Patent Application
20140140776
The invention is directed to ground surface covers, including methods for producing said devices, the devices themselves and applications for said devices. The invention satisfies a need for environmentally friendly ground surface covers which can be easily anchored to terrain of varied slope, pitch and constitution and offering exemplary performance as an erosion control applications. The term constitution in the context of this patent application refers to different terrains composed from a wide variety of soils, rocks, organic materials, vegetation, biomass and a wide range of moisture contents.
Included in the disclosure are exemplary devices, systems, and methods, embodiments of which can be useful for controlling erosion, treating runoff, removing pollutants, remediating environmental damage, protecting plants, establishing vegetation, protecting ecosystems, and/or restoring waterways and/or other riparian areas, building structures such as roads, work spaces, buildings or berms and otherwise organizing biomass into a useful product.
In the context of this patent application biomass refers primarily to biomass materials such as those associated with, but not primarily harvested or used in logging operations, road construction, building construction, agriculture operations, thinning operations, fire suppression, post fire debris and land fill debris. It should be noted that the innovation can be practiced using single or multiple sources of biomass.
It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject of the technical disclosure. This abstract is submitted with the understanding that it will not be used to limit the scope or meaning of the claims.
Many of today's logging, construction, road building, landfill and under developed landscapes can benefit from erosion control, wind or dust breaks and/or infrastructure such as roads, buildings, landing strips and work zones. Many of these locations are distant from construction material sources, necessitating transportation of structural materials, construction equipment and trained personnel to meet the raw material, processing, construction and installation requirements. Transportation requirements can be capital intensive, inefficient, require significant amounts of man-hours, capital expenditure, produce undue amounts of green house gases and can be a limiting factor to the implementation of erosion control media.
Transporting raw materials and machinery from distant locations to an erosion prone area can introduce pollutants and biological or chemical species not native to the application site or work zone. The invention disclosed offers an erosion control system, methods for producing said system and applications for said system utilizing locally available biomass materials processed to offer exemplary performance as an erosion control barrier, construction medium or containment system. Though the following discussion speaks primarily to erosion control barriers, it should be understood that the invention is not limited to erosion control media but also offers exemplary utility in other structural applications. Structures produced can be either permanent or semi-permanent. Permanent structures in the context of this application are those structures build to last a minimum of twenty years. Semi-permanent in the context of this application means lasting or intended to last for one week to five years.
Erosive wear occurs when a surface is exposed to the movement of a flowing liquid. Erosive wear increases dramatically if the flowing liquid has a solid material suspended in it. Particles and pieces of debris within the flowing liquid impact an exposed surface and impart some of their kinetic energy to said surface. If the energy is sufficiently high, the kinetic energy of the impacting particles can create significant tensile residual stress in the exposed surface. Repeated impacts cause the accumulation of tensile stress in the prone surface leaving the exposed surface brittle, leading to cracking, crack linkage and eventually gross material loss. Material loss results in a reduction of vegetative growth, a reduction in the habitat suitable for microorganisms, and the deleterious effects commonly associated with the movement of materials into bodies of water and the aquifer.
As a result, erosion control techniques and devices are often required to inhibit soil movement in areas undergoing logging operations, reforestation, road construction, waterway construction, building and home construction, mine or landfill sites or other sloped areas that are prone to erosive wear. These techniques commonly include, for example, the installation of perimeter barriers such as straw bales, silt fences, compost filter berms, erosion barriers or most recently systems comprised of biomass and synthetic fibers. The following text relates to related art, which is not admitted to be prior art with respect to the invention by its mention in this Background Section.
Straw bales have been shown to be effective at providing some measure of erosion control. Straw bales are typically placed around a designated area to physically impede the flow of water and water born solids. While these bales are relatively inexpensive to purchase and easy to install, they are unsightly, must be transported to the site being eroded and must be removed after soil stabilization has been effected. Furthermore, the bales may be displaced by heavy water run-off events, thereby rendering them ineffectual for controlling soil movement.
Silt fences are also known to impede soil movement in erosion prone areas. However, they are aesthetically unpleasing, must be removed after use and require a means of securement to the eroding surface. In addition, as compared with other erosion control techniques, construction and installation of silt fences is expensive.
In contrast, U.S. Pat. Nos. 6,921,484, and 6,709,202 describe filter berm erosion barriers comprising a biodegradable “sock” filled with a biodegradable material. Said socks are filled using conventional blower techniques. The sock is composed of material, such as burlap, that naturally rots and decomposes. Thus, when the sock decays, it merges into the surrounding soil and thus leaves a minimal trace. The materials used to fill said socks can be pre-seeded compost, which allow desired vegetation to grow from the compost into the underlying soil.
