing (i.e., 56 days) was attributed to the delayed hydration effect of this additive. As observed in Error! Reference source not found.E, the workability of the Bio_PAA batch was higher compared to the Bio_Grn and Bio_Control, which enabled the formation of a denser matrix after the addition of Bio_PAA and hence resulted in a higher compressive strength.

[0156] 45808306.1 20 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0157] Effects on the Crystalline Phase Formations

[0158] The XRD patterns of the sealed-cured samples confirmed the presence of calcite, vaterite, calcium silicate phases (alite and belite), ettringite, gypsum, and portlandite (FIG. 9). Compared to the control batch, the sample containing Bio_Grn showed reduced intensity for portlandite and ettringite (FIG. 9A). The reduction in these typical cement hydration products is attributed to the dilution effect resulting from the replacement of binder with ground biochar. Similar reduction in the intensity of the hydration products was observed in the case of Bio_PDA and Bio_PAA batches as shown in FIG. 9B and Figure 9C, respectively. In addition to the dilution effect, the negative charges of PDA and PAA (FIG. 4(b)) capture the Ca2+ ions, hindering the formation of portlandite and ettringite in the matrix. However, Bio_Grn and Bio_PDA batches showed higher intensity of different calcium carbonate polymorphs (i.e., calcite and vaterite) compared to the control batch. The formation of CaCO3 in these samples is due to the presence of CO2 in the atmosphere, indicating that adding biochar may have made these samples more vulnerable to atmospheric carbonation.

[0159] Effects on the Bound Water Contents

[0160] The thermal analysis plots for paste samples containing various functionalized biochar after 28 days of sealed curing is presented in FIG. 10A. The weight loss from 40°C-100°C corresponds to the decomposition of C-S-H and ettringite., the dehydration of AFm occurs at 100oC-200°C due to the heat treatment, 400oC-500°C is the range for the decomposition of portlandite and carbonates decomposes above 550°C

[0044] ,

[0060] —

[0062] . FIG. 10A reveals that the decomposition up to 200°C is relatively higher for the control batch, indicating that the control batch produced more hydrated products than the biochar batches. As a result of the dilution effect, the total amount of hydrated products (C-S-H, AFm) is comparatively lower for biochar batches than the control batch. As observed from FIG. 10 A, the biochar containing batches showed a broad weight loss peak within the temperature range of 450 to 700°C. This relatively gradual weight loss is due to the decomposition of biochar (as observed in FIG. 2) as well as the dehydration of C-S-H. FIG. 10B represents the chemically bound water and weight loss due to the biochar decomposition for different batches. The chemically bound water and biochar decomposition were measured by considering the weight loss between the range of 105°C-600°C. The weight losses due to the biochar decomposition (FIG. 2) were 2.79% and 3.51% for 23% and 30% biochar batches, respectively, within the same temperature range. The amount of chemically bound water was lowest for Bio_Grn batches, whereas it was higher for Bio_PDA and Bio_PAA batches compared to the Bio_Grn batches.

[0161] Effects of Functionalized Biochar in Carbonation Curing System

[0162] 45808306.1 21 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0163] Role in Compressive Strength

[0164] The compressive strength of the mortar samples containing various dosages of functionalized biochar and exposed to carbonation curing are shown in Error! Reference source not found.. The compressive strength of the control batch (without biochar) exposed to carbonation curing was lower than that achieved in the case of sealed curing after the same curing duration. Noteworthy, for this study, the binder mixture contained a blend of OPC and slag cement in a 1 : 1 ratio. Such blended binders with high SCM dosage are likely to form a very small amount of portlandite. As a result, when these samples are exposed to long-term carbonation curing, as in this study, the C-S-H starts decalcifying, which caused poorer strength compared to the sealed cured control sample. This is similar to the findings observed by Gupta et al.

