Patent ID: 12233575

DETAILED DESCRIPTION

For a further understanding of the nature, function, and objects of the present invention, reference should now be made to the following detailed description. While detailed descriptions of the preferred embodiments are provided herein, as well as the best mode of carrying out and employing the present invention, it is to be understood that the present invention may be embodied in various forms. Specific details disclosed herein are not to be interpreted as limiting but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or manner.

For purposes of this disclosure, a “jointless” concrete slab refers to a slab that does not have cut joints and that is capable of managing the cracks and fractures without the cut joints. Percent (%) by weight refers to the aggregate weight of the silica particles in comparison to the final weight of cement in a final concrete product. A “fiberless” concrete slab refers to a slab that does not have steel fibers, synthetic fibers, or other like internal reinforcements, and that still remains capable of managing the cracks and fractures without the fibers. This disclosure is not limited to jointless concrete slabs, rafts, or other concrete products, and this disclosure is not limited to fiberless concrete slabs, rafts, or other concrete products.

Embodiments and aspects of the present disclosure provide a system for, and method of, preparing and pouring a concrete slurry for the formation of concrete products, which are not susceptible to the limitations and deficiencies of the prior art. The inventive concepts described herein allow for the formation, in certain non-limiting embodiments, of concrete slabs and rafts, based on the addition of a chemical admixture when preparing the concrete slurry. In other non-limiting embodiments, the inventive concepts described herein allow for the formation of concrete slabs and rafts based on the application of a chemical treatment to a poured concrete slurry, which in some instances facilitates curing of the poured concrete. In other non-limiting embodiments, the inventive concepts described herein allow for the formation of concrete slabs and rafts, based on the synergistic combination of a prepared concrete slurry with a curing technique. Further, the inventive concepts described herein also allow for the formation, in certain non-limiting embodiments, of concrete products that are less susceptible to cracking or fracturing, and that are less susceptible to the complications derived therefrom.

The inventive concepts described herein also allow for a decreased need for and a decreased use of traditional reinforcements such as rebar and/or mattings. This allows for efficiencies in time, labor, and resources, and allows for a streamlining and simplifying of the process for forming and maintaining a concrete product.

A first exemplary embodiment of the inventive concepts provides a system for, and method of, preparing and pouring a concrete slurry for the formation of concrete products, wherein micro- and/or nano-particles and/or fibers are paired with a durable and flexible blend of aggregates, pastes, and admixtures, to provide a mass of substantially impermeable concrete exhibiting exceptional tensile strength and durability for the heaviest loads and equipment.

A second exemplary embodiment provides a system for, and method of, forming of a concrete product via a concrete slurry and curing technique, wherein the concrete slurry leverages aluminum-coated colloidal silica (herein simply, “colloidal silica”) in combination with entirely optional graphene oxide and/or fibers (steel and/or macro synthetic, for example) to create a concrete mass. The colloidal silica and graphene oxide composite may be used as an admixture and/or sprayed, individually or in combination, onto the surface as a “cure” soon after or right after the trowel machine is removed.

The colloidal silica and optional graphene oxide work to fill the capillary structure to reduce internal tensile forces or to provide stiffness and strength, which drastically reduces the likelihood of shrinking and cracking of the concrete. With regard to the colloidal silica, open capillaries, or open capillary structures, are filled with reactive nanometer-sized aluminum-coated silica that react with the free lime to produce a stable gel structure of calcium silicate hydrate, which eliminates moisture loss by plugging the pores of the capillary structures. With regard to the optional graphene oxide, the concrete structure defining the capillaries is embedded with nanometer-sized graphene oxide monolayers, which are defined by stiffness and strength due to the presence of a two-dimensional graphene backbone. It is possible that the graphene oxide monolayers may overlap to create an interwoven layer structure that distributes load. These liquid-dispersed monomolecular sheets are defined herein as graphene oxide sheets or flakes. The inventor has also found that this process is not temporary, and is instead a permanent solution.