Though compost filter berms must be transported to the worksite thereby incurring costs and equipment use, they are relatively inexpensive to install and need not be removed. These berms physically filter settle able solids from water runoff, and can provide an environment for microorganisms capable of degrading organic compounds and binding pollutants. Furthermore, compost filter berms can promote seed establishment and plant growth. Wattles must be properly installed with these systems or they can concentrate sheet flows resulting in a rapid rate of erosion. These systems must be embedded into the soil by excavating a shallow trench and backfilling, leading to extensive labor requirements for installation. Compost filer berms are also known to catastrophically fail in major water events and suffer from ultraviolet degradation resulting in premature failure and distribution of the berm constituents. Said filter berms can be expensive to install and transport and are known to introduce non-native species to application environment. The berms are also known to not intrinsically bind to the erodible surface and known to divert water around said berm and under said berm thereby propagating the erosive behavior to a different location or focusing it to a specific location. Therefore they provide less than ideal erosion control. Compost filter berms require wattles, which are known to fail by spillway effects, undercutting, and flanking further exacerbating failure mechanism resulting in erosion.
Recently, the industry has developed blanket-type products called turf reinforcement constructs such as that expressed in U.S. Pat. No. 4,372,705 which describes an articulated construct comprising a plurality of blocks which interlock in a three dimensional fashion which allow a construct formed of the blocks to conform to changes in terrain. Though this technology conforms to the terrain, conformation is limited to the size of the blocks used in the construct. U.S. Pat. No. 3,597,928 discloses the use of porous flexible supporting sheets with blocks placed on said sheets. Each construct consists of a plurality of blocks with drainage passageways, which allow the movement of water through the blocks facilitating vegetative growth through the blocks. The constructs are secured to the sheets by adhesive means resulting in a structurally sound erosion control medium. Turf reinforcement constructs are expensive, require a significant amount of labor to install and rely upon transportation to bring the devices to the work zone. Furthermore, these constructs are not amenable to excessively steep slopes, narrow ravines or highly irregular slopes. Though these systems conform to terrain they are also limited in conformation to the size of the interlocking blocks.
The industry has also developed earthen containment reinforcement systems such as that described in U.S. Pat. No. 7,563,057 to convey water and withstand designated loads. While such turf reinforcement constructs do little to reduce or mechanically dissipate the energy of runoff water energy themselves, their installation allows for the growth of vegetation, which, in turn, mechanically reduces energy associated with runoff water. Such blankets are typically three-dimensional, flexible constructs constructed of plastic webbing. The open weave of such constructs allows vegetation to grow through the barrier. The combination of a mechanical stable structure and open weave design results in a significant synergistic effect, with the capacity to carry much greater velocity and sheet force loads because roots and stems associated with the growing vegetation are reinforced by the construct.
Although turf reinforcement and erosion control constructs have numerous advantages over the prior efforts in terms of reducing erosion, it is often difficult to securely mount these types of constructs in an erosion prone area and they are not applicable in steep or highly uneven terrain. Another draw back to turf reinforcement and erosion control constructs of this type is that they typically require complex anchoring systems and multiple personnel to install. Once installed these systems can also suffer from excessive movement between the construct and the ground thereby allowing erosive flow beneath and around the construct, resulting in undesired erosion. Play or movement in these systems is a major failure mechanism in steep terrain, highly uneven terrain, terrain already suffering from erosion or terrain where it is difficult to properly secure said erosion control devices. If the movement is chronic or becomes substantial, the anchor can become dislodged, allowing the construct to move away from the erosion susceptible surface or fail completely, thereby defeating the purpose of the construct. These systems also require significant time and cost to transport the devices to the work site. Another significant draw back is that many of these systems are produced from environmentally unfriendly materials.
In order to provide an alternative approach, certain pre-blended mulch products have been introduced into the marketplace. U.S. Pat. No. 5,476,711 describes a fiber blending system, which forms a construct produced from a combination of cellulosic and synthetic fibers. According to U.S. Pat. No. 5,476,711, the method disclosed describes fiberizing cellulosic materials into cellulosic fibers in a fiberizer, volumetrically metering an amount of synthetic fibers, and injecting the metered amount of synthetic fibers into the cellulosic fibers. The cellulosic fibers are blended with the metered amount of synthetic fibers in a blending chamber to form a fiber blend. The fiber blend is then dispersed through a fiber disperser. A third type of fiber may also be mixed with the dispersed fiber blend. The dispersed fiber blend is collected as a construct on a fiber collector to provide a construct of blended cellulosic and synthetic fibers. The construct may be thermo bonded and sandwiched between a facing sheet and a backing sheet.
U.S. Pat. No. 5,942,029 describes a water absorbent fiber mulch made from natural and crimped, synthetic fibers that are intimately mixed together to form the fiber mulch. Said fiber mulch is mechanically bonded into an open weave system produced by the entanglement of the crimped synthetic fibers with one another and said natural fibers. The entanglement holds the mulch together in a construct, which is sufficiently permeable to air and porous enough to allow seedlings to grow up through said mulch. A water-absorbent polymer-based construction material is dispersed throughout the fiber mulch to increase its water absorption capacity. Similar mulch products are found in U.S. Pat. No. 5,779,782 and U.S. Pat. No. 5,741,832.
Systems that promote seed retention and growth have also been developed, such as that described in U.S. Pat. No. 7,384,217. U.S. Pat. No. 7,384,217 describes a system and method for promoting vegetative growth on a steeply sloping surface. The patent describes a series of synthetic and geosynthetic layers, seeded compost and an anchoring system. Vegetation grows in the compost construction material establishing a root system thereby stabilizing the erosion prone slope.
