US20050210795A1

US20050210795A1 - Method for constructing a plastic lined concrete structure and structure built thereby

Info

Publication number: US20050210795A1
Application number: US10/793,580
Authority: US
Inventors: Clark Gunness; Ryan Leisey; James Wornick
Original assignee: Individual
Current assignee: Crom Corp
Priority date: 2004-03-04
Filing date: 2004-03-04
Publication date: 2005-09-29
Also published as: CA2499450A1

Abstract

A method for constructing a plastic lined concrete tank includes the forming of a plurality of plastic lined concrete panels. Each of the panels is made up of a concrete slab and a plastic sheet. The concrete slabs have opposed, laterally spaced, elongated edges and an inner surface and the plastic sheet each have a plurality of anchoring projections protruding outwardly from a face thereof. The panels are formed in such a way that the face of each plastic sheet is engaged against the surface of a corresponding concrete slab with the anchoring projections embedded in the concrete of said corresponding slab. The plastic sheets are arranged, configured and positioned such that a respective edge flap portion thereof projects outwardly beyond each edge of the corresponding slab and each such edge flap portion has an outboard segment. The panels are preferably constructed flat on the ground and then erected into a standing position and arranged in adjacent, aligned positions around a periphery of a tank foundation with the inner surfaces of the slabs facing inwardly, with the elongated edges of the slabs extending upwardly, with the respective elongated edges of each slab disposed in opposing spaced relationship relative to the elongated edges of adjacent slabs to thereby present elongated gaps therebetween, with the plastic sheets disposed within the tank periphery, and with the outboard segments of the edge flap portions of each sheet overlapping the outboard segments of the edge flap portions of the sheets of adjacent panels at said gap. The overlapping outboard segments are then welded together.

Description

CROSS REFERENCE TO RELATED APPLICATION

None

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to the field of concrete structures of the sort which may often be used in the construction of open topped or domed, ground level or elevated tanks and the like that may generally be used to hold liquids, for example, water. In particular the present invention relates to plastic lined concrete structures and the methodology used in the fabrication of composite plastic lined concrete structures where the plastic lining is securely affixed to a concrete wall. The invention has special utility in connection with plastic lined prestressed/post-tensioned concrete tanks.
2. The Prior Art Background
Concrete tanks have been widely used for decades to hold fresh or waste water, and the like. Generally speaking such tanks are highly commercially valuable properties, and a large construction industry has been established to serve the needs of a variety of activities and enterprises which desire an economical and reliable means for holding a readily available supply of fresh water or for storing waste water during and/or prior to treatment. Such tanks are currently available in sizes ranging from about 50,000 gallons to several million gallons or more.
Prior art concrete tanks, while extremely successful in many regards, have had limited applicability in situations where the liquid to be contained is capable of reacting with or otherwise harming concrete.
To increase the overall applicability of concrete tanks, plastic linings have been proposed to limit the exposure of the interior walls of tanks to the material contained therein. However, it has been a very difficult and expensive operation to attach large sheets of plastic to concrete walls in such a way that the plastic sheets are securely attached to the walls and all of the seams between adjacent sheets have complete integrity.

