LIGHTWEIGHT AGGREGATE UNIT AND METHOD OF MANUFACTURE

Erik Anderlind

Dag Landvik

Terence Nielsen

PRIORITY INFORMATION

[oooii This application claims priority to U.S. Provisional Patent Application 60/911 ,751 filed April 13, 2007, entitled "Lightweight Aggregate Unit and Method of Manufacture," the disclosure of which is incorporated by reference herein.

BACKGROUND

[0002] 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.

[00031 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.

[0004] 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.

[0005] 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.

100061 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.

BRIEF DESCRIPTION OF FIGURES

[0007] 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:

[0008] FIG. 1 depicts a perspective view of an exemplary embodiment of an elongate unit of an underground water channeling system that includes a piece of pipe enclosed therein.

[00091 FIG. 2 depicts a perspective view of an alternate exemplary embodiment of an elongate unit of an underground water channeling system that does not include a piece of pipe enclosed therein.

[ooio] FIG. 3 depicts a perspective view of an exemplary embodiment of individual aggregate particles used in the unit shown in FIG. 1.

[ooiii FIG. 4 depicts a cross-sectional view of an exemplary installation of the unit shown in FIG. 1.

[0012] FIG. 5 depicts a cross-sectional view of an alternate exemplary underground water channeling system that includes a unit as shown in FIG. 1 and an exemplary embodiment of a vertical drainage panel.

[00131 FIG. 6 depicts a perspective view of the exemplary vertical drainage panel shown in FIG. 5.

[0014] FIG. 7 depicts a front view of the exemplary vertical drainage panel shown in

FIG. 5.

DETAILED DESCRIPTION

[0015] Referring now to FIG. 1 , one embodiment of the present invention is an elongate unit 10 including a length of perforated pipe 20 encased in a formed body 30. The body 30 may be formed of a porous concrete consisting of aggregate particles held together. (As used herein, unless otherwise indicated, the term "concrete" means a porous material comprising aggregate particles effectively held together following forming of the material in any suitable manner.) Additionally, the unit 10 may have a layer of barrier material 40 placed over one or more surfaces thereof. A layer of suitable barrier material 40 also may be bonded or glued onto or about one or more surfaces of the unit 10. Although the body 30 of the unit 10 depicted in FIG. 1 has a square cross section, it will be understood based on the description herein that the body 30 can be formed to have a circular cross section or any other suitable cross-sectional shape. Additionally, it will be understood

that, if a pipe is included in the unit, the longitudinal axis of the pipe can be centered within the cross section of the body, or offset in any desired location such as, for example, the location shown in FIG. 1.

[0016] 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.

[ooi7] 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 Ib per cubic foot. A relatively low density, such as this, may provide a financial benefit compared to aggregate material of a higher density.

[0018] 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 FIG. 3. In one embodiment, the aggregate particles may be shaped to produce a percentage of void of at least about 55%. Depending upon the aggregate material used, the shapes selected should be effectively strong enough to withstand compression of the unit 10 by in-service soil pressures so as not to break up to an extent that interstitial spaces or voids are substantially reduced in number and/or volume.

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 671 A sold by DuPont Performance Elastomers L. L. C, Wilmington, Delaware, in a ratio of three parts Cromaprufe to one part Neoprene Liquid Dispersion 671 A, 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, Tennessee 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.

[0020] 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.

[00211 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.

100221 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.

[00231 In an alternate embodiment, shown in FIG. 2, a unit 10' is formed of a suitable concrete as described above with regard to unit 10, with no included length of pipe. The interstitial spaces or voids in the concrete will still serve to function to

relieve hydrostatic pressure in surrounding soils and allow water to pass therethrough, while the channel formed and held open by the presence of unit 10' in the earth can serve to channel water away from an area, in the same way that drainage systems relying only on gravel beds without pipes function. In another embodiment, a unit (not shown) may be formed to have an open channel through its length having a circular or any other suitably shaped cross section. It will be appreciated that in drainage systems, it may be desirable for a unit to have an open channel along its length, or perforated pipe encased therein, where high water passage capacity is desired. Conversely, where high water passage capacity is deemed unnecessary, an open channel or perforated pipe may not be deemed necessary.

