SYSTEM FOR MAKING NANOCARBON PARTICLE ADMIXTURES FOR CONCRETE

Abstract

A system for making an admixture for concrete includes a catalyst and a reactor configured to produce a nanocarbon mixture and a product gas, with the nanocarbon mixture including at least two different types of nanocarbon particles in selected mass percentage ranges. The system also includes a nano-silica-based suspension stabilizer configured for mixing with the nanocarbon mixture to improve the long term stability of the nanocarbon particles in the admixture; and a surfactant configured for mixing with the nanocarbon mixture to facilitate dispersion of the nanocarbon particles in the admixture.

Claims

1. A system for making an admixture in liquid form for making concrete comprising: a catalyst; a reactor comprising a reaction chamber in fluid communication with a hydrocarbon feed gas supply, the catalyst and the reactor configured to produce a nanocarbon mixture and a product gas by catalytic decomposition of a hydrocarbon feed gas, the nanocarbon mixture comprising at least two different types of nanocarbon particles in selected mass percentage ranges, the nanocarbon particles selected from the group consisting of carbon nanotube particles, carbon nanofiber particles, graphene particles, graphite particles, carbon black, paracrystalline carbon particles, polycrystalline carbon particles, nanodiamonds, single-layer fullerene particles, and multi-layer fullerene particles, the nanocarbon particles having a first percentage range of from 0.4% to 1.9% of a mass of the admixture; a carbon separator configured to separate the nanocarbon mixture from the product gas; a nano-silica-based suspension stabilizer configured for mixing with the nanocarbon mixture having a second percentage range of from 5% to 21% of the mass of the admixture; and a surfactant configured for mixing with the nanocarbon mixture having a third percentage range of from 2% to 9% of the mass of the admixture.

2. The system of claim 1 further comprising a catalyst transport system configured to move the catalyst through the reaction chamber in contact with the hydrocarbon feed gas.

3. The system of claim 1 wherein the nanocarbon particles comprise 43% to 58% of carbon nanotube particles based on a total mass of the nanocarbon particles.

4. The system of claim 1 wherein the nanocarbon particles comprise 30% to 50% of carbon nanofiber particles based on a total mass of the nanocarbon particles.

5. The system of claim 1 wherein the catalyst comprises a metal selected from the group consisting of NiAl and Ni alloyed with Cu, Pd, Fe, or Co.

6. The system of claim 1 wherein the catalyst comprises an oxide selected from the group consisting of MgO, ZnO, Mo.sub.2O.sub.3 and SiO.sub.2.

7. The system of claim 1 wherein the catalyst comprises a group VIII metal selected from the group consisting of Fe, Co, Ru, Pd and Pt.

8. The system of claim 1 wherein the hydrocarbon feed gas comprises a gas selected from the group consisting of methane and natural gas.

9. The system of claim 1 wherein the hydrocarbon feed gas comprises a gas selected from the group consisting of ethylene and propane.

10. The system of claim 1 further comprising an organic compound including a functional group that contains a basic nitrogen atom with a lone pair in a dosage of from 0.5% to 20% by the mass of the admixture.

11. A system for making an admixture in liquid form for making concrete comprising: a catalyst; a reactor comprising a reaction chamber in fluid communication with a hydrocarbon feed gas supply, the catalyst and the reactor configured to produce a nanocarbon mixture and a product gas by catalytic decomposition of a hydrocarbon feed gas, the nanocarbon mixture comprising at least two different types of nanocarbon particles in selected mass percentage ranges, the nanocarbon particles selected from the group consisting of carbon nanotube particles, carbon nanofiber particles, graphene particles, graphite particles, carbon black, paracrystalline carbon particles, polycrystalline carbon particles, nanodiamonds, single-layer fullerene particles, and multi-layer fullerene particles, the nanocarbon particles having a first percentage range of from 0.4% to 1.9% of a mass of the admixture; a catalyst transport system configured to move the catalyst through the reaction chamber in contact with the hydrocarbon feed gas; a carbon separator configured to separate the nanocarbon mixture from the product gas; a nano-silica-based suspension stabilizer configured for mixing with the nanocarbon mixture having a second percentage range of from 5% to 21% of the mass of the admixture; a surfactant configured for mixing with the nanocarbon mixture having a third percentage range of from 2% to 9% of the mass of the admixture; and an organic compound including a functional group that contains a basic nitrogen atom with a lone pair in a dosage of from 0.5% to 20% of the mass of the admixture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Exemplary embodiments are illustrated in the referenced figures of the drawings. It is intended that the embodiments and the figures disclosed herein be considered illustrative rather than limiting.