At this high-level non-limiting example, the use of colloidal silica as an admixture and/or spray works with the internal cement molecule. Colloidal silica, which is included within the category of pozzolans, is a suspension of fine amorphous, nonporous, and typically spherical silica particles in a liquid phase. During curing and thereafter, the colloidal silica will react with free lime, increasing the density and structural strength of the solid structures formed. The increased density and long-term pozzolanic action ties up free lime, which limits the creation of channels and decreases the permeability in the concrete structure. Moreover, the resultant chemical and structural effect also helps keep contaminants and particles on the surface of the concrete. Moreover, due to the aluminum coating, the colloidal silica helps buffer against the effects of fly ash, which varies geographically (based on how the concrete materials are sourced), and therefore helps yield a more consistent final product independent of where the concrete is being placed.

The use of the optional dispersed graphene oxide flakes as an admixture and/or spray in an exemplary embodiment works to prevent shrink cracking and moisture loss and provides a reinforcement effect to the concrete product. Graphite oxide generally is hydrophilic and easily hydrated when exposed to water in liquid or gas phase, resulting in a distinct increase of the inter-planar distance (up to about 1.2 nm in its saturated state). Additional water may be incorporated into the interlayer space between monolayers of graphene oxide due to high-pressure induced effects. The hydration state of graphene oxide in liquid water corresponds to insertion of about 2-3 water monolayers, for example. Complete removal of water from graphene oxide is known to be difficult as direct heating at 60-80° C. commonly results in partial decomposition and degradation of the chemical structure.

A third exemplary embodiment provides a process for placing a concrete slab on a substrate for industrial and commercial applications. The slab is characterized by having higher than normal resistance to the effects of aggressive water and chemical attack, such as salt, when compared to traditional concrete composite materials. The slab also provides a highly dense, highly accurate, and planar concrete surface with limited internal macro-reinforcements and a thinner cross section than a conventional concrete slab of the same strength.

For this particular embodiment, the process comprises: (1) preparing a concrete slurry with a water to cement ratio of between about 0.400 to about 0.450, with steel fibers or macro synthetic fibers, or a combination of these fibers; (2) preparing the concrete slurry with a colloidal silica, integral thereto; (3) performing a “spray-apply” step using colloidal silica; and (4) providing reaction and performance enhancing chemicals to the slurry or to the curing/to-be finished product. The overall process comprises establishing a highly accurate, and well compacted sub-base preparation as a foundation in preparation for placement of the concrete. Optionally, the preparing the concrete slurry step may comprise graphene oxide, integral thereto.

A fourth exemplary embodiment provides a method comprising the entirely optional step of using steel fibers to mitigate shrinkage cracks in the concrete. Fibers help mitigate plastic and drying shrinkage by arresting the movement of the concrete slab and distributing any shrinkage across the entire slab and fiber network area by means of micro cracking, i.e., when shrinkage occurs the fibers engage and redistribute the shrinkage. This holds true for both steel and macro-synthetic fibers, as described in greater detail herein.

This step may be one step in a series of steps making up an exemplary embodiment. As is described in greater detail herein, shrinkage cracks occur either as early plastic shrinkage, nucleating in the first 24 hours while the concrete has low strength, or nucleating as late cracks, due to the external restraint of the volume change during the drying shrinkage. As water is lost in the cement paste, shrinking places the aggregates in compression. Fine and discrete cracks nucleate and extend from the perimeter of the aggregates, and the numerous fine cracks continue to extend, while shrinkage increases over time and the cracks coalesce. As the concrete slab shrinks, the concrete slab shortens in all directions. The microcracks then combine at the location of the greatest strain and stress, where subsequently a crack will form.

For this particular embodiment, the step of using steel fibers to mitigate shrinkage cracks in the concrete allows for fibers to be randomly distributed throughout the concrete slab and can, with close spacing and good bonding, intercept the formation of cracks. Different types of steel fibers may be used for different applications. Some Type 2 steel fibers are sized to number about 9000.0 fibers per pound (lb.) and are used typically in dosages of about 33.0 lbs./cuyd (representing about 0.25% by volume of concrete) to about 66.0 lbs./cuyd (representing about 0.50% by volume of concrete). Some Type 1 steel fibers are sized and number about 2500.0 fibers per pound and may also be used.