SUMMARY OF THE INVENTION

The present invention provides a solution for many of the problems encountered previously in the construction of plastic lined concrete tanks. That is to say, in accordance with the concepts and principles of the invention, a method is provided for efficiently and economically constructing plastic lined concrete structures wherein the structural integrity of the incorporated plastic linings is greatly enhanced. In this latter regard, the methodology provided by the invention is particularly applicable to all varieties of concrete tanks, including, for example, and without limitation, concrete tanks that are standard cast-in place, wire wound and prestressed, and internally tendoned and post-tensioned. Thus, in one form of the invention, the same provides a method that includes forming first and second plastic lined concrete panels, each panel including a concrete slab having an elongated edge and a surface, and a plastic sheet having a plurality of anchoring projections protruding outwardly from a face thereof. The forming of the panels is conducted in such a way that the face of each plastic sheet is engaged against the surface of a corresponding concrete slab and the anchoring projections are embedded in the concrete of the corresponding slab. In addition, the plastic sheets are each arranged and positioned such that an edge flap portion thereof projects outwardly beyond the edge of the corresponding slab. The formed panels are arranged in adjacent, aligned positions with the elongated edge of the concrete slab of the first panel disposed in opposing spaced relationship relative to the elongated edge of the concrete slab of the second panel so that an elongated gap is presented between the edges. In addition, an outboard segment of the edge flap portion of the plastic sheet of the first panel is disposed in overlapping relationship relative to an outboard segment of the edge flap portion of the plastic sheet of the second panel at said gap. The overlapping segments are then welded together with an upwardly extending seam.
In another adaptation of the invention, a method is provided for constructing a plastic lined concrete structure which comprises providing first and second plastic sheets, each sheet having a face and a plurality of anchoring projections protruding outwardly from the face. In this adaptation, the method further includes forming a first plastic lined concrete panel by causing a first quantity of wet cementitious material to come into contact with a portion of the face of the first plastic sheet, permitting the first quantity of cementitious material to set in the form of a first solid concrete slab having the anchoring projections of the first plastic sheet embedded therein. The first concrete slab desirably has an elongated edge and the first plastic sheet and the first quantity of wet cementitious material are initially arranged relative to one another such that an edge flap portion of the first plastic sheet projects outwardly beyond the edge of the first slab after the cementitious material has become set. Also in this adaptation of the invention, a second plastic lined concrete panel is formed in essentially the same manner as the first plastic lined panel. The formed panels are arranged in adjacent, aligned positions with the elongated edge of the first concrete slab disposed in opposing spaced relationship relative to the elongated edge of the second concrete slab to thereby present an elongated gap between the edges. In addition, an outboard segment of the edge flap portion of the plastic sheet of the first panel is arranged in overlapping relationship relative to an outboard segment of the edge flap portion of the plastic sheet of the second panel at said gap. The overlapping outboard segments are then welded together in situ with an upwardly extending seam.
In yet another aspect of the invention, a method is provided for constructing a plastic lined concrete tank. In accordance with this aspect of the invention, the method includes forming a plurality of plastic lined concrete panels. Each of the panels includes a concrete slab having opposed, laterally spaced, elongated edges and an inner surface, and a plastic sheet having a plurality of anchoring projections protruding outwardly from a face thereof. The forming of the panels is conducted in such a way that the face of each plastic sheet is engaged against the surface of a corresponding concrete slab with the anchoring projections embedded in the concrete of the corresponding slab. The plastic sheets are arranged, configured and positioned such that a respective edge flap portion thereof projects outwardly beyond each edge of the corresponding slab. Each of the edge flap portions has an outboard segment. The formed panels are arranged in adjacent, aligned positions around a periphery of a tank foundation with the inner surfaces of the slabs facing inwardly, with the elongated edges of the slabs extending upwardly, with the respective elongated edges of each slab disposed in opposing spaced relationship relative to the elongated edges of adjacent slabs to thereby present elongated gaps therebetween, with the plastic sheets disposed within the periphery, and with the outboard segments of the edge flap portions of each sheet overlapping the outboard segments of the edge flap portions of the sheets of adjacent panels at said gap. The overlapping outboard segments are welded together in situ with an upwardly extending seam.
Desirably, although not necessarily, a wedge welder may be used for welding the overlapping segments together. When a wedge welder is used, a main body portion of the welder may ideally be located on an opposite side of the plastic sheets from the concrete slabs during the welding. Ideally, a second portion of the wedge welder may be positioned within the gap between the edges during said welding.
