WO2024018281A2 - Dispersed graphite additive for concrete, and methods of making and using the additive - Google Patents

Abstract

A dispersed graphite additive for concrete compositions results in increased strength when used to produce cured concrete articles. Methods and systems of preparing and using concrete compositions with the dispersed graphite additive are inexpensive and convenient.

Description

DISPERSED GRAPHITE ADDITIVE FOR CONCRETE, AND METHODS OF MAKING AND USING THE ADDITIVE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63/390,548, filed July 19, 2022, the contents of which are incorporated herein by reference in their entirety.

BACKGROUND

[0002] Concrete has been used as a building material for thousands of years. Concrete is made from fine and/or coarse particles bonded together with a cement or cementitious-type materials that hardens after curing. Hydraulic cements undergo curing by a reaction between dry cementitious materials and water and it is the resulting mechanical interlocking of the cement with itself and other components of the concrete that are responsible for giving the concrete a significant part of its strength. The physical properties of concretes can be enhanced by including a reinforcing material such as steel reinforcing bars (rebar) or carbon fibers.

[0003] Concrete is often graded by the minimum strength it must possess 28 days after curing. One convention for grading concrete uses the prefix M with a number to refer to the compressive strength in MPa. For example, M20 grade concrete has a strength of 20 MPa.

[0004] Concrete is the most used man-made material and the second most consumed material after water. Cement is the main functional component of concrete. Cement production is responsible for 8% of global man-made CO2 emissions and growing, so concrete production is indirectly responsible for CO2 emissions by virtue of its requirements for cement. Production of cement releases a significant amount of CO2. In almost a 1 : 1 ratio, 1 (one) kg of cement production releases 1 (one) kg of CO2. The calculation of CO2 emitted is based on the direct release of carbon dioxide due to chemical processes in cement production, and indirect CO2 released via high energy consumption. Therefore, potential solutions to reduce cement usage are a key priority for the world.

[0005] In addition to that, due to the constant raise of the concrete production, some regions in the world already started to face problems with shortage of another key ingredient - sand. It’s being currently consumed faster then it can be replaced by the normal geological process.

[0006] Another approach to enhanced physical properties of concrete mixes is to use one or more additives Numerous chemical admixtures are being widely used by the concrete industry, such as, retarders and acceleraters, superplasticizers, air entrainment, waterproofers, water reduces etc. Now, the use of these additives is rapidly increasing because of the multiple physical and economical benefits. However, there are some downsides when using chemical admixures. For instance, incompatibility of cement and admixtures can be either due to cement or admixtures or both. Also, the excessive amounts of admixures can cause serious performance issues. In some cases, it might be severe.

[0007] Because of these raising complex problems in the construction industry, humanity will be facing serious problems in the nearest future. Alternative solutions are required, which can improve from one side, the ecological impact and from another side, the overall durability of the constructions. Indeed, cement savings can reduce the current ecological impact, but improving the quality and longevity will bring significantly more benefits on a long-term.

[0008] One such solution can be implementation of carbon-based nanometarials in mortar and concrete mixes. Graphitic materials attract particular interest as a potential candidate for this use. Graphite is a naturally occurring form of carbon with the excellent electric and thermal conductivity and mechanical properties. Also, it is inert and has a has a high thermal resistance. [0009] Veedu US Patent 7,666,327 discusses a a process to create nano admixtures that transform traditional cementitious composite material, such as concrete, into multifunctional smart structural material (nanoconcrete). Multistep preparation of nano admixuteres includes the dispersing and sonication of carbon material (preferably carbon nanotube) in a solvent. Then, the resulting solvent with dispersed nanomaterial is being added to the water with dispersed hydrophilic emulsifier, thickener, additive or cellulose derived compound, and the combination of solvent with dispersed nanomaterials and water with dispersed hydrophilic emulsifier, thickener, additive, or cellulose derived compound is mechanically stirred.

[0010] Sadiq et al. US 20140060388 Al discusses ultra-high-performance cementitious materials made using suitably dispersed low-cost carbon nanofibers and graphite nanomaterials in a water-based solutions. Dispersion process of graphite nanomaterials and microfibers includes mechanical stirring and sonication with polyacrylic acid (in 1 : 1 weight ratio) in a water.

[0011] Balachandra US 20190315654 Al discusses beneficiation of inorganic matrices via addition of commercially available wet non-agglomerated and highly concentrated graphite nanoplatelets without altering the production conditions of the inorganic matrix, and more specifically it relates to enhancement of concrete with wet graphite nanoplatelets using conventional concrete production equipment and procedures without any need for extra measures such as sonication, use of surfactants or functionalization of nanomaterials for dispersion of nanoplatelets. However, this disclosure does not describe the perparation method of such material and it might have a very limited supply.

[0012] Cracium et al. US 20200339473 Al discusses the method of production of concrete comprising the steps of forming a substantially uniform suspension of graphene with water, and mixing the suspension with a cementitious material to form a concrete material. The method of graphene dispersion preparation compromises the steps of mixing graphite or graphene materials and a surfactant in the form of sodium cholate in water using high shear mixing device. After that any relatively heavy remaining powder material is removed by decanting the graphene/water suspension.

[0013] Despite the foregoing and other disclosures, there remains an unmet need for inexpensive and convenient materials for increasing strength of cured concrete article. There also remains an unmet need for inexpensive and convenient methods of preparing and using concrete compositions. There also remains an unmet need for concrete production methods that release less CO2 than existing approaches.

SUMMARY

[0014] As one aspect of the present technology, methods are provided for making a dispersed graphite additive for a concrete composition. The methods comprise mixing predispersion graphite with an aqueous medium to form a homogeneous dispersion, wherein the predispersion graphite has a surface area less than 100 m2/g and a D50 particle size between 1 and 500 pm. The present technology also includes concrete compositions comprising the dispersed graphite additive, a cementitious material, aggregates, and water.

[0015] As another aspect of the present technology, methods are provided for producing a concrete composition. The methods comprise (a) mixing predispersion graphite with an aqueous medium to form a homogeneous dispersion, wherein the predispersion graphite has a surface area less than 100 m2/g and a D50 particle size between 1 and 100 pm; and (b) mixing the dispersed graphite additive with a cementitious material, aggregates and water to form a concrete composition. Tn some embodiments, step (a) and step (b) are both performed at a concrete manufacturing site or at a construction site.

