WO2000049322A1

WO2000049322A1 - Method and material for repair of conduits and the like

Info

Publication number: WO2000049322A1
Application number: PCT/US1999/010471
Authority: WO
Inventors: Thomas Gianfrancisco
Original assignee: Thomas Gianfrancisco
Priority date: 1999-02-17
Filing date: 1999-05-27
Publication date: 2000-08-24
Also published as: AU4185599A

Abstract

An improved method for repairing sewer pipes, water mains, tunnels, storage tanks, and the like is described, based on the use of selected fly-ash fillers which serves to reduce material costs and enhance the structural strength of the final system. Repairs are carried out by assembling a cavity system (13, 15, 17) which is anchored to the conduit pipes (10) to be repaired, preparing a suitable mixture of liquid resin with selected fillers and sequential filling of the cavity with resin-filler mixture. By using such a procedure, the likelihood of trapping air and waste water is minimized. At the same time, the structures so repaired also gain the advantage of additional mechanical support.

Description

METHOD AND MATERIAL FOR REPAIR OF CONDUITS AND THE LIKE

BACKGROUND OF THE INVENTION Field of the Invention

In general, the invention relates to an improved method and material for repairing sewer pipes, water mains, tunnels, storage tanks, and the like. It is based on the use of a structure which minimizes voids and contaminants, and the use of selected fly-ash fillers which serves to reduce material costs and to enhance the structural strength of the final system. Description of Related Art

Tunnels and particularly sewer structures in the United States and throughout the world are frequently deteriorated to the point where they do not retain the liquids and other effluent they need to contain; often, they do not exclude ground water from entering or lose their structural capability. These normally brick or masonry structures require repairs which necessitate replacement of the masonry structure with a new one. This requires digging up of the old sewer structure, removing the old materials and replacing the brick or concrete sewer line with a new one made of similar materials. All of this involves enormous cost and disruption of pedestrian or vehicular traffic since many sewer lines are b-uried under streets or sidewalks in cities.

The problem is particularly acute for the larger sewer lines which have to be built up in place, in contrast to smaller sewer lines which can be preformed pipe-like elements laid end-to-end.

There have been various attempts to rebuild these types of sewer lines utilizing plastic liners. One example is US Patent No. 4,585,371 to Jones-Hinton. This patent shows a sewer liner composed of two types of longitudinal plastic shapes linked edge-to-edge to form an approximately semi-circular tunnel liner open at the bottom. The liner is formed of rib-like elements or spacer elements located between and interlocked with the side members of the relatively wider, flat lining wall of the assembly. When in place, a settable liquid or semi- liquid compound is injected into the longitudinal end openings or hollow portions of lining elements to strengthen and stiffen them. In addition, the settable compound can be injected separately between the inner surface of the sewer to be repaired and the outer surface of liner elements to fill in the space between the various rib-like elements and the tunnel to be repaired. Since the whole liner structure of Jones-Hinton loosely contacts the tunnel liner and the whole assembly is not fastened, it is allowed to move when set with the structure composed of spacer elements and lining elements or with the tunnel wall. Other problems are apparent from the statement in this reference that the lubricants must be introduced to slidably assemble the elements together. This would create extensive problems since these elements, when put in place in the sewer to be repaired, might be many feet long, perhaps 50 feet to 200 feet in length, requiring sliding of the elements within each other in the whole distance. Other deficiencies are obvious in that the bottom of the whole structure is open, thereby not functioning to retain sewer liquids or exclude ground water, in addition to not having significant structural strength to reinforce the weakened physical structure of the deteriorated sewer.

Another prior effort is illustrated by the technology disclosed in US Patent 4,336,012. This patent relates to lining a sewer to be repaired with a tube of felt with an impervious plastic outer layer, applying a "slug" of resin to the inner tube of fibrous felt-like material and drawing the tube through squeezing rollers while a vacuum is drawn through one or more openings in advance of the spreading resin. The process involves placing a measured quantity of semi-liquid settable plastic at the end of the tunnel segment to be repaired, spreading the settable plastic through the inner fibrous tube sequentially from the far portion to the near portion by using rollers and drawing air from the fiber tube.