Not withstanding the aforementioned products in the field, there remains a need in the art for an erosion control device which is easily produced and deployed, uses locally sourced construction materials minimizing the need for transporting erosion control media, a device which conforms and bonds to an erosion prone ground surface regardless of slope, terrain or constitution without the requirement of a separate retention system. Furthermore, there remains a need in the art for an erosion control medium, which can be produced in remote locations with a minimum of mechanical equipment and personnel. Furthermore yet, there remains a need in the art for an erosion control device that can convert locally sourced biomass containing biota specific to the site, which is important in re-establishing natural biological functions, to a useful constructive media. Furthermore yet, there remains a need in the art for an erosion control medium, which requires a minimum of installation and maintenance during the lifetime of the constructed system that can be applied in a continuously variable embodiment in response to the variable requirements of the landscape. Furthermore yet, there remains a need in the construction, timber and fire suppression industries to sequester biomass in order to reduce fire danger.
The difficulties encountered in prior efforts discussed hereinabove are substantially eliminated by the present invention.
An objective of the invention is to provide a biomass construct, produced from locally sourced biomass converted to a value added construction material.
A further objective of the invention is to provide a biomass construct, containing local biota thereby enabling improved integration into the environment without introducing foreign biota, microorganisms or pollutants.
A further objective of the invention is to provide a biomass construct, which reduces the energy associated with erosive fluid flow while maintaining fluid flow through the biomass construct.
A further objective of the invention is to provide a biomass construct, which is produced and installed in an environmentally friendly manner.
A further objective of the invention is to provide a biomass construct, which is comprised from organic materials.
A further objective of the invention is to provide a biomass construct, which does not require the addition of synthetic fibers, rods, sheets or other synthetic materials.
A further objective of the invention is to provide a biomass construct, which is produced from a minimum of transported materials thereby vastly reducing the environmental impact and costs associated with the transportation of materials.
A further objective of the invention is to provide a biomass construct, which is lightweight and low cost.
A further objective of the invention is to provide a biomass construct, which is easy to install.
A further objective of the invention is to provide a biomass construct, which does not need to be removed once installed.
A further objective of the invention is to provide a biomass construct, which easily accommodates various depths, pitches, angles and slopes in the application terrain.
A further objective of the invention is to provide a biomass construct, which allows for quick installation without the need for heavy or costly tools or machinery.
A further objective of the invention is to provide a biomass construct that can be installed with no need to excavate, compact, pre-treat or otherwise disturbance the application surface.
A further objective of the invention is to provide a biomass construct, which allows greater securement to a surface without the need of securement beyond the biomass construct itself.
A further objective of the invention is to provide a biomass construct, which is durable and long lasting.
A further objective of the invention is to provide a biomass construct, capable of being used as a structural component for roads, buildings, landing strips or berms.
A further objective of the invention is to provide a biomass construct, which provides an environment amenable to plant and microorganism growth.
A further objective of the invention is to provide a biomass construct, which has sufficient porosity to allow water to follow an impeded but minimally diverting course.
A further objective of the invention is to provide a biomass construct, which can be sprayed from a blower, applied by hand, applied with buckets and spilled from a container.
A further objective of the invention is to provide a biomass construct, which can be produced in remote locations with a minimum of transportation requirements.
A further objective of the invention is to provide a biomass construct, using locally available biomass.
A further objective of the invention is to provide a biomass construct and method of use that is simple to apply.
A further objective of the invention is to provide a biomass construct, which can be produced and applied in isolated environments. Isolated in the context of this patent application refers to areas which are difficult to reach for conventional mechanical application equipment.
A further objective of the invention is to provide a biomass construct, which reduces the risk of fire by sequestering biomass into bound and coherent biomass products.
A further objective of the invention is to provide a biomass construct, which impedes the evaporation of soil moisture into the atmosphere.
A further objective of the invention is to provide a biomass construct, which is not confined to a specific form, rather conforms to the deposition surface and desired shape of the final construct.
A further objective of the invention is to provide a biomass construct, which is produced from a variety of sources such as but not limited to restoration, lumber, construction, agricultural, biomass, pulp, paper and pallet byproducts.
A further objective of the invention is to provide a biomass construct, which can be made by hand or by machinery with no change in performance.
A further objective of the invention is to provide a biomass construct, which can be used as a final cover for landfill, agricultural, fire and construction sites.
A further objective of the invention is to provide a biomass construct and method of making same.
A further objective of the invention is to provide a biomass construct and method of installation of said construct.