[0021] FIG. 1 is a photo of a CNT nanocarbon mixture containing carbon nanotubes (CNTs) prior to crushing or grinding;

[0022] FIG. 2 is a photo of the CNT nanocarbon mixture following crushing or grinding into a coarse powder;

[0023] FIG. 3 is a TEM (transmission electron microscopy) photo, with a 10,000 nm scale shown in the lower right hand corner, of a CNT/amorphous carbon bundle and a few, long individual tubes in the CNT nanocarbon mixture, with the tube lengths varying from <200 nm to >20,000 nm;

[0024] FIG. 4 is a TEM photo, with a 2000 nm scale shown in the lower right hand corner, of a CNT/nanocarbon bundle in the CNT nanocarbon mixture with the finely ground bundles typically ranging from 5 μm to 1500 μm;

[0025] FIG. 5 is a SEM (scanning electron microscopy) photo, with a 1 μm scale shown in the lower left hand corner, which provides a closer view of the surfaces and 3D structures on a nanocarbon bundle in the CNT nanocarbon mixture;

[0026] FIG. 6 is a TEM photo, with a 500 nm scale shown in the lower right hand corner, showing CNTs in the CNT nanocarbon mixture having hollow cores and many defects, such as bends, twists, and bamboo sections;

[0027] FIG. 7 is a SEM photo, with a 1 μm scale shown in the lower left hand corner, showing in addition to CNTs clusters of amorphous carbon included in the CNT nanocarbon mixture;

[0028] FIG. 8 is a SHIM (scanning helium ion microscopy) photo, with a 1.50 μm field of view, a working distance of 11.9 mm, a scale of 200 nm shown in the lower middle, an Acceleration V of 29.8 kV, a Dwell Time of 3.0 μs, a Magnification (4×5 Polaroid) of 76.200×, and a Blanker Current of 0.5 pA, showing surfaces of CNTs in the CNT nanocarbon mixture with much better focus and depth of field than SEM;

[0029] FIG. 9 is a TEM photo, with a 100 nm scale shown in the lower right hand corner, showing the hollow structure of CNTs in the CNT nanocarbon mixture at high magnification, with the dark spots comprising catalyst particles;

[0030] FIG. 10 is a TEM photo, with a 20 nm scale shown in the lower right hand corner, with the image grainy, but with individual tube walls (layers) in CNTs in the CNT nanocarbon mixture shown;

[0031] FIG. 11 is a TEM photo, with a 50 nm scale shown in the lower right hand corner, showing a darker, peanut shaped object, which is a catalyst particle encapsulated in carbon layers at the end of a CNT;

[0032] FIG. 12 is a TEM photo, with a 20 nm scale shown in the lower right hand corner, showing the same catalyst particle as shown in FIG. 11 but with individual graphitic carbon walls (layers) shown;

[0033] FIG. 13 is a TEM photo, with a 10 nm scale shown in the lower right hand corner, showing another CNT at the highest magnification, with the end of the CNT appearing to be closed but without a catalyst particle;

[0034] FIG. 14 is a TEM photo, with a 5 nm scale shown in the lower left hand corner, showing a nanocarbon particle in the CNT nanocarbon mixture with some graphitic internal structure, but not specifically a hollow CNT or strictly amorphous;

[0035] FIG. 15 is a broad Raman spectrum for a typical CNT nanocarbon mixture produced using a heated reactor and catalytic decomposition of a hydrocarbon feed gas;

[0036] FIG. 16 is a close up view of the D and G mode peaks of the Raman spectrum of FIG. 15;

[0037] FIG. 17 is a photo of a raw, bulk CNF nanocarbon mixture containing carbon nanofibers (CNFs) prior to crushing or grinding;

