Title:
Lightweight portable concrete enclosure and associated method of construction
Kind Code:
A1


Abstract:
Disclosed is a lightweight, portable concrete enclosure and an associated manufacturing method. The manufacturing method employs a structural member made up of two wire mesh grids that are spaced via web wires. The structural member further includes an intermediate layer of insulation positioned along the web wires. A lightweight concrete mix is then sprayed over the external surface of the structural members to yield a lightweight enclosure that can be easily transported.



Inventors:
Konersmann, Ronald D. (Charleston, SC, US)
Application Number:
11/264660
Publication Date:
05/03/2007
Filing Date:
11/01/2005
Primary Class:
International Classes:
E04B1/00
View Patent Images:
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Primary Examiner:
WENDELL, MARK R
Attorney, Agent or Firm:
HOLLAND & KNIGHT LLP (BOSTON, MA, US)
Claims:
What is claimed is:

1. a method for constructing a lightweight, portable concrete: shelter comprising the following steps: providing a number of structural building elements, the building elements formed from interior and exterior wire grids separated by web wires and an insulation material positioned upon the web wires and intermediate the interior and exterior wire grids; assembling the building elements together with joints and corner splices to form the walls, floor and ceiling of the shelter, the ceiling defined by a number of upper edges, the walls defined by a number of corner edges and the floor defined by a number of lower edges; inserting ferring strips intermediate the interior wire grid and the insulation; inserting reinforcing bars along all the edges of the shelter intermediate the exterior wire grid and the adjacent insulation material; inserting a number of reinforcing bars at spaced intervals along the length of the floor of the shelter intermediate the exterior wire grid and the adjacent insulation material; preparing a lightweight concrete mix that includes a beneficiated aggregate with fines between ¼″ and 200 mesh screen; immersing the lower edges of the shelter into a pool of the lightweight concrete mix and applying concrete to the inside floor and thereafter allowing the concrete to harden; assembling concrete forms around the upper and corner edges of the shelter; spraying the lightweight concrete mix over the ceiling of the shelter so as to cover the exterior wire grid and allowing the sprayed concrete to fill the concrete forms of the upper edges and the corner edges and thereafter allowing the sprayed concrete to harden; removing the concrete forms from the upper edges and corner edges of the shelter; spraying the lightweight concrete mix upon the walls of the shelter so as to cover the exterior wire grid and thereafter allowing the concrete to harden; nailing wall board to the ferring strips to complete the interior of the shelter.

2. A method for constructing a concrete box comprising the following steps: providing a number of structural building elements, the building elements having exposed wire reinforcement; assembling the building elements together into the box; preparing a lightweight concrete mix; spraying the lightweight concrete mix over the exterior of the box so as to cover the exposed wire reinforcement; allowing the concrete to harden over the wire reinforcement so that it becomes reinforced.

3. The method as described in claim 2 wherein the lightweight concrete mix includes a beneficiated aggregate.

4. The method as described in claim 3 wherein the beneficiated aggregate includes with fines between ¼″ and 200 mesh screen.

5. The method as described in claim 2 wherein the assembled building elements include upper edges and corner edges and wherein concrete forms are assembled around the upper and corner edges and wherein the sprayed concrete is allowed to accumulate within the forms such that the concrete therein hardens into solid columns.

6. A method for constructing a portable concrete enclosure comprising the following steps: providing a number of structural building elements, the building elements formed from interior and exterior wire screens and an intermediate insulation material; preparing a lightweight concrete mix that includes a beneficiated aggregate; assembling the building elements together to form the walls, floor and ceiling of the enclosure, the walls defined by a number of corner edges; assembling concrete forms around the corner edges of the enclosure; spraying the lightweight concrete mix over the ceiling of the enclosure so as to cover the exterior wire screen; allowing the sprayed concrete to fill the concrete forms of the corner edges and thereafter allowing the sprayed concrete to harden into solid columns; spraying the lightweight concrete mix upon the walls of the enclosure so as to cover the exterior wire grid and thereafter allowing the concrete to harden.