[0016] As another aspect, systems are provided for producing concrete, including mobile systems or stationary systems. The systems comprise a first mixer adapted for mixing predispersion graphite with an aqueous medium to form a homogeneous dispersion, and a second mixer adapted for mixing the dispersed graphite additive with a cementitious material, aggregates and water to form a concrete composition. The first mixer is fluidically connected to the second mixer.

[0017] As another aspect, mobile systems are provided for producing a dispersed graphite additive. The mobile systems comprise a mixing tank adapted for holding an aqueous medium, a mixer fluidically connected to the mixing tank, and a mobile unit (such as a vehicle or a trailer), wherein the mixing tank and the mixer are installed on the mobile unit.

[0018] These and other features and advantages of the present methods, compositions and systems will be apparent from the following detailed description, in conjunction with the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIGs. 1 A to ID are scanning electron microscopy images of an embodiment of the present dispered graphite addive prepared accoridng ot Example 1.

[0020] FTGs. 2A to 2D are Energy Dispersive X-ray Spectroscopy (EDS) atomic composition analysis of an embodiment of the present dispered graphite addive prepared accoridng ot Example 1. [0021] FTGs. 3 A to 3C are microstructure analysis of mortar samples prepared according to

Example 2 after compression testing.

DETAILED DESCRIPTION

[0022] As one aspect of the present invention, a dispersed graphite additive is provided which can replace water in whole or in part in various applications such as formation of cement and concrete. The dispersed graphite additive comprises dispersed graphite throughout the water or aqueous medium.

[0023] As another aspect of the present invention, manufacturing methods of the dispersed graphite additive are provided, wherein predispersion graphite is dispersed in an aqueous medium.

[0024] The present technology has numerous advantages over existing approaches. It provides ecologically friendly production, since it is water-based and uses a closed-loop system, with 100% conversion of input materials into the additive and without generating wastes requiring disposal.

[0025] The present technology reduces CO2 emissions attributable to concrete production. Generally, this problem can be approached from 2 directions: (1) Improving the quality of the produced concrete making it last longer and thereby reduce the amount of the materials needed for rebuilding, repair etc. Based on the improvement of concrete’s mechanical properties together with its resistance to the environmental factors. (2) Using an additive that reduces the amount of cement required for a given mass and quality of concrete. Finding the new additives. Cement reducing additives are being used already by the industry. For instance, fly ash and ground granulated blast-furnace slag. [0026] The dispersed graphite additive of the present disclosure can be used in both directions indicated above: Some regions of the world are already experiencing the problems with the supply of the aggregates and river sand - one of the key components of concrete. Potentially this will lead to the global shortage of the concrete. The use of the present dispersed graphite additive can allow improvement not just of the mechanical properties of the concrete, but also the properties, which affecting its longevity. Such as water, salt and chemical resistivity. In this approach, the dispersed graphite additive can increase the cost of the concrete, but this increase is very negligible when compared to the significant economic benefits from a long-term perspective.

[0027] The dispersed graphite additive can also be used to decrease the amount of cement in a concrete mix. A common approach to increase the mechanical strength of concrete is to increase the amount of the cement in the concrete composition. The use of the present dispersed graphite additive allows the concrete manufacturer to improve significantly the mechanical properties of the concrete without any extra cement addition. As a result, with the use of the present additives the savings in cement estimated at 15-45%, depending on the amount of cement, type of cement and amount of additive used. With the subtraction of the energy (electricity) required in the production, the use of the dispersed graphite additive allows reduction carbon dioxide emission by 19% on average (since less cement is required).

[0028] The present dispersed graphite additive can reduce concrete waste related to the quality of the cement received by the concrete manufacturer. Cement is a very moisture-sensitive material. If it not adequately protected from environmental moisture/wetness prior to the cements use in forming concrete, quality is reduced significantly and this directly diminishes the quality of the concrete. As a result, a concrete manufacturer may choose to dispose of a reduced-quality cement, return to the cement manufacturer for reprocessing, or to use a higher amount of the cement in the concrete formula. In this case, the present dispersed graphite additive can be used as a “booster” to correct short-comings in moisture exposed cement and avoid disposal or increased amounts.

[0029] The present technology has numerous economic benefits. Since the concrete industry has low margins, the industry is resistant to adopt and solutions that requier a higher cost than existing manufacturing methods and additives. Further, the concrete industry is highly resistant to changes in manfucaturing methodology even at the same cost, thus the industry requiers simple solutions that provide upfront cost savings. The present technology provides very simple and robust 1-step production, and it does not require any costly separation steps like some existing approaches. It uses inexpensive basic raw materials. Most of them are readily available from regional suppliers. The dispersed graphite additive is easy to use, safe to handle and does not require any extra modifications or equipment. If desired, the dispersed graphite additive can be easily implemented into an existing automated system or method of concrete production. In order to run the production no skilled workers are required, and it is not a labor-intensive production.

Dispersed Graphite Additive

[0030] The present disclosure provides a dispersed graphite additive for use in preparation of concrete and other curable compositions in which water is used for preparation. The dispersed graphite additive yields surprisingly good performance in the form of increased strength in the resulting concrete while being extremely economical regarding costs of both materials and labor for preparation. [0031] In some embodiments, the dispersed graphite additive comprises, or consists essentially of, or consists of a selected amount of dispersed graphite; and an aqueous medium. In some embodiments, the dispersed graphite additive further comprises, or consists essentially of, or consists of a selected amount of carbon nanotubes in addition to the dispersed graphite and the aqueous medium.

[0032] The selected amount of dispersed graphite in the dispersed graphite additive can be a minimum of 0.01%, or 0.02%, or 0.05%, or 0.1%, or 0.2%, or 0.33%, or 0.5%, or 0.67%, or 1%, or 1.25%, or 1.5%, or 1.75%, or 2%, or 2.5%, or 3%, or 4%, or 5%, or 7%, or 8.5%, or 10%, based on weight over total volume (or “w/v”). Alternatively or additionally, the selected amount of graphite in the additive can be a maximum of 50%, or 45%, or 40%, or 35%, or 30%, or 25%, or 20%, or 15%, or 10%, or 8%, or 5%, or 4.5%, or 4%, or 3.5%, or 3%, or 2.75%, or 2.5%, or 2.25%, or 2%, or 1.75%, or 1.5%, or 1% w/v. It is contemplated that any of the foregoing minimums and maximums can be combined to form a range for the selected amount of graphite, so long as the minimum is smaller than the maximum.