The present invention is directed to an improved biomass construct and method of making the same. The present invention is directed to a process for preparing a solid biomass construct for application to a ground surface in order to reduce erosion that satisfies the need to be environmentally friendly, easy to apply and capable of being secured to a wide variety of terrains. An erosion control barrier having features of the present invention comprises the steps of formulating a cementitious binder, thoroughly mixing said cementitious binder in a quantity of water so as to form a cementitious binder slurry. Adding said cementitious binder slurry to a quantity of biomass and thoroughly mixing said slurry and said biomass together so as to substantially coat said biomass with said slurry. Applying said slurry coated biomass to said ground surface and allowing said slurry coated biomass applied to said ground surface to cure into a solid biomass construct. Said biomass construct provides a cost effective, easily manufacturable construction material with applications in erosion control, airborne particulate control, fire suppression and as a hard and durable surface for machines, livestock and personnel. Said biomass construct further provides as an impact barrier for vehicles or shooting ranges and as a demarcation or marker system visible from large distances or heights. Said invention further offers as a medium for controlled burns and a method to organize and sequester biomass into a value added construction medium. The present invention further offers utility as a building construction material for housing, storage, wind and snow barriers.
To practice the innovation, a cementitious binder slurry is prepared in a suitable container. Additional additives can be mixed into said cementitious binder slurry forming a binder additive slurry which is mixed to a homogeneous distribution. The cementitious binder additive slurry is added to the mechanically refined or virgin biomass and mixed such that said biomass becomes coated with said slurry.
Typically, the biomass water mixture is formed within a mix tank, wheelbarrow or container. Commonly, said mix tank is equipped with mechanical agitators or circulation pumps power by a motor. It should be noted that the innovation disclosed is amenable to mixing done by hand without the requirement for any mechanical assistance. The coated biomass system can now be applied to an application surface by manual or mechanical means. Once applied, the mixture dries into a cured and hardened structure providing exemplary physical characteristics useful in applications such as erosion barriers or construction materials.
For the purpose of promoting an understanding of the principles of the present invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the illustrated device, and any further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates are also included.
The following description describes the innovation in terms of its application as an erosion barrier though it should be understood that the biomass construct described and the methods of preparation expressed are applicable to other applications as discussed elsewhere in this patent. Reference will now be made in detail to production, implementation and embodiments of the invention, examples of which are illustrated in the accompanying drawings.
For the purposes of this specification, a biomass material (2) is defined as material from a plant, tree, shrub, grass, vegetation or agricultural byproduct. One of the distinguishing factors of the innovation is that it can accommodate a large range of biomass shapes, sizes and size distributions. Irregular shapes including those commonly associated with chipping, thinning, cutting, crushing or breaking up larger pieces of wood in to smaller pieces of wood can be used to produce said biomass construct. Angular, rounded and irregular pieces can be used separately or in combination to produce said biomass construct.
Biomass material (2) of different sizes and size distributions can be combined in the practice the innovation. Very large pieces of biomass, such as trees (4) can be incorporated into said biomass construct. Small pieces of biomass such as grasses, wood chips, wood flakes or twigs (6) can also be used in the production of said biomass construct. The variety of shapes and sizes within the biomass construct assist in anchoring said construct to the ground (8).
Suitable biomass materials can be produced by several methods including chopping, chipping, cutting, shaving, mulching, natural refining or gathering biomass within the suitable size ranges. Natural refining can also occur or can be a result of the natural growth of the chosen biomass. Sources for biomass materials include but are not limited to remnants from lumber operations, fire remnants, bamboo, tree and shrub clippings, urban waste such as pallets, demolition wood, saw mill remnants, firewood operations and grasses.
Biomass materials of widely varying moisture content can be used in practice of the invention. Moisture content from less than 5% to more than 75% can be successfully processed into a high quality and functional biomass construct embodying the invention. Biomass with different water contents can be used in a singular instance of the invention. Water content is an important variable to consider in the practice of this innovation.
When practicing the innovation on a dryer biomass, that is a biomass with a small amount of water content, for example 10%, additional water may be required to insure sufficient wetting of the biomass with the a binder containing slurry. Said binder containing slurry is shown in its cured form (10) in the accompanied figures as a coating around the individual pieces of biomass. Biomass is considered to be sufficiently wet if 90% of the biomass surface area is coated with the water binder mixture during the mixing process. The biomass material usually forms the predominant component in the blended product, comprising about 25% to about 90% by weight of the cured biomass construct. More preferably, the biomass material comprises between 50% to 85% by weight of the cured biomass construct. The high concentration of biomass construction material provides the bulk required to form the biomass construct.
The surface area of the biomass material is an important parameter to consider. As surface area increases, the adhesion and loading of the water binder mixture also increases. Loading in this case refers to the amount of water binder mixture that adheres to the biomass material. The increase in surface area also increases the amount of contact between individual biomass pieces resulting in increased physical strength and improved adhesion characteristics in the cured biomass construct. Further, increased surface area can improve the permeability in the resulting cured biomass construct. Increasing the surface area also affects the flow characteristics of biomass and coated biomass through conveyance means. In particular, increased surface area has been found to improve conveyance of water binder mixture coated biomass through forced air assisted conveyance means as described later in this text. Increased surface area is most often accomplished by roughening through well-known techniques such as physical agitation of the type commonly associated with hammer milling or re-chipping processes. Chemical roughening techniques are also known in the art. Increased surface area is predominantly a function of an increase in the amount of biomass fibers partially separating from the main biomass body and flattening, bending or further disconnection of said separated biomass fibers. Partial separation is defined as those fibers or groups of fibers that have some percentage greater than 1% but less than 99% connected to a larger biomass body, the remainder of which is not connected to the biomass body. It should be noted that increasing the surface area too much, could result in different performance attributes. For example, if biomass shavings or fines are used in the described process, additional binder may be required to achieve high quality cohesion.