In preferred forms of the invention, the edges of the panels may be coextensive in length and the edge flap portions may project outwardly beyond the edges along essentially the entire length thereof. In other preferred forms of the invention, the panels may initially be formed with the edges thereof disposed to extend in an essentially horizontal direction. That is to say, the panels may be formed on the ground and thereafter erected so that the edges extend in an essentially upright direction. When the panels are erect, the welding may ideally be accomplished by causing a welder mechanism to move upwardly along the overlapping segments of the edge flap portions of the plastic sheets. In further accordance with the concepts and principles of the invention, the gap between the edges of the panels may be filled with a grouting material after the welding has been completed. In this latter regard, it is a very desirable feature of the invention for the plastic sheets to be arranged and constructed such that anchoring projections are provided on the edge flap portions so that the same project into the gap. Accordingly, during the grouting operation, a firm bond may be created between the anchoring projections and the grout to hold the plastic sheet firmly against the concrete at all locations including the gaps.
In further accordance with the concepts and principles of the invention, the same provides plastic lined structures and plastic lined tanks that have been built employing the methodology of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, partial, perspective, elevational view of a tank which has been constructed from a series of side-by-side aligned panels in accordance with the methodology provided by the present invention;
FIG. 2 is an enlarged, fragmentary, partial cross-sectional view taken essentially in a downward direction along the line 2-2 of FIG. 1 and which also schematically illustrates the positioning of a welder used in accordance with the concepts and principles of the invention;
FIG. 3 is a perspective view illustrating the methodology used in constructing the panels used to construct the tank of FIG. 1;
FIG. 4 is a fragmentary, partial, perspective view of a panel used to construct the tank of FIG. 1, and wherein certain parts have been broken away to illustrate the internal construction of the panel;
FIG. 5 is perspective view illustrating the manner in which the erected panels are supported during construction of a tank;
FIG. 6 is a side elevational view of a wedge welder of the sort used to weld overlapping sheets of plastic together; and
FIG. 7 is an elevational cross-sectional view illustrating an alternative procedure for constructing plastic-lined concrete tanks in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As mentioned above, the present invention relates generally to the field of concrete structures of the sort which may often be used in the construction of ground level or elevated concrete liquid containing storage tanks and the like, and to plastic lined concrete structures and the methodology used in the fabrication of composite plastic lined concrete structures whereby the plastic lining is securely affixed to a concrete wall. In connection with the foregoing, and in further accordance with the invention, the tanks may have no roof or a roof that comprises a dome made from concrete, aluminum, fabric, or a flat panel roof with or without column supports that bear at or beneath the floor of the tank.
In a particularly preferred mode of the invention, the same provides methodology for constructing plastic lined concrete tanks; however, as will be apparent to those of ordinary skill in the concrete construction art, the invention more broadly relates to the construction of any sort of plastic lined concrete structures where it is desirable to prefabricate a plurality of lined concrete panels, cause the panels to be arranged in an aligned, side-by-side relationship, and thereafter weld the separate linings on adjacent panels together in situ to thereby present a continuous sealed barrier.
Broadly, and with particular reference to FIGS. 1 through 5 of the drawings, the method for constructing plastic lined concrete structures includes forming a plurality of plastic lined concrete panels 10. Such panels may be constructed adjacent the site where a tank is to be built or at a remote location and shipped to the site. Panels 10 are similarly constructed and each includes a concrete slab 12, which may be generally rectangular in shape and which desirably has a pair of opposed, laterally spaced, elongated lateral edges 14, 16 and a surface 18 which extends laterally between edges 14, 16. As can be seen from the drawings, in a preferred form of the invention, the slabs 12 may desirably be curved so that when a series of the same are placed in an aligned, side-by-side relationship, together they may be arranged so as to present the outer periphery of a generally round concrete tank 20 which may be used to contain liquids generally, including water and the like.
Each of the panels 10 also includes a plastic sheet 22 having a plurality of anchoring projections 24 protruding outwardly from a face 26 thereof, and the panels 10 are desirably formed in such a way that the face 26 of each plastic sheet 22 is engaged against the surface 18 of the corresponding concrete slab 12 with the anchoring projections 24 embedded within the concrete of the slab 12. The sheets 22 may be formed from any sort of thermoplastic material which is essentially inert to the substances that it will come into contact with during operation and tough enough to withstand the physical rigors associated with the construction and/or use of the lined structure. Ideally, the sheets 22 may be formed from high density polyethylene, linear low density polyethylene, polypropylene and/or PVC. Desirably the plastic sheets 22 are wider than the concrete slabs 12, and each sheet 22 is arranged and positioned on its corresponding slab 12 in such a way that an edge flap portion 28 thereof projects outwardly beyond the edge 14 of the corresponding slab 12 and an edge flap portion 30 projects outwardly beyond the opposite edge 16 of the corresponding slab 12.
The sheets 22 generally may have a thickness ranging from about 0.5 mm (0.020 inch) to about 7 mm (0.28 inch), and desirably the thickness may be within the range of from about 1.5 to 4 mm. For heavy duty operation under adverse and/or corrosive chemical conditions, it has been found that a high density polyethylene material having a thickness of about 3 mm may be desirable. Conversely, for applications where the tank will contain relatively pure water and be exposed to mild temperature conditions, it may be desirable, for economical reasons, to use a linear low density polyethylene having a thickness of 2 mm.