[0033] A surprising aspect of the present technology is that the dispersed graphite additive can be prepared from relatively inexpensive and easily obtained starting materials. The present inventors have discovered an alternative to the complex, expensive, and/or difficult materials required by other approaches, such as graphene flakes having specific lateral dimensions or graphite nanoplatelets having specific thicknesses and planar dimensions. An unexpected benefit of the present technology is the ability to use predispersion graphite that is not costly or difficult to obtain. [0034] In some embodiments, the predispersion graphite comprises, consists essentially of, or consists of natural graphite. In some embodiments, the predispersion graphite comprises, consists essentially of, or consists of micronized graphite.

[0035] In some embodiments, the predispersion graphite has a characteristic surface area, such as a BET surface area. Specific surface areas of predispersion graphite can be determined by nitrogen (N2) adsorption-desorption isotherms on a suitable instrument, such as a Micrometric ASAP 2010. In one suitable protocol, samples are outgassed at 0.13 Pa and 100° C. for 6 hours prior to adsorption studies. The volume of gas adsorbed to the surface of the predispersion graphite is measured at the boiling point of nitrogen (-196° C.). The amount of adsorbed gas is correlated to the total surface area of the adsorbent particles including pores in the surface. Specific surface area calculations are carried out using the BET (Brunauer-Emmett-Teller) method.

[0036] The predispersion graphite can have desired surface area characteristics, such as a surface area of 100 m²/g or less, or 80 m²/g or less, or 50 m²/g or less, or 30 m²/g or less, or 25 m²/g or less, or 20 m²/g or less, or 18 m²/g or less, or 16 m²/g or less, or another maximum. The desired surface area the predispersion graphite can be 1 m²/g or more, or 2 m²/g or more, or 3 m²/g or more, or another minimum. It is contemplated that any of the foregoing minimums and maximums can be combined to form a range for the desired surface area of predispersed graphite, so long as the minimum is smaller than the maximum. Exemplary surface area ranges include from 1 m²/g to 100 m²/g, or from 2 m²/g to 30 m²/g, or from 3 m²/g to 18 m²/g.

[0037] In some embodiments, the predispersion graphite has a characteristic particle size, such as a D50 particle size. D50 particle size refers to the value of the particle diameter at 50% in the cumulative distribution. For example, for sample of particles having a D50 particle size of 10 pm, then 50% of the particles in the sample are larger than 10 pm, and 50% are smaller than 10 pm. Other particle size characteristics that may be used to define the predispersion graphite include DIO and D90 particle sizes, which are the sizes below which 10% or 90%, respectively, of all particles in the sample are found. Particle size characteristics of predispersion graphite is generally indicated by graphite suppliers, or it can be measured using a light scattering instrument. In one suitable protocol for measuring D50 particle size, 5 mg of predispersion graphite is dispersed in 1 mL toluene. Light scattering measurements can be obtained at a suitable wavelength (e.g., 633 nm) with a constant angle (e.g., 173°) at a desired temperature (e.g., 25°C). The D50 particle size or other particle size characteristics can be obtained from the instrument.

[0038] The predispersion graphite can have desired particle size characteristics, such as a D50 particle size. The desired D50 particle size of the graphite in the additive can be a minimum of 0.5 micron, or 1 micron, or 2 microns, or 3 microns, or 5 microns, or 10 microns, or 20 microns, or 30 microns, or 40 microns, or 50 microns, or 60 microns, or 80 microns, or 100 microns. Alternatively, or additionally, the desired D50 particle size of the graphite in the additive can be a maximum of 1 mm, or 500 microns, or 250 microns, or 200 microns, or 150 microns, or 100 microns, or 80 microns, or 60 microns, or 50 microns. It is contemplated that any of the foregoing minimums and maximums can be combined to form a range for the desired D50 particle size of graphite, so long as the minimum is smaller than the maximum. Exemplary D50 particle size ranges include from 1 to 100 microns, or from 2 to 80 microns, or from 3 to 60 microns, or from 3 to 20 microns. [0039] The aqueous medium of the dispersed graphite additive can be any suitable mixture of water and other solvents. In some embodiments, the aqueous medium is only water or mostly water. In some embodiments, an additional solvent is included, such as an alcohol.

Non-graphite Carbon Components

[0040] The dispersed graphite additive (or the concrete composition containing the dispersed graphite additive) also contains a selected amount of one or more non-graphite carbon components (i.e., carbon-based materials other than graphite). For example, the dispersed graphite additive can include carbon nanotubes dispersed throughout the water or other aqueous medium. The selected amount of carbon nanotubes or other non-graphite carbon components in the dispersed graphite additive can be a minimum of 0.001%, or 0.002%, or 0.005%, or 0.01%, or 0.02%, or 0.033%, or 0.05%, or 0.067%, or 0.1%, or 0.125%, or 0.15%, or 0.175%, or 0.2%, or 0.25%, or 0.3%, or 0.4%, or 0.5%, or 0.7%, or 0.85%, or 1%, based on weight over total volume (or “w/v”). Alternatively or additionally, the selected amount of non-graphite carbon components in the dispersed graphite additive can be a maximum of 5%, or 4.5%, or 4%, or 3.5%, or 3%, or 2.5%, or 2%, or 1.5%, or 1%, or 0.8%, or 0.5%, or 0.45%, or 0.4%, or 0.35%, or 0.3%, or 0.275%, or 0.25%, or 0.225%, or 0.2%, or 0.175%, or 0.15%, or 0.1%, based on weight over total volume (or “w/v”). It is contemplated that any of the foregoing minimums and maximums can be combined to form a range for the selected amount of non-graphite carbon components, so long as the minimum is smaller than the maximum.

[0041] In some embodiments, the dispersed graphite additive has a selected concentration of total carbon materials (dispersed graphite and dispersed non-graphite carbon components) in the aqueous medium. The selected amount of total carbon materials in the dispersed graphite additive can be a minimum of 0.015%, or 0.02%, or 0.05%, or 0.1%, or 0.2%, or 0.25%, or 0.5%, or 0.75%, or 1%, or 1.3%, or 1.5%, or 1.7%, or 1.85%, or 2%, or 2.25%, or 2.5%, or 3%, or 4%, or 5%, or 7%, or 8.5%, or 10%, based on weight over total volume (or “w/v”).