A fifth exemplary embodiment provides a method comprising the step of using macro synthetic fibers to mitigate shrinkage cracks in concrete. This step may be one step in a series of steps making up an exemplary method of the present invention. The effect of the macro synthetic fibers is similar to the step of using steel fibers to mitigate shrinkage cracks in the concrete. However, the step of using macro synthetic fibers to mitigate shrinkage cracks in concrete also improves water retention and, therefore, assures a more complete hydration of the cement, and may also reduce plastic shrinkage more effectively than steel fibers in some circumstances. Further, the high fiber count associated with the step of using macro synthetic fibers intercepts the formation of microcracks and, therefore, reduces the formation of larger cracks. The macro synthetic fibers also may be added to the concrete in dosage rates of about 3.0 lbs./cuyd representing about 0.20% by volume of concrete to about 7.50 lbs./cuyd, representing about 0.50% by volume of concrete.

A sixth exemplary embodiment provides a method comprising the step of using, preparing, or adding colloidal silica and/or graphene oxide flakes to the slurry. This step may be one step in a series of steps making up an exemplary method of the present invention.

With regard to the graphene oxide fakes, an oxidation product of the compound carbon, oxygen, and hydrogen in variable C:O ratios of between 2.1 and 2.9 is in aqueous solution. In its dry form, it essentially presents as a black powder or soot. The bulk oxidation-product is dispersed in solution and defined as having monomolecular sheets similar to the single-layer spatial arrangement of atoms for graphite but with a larger and more irregular spacing.

The graphene oxide flakes, in comparison to graphite, have monomolecular sheets that are buckled, and the interlayer spacing is about two times larger (˜0.7 nm) than that of graphite. The graphene oxide layers are about 1.10±0.20 nm thick and the graphene oxide layers are spontaneously dispersed in a basic solution or mechanically dispersed by sonication in a polar solvent, as needed. Scanning tunneling microscopy shows the presence of local regions where oxygen atoms are arranged in a rectangular pattern with lattice constant of about 0.27 nm×0.41 nm. Graphene oxide has unique surface properties, which make it a very good surfactant material stabilizing various colloidal systems.

For this particular embodiment, the dispersed graphene oxide flake admixture is added to the concrete during the preparation phase in ranges of between about 0.01% to about 0.10% by weight of cement, depending on the concrete slurry design and the application.

With regard to colloidal silica, amorphous nanometer-sized silica (SiO2) in a particle size ranging from between about 3.0 nm to about 100.0 nm, or from between about 5.0 nm to about 100.0 nm, is in aqueous solution and is added to the concrete slurry with an aluminum-coating along with the graphene oxide admixture and the reaction enhancing and workability enhancing (rheology enhancing) admixtures, such as polycarboxylate. The aluminum coated colloidal silica are produced via a preliminary solution, prior to addition to the concrete slurry, through the incorporation of varied aluminized counter-ion conversions of silicic acid. The silica particles in the preliminary solution have varied ionically coated levels of aluminum. The aluminum coated silica solution has a pH from between about 6 to about 10, depending on the level of treatment and the exact counter-ion make-up, and is used to create the final colloidal solution product before addition to the concrete slurry. The colloidal silica will react with the free lime or calcium hydroxide (Ca(OH)2) from the cement hydration to form a solid gel product called CSH, or calcium silicate hydrate (CaSiO3+H2O).

For this particular embodiment, as is shown in the following Formula 1:
Ca(OH)2+SiO2⇔CaSiO3+H2O  (1)
the colloidal silica aqueous solution is added to the concrete during the preparation phase in ranges of between about 0.50% to about 1.50% by weight of cement, depending on the concrete slurry design and the application. The above-described chemical reaction will consume some of the capillary water and will fill the pores with the hydration products CSH and, therefore, greatly reduce drying shrinkage.