The relative density of the biomass is not a major factor in the biomass construct's physical performance. The addition of a cementitious binder (12) produces a solid biomass construct by binding the biomass particles together rather than relying on the density of the biomass to produce structural integrity. The use of cementitious binders allows the utilization of a wide variety of biomass materials of varying density, size, width, and shape to produce the described biomass constructs. Materials such as grass, manure, wood chips, brush, bamboo, mulch, biomass left over from logging, road building or construction projects and other biomass materials can be used to practice the innovation.
The biomass construct obtains the desired strength, hardness, resiliency and longevity from the use of a cementitious binder, which upon curing binds the individual biomass pieces into a solid biomass construct. By binder we infer an ingredient that is used to bind together two or more materials in a mixture. Many different binders and binder formulations exist. The two principal properties involved in the binding mechanism are adhesion and cohesion. Though both organic and inorganic binders can be used, the preferred binder is cementitious in nature and can be either insoluble such as cement, clay and lime or soluble. Preferred inorganic binders include but are not limited to magnesium oxysulfate, magnesium oxychloride, or magnesium phosphate. Within the text of this patent, the use of the word binder and cementitious binder and their plurals are to be considered one and the same.
The aforementioned binders have shown no toxicity in the quantities used for erosion control purposes. Regardless of which binder is used, the choice of binder should not include those binders that re-dissolve once the biomass construct is allowed to cure. The binder comprises between 10 weight percent to 75 weight percent of the blended biomass product described herein. More preferably, the binder comprises between 15 weight percent and 50 weight percent of the blended biomass.
Admixtures (14), such as boric acid, may be incorporated into the binder slurry. Boric acid is used to increase the amount of time the biomass can be manipulated or handled before curing. Other additives (16) such as natural or synthetic binders, tackifiers, dispersants, admixtures, flocculants, emulsifiers or de-flocculants can optionally be added to the binder water mixture to improve the viscosity, density, workability or properties of the biomass slurry mixture, though they are not required to achieve a satisfactory product. Said additives are commonly used to improve the consistency of binder slurries, promote distribution of additives or reduce the friction associated with solid materials in a pump. These additives (16) can be used to prevent plugging of the pumps and to aid in the adherence of the biomass construct to the application surface.
The addition of foam (18) has been found to be beneficial in controlling the adherence of the binder water slurry to said biomass surface. The addition of foam produces tiny bubbles in the binder water slurry, increasing its ability to adhere to surfaces. Increased adherence of the binder results in increased binding of the biomass and improves strength, hardness and durability of the resulting cured biomass construct.
To produce said foam, a foaming agent, such as CreteFoam produced by Richway, is diluted with water and pumped through a foaming making machine. Foam making machines are known in the art. Said foam making machines process a foaming agent into a foam which can then be blended into a given binder slurry and mixed to a homogeneous distribution. Foam to binder slurry ratios varying in volume from 0.5-1 to 3-1 (foam-binder slurry), were found to improve binder slurry adhesion to biomass and ground surfaces. More preferably, foam to binder slurry volumetric ratios between 1-1 and 2-1 (foam-binder slurry), have been found to greatly improve binder slurry adhesion to biomass and ground surfaces.
The function of the binder (12) and any additional additives (16) is multifold. In the binder slurry, the binder coats the biomass and increases the viscosity of the slurry. The binder coated biomass has a reduced friction coefficient, thereby reducing stress in any machinery used to prepare, process or convey said coated biomass. Further yet, binder increases the homogeneity of the resulting coated biomass mixture. The combination of reduced friction and increased homogeneity result in the ultimate delivery of a relatively even and consistent mixture of coated biomass, which may be applied to a ground surface to form a biomass construct having a substantially homogenous distribution of biomass material. Further yet, the reduced friction also extends pump and hose life and lowers the requirement for pumping energy. The addition of a cementitious binder further provides adhesion of biomass-to-biomass, biomass to soil and soil to soil in a biomass construct or an erosion control medium formed on a ground surface.
Binder slurry is prepared by thoroughly mixing a cementitious binder (12) in water (20) until it dissolves forming a cementitious binder slurry (22). Mixing can be accomplished by mechanical or manual means. Mechanical blending is most commonly used. If admixtures (14) or additives (16) are required, they are added to the binder slurry once the binder is dissolved in said water. If additives are required, mechanical or manual blending is used to homogeneously distribute said additives within the binder slurry.
Mixing of the cementitious binder, admixtures, and additives is most commonly done by using a mechanical mixer of the type commonly used to mix paints, though it should be understood that manual mixing and other mixing techniques are known in the art and amenable to the practice of this innovation. In one example, an electric drill (24) and a mixing paddle (26) of the type commonly used to mix paints and a five gallon bucket (28) was used to facilitate mixing. It should be understood that mixing times can vary as a function of water temperature, the amounts being mixed, the means for mixing, elevation and the type of binder used. Mixing is considered complete when a substantially homogeneous mixture is produced. If additives or admixtures are to be included, they are mixed into the binder slurry in a similar manner.