_ From both an environmental and an economic point of view, it would be desirable for any method relying on settable liquid resins to use a filler. To find a filler which would be suitable for a specific purpose, however, is typically more an art than something that could be developed through a mathematical formula. It is, therefore, one of the objectives of the instant invention to provide a filler or fillers which would be practical and advantageous.

SUMMARY OF THE INVENTION

The objective of the present invention is, therefore, to repair a conduit without the necessity of drawing a vacuum, without the disadvantages of the prior art, and to use a filler material which would improve the economic and functional aspects of the process.

It is a further object of the invention to provide a general method for forming solid plastic resin objects based on the use of selected resins and fillers.

To achieve these and other objectives, the invention provides a method for repair of a length of a conduit having a circumferential inner surface, comprising the steps of: a) anchoring to the inner surface in a direction parallel to the length a plurality of sections of tubing of generally rectangular cross-section spaced around the onduit in the circumferential direction, each of the sections of tubing having therein a plurality of openings in a direction parallel to the circumferential direction; b) anchoring to the tubing on a surface thereof opposite to a surface of the tubing anchored to the inner surface a plurality of strips of plastic sheeting, the strips of plastic sheeting extending circumferentially around the conduit along the length of the repair, defining thereby a space between the plastic sheeting and the inner surface, the plastic sheeting being primed on a surface thereof facing the inner surface of the conduit; c) sealing a first end of each of the plurality of sections of tubing, and the adjacent space between the sheeting and the conduit; d) priming the plastic sheeting with a suitable primer; e) pumping into a second end of a plurality of sections of the tubing a settable liquid plastic composition, which exits through the openings and fills the space; and f) permitting the plastic composition to cure, thereby repairing the conduit. The first of the components used in the repair is PVC tubing of generally rectangular cross-section which is slotted or perforated throughout its length. The tubing is generally 1-1.5 inches square or rectangular with slots or perforations extending its 8-15 foot length, which is normally about 50 to 100 feet when extended end to end. The second component is PVC sheeting, about 2 feet wide, 8-15 feet long arranged end to end and 1/4 to 1/8 inch thick.

The third component is a settable liquid plastic, comprising generally an epoxy grout and a selected filler. This settable liquid plastic is also generally part of a system including a primer. In a preferred embodiment, the primer combines an isocyanate functional material with a co-reactant polymer capable of reaction with the isocyanate . The isocyanate may be aliphatic or aromatic in nature and may be a monomer, a dimer, a trimer, a biuret, or a prepolymer. The co-reactant polymer may be a hydroxyl, amine or mercaptan terminated polyester, polyether, acrylic or vinyl polymer. Since the isocyanate and co- reactant polymers are selected to react with each other, they must be supplied in separate packages, and combined just prior to use.

The settable liquid plastic is preferably an epoxy grout, which is a combination of liquid epoxy resin, mineral filler and amine curing agent for the epoxy resin. The epoxy resin may be of the Biphenol A, Biphenol F or cycloaliphatic type. The preferred epoxy is a commercial epoxy binder which has a pot life (1/2 gallon) of 35 minutes, viscosity of about 150 cps, compressive strength of about 11,000 psi and tensile strength of about 8000 psi .

The preferred mineral filler is Class C fly ash. Fly ash is the fine ash product which results from the combustion of coal, typically recovered with an electrostatic precipitator . Class C fly ash is a high lime material which is pumpable at the percentage by volume used and controls the heat generated by the curing. Class F fly ash may also be used under some circumstances. Other fillers used in plastic resins such as ground silica, calcium carbonate, mica, talc and glass fibers, flakes and spheres are not suitable because of difficulty in pumpability when sufficient amounts are used to control heat which affects the PVC.

The amine hardener may be aliphatic, cyclaliphatic or aromatic in nature; amides, amidoamines and adducts of aliphatic, cycloaliphatic and aromatic amines may also be used.

