Carbon Sequestration Sand-Based Material for Synthetic Turf Fields

The application claims priority to and the benefit of U.S. Provisional Patent Application No. 63/569,558, filed on Mar. 25, 2024, entitled “Carbon Capture System and Method for Synthetic Turf Fields”, which we incorporate by reference in its entirety.

Artificial or synthetic turf fields are composed of three primary components—from bottom to top: shock pad, carpet, and infill. These components are generally assembled on top of a base of compacted stone. The shock pad is optional and serves to convey much of the shock absorption performance of the turf field, required for the safety of those playing on the surface in the case of impact with the surface. The carpet serves to mimic the blades of grass and root zone, conveying the softness and traction of the surface as well as many of the ball interaction properties. The infill is generally constituted of at least two layers, the bottom layer of which serves to weight down and stabilize the carpets that it is laid onto, whereas the top layers serve as an additional interface layer to those playing on the field, conveying surface softness, friction, traction, and much of the mechanical properties of the field that are felt directly by the players.

As a matter of background, a significant amount of engineering and development is devoted to developing artificial turf field systems. With respect to the infill, each kind of material has its own performance and structural characteristics. Obtaining the right composition and arrangement of materials can be challenging.

Furthermore, when installation of a synthetic turf field occurs, generally speaking, a living, natural turf field is being replaced with an artificial one. In this process, a living organism, e.g., grass, plants, etc., which naturally removes carbon dioxide from the atmosphere is removed. Additionally, the construction associated with a synthetic turf field, as well as the actual manufacturing of the synthetic turf, result in additional carbon entering the atmosphere.

As such, there remains a need for environmentally friendly and ultimately carbon-neutral or carbon-offsetting infill materials that present good mechanical properties and mechanical resistance, while presenting high availability, easy transportation, and low cost.

The following presents a simplified summary to provide a basic understanding of some aspects of the disclosed subject matter. This summary is not an extensive overview. It is not intended to identify key/critical elements or to delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description presented later.

According to one aspect, a synthetic turf system includes a backing, turf fibers extended upward from the backing, and one or more infill layers positioned above the backing, below a top portion of the turf fibers. The one or more infill layers includes carbon sequestration sand, or the synthetic turf system further includes a layer of carbon sequestration sand disposed above or below the one or more infill layers.

According to another aspect, infill for a synthetic turf system includes carbon sequestration sand. The carbon sequestration sand includes silicate rock, ultramafic rock, or reactive rock that forms a carbonate or bicarbonate with rainwater, and has a particle size of about #4 mesh to about #270 mesh. The synthetic turf system may also includes organic particles, rubber particles, elastomer particles, coated particles, or thermoplastic particles blended or layered with the carbon sequestration sand.

According to another aspect, a method of preparing a synthetic turf system includes dispersing carbon sequestration sand over a top portion of turf fibers, where the carbon sequestration sand includes silicate rock, ultramafic rock, or reactive rock that forms a bicarbonate or carbonate with rainwater traveling through infill.

In other aspects, a carbon sequestration sand-based infill employs a shock pad to achieve a desired and/or proper shock absorption on the turf. The carbon sequestration sand-based infill is most often installed over a layer of permeable backing, where the carbon sequestration sand acts as a stabilizing infill or as part of a stabilizing infill layer. As a stabilizing infill, the carbon sequestration sand performs as a ballast layer that weighs down the turf carpets and mitigates movement.

In other aspects, an infill composition for artificial turf fields includes at least one layer of carbon sequestration sand. The carbon sequestration sand includes a particle size distribution of carbon sequestration sand with a size of approximately #4 mesh to #270 mesh. The infill can be installed according to a method of spreading a layer of carbon sequestration sand over a carpet that is on a base of compacted stone. The layers of the carbon sequestration sand are brushed and de-compacted such that the carbon sequestration sand is evenly distributed over the carpet of the turf system.