As can be seen from FIGS. 1 and 2, the panels 10 of a series 32 thereof are disposed in adjacent, aligned positions with the elongated edge 14 of each concrete slab 12 arranged in opposing spaced relationship relative to the elongated edge 16 of an adjacent concrete slab 12 so as to thereby present an elongated gap 34 between the edge 14 of one slab 12 and the edge 16 of the adjacent slab 12. Desirably, the panels 10 are arranged so that an outboard segment 36 of the edge flap portion 30 of the plastic sheet of one panel 10 is disposed in overlapping relationship to an outboard segment 38 of the edge flap portion 28 of the plastic sheet 22 of the adjacent panel at the gap 34. In accordance with the concepts and principles of the invention, the overlapping segments 36, 38 are welded together in situ.
A preferred procedure for forming the panels 10 is illustrated in FIGS. 3 and 4. FIG. 3 illustrates a form box 40 which can be used in the fabrication of a panel 10. Form box 40 includes a lower former 41 having an upper form surface 42, the lateral cross-section of which can best be seen in FIG. 4. It is to be noted in this regard that surface 42 is convex and upwardly curved at the same degree of curvature as the inside circumference of a tank to be constructed from the panels 10 formed in box 40. A sheet 22 is then laid out on the surface 42 so that face 26 faces upwardly and projections 24 protrude upwardly. It is to be noted in this latter regard that the projections 24 as illustrated are preferably in the form of a multiplicity of elongated, generally parallel T-shaped ribs 44 which are integral with the sheet 22. However, as will be apparent to those skilled in the field of plastic linings for concrete panels, there are a variety of known shapes and forms for such anchoring projections which have previously been in conventional use.
The sheet 22 is laid out such that the edge flap portions 28 and 30 extend laterally beyond the lateral extremities of the upper form surface 42 on each side thereof. In this regard, edge flap portion 30 can be seen in FIG. 3; however, edge flap portion 28 on the opposite side of sheet 22 is hidden from view. It is to be noted that in FIG. 3, the ribs 44 on edge flap portion 28 are shown schematically as single lines. After sheet 22 has been appropriately positioned relative to upper form surface 42, reinforcing steel 46 is arranged atop sheet 22 and side boards 48 are installed in locations for appropriately defining the edges 14, 16 of the slab 12. In this latter regard, in the preferred form of the invention illustrated in the drawings and described herein, the side boards 48 and the edges 14, 16 defined thereby, desirably extend in general parallelism with ribs 44. End boards 50 complete the internal periphery of form box 40 which is intended to retain wet cementitious material after it is poured and while it is setting up into a solid form. A quantity of wet cementitious material is then poured onto the face 26 of sheet 22, appropriately shaped with a curved screed board 51, and then allowed to harden to thereby form slab 12. After the slab 12 is formed, it is clear that the surface 18 thereof is engaged against the face 26 of sheet 22, and that the T-shaped ribs 44 are embedded within the concrete.
As can be appreciated from FIGS. 3 and 4 of the drawings, in one particularly preferred form of the invention, at the time the panels 10 are formed, the edges 14, 16 of the slab 12 extend horizontally. That is to say, the panel 10 is lying in a generally horizontal position. Accordingly, in order to use the panels 10 to form a concrete tank, the same must be erected so that the edges 14, 16 extend in an upward direction. Such erection may be accomplished in a conventional manner using a crane or a hoist or the like. After erection and prior to the completion of the entire tank, the individual panels 10 may be held in place by respective sets of conventional braces 52 such as those illustrated in FIG. 5. Conventional weld plates (not shown) may also be used to further support the panels 10 during welding of the overlapping segments 36, 38. Desirably, the panels 10 may be erected on a concrete base or foundation 33, or the like which may be lined or unlined.
As is illustrated in FIG. 1, a plurality of the pre-fabricated panels 10 may be arranged so as to present a tank 20, the interior surfaces of which will be lined with a plastic lining upon completion of the construction of the tank. Thus, a plurality of the panels 10 may be arranged in an aligned, side-by-side relationship as shown, with the elongated edges 14, 16 of adjacent panels 10, which are essentially coextensive in length, disposed in an opposing, spaced apart relationship so as to present the upwardly extending gap 34 therebetween. As mentioned above, adjacent panels 10 are positioned and arranged so that an outboard segment 36 of the edge flap portion 30 of the plastic sheet 22 of one panel 10 is disposed in overlapping relationship to an outboard segment 38 of the edge flap portion 28 of the plastic sheet 22 of the adjacent panel 10 at the gap 34. This relationship can best be seen from FIG. 2, where it can also be seen that at least one of the ribs 44 may be removed from the outboard segment 36 of edge flap portion 30 so as to avoid interference with the welding operation. It should also be noted in connection with the foregoing that the ribs 44 on the edge flap portion 28 remain intact so as to provide a secure connection between the grouting material 70 and the sheet 22 when the gap 34 is grouted as described hereinafter. In further connection with the foregoing, it should be noted also from FIG. 1 that the edge flap portions 28, 30, which project outwardly beyond the elongated edges 14, 16, are desirably coextensive in vertical length with one another as well as with the elongated edges 14, 16.