[0048] where they found that the compressive strength of cement blocks with 1% and 3% biochar decreased when they were subjected to long-term carbonation curing (7 days and 28 days). This prolonged carbonation leads to moisture starvations, increasing porosity, and degraded binder gel structure, which negatively affects strength development

[0048] ,

[0165] Similar to the sealed cured batch, the addition of raw biochar drastically reduced the compressive strengths of the mortars. Specifically, the Bio_Control batches showed a compressive strength of around 5 MPa after 56 days of carbonation curing, confirming that such samples containing direct use of raw biochar are unlikely to be useful for load-bearing applications. However, the addition of functionalized biochar significantly enhanced their effects on the compressive strength of the mortar samples. Specifically, at a 23% dosage level, all of the mortar samples containing functionalized biochar resulted in a higher compressive strength compared to the control batch (without biochar) after 56 days of carbonation curing. The highest strength after 56 days of carbonation curing was 43 MPa for the 23% Bio_PDA sample, which was 24% higher than the control batch. Among the batches containing functionalized biochar, only the Bio_PAA at 30% dosage showed lesser strength than the control batch. To further understand the role of these functionalized biochar on the strength, microstructural studies were performed.

[0166] Effects on the Crystalline Phase Formations

[0167] The XRD patterns of the paste samples containing various functionalized biochar are shown in Error! Reference source not found.. Calcite was the primary phase present in these samples in addition to vaterite and calcium silicate phases (i.e., alite and belite). The control batch showed the highest peak intensity for calcite compared to the biochar batches, regardless of the biochar processing and dosages. In addition to the dilution effect, the inclusion of biochar hinders the carbonation process by making the matrix denser, resulting in low calcite formation

[0168] 45808306.1 22 ATTORNEY DOCKET NO. UTSB 24-27 PCT in the case of accelerated carbonation curing. Similar to the calcite observation, the vaterite peak was also the highest in the control batch.

[0169] Effects on the Carbonate Formation

[0170] The thermal analysis plots of the 28 days carbonation cured samples with various dosages biochar are shown in FIG. 12. It is evident from this figure that the weight loss associated with dehydration up to 200°C was relatively higher for the biochar containing batches compared the control batch, indicating that biochar batches contained more hydrated phases compared to the control batch

[0064] , This is because of the water retention capacity of biochar within the pores, which can improve the long-term hydration properties of the samples

[0065] ,

[0066] , FIG. 13B presents the total calcium carbonate content (%) without biochar adjustment and with biochar adjustment. In 100g of paste sample, the amount of biochar is 12.92g and 16.22g for 23% and 30% biochar batches, respectively. From FIG. FIG. 2, it is observed that the weight loss due to the biochar decomposition is 23.98% within the same temperature range(550-900°C). Then Equation 3 is used to calculate the decomposition of biochar in FIG. 13 A. According to the calculation, the weight loss due to the biochar decomposition was obtained 3.09% and 3.89% for 23% and 30% biochar batches, respectively. Then finally, Equation 2 is used to determine the CaCO3 with biochar adjustment (detailed calculation is given in supplementary section Table SI).

[0171] Table 5: CaCOa calculation (without biochar adjustments and with biochar adjustments)

[0172] 45808306.1 23 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0173] FIG. 13B shows that the control batch had the highest CaCO3 content compared to the biochar containing batches, matching the observations from XRD in FIG. 12. Such reduced amounts of CaCO3 formation in the biochar containing batches are primarily due to the dilution effect. However, the addition of these biochar samples hindered the carbonation of the matrix. This denser cement matrix inhibited CO2 from entering the system (diffusion) during the carbonation curing process. As a result, total weight loss due to the decomposition of CaCO3 was comparatively lower for the biochar batches. The CaCO3 content for Bio_PAA_30% was the lowest compared to the other batches due to the limited diffusion of CO2, which also resulted in the poor compressive strength of this batch.

[0174] Dispersion of Biochar in Cementitious System

[0175] Due to the low density, the uniform dispersion of biochar in binder mixtures can be challenging. Therefore, to evaluate the dispersion of the functionalized biochar in the binder mixture, BSE images with elemental mapping were collected. FIG, 14A) and FIG. 14C illustrate the low- and high-resolution BSE images, and FIG. 14B and FIG, 14D represent carbon element mapping showing the biochar distribution in the hardened matrix for the sample containing 23% Bio_PDA. As observed from these images, biochar was uniformly distributed throughout the matrix for the Bio_PDA sample. Similar images were collected for the Bio_Gm and Bio_PAA containing samples (FIG. 18A-18D and FIG. 19A-19D), which ensured uniform biochar distribution in these samples as well.