In other aspects, a carbon sequestration sand-based layer may be positioned immediately below the shock pad (if used), on top of the substrate material, e.g., a rock layer. In such a position, the carbon sequestration sand-based layer may have a thickness of 1/16″ to ¼″, with a mesh size in the range of #4 to #270.

In still other aspects, carbon sequestration sand may be blended into a stone base layer positioned immediately below the shock pad (if so equipped). In some embodiments, the carbon sequestration sand may be blended into a first of two topping stone base layer system. In other embodiments, the carbon sequestration sand may be blended into some or all of a stone base layer system.

In yet another aspect, a layer of carbon sequestration sand may be positioned on a geotextile or subgrade layer. In such a position, the carbon sequestration sand-based layer may have a thickness of 1/16″ to ¼″, with a mesh size in the range of about #4 to #270.

In still yet another aspect, carbon sequestration sand may be tilled or blended into native subgrade material. In such a position, the carbon sequestration sand may be blended within the subgrade, e.g., soil, as discussed below.

In each of the foregoing aspects, certain carbon sequestration processes can occur as rainwater interacts with the carbon sequestration sand, regardless of the position in the artificial turf system. Further discussion of the processes referenced above are included in the following description.

The innovation described herein introduces a carbon sequestration sand-based infill material designed to enhance the mechanical performance or environmental sustainability of synthetic turf systems. The infill material offers ease of application across various layers of the turf system and provides stabilization of the turf fibers while supporting upright positioning. When dispersed over the turf system as a top dressing or integrated within infill layers, the carbon sequestration sand performs as a ballast that mitigates infill migration and enhances field durability. Additionally, the material facilitates carbon capture through chemical reactions with rainwater, enabling the formation of bicarbonates or carbonates that contribute to carbon sequestration while maintaining desired surface properties such as traction, softness, and shock absorption.

To the accomplishment of the foregoing and related ends, certain illustrative aspects of the claimed subject matter are described herein in connection with the following description and the annexed drawings. These aspects indicate various ways in which the subject matter may be practiced, all of which are intended to be within the scope of the disclosed subject matter. Other advantages and novel features may become apparent from the following detailed description when considered in conjunction with the drawings.

These and other systems, methods, objects, features, and advantages of the present disclosure will be apparent to those skilled in the art from the following detailed description of the preferred embodiment and the drawings.

All documents mentioned herein are hereby incorporated in their entirety by reference. References to items in the singular should be understood to include items in the plural, and vice versa, unless explicitly stated otherwise or clear from the text. Grammatical conjunctions are intended to express any and all disjunctive and conjunctive combinations of conjoined clauses, sentences, words, and the like, unless otherwise stated or clear from the context.

Various aspects of the subject disclosure are now described in more detail with reference to the annexed drawings, wherein like numerals generally refer to like or corresponding elements throughout. It should be understood, however, that the drawings and detailed description relating thereto are not intended to limit the claimed subject matter to the particular form disclosed. Instead, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the described and claimed subject matter.

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Numerical values in the specification and claims of this application should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement technique of the type described in the present application to determine the value. All ranges disclosed herein are inclusive of the recited endpoint.

The term “about” can be used to include any numerical value that can vary without changing the basic function of that value. When used with a range, “about” also discloses the range defined by the absolute values of the two endpoints, e.g., “about 2 to about 4” also discloses the range “from 2 to 4.” The term “about” may refer to plus or minus 10% of the indicated number.

In accordance with varying embodiments discussed herein, there is provided an artificial turf system that utilizes a material derived from one or more types of carbon sequestration sands, including, for example and without limitation, wollastonite sand (general formula CaSiO), limestone, basalt, or the like. More specifically, the carbon sequestration sands may be formed from silicate rock, ultramafic rock, or reactive rock, and specifically include, for example, wollastonite, basalt, peridotite, olivine, dunite, limestone, and dolostone.