As described above, the panels 10 are pre-fabricated and arranged in place after the concrete has become set. Alternatively, in accordance with another embodiment of the invention, the panels 10 may be formed in situ in an already erect condition. In accordance with this aspect of the invention, and with specific reference to FIG. 7, an upstanding form assembly 140 may be employed to construct each panel 10. Form assembly 140 may be erected on the base pad 33, and the same includes an inner form element 142 and an outer form element 144. These form elements 142, 144 may be made from plywood or other prefabricated form system material and may be appropriately curved to simulate the curvature of the completed concrete structure. As built, the elements 142, 144 are disposed in a horizontally spaced, facing relationship so as to present a concrete fillable space 145 therebetween. To construct each panel 10 in situ, a plastic sheet 22 is placed over the interior face 146 of form element 142 with the ribs 44 thereof (not shown in FIG. 7) projecting into the space 145. Reinforcing steel (not shown in FIG. 7) may then be arranged in space 145 and fluid concrete may be poured into the space 145. Upon drying, the concrete poured into space 145 presents slab 12. Thereafter, the form assembly 140 is removed to present an already in place panel 10. As will be appreciated by those skilled in the art, a series of laterally spaced and aligned panels 10 may be constructed in this manner around the periphery of the tank. These panels will be spaced apart laterally as described above so as to present a gap 34 between adjacent aligned panels 10. In addition, the plastic sheets extend laterally outwardly beyond the lateral edges of the panels as described above so as to present corresponding outboard segment 36, 38 which may then be welded together in accordance with the concepts and principles of the invention.
In another embodiment of the invention, the panels 10 may be formed using concrete spraying methodology. In accordance with this form of the invention, a form assembly similar to the assembly 140 may be used. However, in this case, the outer form element 144 is not needed. The construction of the panel 10 in this case simply involves constructing the form element 144, placing the plastic sheet over the face 146 of the latter with the ribs projecting outwardly, installing the steel reinforcing material, and spraying concrete onto the exposed surface of plastic sheet 22.
In each of the embodiments described above, the final arrangement of the panels 10 is as illustrated in FIGS. 1 and 2.
Preferably, each gap 34 may vary in width from about 4 inches to about 20 inches, and desirably the width of the gap 34 should be about 6 to 8 inches. Advantageously, each of the flap portions 28, 30 may project laterally and outwardly beyond edges 14, 16 of slab 12 for a distance of from about 4 inches to about 20 inches, and ideally the outboard segments 36, 38 should overlap a minimum of 2 inches and a maximum of 10 inches. Generally, it is preferred for the overlapping segments 36, 38 to be positioned centrally of the gap 34. In a particularly preferred form of the invention, the gap 34 may be about 7 inches wide and the flap portions 28, 30 may project outwardly beyond the edges 14, 16 of slab 12 for a distance of about 5 inches, whereby the overlap is about 3 inches wide.
The overlapping outboard segments 36 and 38 may be welded together in situ using hot air welding, hot gas welding, infrared element welding and/or wedge welding. However, wedge welding may desirably be used in accordance with the preferred aspects of the invention. A typical wedge welder 56 is illustrated in FIG. 6 where it can be seen that the welder 56 includes a main body portion 58 where the controls and drive mechanisms are located and a bottom sled portion 60. The overall operational characteristics of wedge welders are conventional and well known, and such mechanisms are commonly used to weld overlapping, horizontally extending edge flap portions of adjacent plastic sheets together. Accordingly, as shown in FIG. 6, the wedge welder is employed to weld overlapping outboard segments 36 and 38 together using a heated wedge 62 and pinch wheels 64, 66. As is well known, pinch wheel 64 may be a driven wheel carried by main body portion 58 while pinch wheel 66 carried by bottom sled portion 60 may be either a driven wheel or an idler wheel. Conventionally, during operation the wedge welder 56 travels in the direction of the arrow 61 in FIG. 6.
In further accordance with the concepts and principles of the present invention, the overlapping outboard segments 36, 38 of the edge flap portions 28, 30 are welded together in situ using a wedge welder 56. This operation is best illustrated in FIG. 2 where it can be seen that the main body portion 58 of the welder 56 is desirably positioned on the opposite sides of the plastic sheets 22 from the concrete slabs 12, whereas the bottom sled portion 60 of the welder 56 is desirably positioned within gap 34. The bottom sled portion 60 may desirably be provided with slots 75 which cooperate with ribs 44 or other anchoring projections on flap 28 for guiding the welder 56 along the gap 34. Ideally, the wedge welder 56 may be started at the bottom of each overlapping set of outboard segments 36, 38 and caused to move upwardly along the sheets 22 while the segments 36, 38 are welded together to produce a continuous, upwardly extending seam 68, which desirably may vary from 0.5 inch to 2 inches in width and ideally is about 1 inch in width. Alternatively, the welder 56 may be started at the top and caused to move downwardly along the edges of the sheets. In accordance with the particularly preferred form of the invention described above where the gap 34 is 7 inches wide, the bottom sled portion 60 may ideally be about 5-6 inches wide.
After each seam is completed, the gap 34 may desirably be filled with a grouting material 70 as illustrated schematically in FIG. 1. As explained above, it is desirable in connection with the invention for anchoring projections 24 to be arranged such that the same project into the gap 34 where they may be surrounded by grout during the grouting process. This insures a rigid and secure connection between the plastic sheets 22 and the grout. After the gaps 34 are fully grouted, the tank 20 may be prestressed/post-tensioned using wires or strands (not shown).