7. The method as described in claim 6 wherein the beneficiated aggregate includes with fines between ¼″ and 200 mesh screen.

8. The method as described in claim 6 wherein the floor is formed by immersing the floor building element into a pool of cement and thereafter allowing the cement to harden.

9. The method as described in claim 6 wherein the constructed enclosure is used to house the equipment associated with a cellular telephone tower.

10. The method as described in claim 6 wherein the enclosure is a shipping or storage container.

11. The method as described in claim 6 wherein the enclosure is a habitable shelter.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to portable enclosure construction. More particularly, the present invention relates to a method for constructing an enclosure from a frame covered by a lightweight concrete mix.

2. Description of the Background Art

Presently, the use of pre-fabricated building elements is known. It is further known to spray such building elements with a layer of concrete. An example of such a building element is the EVG-3D® construction system produced by EVG Entwicklungs-U. Verwertungs-Gesellschaft mbH of Raab, Austria.

An EVG building element is described in U.S. Pat. No. 6,705,055 to Ritter et al. The '055 Patent describes a building element having two parallel welded wire grid mats and associated web wires that hold the wire grid mats at a distance from one another. An insulating body is arranged between the wire grid mats. The web wires extend through the insulating body and support it inbetween the wire grid mats. An outer and inner shell of concrete can be sprayed on the wire grid mats. To improve the adhesion of the concrete to the insulating body, the insulating body may include roughened cover surfaces. The resulting structure can be used as a wall or ceiling element.

Another EVG building element is disclosed in U.S. Pat. No. 6,185,890 to Ritter. The building element in the '890 Patent is aimed at improving sound damping in prefabricated building elements. Again, the building element of the '890 patent includes two wire mesh mats interconnected by web wires that enclose an insulting body therebetween. Concrete is then applied to cover and inner and outer wire mesh mats and form concrete shells. The concrete shells are then interconnected by forming the insulating body with through-holes, which, upon application of the concrete, will form concrete webs or plugs that interconnect the two shells. By interconnecting the concrete shells resonant sound vibrations are prevented within the concrete shells.

Although each of the above referenced inventions achieves its individual objective, none of the described systems is intended for use with a lightweight concrete mix or for use in constructing a portable box.

SUMMARY OF THE INVENTION

It is therefore one of the objectives of this invention to provide a construction method which uses a number of building elements that allow lightweight enclosures to be quickly and efficiently constructed.

It is also an object of this invention to utilize a lightweight concrete mix in the construction of a portable box or enclosure.

Still another object of this invention is to utilize a number of building elements in forming an enclosure wherein the building elements are adapted to be sprayed with concrete to yield a lightweight monolithic design.

These and other objectives are carried out in a method for constructing a concrete enclosure. The method includes providing a number of structural building elements, with the individual building elements having exposed wire reinforcement. The various building elements are thereafter assembled together to form the enclosure. Thereafter, a lightweight concrete mix is prepared and sprayed to cover the exposed wire reinforcement of the building elements. As the concrete hardens it is reinforced by the exposed wire reinforcement.

The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description of the invention that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1 is a view of one anticipated application of the concrete enclosure of the present invention.

FIG. 2 is a detailed view taken from FIG. 1.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2.

FIG. 4 is a side elevational view of a concrete shelter constructed in accordance with the present invention.

FIG. 5 is a side elevational view of the concrete shelter of FIG. 4

FIG. 6 is a view of the concrete shelter taken along line 6-6 of FIG. 4.

FIG. 7 is a view of the concrete shelter taken along line 7-7 of FIG. 5.

FIG. 8 is a flow chart illustrating the various steps associated with the method of the present invention.

FIG. 9 is a partial sectional view of the interior of the enclosure of the present invention illustrating the underlying wire mesh grid.

FIG. 10 is a sectional view taken along line 10-10 of FIG. 9.

FIG. 11 is a view of an upper corner of the assembled building elements.

FIG. 12 is a view of a lower corner of the assembled building elements.

FIG. 13 is a top plan view of the floor frame used in constructing the floor of the shelter.