In some embodiments, the carbon sequestration sand may be used as an infill material, an intervening layer of material between existing layers of the system, mixed within a particular layer, on or mixed within a substrate, or combinations thereof.

In addition to its excellent performance on the field, this carbon sequestration sand also exhibits behaviors that provide for carbon sequestration. Specifically, the material, when in contact with rainwater, causes a chemical reaction to occur between carbonic acid naturally present in the rainwater and the sand, e.g., olivine, wollastonite, etc. The reaction weathers the olivine, wollastonite, etc., and converts the carbonic acid into bicarbonate or carbonate. In this regard, carbonate and bicarbonate tend to be in equilibrium in aqueous solutions caused by weathering reactions because the dissolution of carbon dioxide and minerals generates a dynamic balance governed by pH-dependent acid-base reactions.

By converting the carbon dioxide into other substances, the carbon dioxide can no longer be released into the atmosphere. Further, the conversion of the carbonic acid has a de-acidifying effect on soils, storm water, rivers, and oceans, simultaneously enriching them with mineral nutrients. These bicarbonate or carbonate solutions are carried by rivers to the sea, where they are ultimately deposited as limestone and dolomites, e.g., carbonate sediments, as well as integrated into marine animal carbonaceous mineral materials. These carbonate sediments form a sink for carbon dioxide.

An example implementation of the embodiment described above is shown in. In this regard,depicts a portion of a synthetic turf systemincluding carbon sequestration sandthat may be olivine-based, wollastonite-based, etc. and is utilized in one or more layers of infill materials. In accordance with some embodiments, the carbon sequestration sandmay be deposited in a layer having a thickness of about 1/16 to about ¼ inches, and have a particle size of about #4 mesh to about #270 mesh in the U.S. Standard Sieve Series. As will be appreciated, mesh may be defined as the number of openings in one square inch of a screen. A large mesh number means the pores in the screen are small. Sand's mesh size is determined by graining, and the numbers refer to the maximum and minimum grain diameters. 40/80 sand means that 90 percent of the sand by volume is small enough to pass through a #40 mesh screen, but too large to pass through an #80 mesh screen. As such, the range of particle size of the carbon sequestration sandreferenced inmay be about #4 mesh (4,750 μm) to about #270 mesh (53 μm).

As shown in, the portion of the synthetic turf systemincludes one or more infill layers(described below), a permeable (e.g., carpet) backing, and turf fibersthat are artificial grass blades extended substantially perpendicular to the backing. With this construction, when the backingis extended flatly in a horizontal direction, such as a stone base layer described in greater detail below, the turf fibersmay extend upward in a vertical direction perpendicular to the horizontal direction. While, as depicted, the turf fibersare artificial grass blades, the turf fibersmay additionally or alternatively include natural grass blades extended upward from the backing, through the carbon sequestration sandand the one or more infill layerswithout departing from the scope of the present disclosure.

The infill layersare positioned above the backing, in between the turf fibers, and below a top portionof the turf fibers. More specifically, the infill layersare disposed directly on top of the backing, where the top portionof the turf fibersextends above the infill layers. While, as depicted, the example embodiment ofincludes multiple layers of infill materials respectively shown as a first layer, a second layer, and a third layer, the synthetic turf systemmay include more or fewer distinct infill layers. Also, while, as depicted, the carbon sequestration sandis disposed below the third layerand directly contacts the backing, where the carbon sequestration sandis interposed between and separates the infill layersfrom the backing, the carbon sequestration sandmay additionally or alternatively be incorporated into the first layer, the second layer, or the third layer, or be applied over the third layeras a top dressing of the synthetic turf systemwithout departing from the scope of the present disclosure.

