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.
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.
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:
Similar reference characters refer to similar parts throughout the several views of the drawings.
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
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
As illustrated in
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
Method of Construction
The construction method of the present invention is next described in association with the flowchart of
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 (
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
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.
With continuing reference to
The third step of the method is next described. Here, as illustrated in
Additional rebar 74 can be likewise inserted at spaced intervals along the floor 44 of the shelter (
The first step in applying the concrete is illustrated in
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
Thereafter, as noted in
In the embodiment illustrated in
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
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
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
The resulting construction is a lightweight concrete shelter 20 that can be transported via flatbed truck 106 to its intended destination (
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
Other alternative constructions can also be achieved using the construction method of the present invention. For example, as noted in
Lightweight Concrete Mix
The preferred concrete mix for constructing the shelter is as follows:
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,