Finding a beneficial use for the large quantities of agricultural waste material produced in the world has been a pursuit of interest to agriculturalists for a very long time. Although many clever innovations have been made, there is still a problem of disposing of this waste in a useful manner. Additionally, there is a constant search for inexpensive building materials. Again, although much progress has been made in this area, there is still a need for additional options in construction materials.
The structural qualities of straw, in its natural undamaged form, provide significant compressive strength. Compressive strength is precisely the type of strength needed in building materials that are used to support heavy loads. In the prior art the structural integrity of the stalks is lost in two ways. First, in the way the straw is bailed for transportation to the building material fabrication facility and, second, in the way the straw is processed into building material. First, in the prior art the method of bailing straw crushes and breaks the straw stalks so that its natural integrity is injured before even beginning the processing phase. Second, when the straw is processed into building materials it is compressed into a dense mass under heat and pressure. In the process the straw is further crushed, hence further losing its natural structural integrity which, in turn, results in the loss of the straw's natural compressive strength. Accordingly, building materials made from straw, under the prior art, are not capable of supporting the necessary weight without the addition of wood as a framing material, or as a skin applied to a straw panel to give it strength. In addition to preserving compressive strength, maintaining the structural integrity of the straw, by not crushing it, also allows for retention of its natural hollow core which has significant insulation value.
In a first separate aspect, the present invention is a method for creating a building material that makes use of a wheeled, moveable apparatus that moves through a field of agricultural waste product, capturing a portion of the waste product onto the apparatus, aligning the captured waste products parallel to each other into rows, and binding, through the addition of cementatious material, the aligned waste product together to create a cemented product.
In a second separate aspect, the present invention is an apparatus for producing a cemented product from agricultural waste. It is comprised of a wheeled, moveable frame that includes a capturer adapted to capture a portion of the agricultural waste product onto the frame, an aligner, mounted on the frame, that is adapted to align the longitudinal agricultural waste products into rows, a binder that is adapted to bind the aligned waste products together, and a finisher that adds a cementatious material to the bound waste product, creating a cemented product.
In a third separate aspect, the present invention is a method for producing a structural product from longitudinal agricultural waste product pieces, each having a natural structure. The method consists of arranging the pieces so that they all have the same orientation, compressing the pieces together in a way that preserves their natural structure, binding the pieces together, and placing cementatious material about the bound pieces.
The foregoing and other objectives, features and advantages of the invention will be more readily understood upon consideration of the following detailed description of the preferred embodiment(s), taken in conjunction with the accompanying drawings.
Referring to
As the tractor pulls the mobile straw harvester and beam fabricator 2 through a field of straw left after the harvesting of grain heads a cutter bar 12, or capturer, cuts and feeds the straw into the harvester. In an alternative embodiment the straw has already been cut and lies in the field in windrows. In such case only a pick-up belt would be needed instead of the cutter bar 12. Either way, both of these embodiments describe standard equipment for harvesting machines in the industry, which will be familiar to skilled persons.
When the feed stock (typically straw) is gathered into the harvester a hollow metal tube with multiple spray nozzles 14 sprays the straw with a matrix mixture that is held in, and pumped from, a reservoir 28 (
Regulating the moisture so that the feed stock can be more easily compressed into a compact cylinder without damaging the structure of the material is an important element of the present embodiment. As noted in the background section, the structural qualities of straw, in its natural undamaged form, provide significant compressive strength. Compressive strength is precisely the type of strength needed in building materials that are used to support heavy loads. This is one great advantage this process has over the prior art.
In addition to the moisturizing value, the mixture that is sprayed onto the feedstock through the hollow tube with multiple spray nozzles 14 also has a binding element. Hence various binders such as clay, boiled linseed or soybean oil, rosin, as well as synthetic and natural adhesives may be part of the mixture that is sprayed onto the feed stock after it is cut and harvested.
After the feed stock is sprayed with the moisturizing and binding elements of the matrix mixture it is carried by a meshed feed belt 16 into one of four parallel compression sections 38. The feed belt is meshed to allow excess moisturizing and binding mixture to fall through to an over-spray tank (not shown) that catches the excess mixture for reuse.