[0176] Role of Functionalized Biochar on the Environmental Impact

[0177] The biochar utilized in this study was derived by pyrolyzing Beetle-killed wood, firedamaged trees, and other woody materials. According to the manufacturer, it contained 87.4% carbon (by total dry mass), resulting in a CO2 sequestration capacity of 3.2 kg CO2 equivalent per kilogram of biochar. However, a more representative carbon footprint for wood waste-based biochar was considered, using global warming potential (GWP) data from various literature 45808306.1 24 ATTORNEY DOCKET NO. UTSB 24-27 PCT sources for analysis in this study. Previous studies showed that among various waste biomasses, wood waste-based biochar (WWB) has the highest carbon content because of having higher lignocellulose, with a maximum of 90.5%

[0018] ,

[0067] , and their carbon sequestration potential can vary from -2740.10 to -1513.07 kg CO2 eq per ton

[0018] , Calculating the net greenhouse gas (GHG) impact for each biochar unit involved combining the total CO2 sequestration from the biochar with the corresponding CO2 emissions resulting from its production.

[0178] Biochar production primarily comprises two main stages: feedstock pretreatment and biochar preparation; feedstock pretreatment includes drying, storage, grinding, chipping, or pelletizing

[0018] , Conversely, the carbon emission due to the biochar preparation process depends on the sources of power used to operate the pyrolysis plant. Puettmann et al. conducted an evaluation of the environmental impact associated with biochar production from forest residues using three portable systems, namely biochar solutions incorporated (BSI), Oregon Kiln, and aircurtain burner

[0046] . Within the BSI system, various power sources were utilized, including grid connection for in-town locations and a diesel or gasifier-based generator for near-forest locations

[0020] ,

[0046] , while another study incorporated natural gas for pyrolyzing wood sawdust

[0029] , These studies considered the biogenic carbon emissions released during biochar production to be equal to the CO2 absorbed during tree growth

[0029] ,

[0046] , Depending on the system used (e.g., gasifierbased generator or diesel-based generator), CO2 emissions from biochar production range from 0.2 to 0.8 kg CO2 eq / kg biochar

[0046] . Conversely, the carbon sequestration potential of these biochars varies from 2.6 to 3 kg CO2 eq / kg biochar

[0046] , The total CO2 emissions during biochar production and the CO2 sequestered within were combined to calculate the net GWP per kg of biochar. Diverse net GWP data for biochar production gathered from various sources, as depicted in Table 5, were employed to illustrate the range of carbon footprints associated with mortar production when biochar is integrated into the process. Polyacrylic acid (PAA) and poly dopamine (PDA) were added during grinding to enhance the workability of biochar. The GWP of PAA was obtained from SimaPro (Table 4), but due to a lack of specific data, the GWP for PDA was assumed to be the same as that of PAA.

[0179] Table 5: Net GWP data per kg of biochar.

[0180] 45808306.1 25 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0181] The primary focus was establishing the functional unit as the mass of binder needed per cubic meter of mortar, subsequently calculating the other raw material quantities for the same mortar sample and summing them up. FIG. 16A and 16B shows the GWP of different biocharbased mortar samples and their corresponding compressive strength and compares them with the biochar-excluded control batch. Nearly all biochar batches subjected to carbonation curing exhibited negative carbon footprints, with GWP reductions ranging from 90% to 170% compared to the control batch (Fig. 16A). Prior research indicated that increased biochar incorporation in mortar typically results in reduced compressive strength [5]: nevertheless, this study demonstrates that even with the addition of 23% biochar by the weight of the binder, compressive strengths of up to 43 MPa was attained in a carbonation system and up to 54 MPa when samples were cured under sealed conditions. Therefore, achieving a greater reduction in carbon footprint without compromising compressive strength is possible. Moreover, an increase in biochar dosage from 23% to 30% resulted in a reduction in carbon footprint, while the compressive strength of the 23% biochar-containing mortar sample remained higher. Bio_Control and Bio_Gm, with similar mix compositions (excluding the grinding energy for Bio_Gm), exhibit comparable carbon footprints; however, Bio_Control's compressive strength is 75-85% lower than that of Bio_Grn for both carbonation-cured and sealed-cured mixes.