The epoxy grout must be supplied with hardener, and mixed just prior to use. The filler may then be combined with the mixed, two-part resin. Initially, the sewer or wastewater conduit to be repaired can be cleansed using a power wash of 1200-3000 PSI water with or without sandblasting for the purpose of removing material to expose a clean and solid surface. Next, the surface is etched using muriatic or similar acid, following by flushing with a solution having a chlorine content to kill bacteria.

The tubing and PVC sheeting affixed along the conduit to be repaired is preferably supplied to repair up to about a total 50 to 300-foot length at a time. The strips of sheeting are on the order of 2 feet wide by 8 to 15 feet long and are laid and sealed end to end to the length of the conduit to be repaired. The rectangular tubing is applied longitudinally to the sewer at 2 foot intervals around the circumference with concrete screws or anchors. The strips of PVC sheeting are then glued or welded end to end and to the tubing using plastic welding techniques.

It is important that the surface of the strips which face the inner surface of the conduit be primed for adhesion, typically with a primer compatible with the settable liquid plastic; other priming methods known to those of ordinary skill in the art may also be used. The surface of the tubing is also preferably primed.

The conduit having a plastic sheet liner assembly fixed therein is prepared for application of the epoxy grout by sealing one end of each of the tubing sections anchored to the conduit, as well as the adjacent spaces between the conduit and sheeting, with epoxy putty. This would normally be the lower end of the conduit or sewer line which is usually sloped. At the opposite end of the tubing sections, the normally higher end, a fitting is inserted to adapt the rectangular tubing for connection with a round hose. The outer round portion of the rectangular-to-round fitting is sized to fit a flexible hose which will extend outwardly to a hose outlet on a manifold. The manifold includes a central chamber for receiving the epoxy grout from a pump and I Dole tubing fittings adapted to receive the rectangular-to-round fittings. The manifold preferably includes one or two outlet tubes to accommodate sequentially from the bottom of the cavity formed by the PVC sheets all of the longitudinal rectangular tubing sections anchored to the conduit to be repaired and holding the PVC liner in place. Pumping is started by first filling the bottom rectangle tube until epoxy fill is in the next higher pair of rectangular tubes. The epoxy input tube is then connected to those tubes, then similarly pumped, successively upward until the top is filled. Epoxy putty should be used to seal the open end and of the cavity formed by the PVC sheets between the rectangular tubes to which the rectangular round inlet fittings are attached.

The epoxy grout is then pumped through the manifold and through the sections of rectangular tubing mounted on the introduction end wall of the conduit to be repaired. At the introduction end of the conduit, one tubing section, preferably at the high point of the system, is not used for introduction of epoxy grout, but is attached to a hose which in turn leads to a bucket or like receptacle located a short distance away. When the epoxy grout material starts coming out of this outlet tube, the operator knows that the space between the PVC liner and the sewer line to be repaired has all of the air and residual waste water removed and has been filled with grout and the pumping can be stopped.

Laterals or lines extending to or outward from a main conduit to be repaired are lined by cutting an opening in the main conduit wall slightly smaller than the size of the lateral conduit, and rolling a piece of PVC sheeting into a cylindrical shape extending about 10 to 15 inches into the lateral pipe. The seam between the opening in the large pipe and small pipe is held in placed and sealed by application of an adhesive or through the use of plastic welding techniques. The sleeve portion that extends into the liner is trimmed even with the inner wall of the liner.

The method of the invention may be used more generally to form solid plastic resin objects, by forming a hollow object with walls at least partially formed of polyvinyl chloride (PVC) sheet, priming the interior surfaces of the PVC sheet, filling the object with a settable liquid epoxy composition containing Class C fly ash, and allowing the composition to cure and form the solid resin object.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood with reference to the following drawing figures, in which:

Figure 1 shows a side elevational view of a length of sewer line under repair illustrating, in somewhat exaggerated form, the disposition of a normal sewer at a very slight angle to the horizontal;

Figure 2 shows a perspective view of the end of the sewer after the inner surface is cleaned and prepared, with the longitudinal, perforated rectangular tubing fastened in place;