Alternatively or additionally, the selected amount of total carbon materials in the additive can be a maximum of 55%, or 50%, or 45%, or 40%, or 35%, or 30%, or 25%, or 20%, or 15%, or 10%, or 8%, or 5%, or 4.5%, or 4.25%, or 4%, or 3.5%, or 3.25%, or 3%, or 2.75%, or 2.5%, or 2.25%, or 2%, or 1.75%, or 1.5%, or 1%, based on weight over total volume (or “w/v”). Suitable concentrations include those in the range of 0.5 g/L to 400 g/L (or 0.05% to 40% w/v).

[0042] The non-graphite carbon components can be carbon nanotubes, such as single-wall carbon nanotubes, multi-wall carbon nanotubes, or a mixture thereof. Single-wall carbon nanotubes are one dimensional, cylindrically shaped carbon structures that have a high surface area and aspect ratio. Multi-wall carbon nanotubes are two or single-wall carbon nanotubes with one nested within the other.

[0043] In some embodiments, the non-graphite carbon components include graphene oxide. In some embodiments, the non-graphite carbon components can be carbon fibers, which are described in more detail below.

Reinforcement Fibers and Particles

[0044] In some embodiments, the dispersed graphite additive (or the concrete composition containing the dispersed graphite additive) also contains one or more reinforcement particles and/or fibers. Suitable reinforcement fibers include steel fibers, polymer fibers, carbon fibers, glass fibers, and mixtures thereof, such as polypropylene, nylon, polyvinyl alcohol, glass, steel, carbon, aramid and cellulose fibers. Fibers can have diameters in the range 0.1 to 5000 microns and length-to-diameter ratio of 10 to 1000 Suitable reinforcement particles include silica particles such as nanosilica particles. In some embodiments, the present concrete composition does not contain reinforcement particles or reinforcement fibers.

Other Concrete Components

[0045] In some embodiments, the dispersed graphite additive (or the concrete composition containing the dispersed graphite additive) also contains other concrete components, including but not limited to dispersants and plasticizers (including superplasticizers), surfactants and emulsifiers, thickeners, air releasing agents, water reducing agents, curing accelerators, shrinkage-reducing agents, retardants, and corrosion inhibitors. Many components have more than one function in an additive or concrete composition, so the terms should be considered mutually inclusive, and a given chemical component may be encompassed by more than one term. Suitable dispersants include hydroxycarboxylic acids such as citric acid; silica fume; a sulfonated-formaldehyde-based dispersant; polystyrene sulfonates, polycarboxylated ethers, and any combination thereof. Suitable plasticizers include sodium lignosulphonates, and suitable superplasticizers include sulfonated naphthalene formaldehyde condensate, sulfonated melamine formaldehyde condensate, acetone formaldehyde condensate and polycarboxylate ethers.

Examples of superplasticizers include PMS (polymelamine sulfonate) and PNS (polynaphthalene sulfonate). Suitable surfactants and emulsifiers include nonionic surfactants such as SITREN® AirVoid® product line.

[0046] In general, the dispersed graphite additive can include any chemical additives, mineral additives, polymer additives, coloring additives, fibers, and combinations thereof suitable for use in concrete. Production of the Dispersed Graphite Additive

[0047] As another aspect of the present invention, methods are provided for producing a dispersed graphite additive. The present methods include mixing predispersion graphite in an aqueous medium such as water. Graphite and other carbon materials can be dispersed in the aqueous medium individually or can be combined and dispersed together.

[0048] Any suitable equipment or technique can be used for dispersion of the predisperson graphite, including high-shear mixers; high-speed mixers or blenders; and cavitators. In some embodiments, the predisperson graphite and aqueous medium are substantially homogenized, or mixed for a time and at a shear such that a homogeneous mixture of graphite and aqueous medium is formed. Homogenization is used to effectively disperse predisperson graphite in an aqueous medium.

[0049] High shear mixers are typically rotor-stator mixers, and they can be batch high-shear mixers and inline high-shear mixers. High shear in rotor-stator mixers is achieved by using a high rotational velocity and/or a small gap between the rotor and the stator.

[0050] Cavitators are devices that induce reductions in static pressure of a liquid below its vapor pressure, thereby forming small cavities (e.g., bubbles) in the liquid; when the cavities collapse, they cause intense mixing of the liquid. Cavitors can induce cavitation by ultrasonic or other types of waves, or mechanical agitation use as rotors with cavities.

[0051] In some embodiments, the present methods or systems for dispersing graphite in an aqueous medium are coupled or inline with steps or apparatus for processing the predisperson graphite, such as wet mills or other wet grinding processes. [0052] In some embodiments, the dispersion of graphite, carbon nanotubes and other components in the aqueous medium remains stable for a desired time period that allows for its use in concrete manufacture without other steps. In some embodiments, the dispersion is substantially free of surfactants or dispersants. In some embodiments, the dispersion is substantially free of hydrophilic cellulose and derivatives thereof.

[0053] In some embodiments, the method for producing a dispersed graphite additive does not comprise sonication or ultrasonication, that is, the graphite is dispersed in water without sonication or ultrasonication.

Concrete Components, Compositions and Articles

[0054] In another aspect, the present disclosure relates to a concrete component suitable for use in making concrete. The concrete component comprises (a) a dispersed graphite additive as described herein; and (b) aggregates. The term “aggregates” refers to durable particles such as gravel, sand and crushed stone used in concrete. Examples of aggregates include crushed stone, gravel, sand, synthetic particles, recycled particles, and combinations thereof. Aggregates are generally classified according to an aggregate characteristic size, which can correspond, for example, to the largest, median, or smallest size particle in the aggregate particle size distribution, such as 37.5 mm, 25 mm, 19 mm, 12.5 mm, 9.5 mm, 4.75 mm, 2.36 mm, 1.18 mm, 0.60 mm, 0.30 mm, 0.15 mm, 0.075 mm, based on standard sieve sizes/techniques. It is contemplated that the aggregate particle size distribution can be within a range formed by any combination of the foregoing sizes. Aggregates used in concrete compositions generally include a combination of fine aggregates (such as sand) with maximum particle size less than 4.75 mm and coarse aggregate (such as stone or gravel) with maximum particle size more than 4.75 mm. The aggregates can be included in any desired amount, typically in a far greater amount than the dispersed graphite additive, such as at least 50x, or lOOx, or 200x the amount of the dispersed graphite additive (by weight).

[0055] In another aspect, the present disclosure relates to a concrete composition comprising (a) a dispersed graphite additive as described herein; (b) aggregates; and (c) a cementitious material. Cementitious materials are mineral-based binders that upon curing form a hardened matrix.