10024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] FIG. 4 schematically depicts one possible installation of a unit 10. Shown in cross-section in FIG. 4, a unit 10 with encased pipe 20 is installed at the bottom of a ditch cut into earth 100. Following installation of unit 10, the ditch may be backfilled with soil or other backfill material 101. In such an installation, if pipe 20 is perforated pipe, the unit 10 installed in this manner will provide a length of a drainage line or system, whereby unit 10 can receive water or other fluid from surrounding soil 100 and relieve hydrostatic pressure therein. In this embodiment, unit 10 and pipe 20 can provide pathways by which water or other fluid can be drawn and channeled away from the area by gravity. The shapes and relative sizes for the unit 10, pipe 20 and ditch shown in FIG. 4 are only examples of a variety of combinations of shapes, sizes and configurations that are possible but still within the scope of the present invention.

100291 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 FIG. 4 will be suitable for use in a water dispersal system, its dispersal capacity being enhanced by situation of pipe 20 at the top of the unit as installed. In this particular exemplary application and installation, the pipe selected may be perforated pipe, oriented and encased within the unit 10 to have a plurality of drainage holes through the pipe wall and situated along the bottom portion of the pipe (relative to its installed position), so that water flowing inside the pipe will tend to drain by gravity out of the pipe through the holes and into the interstitial spaces in the aggregate beneath, and subsequently, be dispersed along the ditch and into the surrounding soils. It also will be appreciated, however, that an alternative embodiment to be used for soil drainage rather than fluid dispersal may have the pipe situated at the bottom of the unit (as installed), and have a plurality of inlet holes through the pipe wall and situated along the bottom portion of the pipe (relative to its installed position), so that fluid draining into the unit from surrounding soils will flow downward by gravity through the interstitial spaces in the aggregate to the bottom, where it can then enter the pipe through the inlet holes therein, and be channeled away.

10030] 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 FIG. 3 may be mixed with the binder material, such as an acrylic material, in a tumbler such as one used for mixing Portland cement-based mortars and concretes, at a ratio of one quart of binder material to 6 cubic feet of loose aggregate. Alternatively, a binder material such as acrylic material, bitumen

material or any other suitable binder material, may be sprayed via several spray atomizers onto dry aggregate particles as they flow through a pipe to a mold, at a similar ratio of binder material to aggregate.

[0031] 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.

[0032] 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.

[0033] 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.

[00341 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.

[0035] FIGS 5-7 depict an alternate embodiment of an underground water channeling system 200. In this embodiment, system 200 comprises an elongated unit 210 and

a panel 260. Similar to body 30 described above, panel 260 may be formed of a porous concrete consisting of aggregate particles held together. Similar to the embodiment described above, panel 260 may comprise individual 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 panel and under pressure exerted by surrounding soils after installation and during service. Panel 260 may also comprise barrier material affixed to one or more surfaces of panel 260. The barrier material may be similar to the barrier material 40 described above. Similar to the embodiments described above, the aggregate particles for panel 260 may be held together using any suitable binder material, including, but not limited to a bitumen material, an acrylic material, or any other suitable material. In particular, panel 260 may be formed using Chromaprufe™ or Kool Seal™.

10036] As shown in FIG. 10, panel 260 is positioned adjacent to the exterior surface 272 of a wall 270. In this version, panel 260 comprises a first surface 262 and second surface 264 and includes the greatest linear dimension of panel 260 is the height H from first surface 262 to second surface 264. A panel 260 may be positioned such that it is entirely underground or it may be positioned such that an upper portion 266 extends above the ground surface 202, as shown in FIG. 5. In the illustrated embodiment, panel 260 is configured to allow water from the surrounding soil 201 to pass into panel 260 providing hydrostatic relief. Once water has passed into panel 260, the interstitial spaces between the aggregate particles allow the water to travel downward toward elongated unit 210. Panel 260 may also facilitate horizontal movement of the water along the length of panel 260. Elongated unit 210 is configured as described above to drain water horizontally away from wall 270. Panel 260 may be configured to provide thermal R- value for wall 270 in addition to facilitating the removal of water surrounding wall 270. Obviously, a panel may be used in conjunction with an elongated unit, as shown in FIG. 5, or, alternatively, an underground water channeling system may exclusively use one or more panels to facilitate water removal.

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.