Figure 3 shows the view of Figure 2 with the longitudinal strips of plastic sheeting having their adjacent edge portions anchored to the tubing by adhesive or a plastic welding technique; Figures 4 and 5 are lateral cross sectional views of the sewer along line 4-4 of Figure 1, Figure 4 showing by arrows where the liquid settable plastic is to be injected initially, and Figure 5 showing where the liquid plastic is injected after completing the injection and filling of the tubing and adjacent spaces between the tubes from the positions shown in Figure 4; Figures 6 and 7 are perspective views depicting the configuration of the rectangular tubing shown in the above figures;

Figure 8 is an end view of the bottom portion of a sewer line ready for repair, with tubing and sheets in place;

Figure 9 is a perspective view of a rectangular to round fitting for connection to the tubing in Figure 8;

Figure 10 illustrates an outlet hose system through a rectangular to round fitting located at the uppermost portion of the segment of the assembly depicted in the above Figures where the liquid plastic is introduced through the lower end portions;

Figure 11 and 12 depict a modified structure for extending the sewer liner to "laterals" or smaller sewer conduits through which sewage enters the main sewer, with Figure 11 in longitudinal cross-section and Figure 12 in lateral cross-section;

Figure 13 illustrates an alternate form of the rectangular tubing/connecting plastic sheet assembly where a single piece of extruded plastic can be snapped together to form the aforementioned assembly with the base portions which form the rectangular tubing fastened to the inner surface of the sewer; and Figure 14 depicts a form of rectangular tube construction having a bottom channel with a snap-on top. DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the figures, the steps involved in carrying out the invention include (1) assemblage of a cavity system, (2) preparation of a suitable mixture of liquid resin with selected fillers, and (3) sequential filling of the cavity with the resin-filler mixture.

(1) Assemblage of the Cavity System

Fig. 1 shows a section of sewer line 10 to be repaired which is inclined at an angle of about 1°, having an upper end 11 and a lower end 12. The repair commences from the upper end 11 to facilitate the latter stages of the process when the settable liquid is introduced so that gravity causes the lower end 12 to fill up first beginning at the bottom portion, extending around the sides and gradually filling the system from the bottom of lower end 12 to the top of the upper end 11, the repair structure then being filled with settable liquid plastic. The processing steps of the invention are applied sequentially to selected lengths of sewer line or tunnel ranging usually from 50 to 300 feet.

Fig. 2 shows the first step in the mechanical application which follows cleaning of the inside of the sewer line, as set forth above. Rectangular tubing sections 13 with slots 19, also shown in Figs. 6 and 7, are mounted longitudinally inside the sewer 10 utilizing metal anchors or fasteners 14. Alternatively, the tubing sections may be adhered with an adhesive; this is discussed further with regard to Fig. 14. The longitudinally mounted rectangular tubes are placed a preselected distance apart circumferentially, such as 2 feet apart, and parallel to each other. Preferably, the rectangular tubes are spaced around the entire circumference of the sewer, as shown in Fig. 2, and along the entire length of the repair. After the tubes are in place, primed vinyl sheets, typically 2 feet wide by about 8 to 15 feet long, are fixed with their edges abutting one another against the rectangular tubes by means of a plastic adhesive, welding or the like. Fig. 3 illustrates the plastic sheeting 15 in the form of strips forming a lining of the sewer mounted on the rectangular tubing 13. These strips, as well as the rectangular tubing, are covered with a primer, the plastic strips being coated on the side toward the sewer. Fig. 3 shows the uppermost plastic liner strip 15 without the last and uppermost strip being in place. This is done to accommodate variances between the inside circumference of the tunnel and the aggregate widths of all of the plastic strips. Since it is common not to end up with the preset widths of strips 15 mounted on rectangular tubes 13 to exactly fill the aggregate spaces between all rectangular tubes 13, the opening between the uppermost rectangular tubes is initially left open, shown a-s gap 16. In this event, the gap 16 is covered by application of a last or filler strip 17 which is applied to the outside of the plastic lining formed on either side of the gap 16. Alternatively, this last plastic strip to fill gap 16 can be trimmed to a narrower width and adhered directly to rectangular tubes 13 on either side of the gap 16 in the sheet liner 15. Subsequently, the seams and unwanted openings of the plastic tube are sealed by hot air welding and/or a suitable sealant to prevent the liquid epoxy from leaking out prior to setting. In this manner, a cavity is formed between the vinyl tube and the conduit or sewer pipe and forms a provision for later receiving the epoxy-filler mixture .