[0056] The dispersed graphite additive can be combined with the cementitious material, either in the course of producing a concrete composition or to form a modified cementitious composition. In some embodiments, the dispersed graphite additive is mixed with a hydraulic cementitious material prior to or while they are combined with aggregates to form a hydrated concrete composition which is ready to undergo curing. Hydraulic cementitious materials undergo curing when mixed with water, so in general, the dispersed graphite additive is combined with a hydraulic cementitious material shortly before or immediately at the time at which curing is intended.

[0057] Suitable cementitious materials include uncured hydraulic cements, such as Portland cement, Portland-limestone cement, Portland-slag cement, Portland-pozzolan cement, ternary blended cement, general use cement, high early strength cement, moderate sulfate resistance cement, high sulfate resistance cement, moderate heat of hydration cement, low heat of hydration cement, masonry cement, calcium aluminate cement, calcium sulfoaluminate cement, aluminosilicate-based cement, shrinkage compensating cement, gypsum, lime, and combinations thereof. Hydraulic cementitious materials typically include one or more of the following minerals: calcium silicate, calcium aluminosilicate, alkali aluminosilicate, calcium aluminate, calcium oxide, calcium aluminosulfate, and combinations thereof. Hydraulic cementitious materials can be prepared with different water-to-solid ratios, and can further include various chemical, mineral and polymer additives.

[0058] In the present concrete compositions, the aggregate can be included in any desired amount, typically ranging from about 25 wt. % to about 1000 wt. % relative to the cementitious material. In some embodiments, the concrete composition comprises aggregates in a minimum of 50%, 100%, 200%, 300%, or 400% by weight relative to the cementitious material. In some embodiments, the concrete composition comprises aggregates in a maximum of 200%, 300%, 400%, 500%, 600%, or 800% by weight relative to the cementitious material. It is contemplated that any of the foregoing minimums and maximums can be combined to form a range for the amount of aggregates in the concrete composition, so long as the minimum is smaller than the maximum. It is also contemplated that the foregoing amounts can apply to an anhydrous concrete composition, a hydrated concrete composition (e.g., a concrete mixed with water and to be applied to a mold), and/or to a cured concrete article.

[0059] In some embodiments, the concrete composition does not include any extra chemical besides the materials which currently are being used by concrete industry. This is very advantageous since the use of any additives which are currently not approved for use in the concrete will complicate the manufacturing process. New chemicals may have to go through a certification process to evaluate its effect on the concrete properties and longevity (leading to extra cost and time, plus potential risk of failure).

[0060] In another aspect, the present disclosure relates to cured concrete articles comprising

(a) a hard matrix comprising reaction products of water and a cementitious material; (b) graphite homogeneously dispersed within the hard matrix; and (c) aggregates distributed throughout the hard matrix. The cured concrete articles can also comprise any of the non-graphite carbon components, reinforcement fibers and particles, and other additive components described herein, as well as other chemical additives, mineral additives, polymer additives, coloring additives, fibers, and combinations thereof suitable for use in concrete.

Concretes & Cured Structures

[0061] In another aspect, the present disclosure relates to a method for curing an uncured concrete composition. The dispersed graphite additive is mixed with other components, such as a cementitious material and aggregates, and cured using suitable conditions for concrete curing. In some embodiments, the method comprises (a) applying (e.g., depositing or pouring) an uncured concrete composition that includes a dispersed graphite additive as described herein to a mold or other surface; and (b) curing the uncured concrete composition for a selected period, thereby forming a cured concrete composition, wherein the cured concrete composition comprises a solid matrix with graphite homogeneously dispersed within the matrix and aggregates dispersed within the matrix. The solid matrix is the reaction product of the cementitious material and water.

[0062] The surfaces or molds on which the pourable concrete composition is applied can include any solid surface such as ground or a compacted base (e.g., for laying a road outside, or a building floor, or footing), formwork (e.g., for construction of wall, beam, column, or other structural building element), another cured cement/concrete surface (e.g., for repair, forming, or creating a multi-layered structure in road, building, or other context). The applied area can further include one or more reinforcing structures such as continuous bars (e.g., steel, other metal, or composite material) and discrete fibers with 0.1 to 5000 micrometer diameter and length-to-diameter ratio of 10 to 1000 of (e.g., steel, glass, polypropylene, nylon, polyvinyl alcohol, Kevlar, or carbon) added to the mix prior to, during and after the addition of other mix ingredients or during mixing with a total fiber volume that is 1 to 100 times volume of the graphite nanoplatelets. Curing can be accomplished in the presence of moisture or in sealed condition at ambient or elevated temperature. The selected period for curing can be at least and/or up to 1, 2, 3, 5, 7, 14, 28, 35, 42, 56, or 60 days prior to putting the cured composition into normal use such as a road, floor, overlay, patch, structural element, or mold for further cement/concrete appli cati on/ curing .

[0063] The cured concrete article made with the present dispersed graphite additive can be characterized in terms of its relative strength, moisture sorption resistance, chloride diffusion resistance, durability, and/or dimensional stability. In some embodiments, the cured concrete article, and/or the concrete composition that produces such a cured concrete article, is M5, M7.5, M10, M15, M20, M25, or M30 grade, or a higher grade. In some embodiments, the present compositions attain a higher grade (or higher compressive strength) with a relatively low amount of cementitious material, or with a lower proportion of cementitous material relative to fine aggregates and coarse aggreates. The conventional understanding in the concrete industry has been that various concrete grades were produced from typical mix ratios of cement : sand : coarse aggregates, which are set forth in Table 1.

Table 1

In some embodiments, the present concrete compositions with the dispersed graphite additive make a cured concrete article having a higher concrete grade than what would be expected for a particular mix ratio. For example, in some embodiments, a concrete composition comprising the present dispersed graphite additive has a mix ratio of 1 : 2 : 4 of cementitious material : fine aggregates : coarse aggregates, yet it produces a cured concrete article having a compressive strength of 20 MPa. More generally, the present concrete compositions containing the dispersed graphite additive can have a mix ratio typical of a lower concrete grade but surprisingly have a compressive strength of a higher concrete grade (as set forth in Table 1).

[0064] In some embodiments, the dispersed graphite additive achieves desirable performance even though it is free of one or more components that are conventionally used in concretes or that are said to improve performance. For instance, the dispersed graphite additive can be substantially free of surfactants and/or polyelectrolytes such as poly(acrylic acid), poly(ethyleneimine), or poly(vinyl alcohol).