Upon homogenization of the binder slurry or binder additive slurry or binder admixture slurry or foam containing binder slurry or any combination thereof, termed for the purposes of this application, a cementitious binder containing slurry (30) are added to the biomass such that biomass is coated with the binder slurry. Many mixing techniques are known in the art including but not limited to manual mixing, mechanical mixers (32), cement mixers, auger mixers, tumble mixers and blower mixers and others which are known to mix multiple components at the same time.
Mechanical mixing is predominantly used as it is known to provide sufficient mixing. Sufficient mixing is one that reduces or prevents clumping of biomass and uneven dispersion of the binder containing slurry. Clumping of biomass and/or uneven dispersion of the binder can cause machinery to clog or breakdown. Clumping of biomass and/or uneven dispersion of the binder containing slurry can result in weak spots in the erosion control medium formed using the blended biomass product. Effective mixing helps to blend the different types of materials and shapes together and form the desired homogeneous distribution of the mixed constituents.
Upon complete mixing of the binder containing slurry and biomass, the resulting coated biomass can be applied to the application surface. Application can be by manual or mechanically assisted means. If the binder coated biomass (34) is to be applied by hand, the operator can position said binder coated biomass (34) using a bucket or similar container onto the application surface.
In another alternative, the binder coated biomass (34) can be applied by mechanical means, for instance by using a blower (40). A number of different types of blower mechanisms exist. By blower we refer to a device that accelerates the biomass such that it is expelled at the end of the blower with sufficient velocity to be advantageously positioned on an application surface (42). One such example is a model BB302 bark blower produced by the Finn Corporation. These types of blowers can facilitate addition of the cementitious binder containing slurry directly onto the biomass at the nozzle end of the blower using a static mixing nozzle (44). Said static mixing nozzle (44) uses a ball valve (46) to supply a measured amount of the cementitious binder containing slurry via injection ports (48) to the static mixing nozzle (44). The static mixing nozzle (44) fully coats the flowing biomass with cementitious binder containing slurry by turbulent mixing prior to expulsion from the nozzle.
Said Finn bark blowers are usually operated at 10 PSI producing an airflow of 500 cubic feet per minute and carry up to 3 cubic feet per minute of biomass. Larger blower systems are known to exist and are capable of airflows of 1500 cubic feet per minute at 15 PSI. It should be understood that said binder coated biomass systems can be processed using both smaller and larger blower systems than those described.
Once the coated biomass has been applied to the application surface, the binder cures forming a durable biomass construct. The cured biomass construct is endowed with sufficient structural integrity to survive water flow, environmental influences such as wind, rain, thermal expansion, ultra violet light exposure and is strong enough for a person to walk on without deforming or losing it's original structure. Curing time can vary as a function of temperature, weather, water loading and binder type and content. In cases of where the invention is practiced in cool, damp or wet environments, curing can take as long as ten days and still result in a suitable constructive medium. On average, curing takes between 24 and 36 hours.
Once cured, the individual biomass pieces within the biomass construct are bound together, forming a protective ground cover that is porous (52) and breathable. The cementitious binder containing slurry binds to the soil (54), terrain features such as topographic changes (56), rocks (58), vegetation (60) and existing features (62) while allowing the natural flow of water to ensue while providing an environment for re-vegetation (64) and both vegetation and microbe growth. The biomass construct can be rewetted over periods of months and still retain its basic initial form with no degradation. Rewetting occurs when the biomass construct, after it has cured, is subjected to water. Typically rewetting occurs via precipitation, dew, snow and/or wet weather. The cured biomass construct forms an open weave three-dimensional morphology. The open weave morphology of the erosion control medium promotes water flow and water retention. Increased water retention promotes germination and rooting of vegetation (60), and the healthy growth of micro-organisms. The erosion control medium also protects the ground surface from the impact of rain and the effects of wind.
It should be understood that the final product produced from the described methods produces a substantially homogeneous product. For the purposes of this specification, “substantially homogeneous” means that substantially the same ratio of components may be found throughout an applicable blended mulch product, slurry, erosion control medium, construction product or biomass construct (as the case may be). The ratio of components should be generally consistent regardless of the cross-section, volume or amount of blended mulch product, slurry or erosion control medium examined. Small deviations, up to about 25%, in the ratio are considered to be substantially homogenous. Preferably, blended biomass products, slurries and erosion control mediums only have deviations up to about 20%. More preferably, blended biomass products, slurries and erosion control mediums only have deviations up to about 15%. Large clumps are a common source of non-homogenous portions of blended mulch products, slurries and erosion control mediums. Large clumps of biomass have not been shown to have deleterious effects in any of the envisioned applications.
In another alternative, dry mixing of the biomass, binder and any additives prior to the addition of water can be accomplished with a small reduction in the optimal behavior characteristics of any slurry produced and the in the resulting physical properties of the cured biomass construct. Though dry blending can affect the resulting product, it is a viable approach to preparing the described biomass construct.