[0038] FIG. 18 is a SEM photo, with a 1 μm scale shown in the upper center, showing a bundle of CNFs in the CNF nanocarbon mixture of FIG. 17;

[0039] FIG. 19 is a TEM photo, with a 1000 nm scale shown in the lower right hand corner, showing no hollow structure in the CNFs of FIG. 18;

[0040] FIG. 20, with a 200 nm scale shown in the lower right hand corner, is a TEM photo showing the “stacked cups” internal structure of the CNFs of FIG. 18 obtained with a higher magnification;

[0041] FIG. 21 is a TEM photo, with a 200 nm scale shown in the lower right hand corner, showing CNF/amorphous nanocarbon clumps in the CNF nanocarbon mixture of FIG. 17;

[0042] FIG. 22 is a TEM photo showing CNF nanocarbon fibers, which commonly have non-uniform diameters and a wide range of lengths, in the CNF nanocarbon mixture of FIG. 17;

[0043] FIG. 23 is a broad Raman spectrum for a typical CNF nanocarbon mixture produced using a heated reactor and catalytic decomposition of a hydrocarbon feed gas; and

[0044] FIG. 24 is a schematic of a system for producing the nanocarbon mixtures of FIGS. 1-24.

DETAILED DESCRIPTION

[0045] As used herein, the term “concrete” means a material in either a cured or an uncured state that includes cement (with or without supplementary cementing materials, such as blast furnace slag, fly ash, limestone fines, and silica fume), mineral aggregate sand and stones, and water. The term “cement” means hydratable cement such as Portland cement produced from clinker containing hydraulic calcium silicates. The term “supplementary cementing” or “cementitious” means materials that form a plastic paste when mixed with a liquid, which harden and function as a glue or binder for holding the composite concrete material together. Cementitious materials form a hard matrix to bind aggregates and contribute to the properties of hardened concrete through hydraulic or pozzolanic activity. While Portland cement is a common concrete matrix material, alternative examples include, but not limited to, various limes and mortars, fly ashes, ground blast-furnace slag, and silica fume. The term “admixture” means ingredients added to concrete before or during mixing. The term “superplasticizer” means a surfactant used to uniformly disperse particles in uncured concrete.

[0046] As used herein, the term “nanocarbon particle” means a particle comprising an allotrope of carbon with one or more particle dimensions on the order of 500 nanometers (nm) or less. “Nanotubes” mean cylindrical nanostructures comprising one or more cylindrical tubes of atoms having a high length to diameter ratio. Nanotubes can be categorized as single-walled nanotubes (SWNTs) or multi-walled nanotubes (MWNTs). “Nanotube particles” comprise individual molecules, particles, or agglomerates of particles comprised of nanotubes. “Nanofibers” means cylindrical nanostructures with a high length to diameter ratio, with atomic layers in a stacked plate, cup, or cone configuration. “Nanofiber particles” comprise individual molecules, particles, or agglomerates of particles comprised of nanofibers. “Graphene” means small particles of a two-dimensional hexagonal lattice of carbon atoms. Graphene is the basic structure of many other allotropes of carbon, including carbon nanotubes, carbon nanofibers, graphite, and other fullerenes. “Graphite” means a carbon crystalline atomic structure comprised of layers of graphene. “Carbon black” means a fine powder comprised of nanometer scale particles and agglomerates with an “amorphous” paracrystalline or polycrystalline atomic structure, usually made from decomposition and incomplete combustion of hydrocarbon feedstocks, but for the purposes of this disclosure, “carbon black” also includes finely-ground charcoal, coal, or activated carbon materials. “Nanodiamonds” means nanometer scale particles of a carbon allotrope with diamond crystal atomic structure. “Fullerene” means molecules or particles comprised of graphitic crystalline structures with defects in the hexagonal atomic lattice that bend or curve the layer(s) into spheres (“onions”), buds, cones, horns, tubes, or other composite shapes built from sub-structures with these simpler forms. “Nano-silica” means silica material with one or more particle dimensions on the order of 500 nanometers (nm) or less.