Claims

1. A method for constructing a plastic lined concrete structure comprising:

forming first and second plastic lined concrete panels, each panel including a concrete slab having an elongated edge and a surface, and a plastic sheet having a plurality of anchoring projections protruding outwardly from a face thereof, said forming being conducted in such a way that said face of each plastic sheet is engaged against the surface of a corresponding concrete slab and said anchoring projections are embedded in the concrete of the corresponding slab, said plastic sheets each being arranged and positioned such that an edge flap portion thereof projects outwardly beyond the edge of the corresponding slab;

causing said panels to be arranged in adjacent, aligned positions with the elongated edge of the concrete slab of the first panel disposed in opposing spaced relationship relative to the elongated edge of the concrete slab of the second panel to thereby present an elongated gap between the edges, and with an outboard segment of the edge flap portion of the plastic sheet of the first panel overlapping an outboard segment of the edge flap portion of the plastic sheet of the second panel at said gap; and

welding said overlapping segments together.

2. A method as set forth in claim 1, wherein a wedge welder is used for welding said overlapping segments together.

3. A method as set forth in claim 2, wherein a main body portion of said welder is located on an opposite side of the plastic sheets from the concrete slabs during said welding.

4. A method as set forth in claim 1, wherein said edges are coextensive in length and said edge flap portions project outwardly beyond the edges along essentially the entire length thereof.

5. A method as set forth in claim 1, wherein said panels are initially formed with said edges thereof disposed to extend in an essentially horizontal direction, and said causing includes erecting said panels so that the edges extend in an essentially upright direction.

6. A method as set forth in claim 3, wherein a second portion of said wedge welder is positioned within said gap between said edges during said welding.

7. A method as set forth in claim 1 comprising filling said gap with a grouting material after said welding has been completed.

8. A method as set forth in claim 2, wherein said panels are initially formed with said edges thereof disposed to extend in an essentially horizontal direction, and said causing includes erecting said panels so that the edges extend in an essentially upright direction.

9. A method as set forth in claim 8, wherein said welding is accomplished by causing said welder to move upwardly along said overlapping segments.