Three movable vanes 18 separate the feed stock into four streams which enter into one of the four compression sections 38 by passing between a series of converging belts 20 that aligns, or arranges, the straw stems so that they are parallel to each other, and simultaneously compresses them so that they will feed into the compression rollers 40.
The compression sections 38 are preceded by four first flow limiting cutters 21 and four sets of parallel belts 23. The first flow limiting cutters 21 and parallel belts 23 limit the swath of feed stock entering the compression sections 38 according to the density of the swath. Greater densities require smaller widths and lesser densities require larger widths.
In an alternative embodiment the parallel belts 23 compress the straw stems from the top and bottom as well as from the sides. On three sides of the feed stock the belts 23 are fixed, while on the fourth side (top, bottom, or either side) one of the belts 23 is free to move (in a horizontal or vertical direction) to accommodate for changes in the volume of the material entering the compression process. Rollers may be used in the place of belts 23, depending on the material being processed.
After passing through the set of parallel belts 23, but before entering the compression rollers 40, a second flow limiting cutter 22 (
Feed stock material next passes through the set of compression rollers 40, each of which has a transversely concave outer surface. The distance between the upper rollers 40 and the lower rollers 40 decreases progressively so that the feed stock is gradually compressed to the desired density and diameter.
During compression, the feed stock is held in place by a fixed roller die 54 made from a hard polymer resin (
The resulting cylinder of feed stock is fed into the first wrapper, or binder, section 24 diagramed in
The result of the foregoing continuous process are four straw strands 42, one from each of the four first wrapper sections 24, each of equal diameter, which depending on the embodiment and setting may range from 1″ to 9″. Each strand 42 is bound together with a spiral wrapping of yarn, twine or wire. A twine made out of polyester yarn would work well with the preferred embodiment. Each straw strand 42 may next be fed from the front section 4 of the machine into a second stage, in the rear section 6 of the machine, where it will be combined with the three other strands 42 which are being formed simultaneously by the other three first wrapper sections 38.
In
When the four strands 42 are wrapped together in the second wrapper section 26 the adhesive will serve to bind the four straw strands 42 together more securely. In the mobile unit the adhesive mixture is pumped from a rear tank 32. In an alternative, stationary, unit a gravity fed system is used, saving the expense of a pump. The adhesive mixture may be a papercrete mixture consisting of paper pulp, clay, Portland cement, straw fiber and other adhesive materials.
In the rear section 6 of the mobile straw harvester and beam fabricator 2 the four straw strands 42 are fed into the second, and subsequent, wrapper, or binder, section 26 which is shown in
Referring to
After passing through the extruder, or finisher, 30 the beam 44 enters a vibrating trowel 34 which further compresses and smoothes the fiber adobe exterior plaster. This assures that a good bond is formed between the beam and the fiber adobe coating. The completed beam is then deposited from the rear of the machine into the field to dry. When the beam dries, it can be cut to length and transported. Alternatively, a saw could be placed at the rear of the machine, before or after the vibrating trowel 34, to cut the beam into predetermined lengths before depositing the cut beams into the field.
The entire process allows a predetermined percentage of straw to be left in the field to preserve the required content of organic matter in the soil. Neither burning nor bailing is able to accomplish this.
The finished beam, properly dried, can either be maintained in its continuous state for such purposes as erosion control, or restoration of fish habitat in streams, etc., or can be cut for use as construction beams and used for such purposes as the construction of load bearing walls.
In an alternative embodiment the machine would be stationary and located at a central location to which the raw material could be transported. The raw material would then be fed into the beam fabricator either by hand, or through some sort of automatic feed. This alternative would be particularly relevant where mechanical harvest is not available, or the particular raw material being used does not lend itself to mechanical harvest.
In another alternative embodiment the feed mechanism could be made larger to accommodate brush and other more rigid materials. Additional rotating saw blades would trim off branches that could not be compressed. The compression and wrapper assemblies would also have to be larger to accommodate the strands and beams that would be fabricated.
The terms and expressions that have been employed in the foregoing specification are used as terms of description and not of limitation. There is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
This application claims priority from provisional application Ser. No. 60/592,558 filed Aug. 2, 2004.
Number | Date | Country | |
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60592558 | Aug 2004 | US |