Nanocarbon Mixture

[0047] Referring to FIG. 1, a nanocarbon mixture containing a selected percentage range of CNTs is shown in raw, bulk form following production using a heated reactor and catalytic decomposition of a hydrocarbon feed gas. The nanocarbon mixture comprises CNTs containing defects as well as other amorphous forms of nanocarbon as well as catalyst particles. Typically, the CNTs comprise multi walled CNTs (MWCNTs) but can also include single walled CNTs (SWCNTs). In addition, the CNTs can occur in bundles of CNTs entrained in amorphous carbon structures. The nanocarbon mixture has the texture of powder but includes large clumps and agglomerates of carbon material such as bundles containing CNTs and amorphous carbon.

[0048] Referring to FIG. 2, the nanocarbon mixture is shown following grinding into a carbon powder. As will be further described, the carbon powder facilitates dispersion of the nanocarbon mixture in a water/surfactant mixture.

[0049] Referring to FIG. 3, a CNT/amorphous carbon bundle and a few, long individual tubes in the nanocarbon mixture are shown, with diameters <100 nm and tube lengths varying from <200 nm to >20,000 nm.

[0050] Referring to FIG. 4, a CNT/nanocarbon bundle in the nanocarbon mixture is shown with the finely ground bundles typically ranging from 5 μm to 1500 μm.

[0051] Referring to FIG. 5, a closer view of the surfaces and 3D structures on a nanocarbon bundle in the nanocarbon mixture is shown.

[0052] Referring to FIG. 6, CNTs in the nanocarbon mixture are shown having hollow cores and many defects, such as bends, twists, and bamboo sections.

[0053] Referring to FIG. 7, clusters of amorphous carbon included in the nanocarbon mixture are shown.

[0054] Referring to FIG. 8, surfaces of CNTs in the nanocarbon mixture are shown.

[0055] Referring to FIG. 9, the hollow structure of CNTs in the nanocarbon mixture are shown at high magnification with the dark spots comprising catalyst particles.

[0056] Referring to FIG. 10, individual tube walls (layers) in CNTs in the nanocarbon mixture are shown.

[0057] Referring to FIG. 11, a catalyst particle encapsulated in carbon layers at the end of a CNT in the nanocarbon mixture is shown.

[0058] Referring to FIG. 12, the same catalyst particle as shown in FIG. 11 is shown but with individual graphitic carbon walls (layers) shown.

[0059] Referring to FIG. 13, another CNT in the nanocarbon mixture is shown, with the end of the CNT appearing to be closed but without a catalyst particle.

[0060] Referring to FIG. 14, a nanocarbon particle in the nanocarbon mixture is shown with some graphitic internal structure, but not specifically a hollow CNT or strictly amorphous.

[0061] Referring to FIG. 15, a broad Raman spectrum is shown for a typical nanocarbon mixture produced using a heated reactor and catalytic decomposition of a hydrocarbon feed gas. FIG. 16 is a close up view of the D and G mode peaks of the Raman spectrum. In this application, Raman spectroscopy was used to characterize the nanocarbon particles in the nanocarbon mixture. In particular, Raman spectroscopy was used to verify that the nanocarbon mixture contains multiwall nanotubes, primarily comprised of carbon arranged in a graphitic crystal structure, along with other “amorphous” carbon.

[0062] In FIGS. 15 and 16, the second major peak at ˜1590 1/cm (“G mode”) shows that a slight majority of the carbon structure is graphitic (CNTs). The first major peak at ˜1360 1/cm (“D mode”) indicates that tube defects and amorphous carbon forms are also present in the nanocarbon mixture. The area of the D peak relative to the G peak shows that defects and amorphous carbon atomic structures are quite common in this carbon multiwall nanotube sample, as verified by the TEM images above. A small “peak” from ˜200 1/cm to ˜500 1/cm (radial breathing mode, or RBM) is indicative of the wide range of tube diameters in the sample. The third major peak at ˜2720 1/cm (G′ mode) is the second harmonic of the D mode peak, which is not very useful for characterization of this product, so it is omitted for the close-up of the D and G peaks shown in FIG. 16. The Raman spectrum shown in FIGS. 15 and 16 indicates that the nanocarbon mixture contains about 50-60% CNTs. The remainder of the nanocarbon particles, which are less than about 50% of the total number of nanocarbon particles, are not in pure graphitic form. By way of example, the nanocarbon particles can comprise from 43% to 58% by mass of CNTs. As another example, the nanocarbon particles comprise from 30% to 50% by mass of CNTs.