FIG. 14 is a side elevational view taken along line 14-14 of FIG. 13.

FIG. 15 is a detailed top plan view taken from FIG. 13.

FIG. 16 is a side view taken along line 16-16 of FIG. 14.

FIG. 17 illustrates the floor frame being filled with concrete.

FIG. 18 is a view of an assembled shelter being lowered into the concrete of the floor frame.

FIG. 18(a) is a view of concrete being applied to the inside floor of the shelter.

FIG. 19 is a view illustrating ceiling, upper edge frames and column frames being filled with concrete.

FIG. 20 is a view taken along line 20-20 of FIG. 19.

FIG. 21 is a view of the assembled shelter being sprayed with concrete.

FIG. 22 is a view taken along line 22-22 of FIG. 21.

FIG. 23 is a top plan view taken along line 23-23 of FIG. 21.

FIG. 24 is a view taken alone line 24-24 of FIG. 21.

FIG. 24(a) is a view of a joint.

FIG. 25 is an illustration of a completed shelter being transported via a flat bed truck.

FIG. 26 is a view of a bottomless embodiment of the shelter of the present invention.

FIG. 27 is a view of a smaller embodiment of the shelter of the present invention.

FIG. 28 is a view taken along line 28-28 of FIG. 27.

Similar reference characters refer to similar parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to a lightweight, portable concrete enclosure and an associated manufacturing method. The manufacturing method employs a structural member made up of two wire mesh grids that are spaced via web wires. The structural member further includes an intermediate layer of insulation positioned along the web wires. The structural members are interconnected to form a shelter. A lightweight concrete mix is then sprayed over the external surface of the structural members to yield a lightweight enclosure, or box, that can be easily transported. The various aspects of the enclosure of the present invention are described in greater detail hereinafter in conjunction with FIGS. 1-28.

An enclosure constructed in accordance with the principles of the present invention can be used in a number of environments. By way of non-limiting example, the shelter can be used as a portable classroom, as a temporary enclosure for a construction site, as a low cost home, or as a temporary house for natural disaster victims. Enclosures of the present invention can also be used as non-habitable enclosures, such containers or equipment boxes. The present invention finds use in any environment where inexpensive, portable, quickly constructed enclosures are needed.

With reference now to FIG. 1, another possible intended use is depicted. Here the enclosure is a shelter 20 that is used to house the telecommunications equipment associated with a cellular telephone tower 22. This equipment is found at the base of all cellular telephone towers and includes radio transmitters and receivers and the associated electronics for routing incoming and outgoing telephone traffic. All of this equipment must be protected both from the elements and from vandals.

As illustrated in FIGS. 4-7 shelter 20 is constructed with a door frame 24 in place to allow the subsequent installation of a door 26 for secure access to the shelter's interior by authorized personnel. Shelter 20 is also constructed with openings for use in installing one or more air conditioning units 28. Such air conditioners are needed to keep the temperature of the internal equipment at a regulated level. Two air conditioners 28 are included to provide redundancy. Additional openings 32 (note FIGS. 6 and 7) are included to provide power and ground wires to the equipment. One or more waveguides 34 (note FIGS. 4 and 5) are also formed in the sides of shelter 20 to route the cabling associated with cell tower 22.

In a manner described in more detail hereinafter, shelter 20 is constructed at an off site location and thereafter transported to the location of cell tower 22. Shelter 20 is secured to a pre-formed concrete foundation 36 by way of anchor bolts 38 and plates 42 (note FIGS. 2-3). A substantial savings in construction costs is realized by manufacturing the shelters off- site. Furthermore, the cellular telephone equipment can be installed within the interior of the shelter prior to its delivery to cell tower 22. This makes the entire shelter “plug-and-play.” Namely, after shelter 20 is anchored at its intended destination, the cabling of cell phone tower 22 is merely coupled to the equipment within shelter 20. Again, this results in a substantial savings in man power as all of the internal equipment associated with shelter 20 can be put together in an assembly line manner at an offsite location. Thereafter, once the equipment is installed, the entire shelter 20 is moved into place.