10. A method for constructing a plastic lined concrete structure comprising:

providing first and second plastic sheets, each sheet having a face and a plurality of anchoring projections protruding outwardly from said face;

forming a first plastic lined concrete panel by causing a first quantity of wet cementitious material to come into contact with and cover a portion of said face of the first plastic sheet, permitting the first quantity of cementitious material to set in the form of a first solid concrete slab having the anchoring projections of the first plastic sheet embedded therein, said concrete slab having an elongated edge, and arranging said first plastic sheet and said first quantity of wet cementitious material relative to one another such that an edge flap portion of the first plastic sheet projects outwardly beyond said edge of the first slab after the cementitious material has become set;

forming a second plastic lined concrete panel by causing a second quantity of wet cementitious material to come into contact with and cover a portion of said face of the second plastic sheet, permitting the second quantity of cementitious material to set in the form of a second solid concrete slab having the anchoring projections of the second plastic sheet embedded therein, said concrete slab having an elongated edge, and arranging said second plastic sheet and said second quantity of wet cementitious material relative to one another such that an edge flap portion of the second plastic sheet projects outwardly beyond said edge of the second slab after the cementitious material has become set;

causing said panels to be arranged in adjacent, aligned positions with the elongated edge of the first concrete slab disposed in opposing spaced relationship relative to the elongated edge of the second concrete slab to thereby present an elongated gap between the edges, and with an outboard segment of the edge flap portion of the plastic sheet of the first panel overlapping an outboard segment of the edge flap portion of the plastic sheet of the second panel at said gap; and

welding said overlapping outboard segments together.

11. A method as set forth in claim 10, wherein a wedge welder is used for welding said overlapping segments together.

12. A method as set forth in claim 11, wherein a main body portion of said welder is located on an opposite side of the plastic sheets from the concrete slabs during said welding.

13. A method as set forth in claim 10, wherein said edges are coextensive in length and said edge flap portions project outwardly beyond the edges along essentially the entire length thereof.

14. A method as set forth in claim 10, wherein said panels are initially formed with said edges thereof disposed to extend in an essentially horizontal direction, and said causing includes erecting said panels so that the edges extend in an essentially upright direction.

15. A method as set forth in claim 12, wherein a second portion of said wedge welder is positioned within said gap between said edges during said welding.

16. A method as set forth in claim 10 comprising filling said gap with a grouting material after said welding has been completed.

17. A method as set forth in claim 11, wherein said panels are initially formed with said edges thereof disposed to extend in an essentially horizontal direction, and said causing includes erecting said panels so that the edges extend in an essentially upright direction.

18. A method as set forth in claim 17, wherein said welding is accomplished by causing said welder to move upwardly along said overlapping segments.

19. A method for constructing a plastic lined concrete tank comprising:

forming a plurality of plastic lined concrete panels, each panel including a concrete slab having opposed, laterally spaced, elongated edges and an inner surface, and a plastic sheet having a plurality of anchoring projections protruding outwardly from a face thereof, said forming being conducted in such a way that said face of each plastic sheet is engaged against the surface of a corresponding concrete slab with said anchoring projections embedded in the concrete of said corresponding slab, said plastic sheets each being arranged, configured and positioned such that a respective edge flap portion thereof projects outwardly beyond each edge of the corresponding slab, each said edge flap portion having an outboard segment;

causing said panels to be arranged in adjacent, aligned positions around a periphery of a tank foundation with the inner surfaces of the slabs facing inwardly, with the elongated edges of the slabs extending upwardly, with the respective elongated edges of each slab disposed in opposing spaced relationship relative to the elongated edges of adjacent slabs to thereby present elongated gaps therebetween, with the plastic sheets disposed within said periphery, and with the outboard segments of the edge flap portions of each sheet overlapping the outboard segments of the edge flap portions of the sheets of adjacent panels at said gap; and

welding said overlapping outboard segments together.

20. A method as set forth in claim 19, wherein a wedge welder is used for welding said overlapping segments together.

21. A method as set forth in claim 20, wherein a main body portion of said welder is located on an opposite side of the plastic sheets from the concrete slabs during said welding.

22. A method as set forth in claim 19, wherein said panels are initially formed with said elongated edges extending in a generally horizontal direction and said causing includes erecting the panels so that said elongated edges extend in an upright direction.

23. A method as set forth in claim 19, wherein said placing includes positioning said elongated edges in a generally parallel relationship on opposite sides of said gap.

24. A method as set forth in claim 19, wherein said forming includes applying a respective quantity of a wet cementitious material to a portion of the face of each of said sheets, and thereafter allowing the respective quantities of cementitious material to set with said anchoring projections submerged therein.

25. A method as set forth in claim 19 comprising filling said gaps with a grouting material after said welding has been completed.

26. A method as set forth in claim 21, wherein a second portion of said wedge welder is positioned within said gap between said edges during said welding.