In this regard, the carbon sequestration sandmay partially or entirely form the first layer, the second layer, or the third layerwith a variety of compositional ranges. In an embodiment, the carbon sequestration sandforms up to 90 percent of the first layer, the second layer, or the third layerby volume. In a further embodiment, the carbon sequestration sandforms up to 10 percent of the first layer, the second layer, or the third layerby volume. With this construction, water insoluble components of the first layer, the second layer, or the third layerreduce an overall wear rate of the synthetic turf system, and maintain a minimum volume in the synthetic turf system. In this manner, a wear rate and minimum volume of the first layer, the second layer, or the third layermay be adjusted as desired by adjusting the compositional range of the carbon sequestration sand. In an embodiment, the carbon sequestration sandmay be preblended or layered with wollastonite, olivine, limestone, or basalt, etc., and additional infill materials complementary to the one or more infill layersfor producing desired field conditions in the synthetic turf system.

The weathering rate and shape of particles forming the carbon sequestration sandare influenced by material selection and particle size distribution. In this regard, consistent particle sizing promotes uniform weathering rates across the one or more infill layers, maintaining overall field performance and carbon sequestration efficiency in the synthetic turf system. The carbon sequestration sandis accessible to rainwater traveling downward by gravity from the top portionof the turf fiberstoward the backing. As the carbon sequestration sandweathers through exposure to rainwater, its constituent particles may substantially change morphology, or alternatively may remain largely the same shape. In embodiments, the selected silicate rock, ultramafic rock, or reactive rock materials form weathered particles that maintain a sphericity of about 0.65 to about 0.85. This sphericity range supports stable packing within the synthetic turf system, reduces compaction variability, and ensures continued mechanical performance while facilitating consistent chemical reactions for carbon capture.

In an embodiment where the carbon sequestration sandis incorporated in the synthetic turf systemas a top dressing, the carbon sequestration sandis periodically dispersed over the top portionof the turf fiberswith an application systemdepicted in. With continued reference to, the application systemincludes a seed tenderand a tractorthat disperses the carbon sequestration sandover the synthetic turf systemfrom a broadcaster tool. The seed tenderis employed in conjunction with a hydraulically-controlled conveyorand a hopper gate, which supply the tractorthe carbon sequestration sand. As the tractormoves at a consistent speed across the synthetic turf systemfollowing a predetermined pattern, the hydraulically-controlled conveyorand the hopper gateprecisely control a flow rate of the carbon sequestration sandto the tractor, ensuring uniform distribution across the synthetic turf system.

While, as depicted, the application systemincludes the broadcaster toolpulled by the tractor, and continuously fed the carbon sequestration sandby the seed tenderalong or across the synthetic turf system, the application systemmay additionally or alternatively include a variety of components configured to spread granular material across a field, such as, for example, a self-propelled, manually powered, or power take-off (PTO) driven broadcast material spreader, a pneumatic spreader, an air boom spreader, a drop spreader, a handheld spreader, or an aerial spreader for dispersing the carbon sequestration sandwithout departing from the scope of the present disclosure.

Once the carbon sequestration sandis dispersed across the synthetic turf systemby the application system, the carbon sequestration sandis brushed into the one or more infill layers, including the first layer, the second layer, and the third layer. In this regard, a brushdepicted ingrooms the carbon sequestration sandinto the one or more infill layers. Rotary brush action on the synthetic turf systemfrom the top portionby the brusheffectively works the carbon sequestration sanddownward between the turf fibers, ensuring proper placement within the infill material forming the one or more infill layers, while maintaining structural integrity and performance characteristics of the synthetic turf system, including at the top portionand the first layer.

While, as depicted, the brushis a motorized, walk-behind rotary brush apparatus, such as a Shindaiwa or Laymor brush system, the brushmay additionally or alternatively include various components for incorporating the carbon sequestration sandinto the one or more infill layerssuch as, for example, a ride-on turf groomer, a tractor-mounted brush that is dragged or PTO driven, or manual turf brushing equipment. Furthermore, brushes employed in such configurations may embody various shapes, sizes, and types, such as, for example, straight brushes, triangular brushes, hydraulic brushes, oscillating brushes, rigid brushes, flexible brushes, or brush assemblies including at least one plurality of brushes. Furthermore, the brushmay additionally or alternatively include specialty turf equipment, such as a vacuum or other devices complementary to the brush, and utilized to integrate the carbon sequestration sandinto the existing infill material of the one or more infill layerswithout departing from the scope of the present disclosure.