[0182] For sealed-cured samples as shown in FIG, 16B, the addition of 23% biochar may not consistently achieve carbon negativity; however, ensuring this outcome is possible by increasing the percentage of biochar addition to 30%. Like the carbonation-cured mixes, the 23% biochar batch exhibited a lower GWP reduction but a higher compressive strength. Moreover, due to the additional CO2 sequestration in the carbonation-cured samples, their carbon footprint consistently remained lower than that of the sealed-cured samples. Lastly, the GWP of mixes containing PDA and PAA was relatively higher compared to other biochar-containing mixes, attributed to the additional carbon footprint introduced by the two additives.

[0183] From the above discussion, it is certain that there is a correlation between biochar dosage, GWP, and compressive strength. Hence, when assessing functional equivalence among binders with or without biochar addition, compressive strength should be regarded as a critical parameter. Consequently, a new functional unit was introduced as the mass of the binder needed per cubic meter of mortar or concrete to achieve 1 MPa of compressive strength (kg / (m3.MPa))

[0069] ,

[0070] . The implication of this functional unit is that achieving comparable compressive strength requires varying the amount of binder needed per cubic meter, thereby influencing the 45808306.1 26 ATTORNEY DOCKET NO. UTSB 24-27 PCT carbon footprint. As depicted in PIG. 17 the carbon footprint of Bio_Control was the lowest among all the mixes containing biochar, while the compressive strength of these mixes ranged only from 4 to 8 MPa. The observed discrepancy arises because the low compressive strength necessitates an increased binder requirement, consequently elevating the carbon footprint. However, the increase in binder content also entails a higher demand for biochar, leading to substantial carbon negativity and ultimately resulting in a net reduction in carbon footprint. However, despite its low carbon footprint, the lack of workability and significantly low compressive strength make it unsuitable for being used as a mix. This is the same reason that the GWP of 30% biochar-contained samples have a lower value despite having lower compressive strength. Nevertheless, carbon negativity was evident in all the biochar samples even when this new functional unit was applied.

[0184] Conclusion:

[0185] This article presented an innovative approach to producing carbon-neutral / negative cementitious composites by engineering the interface between cement paste matrix and biochar using organic polymers. The following are the concluding remarks that can be drawn from the results of this study:

[0186] I. The carbon neutral / negative cementitious composites produced using raw biochar was unworkable due to the high-water retention capacity of biochar. Compared to the raw biochar, the addition of functionalized biochar drastically (up to 63%) improved the workability of the fresh mixtures.

[0187] II. The addition of ground biochar (Bio_Grn) accelerated the cement hydration by providing additional surface area for hydration products to nucleate. However, the polymer- modified functionalized biochar (Bio_PDA and Bio_PAA) suppressed cement hydration at an early age. However, after 7 days, Bio_PDA-containing batches showed the same or higher cement hydration heat compared to the control batch.

[0188] III. The use of functionalized biochar enables reducing the carbon footprint of cementitious composites up to 170% after considering the GWP associated with all the raw ingredients, including biochar production and use of the organic polymers.

[0189] IV. This study showed a pathway to produce workable carbon-neutral (or net zero carbon) and carbon-negative cementitious composites. For the 56 days sealed curing environment, the maximum strength of the carbon-neutral batches was 54 MPa, which was achieved by using 23% Bio_PDA. This strength was 22% higher than the control batch produced without any biochar. For this curing condition, the maximum compressive strength for the carbon-negative batch was 47 MPa, achieved by using 30%

[0190] 45808306.1 27 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0191] Bio_PAA. The use of this carbon-negative cementitious composite enables permanent sequestration of up to 120kg CO2 eq per m3of the structure constructed using this composite.