Method of Construction

The construction method of the present invention is next described in association with the flowchart of FIG. 8. In the first step of the method, the floor, walls and ceiling (44, 46, and 48, respectively) of portable structure 20 are assembled from a number of structural building elements 52. The size and shape of the structural building element 52 employed will depend upon the size and shape of the intended shelter. In the embodiment depicted in FIGS. 1 through 7, a rectangular shelter 20 is constructed from six building elements, representing the four walls 46, ceiling 48 and floor 44. A greater or lesser number of building elements 52 of varying size and shape can be used depending upon the configuration of the intended shelter.

In the second step, building elements 52 are secured to one another along their respective edges by way of corner splices 54 and joints 54a. Corner splices 54 and joints 54a are depicted interconnecting adjacent building elements 52 in the cross sectional views of FIGS. 22-24(a). Corner splices 54 are used to join building elements 52 at an angle, whereas joints 54a can be used to form a continuous flat surface from adjacent building elements 52. The assembly of building elements 52 results in a shelter 20 with exposed wire grids and without concrete reinforcement. This structure is further defined by a number of upper edges 56 (FIG. 11) about the periphery of the ceiling 48, a number of lower edges 58 (FIG. 12) about the periphery of the floor 44, and by a number of side edges 62 (FIGS. 11 and 12) that are formed by the abutting walls 48 of shelter 20. As will be explained in conjunction with future steps, each of these edges receives additional concrete reinforcement during construction.

During assembly, ferring strips 102 can be installed within the interior of shelter 20 to facilitate the subsequent placement of wallboard within the interior. As noted in the cross section of FIG. 10, the ferring strips 102 are installed within the interior of shelter 20 along both walls 46 and ceiling 48.

The preferred building element for the walls 46, ceiling 48 and floor 44 is manufactured by EVG Entwicklungs-U. Verwertungs-Gesellschaft mbH of Raab, Austria. This building element is described in U.S. Pat. Nos. 6,706,055 to Ritter et al. and 6,185,890 to Ritter., both of which are assigned to EVG. The contents of both these patents are fully incorporated herein.

FIG. 10 is a cross section of a suitable building element 52, which includes interior and exterior wire grids (64 and 66, respectively) that are spaced from one another by web wires 68. Wire grids (64 and 66) are formed from a series of individual wires that are welded to each other at 90 degree angles and which together form a mesh or wire screen, as noted in the partial sectional view of FIG. 9. In the preferred embodiment, web wires 68 are welded to adjacent wire grids (64 and 66) at approximately a 30 degree angle, with opposing web wires 68 having opposite orientations (note FIG. 10). However, it is within the scope of the present invention to use web wires 68 with other configurations, such as web wires 68 that are formed at a 90 degree angle to the wire grids (64 and 66), or web wires 68 that are all angled in a uniform direction.

With continuing reference to FIG. 10, the insulation layer 72 of building element 52 is next described. More specifically, building elements 52 include an insulation layer 72 positioned between the interior and exterior wire grids (64 and 66). This insulation can consist of, for example, foam plastic such as polystyrene or polyurethane foam or other foam materials which have desirable insulating characteristics. Preformed holes are included through the width of insulation 72 to allow it to be positioned along the length of web wires 68. As noted in the cross section of FIG. 10, insulation layer 72 is equidistant from both the interior and exterior wire grids (64 and 66). However, the insulation layer 72 can be positioned closer to either of the two wire grids (64 and 66) if desired. As noted in FIG. 10, ferring strips 102 are inserted in-between the interior wire grids 64 and the insulation 72 and between adjacent web wires 68. These ferring strips are subsequently used in the installation of wallboard upon the interior of the shelter.