Referring back to, infill is representative of material that is deposited over the backingand forms the one or more infill layersaround the turf fibers. Infill is interspersed between the turf fibersrising out of the backing. Infill generally has a depth that covers a portion of the turf fibers(unexposed portion of the artificial fibers/blades) leaving part of the turf fibers, i.e., the top portionextending above the infill (exposed portion of the artificial fibers/blades).

In accordance with some embodiments, the one or more infill layersassists in supporting the turf fibersin an upright position and is used to provide traction and shock absorption. As a general matter, various types of infill arrangements are contemplated. For example, two layer, three layers, or other arrangements are contemplated. For convenience, the present description primarily discusses two and three layer embodiments.

In some embodiments, the first layermay include, for example and without limitation, heartwood or sapwood portions of hardwood or softwood, such as bamboo, cypress, poplar, pine, and cedar. The first layermay additionally or alternatively include, for example and without limitation, cork, corn cobs, olive pits, barks, coconut peat or other organic materials, as well as styrene-butadiene rubber (SBR) particles ethylene propylene diene monomer (EPDM) rubber, other thermoplastics such as polyethylene, polypropylene, or composite materials can be used that combine thermoplastics, elastomers, reinforcements and/or fillers or other sufficient material. In accordance with some embodiments, the second layerof infill material depicted inmay include a mixture of materials, e.g., material of the first layerand a sand material. In such embodiments, the third layerof infill material may include the aforementioned sand material, such that the fourth or lowermost layer is that of the carbon sequestration sand.

In accordance with some embodiments, a shock pad (not shown) may be employed to achieve a desired shock absorption in accordance with a particular installation/purpose. For example, a shock pad (not shown) may be positioned below the one or more infill layersshown in. As such, the material of the infill layersconveys many of the mechanical properties that may be desired for use as artificial turf infill.

In some embodiments, the carbon sequestration sandcan be used in combination with the backing, and/or a stabilizing infill layer (e.g., sand)to make up the synthetic turf system. The synthetic turf system, using the described infill material, exhibits superior mechanical performance, a greater mechanical durability, easy availability and mitigates or otherwise avoids issues of floating away when subjected to large amounts of water.

In some other embodiments, the backingmay be positioned below the carbon sequestration sandshown in. In such embodiments, the backingmay correspond to the material into which the turf fibersare woven, held, inserted, etc. Accordingly, the carbon sequestration sandis positioned directly on the backing, thereby functioning as a ballast layer. The backingis water permeable, without punched holes, such that the carbon sequestration sandmay remain in place at the backing, underlying the remainder of the infill layers, thereby maximizing contact with rainwater while preventing the carbon sequestration sandfrom being flushed out of the synthetic turf systemvia regular drainage measures. More specifically, the backinghas a porosity that filters rainwater from the carbon sequestration sandand the one or more infill layersas the rainwater travels downward through the synthetic turf systemfrom the one or more infill layersto below the backing.

Turning now to, there is shown a more detailed three-dimensional cross-sectional view of a portion of the synthetic turf systemutilizing the carbon sequestration sandas a ballast infill material in accordance with the embodiment set forth above in. It will be appreciated that while illustrated inas a multi-stone layered installation, the carbon sequestration sandmay be used in other types of turf systems and in varying mesh sizes, and the illustrations inare intended solely as one non-limiting example of turf carpet systems in which the carbon sequestration sandmay be utilized.