[0065] The dispersed graphite additive, at relatively low amounts (for example, at about 0.1% by weight or less of the concrete composition), can produce improvements in fracture toughness, crack resistance, impact and abrasion resistance, barrier qualities, durability, and other engineering properties of cured concrete articles.

[0066] As another aspect of the present disclosure, a method for preparing and using a dispersed graphite additive comprises mixing predispersion graphite with at least one other type of carbon, carbon nanofiber, carbon nanotube single or multi-walled, and/or amorphous carbon to form a dispersion. The method also comprises of adding a plasticizer and aggregate to the dispersion within 1 minute, or within 3 minutes, or within 5 minutes, or within 10 minutes, or within 15 minutes. The method also comprises adding at least one part of the graphite additive dispersion to water and a cementitious material to form a liquid concrete mixture after the plasticizer and the aggregate have been added.

Method of Using the Dispersed Graphite Additive

[0067] The present disclosure also provides methods and systems for using the dispersed graphite additive in concrete compositions. In general, the dispersed graphite additive replaces or is a substitute for a portion of the water that is used to form concrete. For example, replaces a minimum of 1%, or 2%, or 5%, or 7%, or 10%, or 12%, or 15%, or 18%, or 20%, or more of water, and/or a maximum of 50%, or 45%, or 40%, or 33%, or 25%, or 15%, or 12%, or 10%; the foregoing minimums and maximums can be combined to form a range, so long as the minimum is less than the maximum, and the percentages can be based on weight or volume. In some embodiments, the dispersed graphite additive is used in a selected ratio relative to water used in a concrete composition. For example, a concrete composition can have a (dispersed graphite additive) : (water) ratio that is between 1:50 and 1: 1, or between 1:20 and 1:3.

[0068] The dispersed graphite additive can be combined with materials such as cementitious materials, aggregates, other additives, reinforcement fibers or particles, and other components to form a concrete composition. The components can be added to a mixer in conjunction with water, and regular concrete mixing can be employed to form a concrete composition ready for use. Regular concrete mixing is typically be performed with rotational equipment such as planetary mixers, drum mixers, pan mixers, vertical axis mixers, and twin shaft mixers that are stationary or mounted on a vehicle. Regular concrete mixing can also be performed manually. Tn some embodiments, the method comprises mixing of the dispersed graphite additive and the cementitious material before combining with the aggregate. In other embodiments, the method comprises mixing of the dispersed graphite additive and the aggregate before combining with the cementitious material. In some embodiments, the method comprises mixing of all components using different mixing speeds and durations. In some embodiments, the method comprises applying the concrete composition, such as by pouring on a surface or into a mold. In some embodiments, the method comprises curing the concrete composition at an ambient temperature (e.g., 20°C to 30°C) or at an elevated temperature to form a cured concrete article.

[0069] The present disclosure provides various systems for concrete manufacturers having various production capacities. Another advantage of the present technology is its adaptability for various concrete manufacturers and manufacturing site.

[0070] The system for producing the dispersed graphite additive can be a Stationary, Central system (for large concrete manufacturers or for the areas with many nearby average or small size concrete manufacturers). One site with the numerous production units.

[0071] Another embodiment is a stationary system installed directly on the concrete manufacturing site. Due to the compact size of production units of the present systems and ease of installation, manufacturing the dispersed graphite additive does not require a lot of space. The additive can be produced on demand by or for the concrete manufacturer. In addition to that, production capacity can be easily adjusted by the increasing or decreasing the amount of the units on a site.

[0072] Another embodiment is a mobile system adapted for temporary installation on a concrete manufacturing site (if, for instance, concrete is produced directly on a construction site).

As another embodiment, the present systems can be installed on one or more mobile units. Tanks, mixers and other equipment can be installed on a vehicle or a trailer adapted to be connected to a vehicle, which can come directly to the concrete manufacturing site for a short period of time. This will allow the dispersed graphite additive to be easily supplied to a smallsized or temporary concrete manufacturers. In some cases, the mobile unit is configured for sites with limited electrical power supply, such as by including a fuel tank for a fuel that powers a mixer. The present technology can be powered by electricity from an electrical grid, or by a liquid fuel. Therefore, another advantage of the present technology is that its use is not just electrically powered equipment, but also fossil-powered equipment (like diesel fuel). Therefore, the dispersed graphite additive can be manufactured even in the areas with limited or even without any electricity supply.

[0073] Others aspects and advantages of the systems with mobile units include simplicity of the production technology, non-toxic, non-flammable production, production does not utilize any hazardous or toxic materials, requires the transportation only dry starting materials and use of the local water supplies or additives, which are being used by the local concrete manufacturer.

[0074] Before the various examples are described, it is to be understood that the teachings of this disclosure are not limited to the particular examples described, and as such can, of course, vary. In view of this disclosure, it is noted that the compositions and methods can be implemented in keeping with the present teachings. Further, various components, materials, steps and parameters are included by way of illustration and example only and not in any limiting sense. In view of this disclosure, the present teachings can be implemented in other applications, and suitable components, materials, structures and equipment to implement these other applications can be determined in light of the present teachings by those skilled in the relevant area.

EXAMPLES

Example 1

[0075] In this example, an embodiment of the dispersed graphite additive was made as follows. An inline high shear emulsifying pump (5.5 KW) was connected with a 50-gallon tank by a feed conduit, and an outlet conduit from the pump returned material to the tank. The arrangement of the emulsifying pump and the tank form a closed-loop system capable of making the dispersed additive. The tank was charged with 1.33 kg of natural graphite having a D50 particle size of 50 microns. 100 L of water was added to the tank, and the resulting mixture of graphite and water was run through the homogenizer pump for 5 hours. Then 133 g of carbon nanotubes (outer diameter 10-40 nm, length 10 - 40 microns) was added to the mixture, and this new mixture was processed through the homogenizer pump for another 20 min and turned off, thereby producing the dispersed carbon additive.

Example 2

[0076] In this example, a dispersed graphite additive made according to Example 1 (referred to as APNT Additive) was used to make a concrete composition. The concrete composition comprised 1% by weight of the additive; 9.8% by weight of a hydraulic cementitious material; 82.8% by weight of sand and aggregates; 6.3% by weight of water and 0.1% by weight of admixture. The dispersed graphite additive was shaken very well before combining with the other components. As a reference, concrete was made using an equivalent amount of water in the place of the dispersed graphite additive. The reference sample and the experimental sample were then poured into a volume of 1.4 L and allowed to set for several days to form cured concrete articles.