[0192] V. For carbonation curing, all the batches containing functionalized biochar were carbonnegative and showed reasonable compressive strength. The maximum compressive strength after 56 days of carbonation curing was 43 MPa, corresponding to the mortar sample containing 23% Bio_PDA. This strength was 24% higher than the traditional control batch, produced under the same curing condition, which also had a significantly high carbon footprint.

[0193] This study demonstrates the potential of using a higher dosage of functionalized biochar to achieve carbon neutral / negative cementitious composites with superior performance. Nevertheless, further exploration is required into various factors. This study utilized a specific type of biochar; however, biochar’s derived from different feedstocks or processed under varying conditions could result in different performance characteristics, affecting both the workability and mechanical properties. More research is needed to generalize the findings to other biochar types. The demonstrated improvements in workability and mechanical performance with higher biochar dosages, bring us significantly closer to making carbon-neutral construction materials a practical reality. This progress sets a solid foundation for future innovations in sustainable building practices, with the potential for even greater advancements as these limitations are addressed.

[0194] References

[0195] [1] International Energy Agency, “Assessing the effects of economic recoveries on global energy demand and CO2 emissions in 2021 Global Energy,” 2021. [Online]. Available: www.iea.org / t&c /

[0196] [2] BBC, “Climate change: EU leaders set 55% target for CO2 emissions cut,” Dec. 2020, Accessed: Dec. 24, 2023. [Online], Available: https: / / www.bbc.com / news / world-europe- 55273004

[0197] [3] BBC, “Climate change: China aims for ‘carbon neutrality by 2060,”’ Sep. 22, 2020. Accessed: Dec. 24, 2023. [Online], Available: https: / / www.bbc.com / news / science- environment-54256826

[0198] [4] United Nations, “For a livable climate: Net-zero commitments must be backed by credible action.” [Online], Available: https: / / www.un.org / en / climatechange / net-zero-coalition

[0199] [5] Chen et al., Chemical Engineering Journal, vol. 431, Mar. 2022.

[0200] 45808306.1 28 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0201] [ 61 Ober et a!., “Mineral commodity summaries 2018,” Reston, VA, 2018. doi: 10.3133 / 70194932.

[0202] [7] Ellis, et al., Proc Natl Acad Sci U S A, vol. 117( 23): 12584-12591, 2020.

[0203] [8] Lin, et al., Sep. 20, 2023, Elsevier Ltd. doi: 10.1016 / j.jclepro.2023.138219.

[0204] [9] Li et al., Mater Lett, doi: 10.1016 / j.matlet.2023.134368.

[0205]

[0010] Zhang et al., doi: 10.1007 / s42773-022-00182-x.

[0206]

[0011] Winters, K. Boakye, Sustainability (Switzerland), doi: 10.3390 / sul4084633.

[0207]

[0012] Sri Shalini et al., doi: 10.1007 / sl3399-020-00604-5.

[0208]

[0013] Korb, et al., Restor Ecol, vol. 12, no. 1, pp. 52-62, Mar. 2004, doi:

[0209] 10.1111 / j.1061-2971.2004.00304.x.

[0210]

[0014] Moreira, et al., doi: 10.1016 / j.biortech.2017.08.041.

[0211]

[0015] Schmidt et al., et al., doi: 10.1111 / gcbb.12553.

[0212]

[0016] Papageorgiou, et al. doi: 10.1016 / j.scitotenv.202L 145953.

[0213]

[0017] Iribarren, et al.. Fuel, vol. 97, pp. 812-821, Jul. 2012, doi:

[0214] 10.1016 / j.fuel.2012.02.053.

[0215]

[0018] Xia, et al., doi: 10.1016 / j.scitotenv.2023.168734.

[0216]

[0019] Zampori, et al., Environ Sci Technol, vol. 47, no. 13, pp. 7413-7420, Jul. 2013, doi: 10.1021 / es401326a.