As shown in, the synthetic turf system, in addition to including the turf fibers, the carbon sequestration sand, the infill layers, and the backing, further includes a first base stone layerdisposed below the backingand above a second base stone layer. The synthetic turf systemfurther includes a geotextile componentthat is a fabric disposed between the second base stone layerand a subgrade. The synthetic turf systemmay further include a subdrain trench componentformed in the subgrade and housing a drainage pipe.

As discussed above, the carbon sequestration sandmay be implemented, for example and without limitation, olivine, wollastonite, basalt, limestone, etc. In operation, with reference to, as rainwater contacts the carbon sequestration sand, a chemical reaction occurs between carbonic acid naturally present in the rainwater and the sequestration sand. The reaction weathers the carbon sequestration sand, e.g., olivine, wollastonite, etc., and converts the carbonic acid into carbonate or bicarbonate. As stated above, the conversion of the carbon dioxide into other substances prevents the release of the carbon dioxide into the atmosphere. Further, the conversion of the carbonic acid has a de-acidifying effect on soils, storm water, rivers, and oceans, simultaneously enriching them with mineral nutrients. Carbonate and bicarbonate solutions may permeate the first base stone layerand the second base stone layer, through the geotextile componentand into the subdrain trench componentand drainage pipe. Thereafter, the carbonate and bicarbonate solutions are carried by rivers to the sea, where they are ultimately deposited as limestone and dolomites, e.g., carbonate sediments, forming a sink for carbon dioxide.

Turning now to, there is shown another embodiment of the synthetic turf systemutilizing the carbon sequestration sand. As illustrated in, the carbon sequestration sandis applied on a top surface of the first base stone layer, below the backing. Application may be made via a suitable top-dressing machine, such as the application systemdepicted in. In the embodiment of, the carbon sequestration sandmay be deposited with a thickness in the range of about 1/16″ to ¼″. The carbon sequestration sandofmay be implemented with a particle size of about #4 mesh to #270 mesh. In such an embodiment, rainwater would flow directly through the one or more infill layers, the backing, and the carbon sequestration sandand into the first base stone layer. Reaction with the rainwater would occur as described above with respect to.

With reference now to, there is illustrated the synthetic turf systemutilizing particles of the carbon sequestration sandin accordance with another embodiment. In the embodiment depicted in, particles of the carbon sequestration sandare incorporated into the first base stone layer. In accordance with one non-limiting example, the first base stone layermay be implemented as a layer of stone having a thickness in the range of about 1 inch to about 6 inches, and in some particular embodiments, in the range of about 1 inch to about 2 inches. In such embodiments, the first base stone layermay include for example and without limitation, a suitable drainage stone, such as gravel (e.g., granite) or the like. The carbon sequestration sandmay be suitably mixed with the stone to distribute the carbon sequestration sandthroughout the first base stone layer. In some embodiments, a single, e.g., uniform, base stone layer (not shown) may be utilized. In such embodiments, the carbon sequestration sandmay be blended into the single base stone layer, e.g., to a certain depth thereof (e.g., the top 1″ or 2″ thereof), or throughout the base stone layer. As described in greater detail above, reaction of the carbon sequestration sandwith rainwater would occur as described above with respect to.

Turning now to, there is shown another embodiment of the synthetic turf systemutilizing carbon sequestration sand. As illustrated in, the carbon sequestration sandmay be on the geotextile component. In such a position, the carbon sequestration sandmay form a layer having a thickness of about 1/16″ to about ¼″, with a mesh size in the range of about #4 to about #270. Stated another way, the layer of carbon sequestration sandmay be applied at a bottom of the second base stone layer, as shown in. In accordance with one non-limiting example, the second base stone layermay be implemented as a layer of stone having a thickness in the range of about 2 inches to about 6 inches, and in some particular embodiments, in the range of about 3 inches to about 4 inches. In such embodiments, the second base stone layermay include, for example and without limitation, a suitable drainage stone, such as gravel (e.g., granite) or the like.