[0077] The concrete articles produced from the experimental concrete composition and the reference concrete composition were tested for several properties important to concrete manufacturers and builders. The compressive strength of the cured concrete articles was measured using ABNT NBR 5739/2018. The elastic modulus was measured using ABNT NBR 8522/2017, and the flexural strength was measured using NBR 12142/10. Water absorption was measured using NBR 9778/2005. The results are shown in Table 2:

Table 2

[0078] The compressive strength testing reveals that the dispersed graphite additive increased the strength of the cured concrete article to a surprising extent, with an approximately 26% improvement over the reference. Elastic modulus and flexural strength were also improved to surprising extents, with approximately 14% and 23% improvements respectively.

[0079] Mortar samples prepared according to this example were subjected to microstructure analysis. FIGs. 3A to 3C are scanning electron microscopy images of mortar samples after compression testing. The black spots on these images are indicating the position of the APNTEK additives. The presence of the dispersed graphite additive prevents the development of microcracks and their propagation (arrest) inside the brittle structure (mortar, concrete).

Example 3

[0080] In this example, the potential reduction of CO2 emissions by use of the dispersed graphite additive made according to Example 1 is calculated. A batch of the dispersed graphite additive is produced in a mixing tank. The batch is enough to feed 13 cubic meters of M20 concrete. Assuming that each cubic meter contains 265 kg of cement then: 256x13 = 3,445 kg total of cement/per one batch of the dispersed graphite additive.

[0081] By using the dispersed graphite additive, a concrete manufacturer can make grade M30 concrete using a mix ratio of cement:sand:coarse aggregates that is typically used for M20 concrete. The savings in cementitious material in one cubic meter is 65 kg. Therefore in 13 cubic meters the savings are: 65x13 = 845 kg of the cementitious material.

[0082] Production of 845 kg of cement typically generates 845 kg of CO2. A typical electricity consumption by a system producing the present dispersed graphite additive is 60 KWh. During the production of 60 KWh of electricity, 25 kg of CO2 is emitted. Per one cubic meter it will add 25/13, or about 2 kg of CO2. Therefore, the total reduction of the CO2 is: 845- 25=820 kg/per one batch of the reactor. [0083] Reduction of CO2 per one cubic meter is 820/13= 63 kg of CO2. The CO2 reduction per one cubic meter of M30 concrete: Taking into account that one cubic meter of M30 concrete has 330 kg of the cement. Production of 330 kg of the cement generates 330 kg of CO2. Production of 265 kg of the cements generates 265 kg of CO2.

[0084] With the present dispersed graphite additive, the total amount of CO2 generated will be 265+2=267 kg of CO2, compared to 330 kg of CO2 from a typical production of concrete composition. This is 330-267=63 kg less of CO2, which is 19% reduction.

[0085] As used in the specification and appended claims, and in addition to their ordinary meanings, the terms "substantial" or "substantially" mean to within acceptable limits or degree to one having ordinary skill in the art. For example, "substantially free of' a material means that one skilled in the art considers the remaining amount of material to be acceptable.

[0086] As used in the specification and the appended claims and in addition to its ordinary meaning, the terms "approximately" and "about" mean to within an acceptable limit or amount to one having ordinary skill in the art. The term "about" generally refers to plus or minus 15% of the indicated number. For example, "about 10" may indicate a range of 8.5 to 11.5. For example, "approximately the same" means that one of ordinary skill in the art considers the items being compared to be the same.

[0087] In the present disclosure, when percentages are used to identify the amount of a component, the percentages are based on the weight of the component over the total weight of the composition (unless the context indicates another basis of calculating the percentage). When a component is provided in a mixture (such as in a mixture comprising a liquid medium), the weight of the component itself (not including the liquid medium or other components in the mixture) is used to calculate its percentage in the composition.

[0088] As used in the specification and appended claims, the terms "a," "an," and "the" include both singular and plural referents, unless the context clearly dictates otherwise. Thus, for example, "a component" includes one component and multiple components.

[0089] In the present disclosure, numeric ranges are inclusive of the numbers defining the range. It should be recognized that chemical structures and formula may be elongated or enlarged for illustrative purposes.

[0090] As disclosed herein, a number of ranges of values are provided. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0091] The term “conduit” generally encompasses any structure configured to define a flowpath for fluid to travel from one point (e.g., an inlet of the conduit) to another point (e.g., an outlet of the conduit), though a conduit can deliver fluid to intermediate points as well. A conduit can be flexible, rigid, or both in some measure or portions. A conduit can be relatively long or short, and/or linear or nonlinear, so long as it provides a flowpath from one component (such as a gas source) to another component (such as a vent). For example, a conduit can be a long tube, a short fitting, or a manifold with multiple entrances and/or exits. A conduit typically has an entrance and an exit, though in some embodiments, a conduit can have multiple entrances and/or exits, such as where a conduit with two or more entrances converges or joins to one exit, or where a conduit with one entrance diverges or splits to two or more exits. A conduit is often described by its length and inner diameter (i.d.) which can be used to calculate a volume of a conduit. The geometry of a conduit may vary widely and includes circular, rectangular, square, D-shaped, trapezoidal or other polygonal cross-sections. A conduit may comprise varying geometries (e.g., rectangular cross-section at one section and trapezoidal cross-section at another section). Copper, stainless steel or other metals are often preferred for conduits, but other materials may be used, such as plastics and polymers.

[0092] The term “connected” means that two components are fluidically connected, or physically connected, or both. The term “fluidically connected” means that two components are in fluid communication and includes direct connections between the two components as well as indirect connections where one or more other components are in the flowpath between the two components. For example, a first component and a second component are fluidically connected if an outlet from the first component is physically connected to an inlet of the second component, or if a conduit connects the first and second components, or if one or more intervening components, such as a valve, a pump, or other structure, is between the two components as fluid flows from the first component to the second component, or vice versa. Components can be physically connected in any suitable way. In general, physical connections that are fluid-tight are desired for the present methods and systems.

[0093] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present teachings, some exemplary methods and materials are now described. [0094] All patents and publications referred to herein are expressly incorporated by reference.

Claims

CLAIMS What is claimed is:

1. A method for making a dispersed graphite additive for a concrete composition, the method comprising: mixing predispersion graphite with an aqueous medium to form a homogeneous dispersion, wherein the predispersion graphite has a surface area less than 100 m²/g and a D50 particle size between 1 and 500 pm.