27. A method as set forth in claim 20, wherein said panels are initially formed with said elongated edges extending in a generally horizontal direction and said causing includes erecting the panels so that said elongated edges extend in an upright direction.

28. A method as set forth in claim 27, wherein said welding is accomplished by causing said welder to move upwardly along said overlapping segments.

29. A method as set forth in claim 6, wherein said panels are initially formed with said edges thereof disposed to extend in an essentially horizontal direction, and said causing includes erecting said panels so that the edges extend in an essentially upright direction.

30. A method as set forth in claim 29, wherein said welding is accomplished by causing said welder to move upwardly along said overlapping segments.

31. A method as set forth in claim 15, wherein said panels are initially formed with said edges thereof disposed to extend in an essentially horizontal direction, and said causing includes erecting said panels so that the edges extend in an essentially upright direction.

32. A method as set forth in claim 31, wherein said welding is accomplished by causing said welder to move upwardly along said overlapping segments.

33. A method as set forth in claim 26, wherein said panels are initially formed with said elongated edges extending in a generally horizontal direction and said causing includes erecting the panels so that said elongated edges extend in an upright direction.

34. A method as set forth in claim 33, wherein said welding is accomplished by causing said welder to move upwardly along said overlapping segments.

35. A plastic lined concrete structure built using the method of claim 1.

36. A plastic lined concrete structure built using the method of claim 30.

37. A plastic lined concrete structure built using the method of claim 10.

38. A plastic lined concrete structure built using the method of claim 32.

39. A plastic lined concrete tank built using the method of claim 19.

40. A plastic lined concrete tank built using the method of claim 34.

41. A method as set forth in claim 1, wherein the edge flap portion of the plastic sheet of the second panel has at least one anchoring projection which projects into said gap after the overlapping segments have been welded together.

42. A method as set forth in claim 41 comprising filling said gap with a grouting material after said welding has been completed.

43. A method as set forth in claim 10, wherein the edge flap portion of the plastic sheet of the second panel has at least one anchoring projection which projects into said gap after the overlapping segments have been welded together.

44. A method as set forth in claim 43 comprising filling said gap with a grouting material after said welding has been completed.

45. A method as set forth in claim 19, wherein the edge flap portions of the plastic sheets of said adjacent panels each has at least one anchoring projection which projects into said gap after the overlapping segments have been welded together.

46. A method as set forth in claim 45 comprising filling said gap with a grouting material after said welding has been completed.

47. A method as set forth in claim 1, wherein said plastic sheets have a thickness ranging from about 0.05 mm to about 7 mm.

48. A method as set forth in claim 1, where in said sheets are formed from either a high density polyethylene or a linear low density polyethylene.

49. A method as set forth in claim 47, where in said sheets are formed from either a high density polyethylene or a linear low density polyethylene.

50. A method as set forth in claim 1, wherein the anchoring projections are in the form of elongated, T-shaped ribs.

51. A method as set forth in claim 10, wherein said plastic sheets have a thickness ranging from about 0.05 mm to about 7 mm.

52. A method as set forth in claim 10, where in said sheets are formed from either a high density polyethylene or a linear low density polyethylene.

53. A method as set forth in claim 51, where in said sheets are formed from either a high density polyethylene or a linear low density polyethylene.

54. A method as set forth in claim 10, wherein the anchoring projections are in the form of elongated, T-shaped ribs.

55. A method as set forth in claim 19, wherein said plastic sheets have a thickness ranging from about 0.05 mm to about 7 mm.

56. A method as set forth in claim 19, where in said sheets are formed from either a high density polyethylene or a linear low density polyethylene.

57. A method as set forth in claim 55, where in said sheets are formed from either a high density polyethylene or a linear low density polyethylene.

58. A method as set forth in claim 19, wherein the anchoring projections are in the form of elongated, T-shaped ribs.

59. A method as set forth in claim 1, wherein said causing includes forming said panels in situ.

60. A method as set forth in claim 10, wherein said causing includes forming said panels in situ.

61. A method as set forth in claim 19, wherein said causing includes forming said panels in situ.

62. A method as set forth in claim 8, wherein said welding is accomplished by causing said welder to move upwardly along said overlapping segments.

63. A method as set forth in claim 17, wherein said welding is accomplished by causing said welder to move upwardly along said overlapping segments.

64. A method as set forth in claim 29, wherein said welding is accomplished by causing said welder to move upwardly along said overlapping segments.