Furthermore, the biomass construct is a porous layer of material, which can capture blown seeds and soil. Blowing materials may be the product of natural occurrences or the resultant of human intervention. The ability to trap materials builds soil content and encourages re-vegetation of eroded areas. Vegetative growth experiments have proven the ability of grass seed to germinate and penetrate a cured biomass construct confirming that the innovation would not impede re-vegetation of eroded terrain.
The described biomass construct does not require the addition of any synthetic additives such as screens, structural elements, positioning elements, securing elements or the like. Optionally, other materials such as seeds, fertilizers, biological materials, spores, lime or other desired additives may be added to biomass blends or biomass slurries, prior to the addition of water or after the addition of water. Such additives are known in the art and facilitate a wide variety of owner benefits.
A variety of additional aspects and characteristics of the present invention are described below, in addition to the various aspects and characteristics discussed above in this specification. Furthermore, as with the aspects and characteristics described above, each of the following aspects and characteristics individually and in various combinations provides a beneficial enhancement and is an embodiment of the present invention.
In one aspect, there is provided a biomass construct formed from a blended mixture comprising a blended biomass product, cementitious binder and water. The biomass construct comprises between 25% to 90% by weight of the cured biomass construct described herein. More preferably, the biomass material comprises between 50% to 85% by weight of the cured biomass described herein. The biomass construct also includes a cementitious binder that comprises between 10% to 75% by weight of the cured biomass product described herein. More preferably, the cementitious binder comprises between 15% to 50% by weight of the cured biomass construct. The biomass and the cementitious binder are mixed with water, which comprises between 5% to 55% water by weight of the total weight of the binder used to construct the biomass construct. More preferably, the amount of water comprises between 15% and 45% by weight of the total weight of the cementitious binder used to construct the biomass construct. The water used in the preparation process is removed from the biomass construct upon curing resulting in a hard and tough biomass construct. In this aspect, the biomass construct forms a substantially homogenous open weave construct on the ground or surface to which it is applied.
In another aspect, there is provided a biomass construct, formed from spray-application on the ground surface of a slurry mixture comprising a blended biomass product, binder and water. The biomass construct comprises between 25% to 90% by weight of the cured biomass construct described herein. More preferably, the biomass material comprises between 50% to 85% by weight of the cured biomass described herein. The biomass construct also includes a cementitious binder that comprises between 10% to 75% by weight of the cured biomass product described herein. More preferably, the cementitious binder comprises between 15% to 50% by weight of the cured biomass construct. The biomass and the cementitious binder are mixed with water which comprises between 5% to 55% water by weight of the total weight of the binder used to construct the biomass construct. More preferably, the amount of water comprises between 15% and 45% by weight of the total weight of the binder used to construct the biomass construct. The water used in the preparation process is removed from the biomass construct upon curing resulting in a hard and tough biomass construct. In this aspect, the biomass construct forms a substantially homogenous open weave construct on the ground or surface to which it is applied.
In another aspect said biomass constructs can be formed into a variety of predefined shapes and allowed to cure. Upon curing said predefined shapes retain the aforementioned performance benefits as well as the predefined shapes. The biomass construct comprises between 25% to 90% by weight of the cured biomass construct described herein. More preferably, the biomass material comprises between 50% to 85% by weight of the cured biomass described herein. The biomass construct also includes a cementitious binder that comprises between 10% to 75% by weight of the cured biomass product described herein. More preferably, the cementitious binder comprises between 15% to 50% by weight of the cured biomass construct. The biomass and the binder are mixed with water, which comprises between 5% to 55% water by weight of the total weight of the binder used to construct the biomass construct. More preferably, the amount of water comprises between 15% and 45% by weight of the total weight of the binder used to construct the biomass construct. The water used in the preparation process is removed from the biomass construct upon curing resulting in a hard and tough biomass construct. In this aspect, the biomass construct forms a substantially homogenous open weave construct on the ground or surface to which it is applied.
Although this invention has been described with reference to illustrative and preferred embodiments of carrying out the invention, this description is not to be construed in a limiting sense. Various modifications of form, arrangement of parts, steps, details and order of operations of the embodiments illustrated, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover such modifications and embodiments as fall within the true scope of the invention.
An electric drill (24) of a type commonly used to mix paints was used to mix 5.7 pounds of MgCl cementitious binder in 3.6 pounds of water (20) in a 5 gallon plastic container (28). Said cementitious binder was agitated for one and a half minutes using a mixing paddle (26) of the type commonly used to mix paint and an electric drill (24) resulting in a homogeneous cementitious binder slurry (22). It should be understood that mixing times can vary as a function of water temperature, the amounts being mixed, the means for mixing, elevation and the type of binder used. 6.3 pounds of MgO was added as an additive (16) to the cementitious binder slurry (22) and mixed as previously described resulting in a homogeneous mixture of all components called a cementitious binder containing slurry (30). The cementitious binder containing slurry (30) was mixed with one cubic foot of biomass (2) in a cement mixer resulting in fully coating said biomass with said cementitious binder containing slurry. In terms of cubic feet, one cubic foot of biomass was combined with 0.16 cubic feet of MgO, 0.14 cubic feet of MgCl and 0.06 cubic feet of water.