A seventh exemplary embodiment provides a method comprising the step of using a spray-applied colloidal silica and/or graphene oxide as a curing technique. This step may be one step in a series of steps making up an exemplary method of the present invention. Amorphous aluminum-coated colloidal silica with sizes of between about 3.0 nm to about 50.0 nm in an aqueous solution and/or graphene oxide flakes with particles sizes of about 0.5 nm is/are sprayed on a surface of the finished concrete slab after final set of the cement, or as described in greater detail herein.

The nanometer-sized silica penetrates up to about 3.0″ deep into the hardened concrete and react with the capillary pore water and available calcium hydroxide to form CSH, calcium silicate hydrate, as described herein. This also will seal the top of the concrete and prevent water from evaporating from the concrete mixture and thus enhance the cement hydration process. The spray-applied colloidal silica can be applied using a pump sprayer, a walk-behind electric-powered “turf” sprayer, and the like, as well as custom-made automated spraying machines. The entire surface of the slab is sprayed such that the nanometer-sized silica and/or graphene oxide penetrate and complete the filling of the capillary structures. This process step of spray-applying colloidal silica may occur after the concrete has been trowel finished and can be walked on without imprinting the surface.

An eighth exemplary embodiment provides a system for, and a method of, preparing and pouring a concrete slurry with colloidal silica, as described herein, for the formation of concrete products, wherein a polycarboxylate ether-based superplasticizer admixture is paired with the cement mixture, aluminum-coated colloidal silica admixture, and/or the secondary spray-applied aluminum-coated silica. With a relatively low dosage (0.15-0.30% by weight of cement, for example), a polycarboxylate ether-based superplasticizer allows water reduction due to its chemical structure, which enables good particle dispersion. Polycarboxylate ether-based superplasticizers are composed of a methoxy-polyethylene glycol copolymer (side-chain) grafted with methacrylic acid copolymer (main-chain). The carboxylate group —COO—Na+ dissociates in water, providing a negative charge along the polycarboxylate ether-based superplasticizer backbone. The polycarboxylate ether-based superplasticizer backbone, which is negatively charged, permits the adsorption on the positively charged colloidal particles. As a consequence of polycarboxylate ether (PCE) adsorption, the zeta potential of the suspended particles changes, due to the adsorption of the COO— groups on the colloid surface. This displacement of the polymer on the particle surface provides the side chains the opportunity to exert repulsion forces, which disperse the particles of the suspension and helps avoid friction.

A ninth exemplary embodiment provides a method of preparing a graphene oxide and colloidal silica admixture comprising the step of adding graphite oxide powder to a colloidal silica admixture, and either mechanically shearing the composite with a high-shear mixing device, and/or mechanically shearing the composite via probe sonication with an ultrasonic cavitation device, such that the resulting graphene oxide flakes are dispersed into the colloidal silica admixture. The resulting composite admixture may then be mixed into a concrete mixture as described herein.

A tenth exemplary embodiment provides a method of preparing a colloidal silica and/or graphene oxide spray application and using it as specific chemical treatment for a poured concrete slurry, which may be prepared without graphene oxide or colloidal silica, whereby the spray application facilitates curing of the poured concrete. This method can be used for the formation of any concrete product like a concrete slab or raft, or any molded concrete product, etc.

FIG.1shows a perspective view of an exemplary slab1. The slab1ofFIG.1is shown placed in warehouse-type setting according to an exemplary embodiment. The slab1is placed on top of a leveled and compacted substrate3and is for industrial and commercial applications in this exemplary embodiment. The slab1is characterized by being virtually free of curling and cracking, and having superior abrasion-resistance.

The slab1is illustrated in partial cut-away form to show layers of internal composition and structure of the composite material. The first cut-away section10illustrates the sub-surface, below the curing/to-be finished exterior2. The sub-surface of the first cut-away section10is porous, unfinished and rough. The second cut-away section20illustrates the slab1having a crack22to expose the internal composition of the composite material of the slab1. In particular, the slab1comprises hardened aggregate and cement as well as one or more of steel fibers and macro synthetic fibers24. However, in other exemplary embodiments, the slab1may be made without such steel fibers and/or macro synthetic fibers. The hardened aggregate and cement, as well as steel fibers and macro synthetic fibers24if such fibers are included, at least in part define capillary structures26(best seen inFIG.2) throughout the slab1. In an exemplary embodiment, capillary structures26(FIG.2) are filled with reactive nanometer-sized aluminum-coated silica that react with free lime to produce a stable gel structure of calcium silicate hydrate within the capillary structures26. The concrete structure defining the capillary structures26is embedded with nanometer-sized graphene oxide monolayers or overlapping graphene oxide layers.