The third step of the method is next described. Here, as illustrated in FIGS. 11 and 12, additional reinforcement 74 is placed along the edges of the assembled shelter 20. More specifically, after the walls 46, ceiling 48 and floor 44 have been assembled via corner splices and joints, concrete reinforcing bars 74, or “rebar,” are inserted along the edges of the shelter. Two reinforcing bars are preferably inserted along the side edges 62 of shelter 20 (FIG. 11) and a single reinforcing bar 74 is inserted along the upper and lower edges (56 and 58) (FIGS. 11 and 12). Reinforcing bars 74 can be conventional rebar with the gauge being selected based upon the .intended application for shelter 20. Reinforcing bars 74 are inserted between the exterior wire grids 66 and insulation material 72. If necessary, rebar 74 can be tied to the exterior wire grids 66 to prevent movement while the concrete is being poured.

Additional rebar 74 can be likewise inserted at spaced intervals along the floor 44 of the shelter (FIG. 12). Again, reinforcing bars 74 are positioned intermediate the exterior wire grid 66 and the insulation 72 and can be tied, if necessary, to prevent movement. Floor reinforcing bars 74 are desirable in the event shelter 20 will house exceptionally heavy equipment. When used for telecommunications equipment, for example, shelter 20 often houses large power supplies. In such instances, additional reinforcing bars 74 are included along the length of floor 44 and especially in areas over which the power supplies will be placed. After all the building elements 52 have been assembled (step 1), fastened together (step 2) and the additional reinforcing bars 74 added (step 3), shelter 20 is ready to be coated with concrete.

The first step in applying the concrete is illustrated in FIG. 17. Here, ground form 76 is assembled in a size and shape that corresponds to floor 44 of shelter 20. Care should be taken to ensure this step is carried out on a flat surface 78 to ensure resulting floor 44 of shelter 20 is uniform. A coating can be applied to area bounded by ground form 76 to prevent concrete from hardening to the ground 78 where shelter 20 is being assembled. Thereafter, a layer of wet cement 82 is added to the form as noted in FIG. 17.

Any of a variety of concrete mixes can be used for this purpose. However, in the preferred embodiment, an especially made lightweight concrete mix is utilized. The details of this concrete mix are described in greater detail hereinafter. After concrete 82 is poured, but before it hardens, assembled shelter 20 is lowered into form 76 and the wet concrete 82. The volume of the concrete within the form is sufficient to fully immerse the lower edges 58 of shelter 20. In order to make sure all the side surfaces of floor 44 are adequately covered in concrete, the floor building element is inwardly stepped 84 in relation to surrounding walls 46. The stepped nature of the floor is noted in FIG. 18. By stepping floor 44 inward, all of the outer surfaces of floor 44 are covered by concrete so as to ensure that exterior wire grid 66 is fully encased in concrete 82.

Thereafter, as noted in FIG. 18a, concrete 82 is delivered into the interior of shelter 20 to form the interior floor. A sufficient amount of concrete is pumped into shelter 20 to completely cover the exposed interior wire grids 64 of building element 52. The interior and exterior floor surfaces are thus formed by allowing concrete 82 to harden on both the exterior and interior wire grids (66 and 64) of the building element 52.

In the embodiment illustrated in FIGS. 13 through 16, lifting plates 86 are positioned in the four corners of floor form 76 prior to concrete 82 being poured. Lifting plates 86 are secured to an adjoining frame member by way of a bolt 38 that is positioned within a coil insert 92. Lifting plates 86 further include a number of nelson studs 94 to promote a firm bond between the plate 86 and surrounding concrete 82. Once the concrete of floor 44 hardens, lifting plates 86 are used to transport shelter 20. Namely, a lifting lug can be fitted to bolt 38 within the lifting plate 86. These lugs, in turn, can be fastened to a crane to enable shelter 20 to be easily maneuvered. Coil inserts 92 diffuse any stresses encountered by the lifting plates and enable shelter 20 to be picked up without any shearing of the associated bolts 38. After construction is completed, anchor plates 42 can be fitted over the bolts 38 to secure shelter 20 to a concrete foundation 36 as noted in FIGS. 2 and 3.

