Patent Application
20090080976
Embodiments of the present invention relate generally to below-ground pipelines, conduits, channels and systems used, for example, for draining water away from objects or areas such as building foundations and footings, septic fields or other systems or areas in which French drains have often been used. More particularly, embodiments of the present invention relate to a pre-formed below-ground system component that eliminates in part or in whole the need for handling and installation of heavy, loose materials such as gravel. Embodiments of the present invention also relate to a method of manufacturing the disclosed system component.
Conventional below-ground drainage systems such as French drains and the like typically comprise a line or lines of perforated pipe buried in a bed of aggregate material such as gravel, crushed stone or like material. The pipe, together with the aggregate material, are typically installed so as to lie at the base of a ditch within or adjacent to the area to be drained. When installed and located properly, these components provide a mechanism that relieves hydrostatic pressure in surrounding soil, and channels water away from the area. Before the gravel is installed, the ditch may be lined with a layer of filter cloth or similar barrier material, and after the gravel and pipe are installed but before the ditch is backfilled with earth, the top of the gravel bed also may be covered by a layer of filter cloth. The barrier or filter cloth will serve to trap, block or otherwise prevent silt or other fine waterborne particles from being carried into and deposited within the gravel bed and eventually filling the interstices thereof, clogging the bed and reducing the effectiveness of the system.
An alternative use of gravel-based systems of this nature has been to serve purposes converse to those of drainage—dispersal of water. For example, such systems have been used as components of leach beds for dispersing overflow from septic tanks, seepage pits, sumps or the like into adjacent soils, or in systems used for dispersing rain- or stormwater piped or channeled away from building structures.
Additionally, other installations of below-ground systems have included a pipeline or conduit buried in a bed of gravel, crushed stone or like materials to distribute pressures and forces within the soil and protect the pipeline or conduit from being crushed.
Persons familiar with installation of such systems are familiar with the difficulty and expense associated with transporting and handling materials such as gravel or crushed stone. Such material is relatively heavy, and because it is loose, its installation often requires substantial machine and/or hand labor to move and place properly. Various alternative systems have been developed in the past which can reduce or eliminate the need for gravel or similar material in a below-ground system. However, to the best of the inventors' knowledge, no prior art systems have all of the features and advantages of the present invention.
It is believed the present invention will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which:
Referring now to
As used herein, the term “member,” shall not be read to be limited to a singular piece or a homogenous continuum of material. In other words, a “member” may, but need not, comprise a plurality of parts joined together in any suitable way.
The aggregate material preferably is of a lower density than gravel, and is preferably effectively non-degradable over the expected service life of the system. The inventors have determined that a suitable aggregate may consist of an expanded polymeric substance such as, for example, particles of expanded polystyrene, but any other suitable material may be employed. In one particular embodiment, the aggregate material is of a density of less than or equal to about 1 lb per cubic foot. A relatively low density, such as this, may provide a financial benefit compared to aggregate material of a higher density.
The aggregate particles may have any suitable shape(s). For example, the aggregate particles may comprise spherical shapes. The inventors have determined that particles having differing and/or irregular shapes that when brought into coalescence leave substantial interstitial spaces or voids in fluid communication within the concrete during formation of the unit and under pressure exerted by surrounding soils after installation and during service can provide for a finished unit having substantial water passage capacity. In the embodiment depicted, the individual aggregate particles 50 consist of expanded polystyrene, extruded in the shapes depicted in
The aggregate particles may be held together by a suitable binder material. The binder material may be any suitable material that is compatible with the aggregate material. In particular the binder material may have the ability to effectively adhere to the aggregate particles while not causing substantial degradation of the aggregate particles over the expected service life of the system. The aggregate material-binder material combination may also allow a reasonable time for molding or forming of the body before setting. The inventors have determined that a rubberized bitumen emulsion product sold under the trademark CROMAPRUFE, sold by Cromar Building Products Limited, North Yorkshire, UK, mixed with a quantity of Neoprene Liquid Dispersion 671A sold by DuPont Performance Elastomers L.L.C., Wilmington, Del., in a ratio of three parts Cromaprufe to one part Neoprene Liquid Dispersion 671A, creates a suitable binder material for use with polystyrene aggregate particles. Of course, alternate binder materials may be used in place of or in addition to the bitumen material described above. For example, the inventors have determined that an acrylic material known as Kool Seal, manufactured by The Sherwin Williams Company, Memphis, Tenn. is a suitable binder material for use with polystyrene aggregate particles. It should be noted that the binder material selected may be, but does not necessarily have to be, effectively non-degradable over the expected service life of the system. Once units embodying features disclosed herein are transported and installed, binding of the aggregate particles may not be critical because the surrounding soils may serve to hold the aggregate particles in place following installation and backfilling. Additionally, in some cases it may be desirable for the body 30 of the unit 10 to be flexible and/or malleable to accommodate, for example, curves or irregularities within a ditch. The inventors have determined that the above-identified bitumen binder provides flexibility and malleability in this regard, being somewhat fluid and elastic after setting. Similarly, the above-identified acrylic material also provides flexibility and malleability in this regard. Alternatively, however, it may be desirable in some applications that the body be relatively rigid and not substantially malleable. In that case, a binder material having differing properties may be used. It should be noted that different types of binder material provide differing levels of flexibility and malleability. Accordingly, the binder material may be selected based on the level of flexibility and malleability desired for a specific use of this embodiment of the invention.