The slab1is illustrated with an optional and exemplary spray-apply system28. The system28may also be used for spray-applying a secondary colloidal silica30as described herein (seeFIG.4andFIG.6). The system28comprises an optional human operator32using an exemplary embodiment of a spraying machine34. The system28optionally is used after a concrete slurry of the present invention is poured, trowel finished, and can be walked on by the human operator32, without imprinting the surface of the hardening slab1. The system28optionally sprays the entire surface of the slab1to saturation such that the nanometer-sized aluminum-coated colloidal silica or the optional graphene oxide flakes in the secondary silica spray30, or in its own separate spray application, can penetrate the capillary structures26and the surrounding concrete structure defining the capillary structures26.

FIG.2is a magnified perspective view of the crack22along the second cut-away section20of the slab1ofFIG.1. The magnified section ofFIG.1illustrated inFIG.2shows a view of the intersection of the hardened aggregate and cement as well as the optional steel fibers and macro synthetic fibers24, if included, that at least in part define the capillary structures26of the slab1.

FIG.3is a flow diagram of a first illustrative method100according to an exemplary embodiment. The method100discloses steps, not all of which are necessarily employed in each and every situation, but which may have similarities to other exemplary embodiments provided herein. The steps in the method100may be performed in or out of the order shown. The method100comprises the steps of: (1) preparing a concrete slurry comprising i) a concrete mixture, ii) colloidal silica admixture, and iii) optional graphene oxide admixture and/or at least one fiber selected from the group consisting of fibers selected from steel fibers and synthetic fibers (102); (2) pouring the concrete slurry onto the substrate (104); and (3) allowing the concrete slurry to cure (106). This method100allows the capillary structures to develop as the concrete product sets from the poured concrete slurry, allows the capillary structures of the concrete product to at least in part fill with silica and lime, allows the silica and lime to react to produce a gel structure of calcium silicate hydrate that at least partially fill, respectively, the capillary structures, and allows the concrete structure defining the capillary structures to be embedded with nanometer-sized graphene oxide monolayers or overlapping graphene oxide layers.

In some exemplary embodiments, the preparing step102of method100comprises: (1) preparing an aluminum-coated colloidal silica admixture via incorporation of varied aluminized counter-ion conversion of silicic acid such that the resultant silica has varied ionically coated levels of aluminum; (2) preparing a graphene oxide and colloidal silica composite admixture comprising the steps of (i) adding graphite oxide powder to the prepared aluminum-coated colloidal silica admixture, and (ii) mechanically shearing the combination with a high-shear mixing device such that the sheared graphene oxide flakes are dispersed into the colloidal silica admixture; and (3) preparing the concrete slurry with the colloidal silica and graphene oxide composite admixture, which comprises silica having a size ranging from between about 10.0 nm to about 100.0 nm, or from between about 5.0 nm to about 100.0 nm, or from between about 3.0 nm to about 100.0 nm, and graphene oxide flakes having a size ranging from between about 1.10±0.20 nm of thickness with size of about 0.5 nm. In another exemplary embodiment, the preparing step102comprises providing a prepared aluminum-coated colloidal silica admixture, and preparing a graphene oxide admixture that is independent from the prepared colloidal silica admixture. The admixtures may then be independently, but not necessarily separately, used to prepare the concrete slurry. In another exemplary embodiment, the preparing step102comprises preparing the graphene oxide and aluminum-coated colloidal silica admixture(s) comprising the steps of adding graphite oxide powder to an aqueous solution and mechanically shearing the graphite oxide via probe sonication with an ultrasonic cavitation device such that sheared graphene oxide flakes are dispersed into solution.