CNF Nanocarbon Mixture

[0063] Referring to FIG. 17, a raw, bulk nanocarbon mixture containing carbon nanofibers (CNFs) is shown. The CNF nanocarbon mixture was produced using a heated reactor and catalytic decomposition of a hydrocarbon feed gas and contains a selected percentage range of CNFs. The nanocarbon mixture comprises CNFs containing defects as well as other amorphous forms of nanocarbon.

[0064] The CNF nanocarbon mixture has the texture of powder but includes large clumps and agglomerates of carbon material. As with the nanocarbon mixture shown in FIG. 2, the CNF nanocarbon mixture can also be crushed or ground into a powder (not shown). While also generally cylindrical in shape, CNFs differ from CNTs because their structure is comprised of stacked disks, cones or cups of generally graphitic sheets of carbon atoms. CNFs typically have a larger average diameter and shorter average length than CNTs, as well.

[0065] Referring to FIG. 18, a bundle of CNFs in the CNF nanocarbon mixture is shown. As shown in FIG. 19, the CNFs do not have a hollow interior structure. As shown in FIG. 20, the CNFs have a “stacked cups” internal structure. In FIG. 21, CNF/amorphous nanocarbon clumps are shown in the nanocarbon mixture. FIG. 22 shows the CNF/nanocarbon fibers with non-uniform diameters and lengths.

[0066] Referring to FIG. 23, Raman spectroscopy can be used to verify that the CNF nanocarbon mixture contains carbon nanofibers (CNFs), which are primarily comprised of the stacked plates, cones, or cups of carbon arranged in layers of a graphite (hexagonal) crystal structure, along with other “amorphous” carbon. FIG. 23 is a typical Raman spectrum for the CNF nanocarbon mixture. The second major peak at the ˜1590 1/cm (“G mode) shows that much of the carbon structure is graphitic (CNFs). The first major peak at ˜1360 1/cm (“D mode”) indicates that defects in the stacked layers of the fibers and amorphous carbon forms are the majority of the CNF/nanocarbon product composition. The Raman spectrum shown in FIG. 23 indicates that the CNF nanocarbon mixture contains about 30-50% CNFs and more than about 50% is not in pure graphitic form. By way of example, the nanocarbon particles can comprise from 43% to 58% by mass of CNFs. As another example, the nanocarbon particles comprise from 30% to 50% by mass of CNFs.

System and Method

[0067] Referring to FIG. 24, a system 10 and method for making the CNT nanocarbon mixture or the CNF nanocarbon mixture are illustrated schematically. In the illustrative embodiment, the system 10 is configured to perform a batch process, but can alternately be configured to continuously produce the CNF nanocarbon mixture. The system 10 includes a hydrocarbon feed gas supply 12 configured to supply a hydrocarbon feed gas 14. The hydrocarbon feed gas 14 can comprise pure methane or natural gas obtained from a “fossil fuel” deposit. Natural gas is typically about 90% methane, along with small amounts of ethane, propane, higher hydrocarbons, and “inerts” like carbon dioxide or nitrogen. Alternately, the hydrocarbon feed gas 14 can comprise a higher order hydrocarbon such as ethylene or propane. In addition, the hydrocarbon feed gas supply 12 can comprise a tank (or a pipeline) configured to supply the hydrocarbon feed gas 14 at a selected temperature, pressure, and flow rate. By way of example the temperature of the hydrocarbon feed gas 14 can be from 600 to 900° C., the pressure can be from 0.0123 to 0.0615 atmospheres and the flow rate can be from 0.05 to 3.0 liter/minute per gram of catalyst.