[0217]

[0020] Sahoo, et al., Int J Life Cycle Assess, pp. 189-213, 2020, doi: 10.1007 / s 11367- 020-01830-9 / Published.

[0218]

[0021] McBeath, et al., Biomass Bioenergy, vol. 73, pp. 155-173, Feb. 2015, doi: 10.1016 / j.biombioe.2014.12.022.

[0219]

[0022] Lehmann, et al., Mar. 2006. doi: 10.1007 / sl 1027-005-9006-5.

[0220]

[0023] Leturcq, et al., doi: 10.1038 / s41598-020-77527-8.

[0221]

[0024] Kua, et al., Cem Conor Compos, vol. 100, pp. 35-52, Jul. 2019, doi: 10.1016 / j.cemconcomp.2019.03.017.

[0222]

[0025] Wang et al., et al., J Clean Prod, vol. 258, p. 120678, 2020, doi: 10.1016 / j.jclepro.2020.120678.

[0223]

[0026] Suarez-riera, et al., Procedia Structural Integrity, vol. 26, no. 2019, pp. 199-210, 2020, doi: 10.1016 / j.prostr.2020.06.023.

[0224]

[0027] Dixit, et al., J Clean Prod, vol. 238, p. 117876, 2019, doi: 10.1016 / j.jclepro.2019.117876.

[0225]

[0028] Gupta et al., Constr Build Mater, vol. 159, pp. 107-125, 2018, doi:

[0226] 10.1016Zj.conbuildmat.2017.10.095.

[0227] 45808306.1 29 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0228] [291 Gupta, et al., Cem Concr Compos, vol. 87, pp. 1 10-129, Mar. 2018, doi: 10.1016 / j .cemconcomp.2017.12.009.

[0229]

[0030] Gupta, et al., Science of the Total Environment, vol. 619-620, pp. 419-435, Apr. 2018, doi: 10.1016 / j.scitotenv.2017.11.044.

[0230]

[0031] Gupta et al., Science of the Total Environment, vol. 662, pp. 952-962, Apr. 2019, doi : 10.1016 / j .scitotenv.2019.01 .269.

[0231]

[0032] Cha, et al., doi: 10.1002 / biot.200700258.

[0232]

[0033] Wilker, “et al., Angewandte Chemie - International Edition, vol. 49, no. 44, pp. 8076-8078, Oct. 2010. doi: 10.1002 / anie.201003171.

[0233]

[0034] Liu et al., Materials Science and Engineering C, vol. 44, pp. 44-51, Nov. 2014, doi: 10.1016 / j.msec.2014.07.063.

[0234]

[0035] Khan, et al., Cem Concr Compos, vol. 134, Nov. 2022, doi: 10.1016 / j.cemconcomp.2022.104766.

[0235]

[0036] Fang, et al., Constr Build Mater, vol. 241, Apr. 2020, doi: 10.1016 / j .conbuildmat.2020.118104.

[0236]

[0037] Chen et al., Constr Build Mater, vol. 407, Dec. 2023, doi: 10.1016 / j .conbuildmat.2023.133550.

[0237]

[0038] Guo et al., Colloids Surf A Physicochem Eng Asp, vol. 535, pp. 139-148, Dec. 2017, doi: 10.1016 / j.colsurfa.2017.09.039.

[0238]

[0039] Haque, et al., Sustainable Materials and Technologies, vol. 28, p. e00279, 2021, doi : 10.1016 / j .susmat.2021 ,e00279.

[0239]

[0040] ASTM C305, “Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency,” 2009. [Online]. Available: www.astm.org

[0240]

[0041] ASTM C1437, “Standard Test Method for Flow of Hydraulic Cement Mortar,” 2007. [Online], Available: www.astm.org

[0241]

[0042] ASTM C109, “Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube Specimens),” 2009. [Online]. Available: www.astm.org,

[0242]

[0043] ASTM Cl 38, “Standard Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete,” 2008. [Online]. Available: www.astm.org,

[0243]

[0044] Karen, et al.,. Lothenbach, A practical guide to microstructural analysis of cementitious materials. CRC Press, 2016.