Experiments using a variety of materials and physical spacing have been conducted. The results show that a spacing of approximately 3/4 inch works satisfactorily, and PVC is a superior sheeting material for sewer conduit pipes on account of its greater resistance to corrosive sewer elements such as sulfides and sulfuric acid.

In order that the vinyl sheet inner portion of the repaired conduit and the cured resin form a single unit, a primer is used, one preferred composition comprising essentially an approximately 4% (by volume) solution of 1, 6-hexamethylene diisocyante polymer in a solvent mixture of xylene and methyl istobutyl ketone. By applying such a prJmer onto the vinyl surfaces which will be in contact with the epoxy resins, the vinyl sheets will adhere rigidly to the cured epoxy, forming a very strong unitary inner tubular structure having, per se, a structural strength in resisting crushing and the like comparable to the original conduit pipes or tunnels.

The vapors from these primers constitute only a moderate toxic hazard. In the instant process, however, additional safety can be afforded by applying the primer up to one month in advance in a controlled setting, e.g., within a factory plant.

(2) Preparation of a suitable mixture of liquid resin with selected fillers

Paradoxically, the relatively low melting, forming, and softening temperatures of PVC offer both the advantage of easier field operations (easier to weld by the hot air technique) , and the difficulty of having to limit the temperature increase as the result of the exothermic setting process. It has been found that the curing temperature of settable resins such as polyester or vinyl esters as so high they will melt or distort sheet vinyl. Even use of epoxy resins generate sufficient heat to weaken or distort vinyl sheet materials which can be below 100° F. Applicant's epoxy system described herein controls or neutralizes the effects of the curing to create a strong bond and combination of the sheet and liquid resins . Since the heat generated in a curing process is caused essentially only by the number of chemical bonds produced, whereas the temperature increase is a function of both the amount of heat generated and the heat capacity of the system, part of the solution is to increase the heat capacity through use of inert fillers.

The use of several resins was investigated. It was found that polyesters and vinyl epoxy resins, though settable, can not be used on account of the high temperatures reached during the curing process (both with and without fillers) and the consequent destruction of the integrity of the vinyl sheet cavity. Epoxy resins such as described herein, on the other hand, work satisfactorily when used with the fillers which have been discovered in the instant invention. In general, several criteria must be considered. The filler selected should be compatible with the epoxy resin both during the setting process and to from the viewpoint of the mechanical strength of the final product. The filler and resin must have comparable densities as otherwise the filler will quickly separate from the liquid resin. From a practical point of view, it should be inexpensive. Most importantly, however, the filler must not impede the flow of the liquid plastic resin during filling because the epoxy/filler combination has to pass through relatively small convoluted openings for relatively long distances.

It was found during the instant development that a number of particulate fillers such as silica powder and certain types of fly ash can lower sufficiently the peak curing temperature of the pure epoxy resins so as not to affect in an untoward manner a repair work using the vinyl sheet tube. Silica powder was found to be unsatisfactory, however, because a mixture of liquid epoxy resin and silica has a reduced pumpability and blockages are created when such a mixture reaches a point of restrict flow. As a result of such restricted flow, in turn, a greater pumping pressure becomes required, additional heat is generated, the flow of the liquid mixture is further impeded, and the heat causes accelerated curing and consequent blockage in the cavity system. The important requirement of high product quality through the uniformity of thickness (through uniform resin distribution and the removal of possible entrapped air and/or waste water) becomes unattainable. Unfortunately, literature offers little guidance correlating the properties and composition of resin and fillers. The whole subject is considered perhaps more of an art rather than science. No mathematical formula appears to exist, and the development for each type of mixtures is a new research. _ It was found during the course of this invention that fly ashes falling under the ASTM designation Class C can be used successfully as a filler for this instant process, and that fly ashes of the ASTM Class F type may also be used, although to a much more limited extent. Fly ashes having an average particle size of 10 microns or smaller work particularly well, although large particle sizes can also be used. Class C and Class F fly ashes have the following approximate compositions (wt%):