As an alternative to use of a binder material to hold the aggregate particles together, the particles may be bound together by other means, for example, by application of heat in an appropriate process to cause surface melting and fusing of polymer particles to one another.
It should be noted that binding the aggregate material together, whether accomplished via use of a binder material, application of heat, or some other method, may reduce the movement of the aggregate after forming, thereby reducing the amount of settling and shape deformation during installation and use of the unit.
As noted, a layer of barrier material 40 may be placed over one or more surfaces of the unit, and may be bonded or glued thereto using at least one of the above-identified binder materials or other suitable adhesive material. The barrier material 40 may be bonded or glued to the body 30 while the body 30 is in a mold, thereby eliminating the need to apply the barrier material to the body 30 at the time of installation. However, this is not required. A layer of barrier material may be desired to serve to prevent silt or other fine waterborne particles from being carried into the interstices of the concrete and deposited therein. A suitable barrier material may be selected to be water permeable, or effectively water impermeable so as to selectively block water pathways into the concrete. A suitable barrier material may comprise paper, natural or synthetic cloth or felt, filter cloth, or any other suitable material having desired properties. In particular, the barrier material may comprise a nonwoven geotextile material.
In an alternate embodiment, shown in
In another alternate embodiment, a unit (not shown) may comprise a plurality of pipes encased in aggregate material. By way of example only, the plurality of pipes may be identical or similar types of pipe, or they may comprise pipes of different shapes and sizes. The plurality of pipes may also include one or more specialty pipes or conduits.
The body 30 of the unit may be formed to have ends that enable two or more units to be connected endwise, to extend a drainage or other below-ground line. The ends may be suitably formed so that an end of one unit will mate or join in any suitable fashion with an end of another unit. Each unit may have, for example, a “male” end and a “female” end. Alternatively, the ends may be adapted, for example, to receive and/or fit into or onto a suitable joint fitting or other coupling fitting. If the unit includes a length of pipe encased in the body, one or both ends of the pipe may include suitable connecting or coupling features. A length of pipe in a unit may have, for example, a “male” end and a “female” end. Alternatively, each pipe end may be adapted, for example, to receive and/or fit into a suitable joint fitting or other coupling fitting.
It will be noted that a pipe encased within a body as described herein can have applications other than use in a drainage system. For example, a unit embodying certain features described herein may consist of a non-perforated pipe encased within a formed concrete body as described herein. In this embodiment, the non-perforated pipe may be protected from being crushed by pressures in the soil after below-ground installation, through distribution of pressure within the concrete body, reducing or eliminating the need for a gravel bed for similar purposes in similar applications. A unit formed with non-perforated pipe might be used as a component in, for example, a water line, a sewage line, a storm drain line, a gas, oil or other fluid line, a below-ground conduit for electrical lines, telephone lines, television or other cable lines, fiber optic cable lines, etc.
In another embodiment, the body 30 may be molded to encase other features and or equipment included with pipe, such as valves, adapters, connectors, and any other suitable features. Following molding, these features or equipment can be accessed as necessary or desired by cutting through the molded concrete, which will be relatively easy if the concrete comprises a relatively soft aggregate material such as expanded polystyrene. Alternatively, a mold as further described below can be designed with features that form access ports or holes in the body that provide ready access to valves, connectors, adapters or other equipment, in the molded body.