[0068] The system 10 also includes a reactor 16 comprising a hollow reactor cylinder having a sealable inlet 22, a reaction chamber 20 in fluid communication with the inlet 22, and a sealable outlet 24 in fluid communication with the reaction chamber 20 adapted to discharge the nanocarbon mixture 38, which can comprise a nanocarbon mixture having the composition shown in FIG. 15, or a CNF nanocarbon mixture having the composition shown in FIG. 23, depending on the process parameters. In addition to the nanocarbon mixture 38, the method produces a product gas 34 comprised of hydrogen and unreacted hydrocarbon feed gas. For performing the method, the reaction chamber 20 can be heated by thermal combustion or electricity to a temperature of from 600 to 900° C. In addition, the reaction chamber 20 can be in fluid communication with an inert gas supply 28.

[0069] The system 10 can also includes a catalyst transport system 18 adapted to move a metal catalyst 30 through the reaction chamber 20 in contact with the hydrocarbon feed gas 14 to produce the nanocarbon mixture 38 and the product gas 28. The catalyst transport system 18 can be in the form of a chain conveyor system, a rotating auger system, a high velocity pneumatic system or a plunger system. In any case, the catalyst transport system 18 is adapted to move a selected amount of the metal catalyst 30 through the reaction chamber 20 at a rate dependent on the flow rate of the hydrocarbon feed gas 14. For example, with the flow rate of the hydrocarbon feed gas 14 between 0.05 and 3.0 liters/minute, the selected amount of the metal catalyst 30 can be about one gram/minute. Alternately, rather than a catalyst transport system 18, the metal catalyst 30 can be simply placed in the reaction chamber 20.

[0070] The metal catalyst 30 can be provided in the form of particles. A preferred metal for the metal catalyst 30 comprises Ni, or an alloy containing Ni. For example, the metal can comprise NiAl, or Ni alloyed with Cu, Pd, Fe, Co, or an oxide such as MgO, ZnO, Mo.sub.2O.sub.3 or SiO.sub.2. However, rather than Ni or an alloy thereof, the metal catalyst 30 can comprise another metal, such as a metal selected from group VIII of the periodic table including Fe, Co, Ru, Pd and Pt.

[0071] The system 10 also includes a carbon separator 40 adapted to separate the nanocarbon mixture 38 from the product gas 34 via gravity or cyclonic separation. The system 10 can also include a high energy mixer (not shown) configured to mix the nanocarbon mixture 38 with water and a superplasticizer surfactant to form the liquid admixture. The high energy mixer can also be used to mix a nano-silica based compound for long-term stability of the suspended nanocarbon particles in the liquid admixture. Suitable high energy mixers can include one or more of the following: high-shear rotating mixers, such as pumps and turbines, rotor/stator mixers, and blade dispersers; mechanical grinding and impact-type mixers, such as attritors, ball mills, and hammer mills; and high pressure fluidic mixing devices, such as nozzles, orifices, and high-velocity impact devices, such as homogenizer pumps, valves and similar equipment.

[0072] By utilizing different compositions for the metal catalyst 32, and by controlling process parameters, the process can be used to produce the nanocarbon mixture 38 with the desired types of particles and mass percentages in the nanocarbon mixture 38. During continuous production of the nanocarbon mixture 38 the amount of hydrogen in a methane/natural gas hydrocarbon feed stock gas 14 remains fairly constant in the range from 10-80% by volume, depending on the material being produced. When using higher hydrocarbon feedstock gas 14 such as ethylene or propane, more carbon production can be expected with less hydrogen in the product gas 34. For example, for obtaining a nanocarbon mixture, the method can be controlled to provide approximately from about 20:1 to 40:1 carbon to catalyst mass ratio. For obtaining a CNF nanocarbon mixture, the method can be controlled to provide from about 200:1 to 500:1 carbon to catalyst mass ratio.

[0073] During the wetting and mixing step a predetermined quantity of the nanocarbon mixture in carbon powder form is mixed with a predetermined quantity of water/surfactant mixture with intense, high energy, large scale mixing equipment. Exemplary quantities of the nanocarbon mixture, superplasticizer surfactant, nano-silica based compound and water in the admixture include: nanocarbon mixture 0.4% to 1.9% mass percentage of total mass of admixture, superplasticizer surfactant 2% to 9% mass percentage of total mass of admixture, nano-silica based compound 5% to 21% mass percentage of total mass of admixture, and water 57% to 93% mass percentage of total mass of admixture. During the wetting and mixing step, an organic compound including a functional group that contains a basic nitrogen atom with a lone pair can also be mixed into the admixture to increase early and/or late strength development in the concrete. A representative dosage can be from 0.5 to 20% by mass of the admixture.