In the fifth step, after the concrete hardens to form floor 44 of shelter 20, the floor forms 76 are removed. Thereafter, additional forms are added about the upper edges and the corner edges. Namely, an upper edge form 96 is attached to the periphery of ceiling 48 and corner edge forms 98 (or column forms) are added to the edges between adjacent walls 46. These additional forms are depicted in FIG. 19. These concrete forms (96 and 98) correspond to the areas where the additional reinforcing bars 74 were previously inserted in step three. With continuing reference to FIG. 19, after additional forms (96 and 98) are assembled, concrete is sprayed upon ceiling 48. The same concrete mix used for floor 44 is likewise used with ceiling 48.

This concrete is sprayed from a concrete pump using any of a number of known concrete spraying techniques, such as those employed in the application of Spray-crete™ or Shot-crete™. Although sprayed, due to the horizontal orientation of ceiling 48, it can just as easily be poured. A sufficient amount of concrete is provided to cover exterior wire grid 66 of ceiling 48. A sufficient amount of concrete is also provided so as to completely fill the forms of the upper edges 96 and the forms of the corner edges 98. Once the concrete covers ceiling 48 and forms (96 and 98), the flow of concrete is stopped and the concrete is allowed to harden.

As will be obvious to those skilled in the art, prior to concrete being applied to ceiling 48, it may be necessary to temporarily reinforce the ceiling from within the interior of shelter 20. This can be accomplished by installing one or more ceiling joists and associated jacks to fully support the weight of the poured concrete until it hardens.

After the concrete hardens the forms of the upper edges and the corner edges (96 and 98) are removed. These areas of shelter 20 will be solid reinforced concrete. As noted in FIG. 8, the step of removing these forms (96 and 98) is carried out in step nine. Thereafter, additional concrete is sprayed, again using a concrete pump, over exterior walls 48 of shelter 20. Again, the same lightweight concrete mix that is used for ceiling and floor (48 and 44) can be used for walls 46. The concrete mix is fluid enough to allow it to be sprayed but not so fluid as to prevent it from adhering to the vertical walls 46 of shelter 20. The spraying of the walls with concrete is shown in FIG. 21. A sufficient volume of concrete is provided to fully cover exposed wire grids 66. Thereafter, walls 46 can be screeded to smoothen the concrete and eliminate any internal voids. If desired, additional steps can be taken to texturize the outer surface of shelter 20 for aesthetic purposes. The addition of other architectural finishes is within the scope of the present invention. Thereafter, the concrete is allowed to harden and cure. After the concrete hardens, the exterior surface of the shelter can be sealed or painted to any desired color.

Next, the interior of shelter 20 is completed. This is accomplished by nailing conventional wallboard 104, such as Sheetroc®, to the previously installed ferring strips 102. As noted above in conjunction with previous steps, the ferring strips 102 are inserted within the interior of the shelter (note FIG. 10) and allow wallboard 104 to be secured to the walls and ceiling.

The resulting construction is a lightweight concrete shelter 20 that can be transported via flatbed truck 106 to its intended destination (FIG. 25). Also, because the concrete is sprayed, the structure is monolithic and does not include any joints. Although some additional reinforcement is provided along the edges, the majority of the concrete is reinforced by the exposed wire grids 66 of building elements 52. The concrete reinforced by the exterior wire grids 66 constitutes the primary load bearing element of the resulting construction.

Also, the inventive construction method allows window and door frames, such as 24, to be formed within the building elements 52 prior to concrete being applied. One of the advantages of the present method is that, because it is not a molding process, it can be used to construct a shelter of any desired size or configuration. For instance, although larger shelters can be constructed as noted in FIGS. 4-7, the method can just as easily be adapted to construct smaller shelters 112 as noted in FIGS. 27 -28. Shelter 112 is approximately eight feet by eight feet in size. Furthermore, in the present invention, because the walls, ceiling, and floor (46, 48, and 44) are not poured in place, as with convention designs, the shelters can be assembled off-site in relatively tight surroundings, such as in a warehouse. Finally, the entire method can be carried out in a time frame of about three to five days with a minimum of labor.