It will be appreciated that several of the exemplary embodiments described herein can be applied for uses in fluid dispersal systems, the converse of drainage systems. For example, the installation depicted in
A method for manufacturing units of the type described herein will now be described. First, suitable aggregate particles of, for example, expanded polystyrene or any other suitable material, may be extruded or otherwise produced by known processes and techniques. Next, a suitable quantity of a binder material, such as, by way of example only, at least one of a bitumen material, an acrylic material, or any other suitable binder, may be introduced to a quantity of aggregate particles. The binder material and the aggregate particles may then be agitated together to achieve effective coverage of aggregate particles. For example, loose expanded polystyrene aggregate particles extruded in the shapes depicted in
Next, the concrete mixture, which still will be relatively fluid, may be introduced into a mold of any desired shape. A suitable mold may be constructed of, for example, any rigid material such as wood, metal, plastic, or any other suitable material. The mold may have one or more lengths of pipe located therewithin, to be encased and fixed within the body formed of the concrete material, held in place by the binder material on the surfaces of the aggregate particles adhering to the surface of the pipe. Of course, one or more lengths of pipe are not required. Alternatively, a pipe length may be coated with oil or other suitable material prior to molding so that the binder will not adhere to it, and so that it may be removed from the body following molding to leave an open channel through the body. Alternatively, the mold may be constructed with other features that form channels or voids in the molded body. The mold surfaces may be coated with oil or other suitable material to prevent the binder material from adhering to the mold, and provide for ease of removal of the molded body from the mold. The concrete material may be compressed in the mold during and/or after filling to ensure that all larger spaces within the mold are filled and no unwanted large voids in the material are present. Compression of the concrete material may be done in order to eliminate large voids that may compromise the structural properties of the finished unit. A layer of barrier material may be placed into the mold before introduction of the concrete, or alternatively, may be laid and pressed over an exposed surface of the concrete, using additional binder material or other adhesive if necessary.
In an alternate method of manufacture, unit 10 may be formed utilizing a pour-in-place method. In the alternate method, the aggregate particles may be produced and mixed with a binder material as described above. Next, a void may be created at the installation site. By way of example only, the void may comprise a ditch dug in the ground. Once the aggregate particles and binder material have been sufficiently combined to produce a fluid concrete mixture, the fluid concrete mixture may be sprayed or poured directly into the void. In this pour-in-place method, the walls of the void function similarly to the mold described above by providing support for the fluid concrete mixture as it solidifies. Similar to the mold described above, the void may have any suitable shape, depth, or length. One or more lengths of pipe may be placed in the void prior to or during pouring to allow the pipe to be encased by the fluid concrete mixture. But, the use of one or more lengths of pipe is not required. A layer of barrier material may be placed in the void prior to pouring the fluid concrete mixture, or, alternatively, a layer of barrier material may be placed on the top surface of the fluid concrete mixture after pouring is complete. The layer of barrier material may be adhered to the aggregate particles as described above. Of course, the use of a layer of barrier material is not required. The void may be filled completely or partially with the fluid concrete mixture. If the void is partially filled with the fluid concrete mixture, then backfill material, such as soil, may be placed on top of the fluid concrete mixture.
If rapid production is desired, application of forced air, forced heated air, or heat will cause water in a bitumen emulsion binder to evaporate faster, causing the emulsion to break faster and the concrete to “set” faster. Alternatively, the water may be allowed to evaporate naturally. After the concrete has set (and cooled, if necessary), the finished unit may be removed from the mold. Multiple units may be formed in a single longer length in this process and then cut to shorter lengths using, for example, a saw or heated wire cutter.
As an alternative to the use of a binder material, the body may be formed without use of a binder. For example, dry polystyrene aggregate particles may be poured into a steam or heat transfer molding machine cavity, which can then be utilized to introduce heat to the mold, thereby causing surface melting and fusing of adjacent aggregate particles.
As shown in
From the foregoing it will be appreciated that use of a concrete material comprising a relatively lightweight aggregate, to form a unit, provides numerous benefits and advantages over use of loose gravel, crushed stone or the like as a component of a below-ground drainage, pipe or conduit system. The unit may be easily portable and may eliminate the need to transport and handle heavy, loose material in a ditch at a project site. The unit may be easily and inexpensively manufactured. If the aggregate particles are suitably sized and shaped to provide for substantial interstitial spaces among the aggregate particles in the formed unit, the unit may allow for rapid passage of substantial volumes of water therethrough. Thus, it will be appreciated that the embodiments disclosed and described herein are only examples of a greater number of possible embodiments of devices and methods that may be constructed and utilized to attain the benefits and advantages described herein. Accordingly, the scope of the invention is limited only by the claims appended hereto, and equivalents thereof.
This application claims priority to U.S. Provisional Patent Application 60/911,751 filed Apr. 13, 2007, entitled “Lightweight Aggregate Unit and Method of Manufacture,” the disclosure of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 60911751 | Apr 2007 | US |