Said coated biomass was applied to the application surface by manual means using a 5-gallon bucket. The resulting biomass construct cured over a period of 24 hours resulting in an erosion control barrier of approximately 1.36 cubic feet. Said cured biomass construct was endowed with the exemplary strength, hardness and structural integrity.
A sloped area fifty feet wide (66) and two hundred feet long (68) was treated with biomass constructs (70) used as erosion control media. The slope area had the remnants of some installed and previously failed wattles and straw bales (72). Other than these remnants the slope was barren with no major rocks, trees or topographic features through out the treated area.
Level contour lines (74) were surveyed at approximate ten-foot intervals down the slope. Several contours were adjusted up or down the slope to optimize the placement of the erosion control media. An optimized placement is one that considers the speed and power at which water moves during an eroding process. As an example, areas of increased slope, for instance a slope steeper than 20 degrees, require shorter distances or intervals between the placement of erosion control media. Areas that have both steep slope and constrained terrain, such as a small ravine two feet wide and three feet deep, may require a thicker layer of erosion control media. Areas of ground that have slight slopes, for instance a slope of less than ten degrees, may require smaller amounts of erosion control media spaced farther apart, i.e. larger intervals between contour lines (74).
In this example a total of nineteen erosion control barriers were placed across a slope. Each barrier spanned the width of the erosion prone zone and had an approximate length of fifty feet at the narrowest and seventy five feet at the widest area being treated. The barriers where placed parallel to one another taking into consideration small variations in slope as previously described and more or less followed a consistent elevation across the slope. The barriers where placed such that any erosive flow impacted the barrier did so perpendicular to the barriers orientation to the slope. Three contours were found to be identical to previously installed wattles and straw bales. The erosion control barriers produced incorporated the remnants of the previously installed wattles and straw bales with no degradation of resulting performance.
The erosion control barriers in this example where produced by combining 800 cubic feet of Ponderosa pine woodchips, 100 cubic feet of composted woody biomass, binder components, and 44 cubic feet of water as previously described.
In another example 570 pounds of MgCl, 630 pounds of MgO, 5.5 cubic feet of foam, 1200 pounds of biomass and 342 gallons of water where combined to produce biomass constructs for use as erosion control barriers (76). The materials where combined as previously described and positioned by hand in a series of ravines (78) facilitating erosion control.
Water penetration is an important performance variable as it relates the amount of water that penetrates the soil versus the amount of water running off the eroding slope on top of or through the upper layer of biomass construct. In order to assess the performance of the said biomass construct, an inclined rainfall simulation test bed was constructed. Said test bed was built to conform to the design specifications published on the Texas Department of Transportation (TXDOT) testing facility website. The test bed had a length of 15 feet and a width of 2.5 feet and was constructed using hydraulic cylinders to achieve different target inclines. The soil used in the test bed was native to New Mexico and known to be highly erodible.
Using said test bed, a control was established by evaluating soil loss on soil with no installed erosion control barrier. In the case of no erosion control barrier, a substantial amount of soil was lost, the equivalent of approximately 9.5 tons per acre, and large channels were formed in the eroded soil. Once the soil dried, a biomass construct such as that described in example 1, was produced and applied to the previously eroded bed. The biomass construct was allowed to cure on said test bed. Once the biomass construct was fully cured, the test bed was subjected to three rain cycles of 30 minutes each. Each rainfall event was equivalent to three 3.5 inch per hour rainfall events. Sediment loss was evaluated as described in the Texas Department of Transportation procedures as follows. All water and sediment was collected in a tank at the base of the sediment bed. The sediment was allowed to settle for a minimum of 12 hours. Once settled, the clear water was drawn off. The remaining sediment and water was removed from the sediment tank and weighed. Weight was taken to the nearest 0.1 lb. Sediment was agitated for two minutes and then 10 samples were taken. Samples were transferred to a desiccating oven and dried. Sediment loss was calculated by determining the water (w) to sediment (s) mass ratio (w/s). This ratio was applied to the full sediment sample to determine total sediment loss. Several trials were run using the biomass construct on said erodible soil. Each test showed no sediment loss, at the most aggressive incline of 2:1, no additional soil was lost and the amount of surface runoff was reduced by more than 22% indicating that the sloped soil was not only stabilized, but also benefited from increased water penetration, that is, percolation of water into the soil which is known to be beneficial to animals and plants alike.
A further important parameter is the strength of the cured biomass construct. In order to assess strength versus biomass constituent ratio, a series of formulation derivatives where prepared and evaluated by a design of experiments. The metric used to evaluate strength was the psi compressive force required to achieve ⅛ of an inch compression on the cured biomass construct. The results of the compression test are presented in table 1.
Results from the design of experiments suggested a formulation ratio to be 1 gram of magnesium hydroxide to 1-gram magnesium chloride hexahydrate, 2 grams water to 3 grams of biomass to produce biomass constructs with exceptional strength characteristics.
Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.