[0074] The system and method can also be configured to produce, co-produce or mix in other forms of nanocarbon (e.g., graphene particles, graphite particles, carbon black, and “amorphous” paracrystalline and polycrystalline carbon particles, nanodiamonds, and single-layer and multi-layer fullerene particles) in a desired ratio (e.g., 50/50 mix by mass). In addition, the system and method utilize high-intensity mixing to de-agglomerate the nanocarbon particles in the water based admixture. Further, the system and method utilize a surfactant, known in the concrete industry as a water reducer or superplasticizer, to keep he nanocarbon particles dispersed in the liquid admixture. Still further, the system and method can utilize a compound with nano-silica, such as silica fume, in the admixture to keep the nanocarbon particles in suspension for relatively long-term storage and distribution of the admixture.

Method for Making Concrete

[0075] A method for making concrete includes the steps of providing the admixture and then mixing the admixture with water, cement (with or without supplementary cementitious materials), and mineral aggregates in selected quantities.

[0076] TABLE 1 identifies the ingredients of a sample concrete made using the admixture. TABLE 2 illustrates ASTM C494 test results for sample concretes made using the admixture, with the admixture identified under the trademark EDENCRETE. By varying the dosage of the admixture, and the amount of cementitious material, a desired ratio of the different nanocarbon particles to cementitious material in the cured concrete can be obtained. Preferably, these quantities are controlled to provide a range of CNT/total cementitious material for a CNT admixture of from 0.0002% to 0.0199% by mass, and/or CNF/total cementitious material for a CNF admixture, of from 0.0002% to 5% by mass.

TABLE-US-00001 TABLE 1 Based upon a concrete unit weight of 4100 lbs./yd..sup.3 Min. % wt. Max. % wt. Material Notes per yd.sup.3 per yd.sup.3 Water corresponding 1.22 16.10 to water/cementitious = 0.25-0.60 Cement 4.88 21.95 Sand 24.39 31.71 Rock 36.59 43.90 Silica Fume 3-5%, 0.15 0.66 replacement by weight of cement Fly Ash 10-30%, 0.49 6.59 replacement by weight of cement Slag 10-70%, 0.49 15.37 replacement by weight of cement Min. % wt. Max. % wt. Admixtures per Yd.sup.3 per Yd.sup.3 Type A 2-5 oz./cwt 0.0064 0.088 Low Range Water Reducer Type A 4-8 oz/cwt 0.012 0.14 Mid-Range Water Reducer Type B 2-4 oz/cwt 0.0064 0.07 Retarders Traditional Sugar-based Type B 2-6 oz/cwt 0.0064 0.11 Retarders Hydration Stabilizers Type C 1%; 0.022 0.18 Accelerators 7-10 oz/cwt Calcium Type C 1%; 0.038 0.28 Accelerators 12-16 oz/cwt Non-Calcium Type D N/A — — Water reducing and retarding Type E N/A — — Type F 7-15 oz/cwt 0.022 0.27 HRWRA Type G obsolete — — Type S 0.25-3 gpy 0.003 0.04 SRA & CNI

TABLE-US-00002 TABLE 2 EdenCrete ™ ASTM C494 Results % Increase Over Reference; Dosage = 3.5 gpy Age (Days) TEST 1 3 7 28 56 90 180 365 Compressive 25% 35% 39% 41% 41% 39% 38% 37% Strength (ASTMC39) Flexural 25% 19% 32% Strength (ASTM C78) Split-tensile 29% 22% Strength (ASTM C496) Abrasion 62% 61% Resistance (ASTM C779 Proc C) Length of 39% reduction Change (ASTM C157; Shrinkage) Time of Set Reduced: Initial Set 3 min, (ASTM C403) Final Set 4 min Freeze/Thaw Reference = 88.0, EdenCrete = 96.4; Resistance 9.55% enhancement (ASTM C666) Program Complete EdenCrete ™ successfully conforms to the ASTM C494 Specification for Type S chemical admixtures used in concrete.

[0077] While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and subcombinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.