In another embodiment, the preparing step102additionally comprises adding the aluminum-coated colloidal silica admixture to the concrete slurry in ranges of between about 0.50% to about 1.50% by weight of cement in the concrete mixture, wherein % by weight refers to the aggregate weight of the silica in comparison to the final weight of cement in the final concrete product. In another exemplary embodiment, the preparing step102comprises adding the graphene oxide flakes, via a composite admixture or an independent graphene oxide admixture, to the concrete slurry in ranges of between about 0.01% to about 0.10% by weight of cement, wherein % by weight in this instance refers to the aggregate weight of the graphene oxide flakes in comparison to the final weight of cement in the final concrete product. In another embodiment, the preparing step102additionally comprises preparing the concrete slurry for pouring with dosages of steel fibers as the at least one fiber selected from the group of fibers of between about 33.0 lbs./cuyd to about 66.0 lbs./cuyd. In another embodiment, the preparing step102additionally comprises preparing the concrete admixture for pouring with dosages of macro synthetic fibers as the at least one fiber selected from the group of fibers of between about 3.0 lbs./cuyd to about 7.5 lbs./cuyd.

FIG.4is a flow diagram of a second illustrative method200according to an exemplary embodiment. Some of the steps of the method200are identical to the steps in the method100ofFIG.3; therefore, only the differences in the method200are detailed herein. The method200additionally comprises the step108of spray-applying a secondary colloidal silica onto the poured concrete slurry to facilitate curing thereof. The spray-applying step108comprises spray-applying the secondary colloidal silica onto the poured concrete slurry subsequent to removal of a trowel machine and prior to cement in the poured concrete slurry being completely set. The spray-applying step108may comprise in other embodiments spray-applying the poured concrete slurry with an amorphous secondary aluminum-coated colloidal silica in an aqueous solution. The spray-applying step108also may comprise spray-applying the secondary colloidal silica onto the poured concrete slurry subsequent to cement in the poured concrete slurry being completely set, and spray-applying to the point of saturation or “flooding state” as is known in the art.

In some exemplary embodiments, the step108of method200comprises spray-applying a graphene oxide and colloidal silica composite admixture similar to the composite admixture defined herein for certain embodiments of step102. In another exemplary embodiment, the step108of method200comprises spray-applying a prepared aluminum-coated colloidal silica admixture and a graphene oxide admixture prepared at the point-of-use and that is independent from the prepared aluminum-coated colloidal silica admixture used for the concrete slurry, those admixtures as defined herein for certain embodiments of step102.

FIG.5is a flow diagram of a third illustrative method300according to an exemplary embodiment. In an exemplary embodiment the method300comprises the steps of: preparing a concrete slurry comprising i) a concrete mixture, ii) a colloidal silica admixture (202), and optional graphene oxide admixture; pouring the concrete slurry onto the substrate (204); and allowing the concrete slurry to cure (206), such that capillary structures develop as the concrete product sets from the poured concrete slurry, such that the capillary structures of the concrete product at least in part fill with silica and lime, such that the silica and lime react to produce a gel structure of calcium silicate hydrate that at least partially fill, respectively, the capillary structures, and such that the concrete structure defining the capillary structures is embedded with nanometer-sized monolayers or overlapping layers of graphene oxide.

In some exemplary embodiments, similar to those described in connection withFIGS.3andFIG.4, the preparing step202of method200comprises: (1) preparing a graphene oxide and colloidal silica composite admixture comprising the steps of (i) adding graphite oxide powder to a prepared aluminum-coated colloidal silica admixture, and (ii) either mechanically shearing the combination with a high-shear mixing device, such that the sheared graphene oxide flakes are dispersed into the colloidal silica admixture, and/or mechanically shearing the graphite oxide via probe sonication with an ultrasonic cavitation device, such that sheared graphene oxide flakes are dispersed into solution; and (2) preparing the concrete slurry with the colloidal silica and graphene oxide composite admixture, which comprises aluminum-coated silica having a size ranging from between about 10.0 nm to about 100.0 nm, or from between about 5.0 nm to about 100.0 nm, or from between about 3.0 nm to about 100.0 nm, and graphene oxide flakes having a size ranging from between about 1.10+/−0.20 nm of thickness with size of about 0.5 nm. In another exemplary embodiment, the preparing step202comprises providing a prepared aluminum-coated colloidal silica admixture, and preparing an optional graphene oxide admixture that is independent from the prepared colloidal silica admixture. The admixtures may then be independently, but not necessarily separately, used to prepare the concrete slurry.