[0244]

[0045] Ashraf et al., J Mater Sci, vol. 51, no. 13, pp. 6173-6191, Jul. 2016, doi:

[0245] 10.1007 / S10853-016-9909-4.

[0246] 45808306.1 30 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0247] [461 Puettmann et a!., J Clean Prod, vol. 250, Mar. 2020, doi:

[0248] 10.1016 / j.jclepro.2019.119564.

[0249]

[0047] Das, et al., J Environ Manage, vol. 278, Jan. 2021, doi: 10.1016 / j.jenvman.2020.111501.

[0250]

[0048] S. Gupta, A. Kashani, A. H. Mahmood, and T. Han, “Carbon sequestration in cementitious composites using biochar and fly ash - Effect on mechanical and durability properties,” Constr Build Mater, vol. 291, Jul. 2021, doi: 10.1016 / j.conbuildmat.2021.123363.

[0251]

[0049] S. Gupta, A. Kashani, and A. H. Mahmood, “Carbon sequestration in engineered lightweight foamed mortar - Effect on rheology, mechanical and durability properties,” Constr Build Mater, vol. 322, Mar. 2022, doi: 10. 1016 / j.conbuildmat.2022.126383.

[0252]

[0050] Gupta, et al., Constr Build Mater, vol. 167, pp. 874-889, Apr. 2018, doi: 10.1016 / j.conbuildmat.2018.02.104.

[0253]

[0051] Chang et al., Journal of the Korean Society of Structural Diagnostics and Maintenance Engineers, vol. 5, pp. 67-74, 2012.

[0254]

[0052] Mindess, Developments in the Formulation and Reinforcement of Concrete, Second Edition. Woodhead Publishing, 2019.

[0255]

[0053] Bouasker, et al., Cem Concr Compos, vol. 30, no. 1, pp. 13-22, Jan. 2008, doi: 10.1016 / j .cemconcomp.2007.06.004.

[0256]

[0054] Goldman et al., Cem Concr Res, vol. 23, pp. 962-972, 1993.

[0257]

[0055] Poppe et al., Cem Concr Res, vol. 35, no. 12, pp. 2290-2299, Dec. 2005, doi: 10.1016 / j .cemconres .2005.03.008.

[0258]

[0056] Duval et al., Influence of fine and ultrafine particles on the heat of hydration and the compressive strength of cement mortars, vol. 28. WIT Press, 2000.

[0259]

[0057] Maljaee, et al., doi: 10. 1016 / j.conbuildmat.2021.122757.

[0260]

[0058] ZGu et al., Constr Build Mater, vol. 414, pp. 1-12, Feb. 2024, doi: 10.1016 / j .conbuildmat.2024.134912.

[0261]

[0059] Lota, et al.. Advances in Cement Research, vol. No. 2, pp. 45-56, 1999.

[0262]

[0060] Ma, et al., Materials, vol. 11, no. 7, Jun. 2018, doi: 10.3390 / mal 1071081.

[0263]

[0061] Haque, et al., Cem Concr Compos, vol. 136, Feb. 2023, doi:

[0264] 10.1016 / j.cemconcomp.2022.104888.

[0265]

[0062] Nielsen, et al., Journal of CO2 Utilization, vol. 36, pp. 124-134, Feb. 2020, doi: 10.1016 / j.jcou.2019.10.022.

[0266]

[0063] Wu et al., Compos B Eng, vol. 182, Feb. 2020, doi: 10.1016 / j .compositesb.2019.107605.

[0267] 45808306.1 31 ATTORNEY DOCKET NO. UTSB 24-27 PCT

[0268]

[0064] Liu et al.. Science of the Total Environment, vol. 902, Dec. 2023, doi: 10.1016 / j.scitotenv.2023.166065.

[0269]

[0065] Sirico et alConstr Build Mater, vol. 303, Oct. 2021, doi: 10.1016 / j .conbuildmat.2021.124500.

[0270]

[0066] Sirico et al., Theoretical and Applied Fracture Mechanics, vol. 122, Dec. 2022, doi : 10.1016 / j .tafmec .2022.103626.