Other alternative constructions can also be achieved using the construction method of the present invention. For example, as noted in FIG. 26, the method can be employed in constructing a floorless embodiment 114. This embodiment finds application in situations where a pre-formed foundation is made at the intended destination and the foundation will also serve as the floor of the shelter. In this embodiment, no building element is needed to form the floor and no floor form is utilized. Instead, building elements 52 are used to form just the walls 46 and ceiling 48. Forms are used for the upper edges and corners (96 and 98) and concrete is applied as noted in the above described method. In this embodiment, the upper peripheral edge 116 of shelter 114 acts as the primary load bearing element. Also, the upper edges 116 will be formed with lifting anchors, similar to the lifting anchors described above. This floorless embodiment can be use in “capping” the existing electrical components associated with a cell phone tower. Here, a floor can be poured around the existing equipment prior to being “capped” with shelter 114, or the equipment can be capped first with the floor being subsequently poured.

Lightweight Concrete Mix

The preferred concrete mix for constructing the shelter is as follows:

QuantityPercent By WeightDescription
188lbs.34.62%Cement
75lbs.13.81%Lime
14lbs. 2.57%Perlite
160lbs.29.47%Aggregate
105lbs.19.34%Water
12oz. .14%Plasticizer
4oz. .05%Retarder

The first ingredient is cement. In the preferred embodiment, a Type I Portland cement is employed. However, other types of cements can be readily employed in the mix. Lime is also added to the mix to improve the adhesion of the final mix. Namely, the lime enables the sprayed concrete to stick and adhere to vertical surfaces. Perlite is the next ingredient and it is added to improve the smoothness and pumpability of the final mix and reduce weight.

Aggregate is the next component. The preferred aggregate is a coal based beneficiated aggregate. However, the use of other types of beneficiated aggregates is within the scope of the present invention. For example, the invention can be used in conjunction with aluminum, shale or slate based aggregates. Beneficiated aggregates are aggregates that have undergone any number of known treatment steps to concentrate valuable constituents.

Again, in the preferred embodiment a coal based beneficiated aggregate is used in the mix. It is also preferred that the beneficial aggregate is a “fine” with particle sizes of between ¼ inch and 200 mesh screen. As will be appreciated by those skilled in the art, “mesh screen” is a reference to a filter having 200 openings per inch. Thus, using a 200 mesh screen is one way to select fines of a suitable size. By using fines of this size, the resulting concrete has less porosity and less capacity to absorb water. This, in turn, means the resulting concrete is lighter without sacrificing any strength. As is typical in concrete mixes, a volume of water is also added to the mix.

The plasticizer is preferably “ADVA® 100 Superplasticizer” manufactured by Grace Construction Products. ADVA® 100 is a water-reducing admixture that produces a low water/cement ratio and a high strength concrete. At the same time, ADVA® 100 also promotes an extremely flowable concrete that provides superior workability and pumpability. As those skilled in the art will undoubtedly appreciate, the use of other plasticizers is within the scope of the present invention.

The final ingredient is a retarder. The preferred retarder is Daratard® 17, which is also manufactured by Grace Construction Products. The retarder delays the setting time of the concrete to allow it to be pumped and sprayed to its intended location. Again, those skilled in the art will undoubtedly appreciate that the use of other retarders is within the scope of the present invention.

This concrete mix produces concrete that, when hardened, weights between 100-110 pounds per cubic foot (lbs/ft3). Despite this light weight, the concrete is also strong and can withstand pressures of between 4,000-6,000 pounds per square inch (psi). The above referenced mix most commonly produces concrete that can withstand 5,000 psi. Although the chart above illustrates preferred weights and percentages, beneficial characteristics can still be achieved using other weights and percentages as well.

When applied to building elements 52 described above, the wire grids on the exterior surface 66 act to reinforce the sprayed on concrete. The resulting structure is lightweight. Many of the structures built in accordance with the method can be picked up by relatively small 70 ton cranes. At the same time, the structures are very strong. Shelters constructed in accordance with the present invention adhere to ballistics standard UL 752 from United Laboratories and meet seismic zone 4/D requirements.

The present disclosure includes that contained in the appended claims, as well as that of the foregoing description. Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention.

Now that the invention has been described,