In another embodiment, the preparing step202additionally comprises adding the colloidal silica admixture to the concrete slurry in ranges of between about 0.50% to about 10.0% by weight of cement in the concrete mixture. In another exemplary embodiment, the preparing step202comprises adding the graphene oxide flakes, via a composite admixture or an independent graphene oxide admixture, to the concrete slurry in ranges of between about 0.01% to about 0.10% by weight of cement.

FIG.6is a flow diagram of a fourth illustrative method400according to an exemplary embodiment. Some of the steps of the method400are identical to steps in the method300ofFIG.5and, therefore, only the differences in the method400are detailed herein. The method400additionally comprises the step208of spray-applying a secondary colloidal silica onto the poured concrete slurry to facilitate curing thereof. The spray-applying step208comprises spray-applying the secondary colloidal silica onto the poured concrete slurry subsequent to removal of a trowel machine and prior to cement in the poured concrete slurry being completely set. The spray-applying step208comprises spray-applying the poured concrete slurry with an amorphous secondary aluminum-coated colloidal silica with size ranging from about 10.0 nm to about 50.0 nm, or from about 3.0 nm to about 50.0 nm. The spray-applying step208comprises spray-applying the secondary aluminum-coated colloidal silica onto the poured concrete slurry subsequent to cement in the poured concrete slurry being completely set.

In some exemplary embodiments, the step208of method400comprises spray-applying a graphene oxide and colloidal silica composite admixture similar to the composite admixture defined herein for certain embodiments of step202. In another exemplary embodiment, the step208of method200comprises spray-applying a prepared aluminum-coated colloidal silica admixture and a graphene oxide admixture prepared at the point-of-use and that is independent from the prepared aluminum-coated colloidal silica admixture for the concrete slurry, those admixtures as defined herein for certain embodiments of step202.

FIG.7shows a perspective view of an exemplary jointless and fiberless slab500. The jointless and fiberless slab500is similar to the jointless slab1ofFIG.1and, therefore, only the differences in the jointless and fiberless slab500are detailed herein. The jointless and fiberless slab500is illustrated in partial cut-away form to show layers of internal composition and structure of the composite material. The second cut-away section20illustrates the jointless and fiberless slab500having a crack22to expose the internal composition of the composite material of the jointless and fiberless slab500. In particular, the jointless and fiberless slab500comprises hardened aggregate and cement524without steel fibers and/or macro synthetic fibers. The hardened aggregate and cement524at least in part define capillary structures26(FIG.2) throughout the jointless and fiberless slab500, and the capillary structures26(FIG.2) are filled with reactive nanometer-sized aluminum-coated silica that react with free lime to produce a stable gel structure of calcium silicate hydrate within the capillary structures26(FIG.2). In embodiments that included the optional application of graphene oxide, the hardened aggregate and cement524defining the capillary structures is embedded with nanometer-sized graphene oxide flakes or overlapping layers of flakes. An optional spray-apply system28may be used for spray-applying a secondary colloidal silica and optional dispersed graphene oxide flake composite30on the entire surface of the jointless and fiberless slab500to saturation such that the nanometer-sized aluminum-coated colloidal silica in the secondary spray30can penetrate and complete the fill of the capillary structures26, and such that the optional graphene oxide flakes can be dispersed and embedded throughout the hardened aggregate and cement524.

In one or more exemplary embodiments described herein, the systems and methods described may be implemented in various ways using various methodologies. Although selected aspects have been illustrated and described in detail, it will be understood that various substitutions and alterations may be made therein without departing from the spirit and scope of the present invention, as defined by the following claims.