2. The method of claim 1, wherein the predispersion graphite has a surface area between 2 and 25 m²/g.

3. The method of claim 1, wherein the predispersion graphite has a D50 particle size between 2 and 100 pm.

4. The method of claim 1, wherein the predispersion graphite is natural graphite.

5. The method of claim 1, wherein the predispersion graphite is mixed with the aqueous medium by circulating them through a homogenization pump for a period of at least 2 hours.

6. The method of claim 1, the predispersion graphite is mixed with the aqueous medium in a closed-loop system.

7. The method of claim 1 , further comprising mixing one or more non-graphite carbon components with the aqueous medium.

8. The method of claim 1, further comprising mixing carbon nanotubes with the aqueous medium.

9. The method of claim 8, wherein the predispersion graphite and carbon nanotubes are mixed with the aqueous medium by circulating them until both the predispersion graphite and the carbon nanotubes are homogeneously dispersed in the aqueous medium.

10. The method of claim 1, wherein the dispersed graphite additive comprises 2% by weight or less of dispersed graphite and 0.2% by weight or less of carbon nanotubes.

11. The method of claim 1, wherein the dispersed graphite additive does not contain a non-graphite carbon component.

12. The method of claim 1, wherein the dispersed graphite additive does not contain reduced graphene oxide, graphene oxide, or a chemically formed graphene particle.

13. The method of claim 1 , wherein the dispersed graphite additive does not contain a surfactant.

14. The method of claim 1 , wherein the dispersed graphite additive does not contain a electrolyte.

15. The method of claim 1, wherein the carbon nanotubes have an outer diameter from 1 nm to 400 nm, and a length from 1 micron to 400 microns.

16. The method of claim 1, wherein the aqueous medium is water.

17. A concrete compositi on compri sin : the dispersed graphite additive made by the method of claim 1; a cementitious material, aggregates, and water.

18. The concrete composition of claim 17, further comprising one or more nongraphite carbon components.

19. The concrete composition of claim 18, wherein the one or more non-graphite carbon components are selected from the group consisting of carbon nanotubes, carbon fibers, carbon nanofibers, and combinations thereof.

20. The concrete composition of claim 17, wherein the composition does not contain a non-graphite carbon component.

21. The concrete composition of claim 17, further comprising reinforcement particles, reinforcement fibers, or both.

22. The concrete composition of claim 17, wherein the composition is substantially free of reinforcement particles, reinforcement fibers, or both.

23. The concrete composition of claim 17, further comprising one or more other concrete components selected from the group consisting of dispersants, plasticizers, surfactants, emulsifiers, thickeners, air releasing agents, water reducing agents, curing accelerators, shrinkage-reducing agents, retardants, corrosion inhibitors, and combinations thereof.

24. The concrete composition of claim 17, wherein the dispersed graphite additive does not contain reduced graphene oxide or graphene oxide.

25. The concrete composition of claim 17, wherein the composition does not contain a surfactant or a polyelectrolyte.

26. A method of producing a concrete composition comprising:

(a) mixing predispersion graphite with an aqueous medium to form a homogeneous dispersion, wherein the predispersion graphite has a surface area less than 100 m²/g and a D50 particle size between 1 and 100 pm; and (b) mixing the dispersed graphite additive with a cementitious material, aggregates and water to form a concrete composition.

27. The method of claim 26, further comprising:

(c) applying the concrete composition to a surface or a mold.

28. The method of claim 26, wherein the homogeneous dispersion is mixed in step (b) within 12 hours of being formed in step (a).

29. The method of claim 26, wherein step (a) and step (b) are both performed at a concrete manufacturing site.

30. The method of claim 26, wherein steps (a) and (b) are performed at a construction site.

31. The method of claim 26, wherein the method further comprises transporting the predispersion graphite to the construction site in dry form.

32. The method of claim 26, wherein the concrete composition does not contain any concrete additive other than the dispersed graphite additive.

33. The method of claim 26, wherein step (a) is performed using a mixer powered by a liquid fuel and which is not plugged into an electrical grid.

34. The method of claim 26, further comprising transporting a mobile mixing apparatus for mixing the predisdespersion graphite and the aqueous medium to a site prior to step (a), wherein mobile mixing apparatus comprises a mixer.

35. The method of claim 34, wherein the mobile mixing apparatus comprises a tank fluidically connected to the mixer.

36. The method of claim 34, wherein the mixer and the tank are installed on a mobile unit.

37. A system for producing concrete comprising: a first mixer adapted for mixing predispersion graphite with an aqueous medium to form a homogeneous dispersion; a second mixer adapted for mixing the dispersed graphite additive with a cementitious material, aggregates and water to form a concrete composition; and the first mixer is fluidically connected to the second mixer.

38. The system of claim 37, wherein the first mixer is a high-shear mixer.

39. The system of claim 37, wherein the second mixer is a planetary mixer, a drum mixer, a pan mixer, a vertical axis mixer, or a twin shaft mixer.

40. The system of claim 37, wherein the system further comprises a mixing tank fluidically connected to both an inlet and an outlet of the first mixer.

41. The system of claim 37, wherein the first mixer and the second mixer are installed at a concrete manufacturing site.

42. The system of claim 37, wherein the first mixer is installed on a first vehicle, and the second mixer is installed on a second vehicle.

43. The system of claim 37, further comprising a water source fluidically connected to the first mixer.

44. The system of claim 43, further comprising a tank adapted for storing predispersion graphite in dry form.

45. The system of claim 44, further comprising a conveyor or hopper adapted for adding dry predispersion graphite to the mixing tank.

46. A mobile system for producing a dispersed graphite additive comprising: a mixing tank adapted for holding an aqueous medium, a mixer fluidically connected to the mixing tank, and a mobile unit, wherein the mixing tank and the mixer are installed on the mobile unit.

47. The system of claim 46, wherein the mobile unit is in a vehicle or a trailer.

48. The system of claim 46, wherein the mixer and the second mixer are installed at a concrete manufacturing site.

49. The system of claim 46, wherein the first mixer is installed on a first vehicle, and the second mixer is installed on a second vehicle.

50. The system of claim 46, further comprising a water source fluidically connected to the first mixer.

51. The system of claim 50, further comprising a tank adapted for storing predispersion graphite in dry form.

52. The system of claim 51, further comprising a conveyor or hopper adapted for adding dry predispersion graphite to the mixing tank.