[0271]

[0067] Azzi, et al., Environ Sci Technol, vol. 53, no. 14, pp. 8466-8476, Jul. 2019, doi: 10.1021 / acs.est.9b()1615.

[0272]

[0068] Azzi, et al., Environ Sci Technol, vol. 53, no. 14, pp. 8466-8476, Jul. 2019, doi: 10.1021 / acs.est.9b01615.

[0273]

[0069] Sagastume Gutierrez, et al., J Clean Prod, vol. 168, pp. 463-473, Dec. 2017, doi: 10.1016 / j.jclcpro.2017.09.007.

[0274]

[0070] Tahsin, et al., J Sustain Cem Based Mater, 2023, doi: 10.1080 / 21650373.2023.2243480.

[0275] It is understood that the disclosed method and compositions are not limited to the particular methodology, protocols, and reagents described as these can vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention which will be limited only by the appended claims.

[0276] Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, many equivalents to the specific embodiments of the method and compositions described herein. Such equivalents are intended to be encompassed by the following claims.

[0277] 45808306.1 32

Claims

ATTORNEY DOCKET NO. UTSB 24-27 PCTCLAIMSWe claim:

1. A composition comprising functionalized biochar comprising biochar and an effective amount of a functionalization agent selected from the group consisting of polydopamine (PDA), polyacrylic acid (PAA), polycarboxylic acid (PCA), maleic acid, and polymers thereof.

2. The composition of claim 1, comprising an effective amount of PDA.

3. The composition of any one of claims 1-2, wherein the functionalization agent is PDA is obtained from a reaction of dopamine hydrochloride (CsHuNCh-HCl, 99%) and biochar.

4. The composition of claim 1, wherein the functionalization agent is PAA at a dosage between about 0.2 to 10% by weight of biochar, preferably between 0.5 and 5 % by weight of biochar and more preferably between 1 and 3 % by weight of biochar.

5. The composition of any one of claims 1-4, further comprising one or more binders selected from the group consisting of mineral binders, bituminous binders, natural binders and synthetic binders.

6. The composition of any one of claims 1-5, wherein the mineral binder is selected from the group consisting of hydraulic binders, which require water to harden and develop strength; non-hydraulic binders.

7. The composition of claim 6, wherein the binder is a non-hydraulic binder selected from the group consisting of wollastonite, Tricalcium silicate (C3S), P-dicalcium silicate ([)- C2S), y-dicalcium silicate (y-C2S), tricalcium disilicate (C3S2) and monocalcium silicate (CS).

8. The composition of claim 6, wherein the semi-hydraulic binder is slag.

9. The composition of claim 6, wherein the hydraulic binder is cement such as Portland cement.

10. The composition of any one of claims 8-9, comprising slag and Portland cement at a ratio of 1 : 1 .45808306.1 33ATTORNEY DOCKET NO. UTSB 24-27 PCT11. The composition of any one of claims 1-10, in the form of a solid, such as a powder.

12. The composition of any one of claims 1-11, wherein the composition is formed into a solid composite mortar and subjected to carbonation curing or sealed curing.

13. The composition of claim 12, wherein the compressive strength of the solid composition is at least 40 MPA, preferably up to 70 MPa.

14. A method of making the composition of any one of claims 1-12, comprising grinding biochar for about one hour, contacting the ground biochar the effective amount of the functionalization agent, and grinding the combination for about one hour.

15. The composition of any one of claims 1-13, wherein when formulated into a composite show an improvement in one or more properties of resulting composites selected from the group consisting of compressive strength and global warming potential (GWP) compared to composites made from the same binders not supplemented with functionalized biochar.

16. The composition of claim 15, formulated in a composite selected from the group consisting of bridge girders, beams, blocks, pavers, edging blocks, and stepping stones.

17. The composition of claim 16, having one or more properties selected from the group consisting of improved compressive strength and / or global warming potential (GWP) compared to composites made from the same binders not supplemented with functionalized biochar45808306.1 34

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