From the view point of simplicity and ease in field operations, preparation of the resin-fly ash mixture by volume would be superior to by weight, provided that the operational range of such a mixture offers a reasonable tolerance. With such an objective in view, it was found that satisfactory conduit pipe repairs can be made by using mixtures containing between approximately 20% to 65% by unpacked volume of fly ash, although mixtures having a fly ash content outside this range still lead to a useable product depending on the nature of the cavity and its resistance to pumping.

(3) Sequential filling of the cavity with the resin-filler mixture

In repairing a sewer conduit pipe, it is advantageous to be able to remove waste water and trapped air from the cavity being filled. Trapped air is created by making and sealing the cavity and trapped waste water comes in through the open laterals. Removal of air and wastewater in the cavity to be filled is achieved by sequential filling.

In the preferred embodiment, the exposed ends 18, as shown in Fig. 4, of the rectangular tubes 13 are exposed to the portion of the repair where the epoxy mixture is to be introduced. The job is initially set up so that these exposed ends will be the upper ends 11 of the downwardly sloping segment of the sewer line on tunnel 10 under repair. These open ends of the rectangular tube are then plugged with a temporary rectangular tube to round fittings 38 shown in Fig. 8 with the round part receiving the tubes 37 from the pumped source of the epoxy resin mixture. The lower end 12 of the cavity between the vinyl inner sheet structure and the sewer line to be repaired is sealed with epoxy putty. Any opening between the ends, including the lateral fittings, are sealed with epoxy putty or welded so as to prevent leakage of the liquid resin-filler mixture prior to setting.

In the preferred embodiment, filling is started by connecting the pump (or pumps) to the end of the rectangular tube in the bottom-most position 20, as shown in Fig. 9, and then the next high pair of rectangular tubes 13. The connection between the pump and the tubing is made via a "rectangular to round" fitting 38, as shown in Fig. 8. The fitting 38 includes a round end 41 for connection to a hose 37 connected to the pump, and a rectangular end 39 for connection to the tubes 13.

The liquid resin-filler mixture is pumped into tubes 13, passing downwardly and away from the pumping area through the rectangular tubes to the end of the rectangular tubes 13 at the far end 12 of the segment of the sewer line being repaired up to approximately 50 feet in length. As the liquid mixture is pumped through the rectangular tubes, it will simultaneously spread through the side holes or slots 19 in the rectangular tubes 13 to the space between the rectangular tubes which are, in turn, between the interior of the vinyl liner and the inner surface of the conduit pipe or sewer pipe under repair. The bottom-most portion of these cavities will then be filled until the level of the resin-filler mixture reaches the next highest pair of inlet points of tubes 13. The outlet tubes from the pumping source of the resin- filler mixture are then raised to the next higher pair of tubes 13 and the same type of filling action continues. Again the liquid mixture will enter circumferentially around the cavity to be filled until the liquid reaches the level of the next (now third) highest pair of inlet tubes. By repeating this process sequentially in as many steps as necessary, the uppermost fill tubes 21 shown in Fig. 5 will be reached at the upper wall end 11, an air cavity will remain atop the cavity, and any waste water which was in the lower portion of the cavity will have been pushed upward into the air cavity.

The last fill of the uppermost pair of tubes will first extend away from the inlet point to the far end of the segment being repaired (Fig. 10). The air cavity will then begin to be filled from the far side to the near side as air and waste water are moved toward the input end 11. To capture the excess resin-filler mixture and any waste water, an exhaust tube 24 which can be a rectangular to round fitting 38 or a tube and a bucket is incorporated to the very top of the cavity of the input end 11. The appearance of the excess resin-filler mixture out of the exhaust tube will serve as an indicator that all air and waste water have been removed from the cavity, and that t e latter is filled with the resin-filler mixture. At this point, the resin is allowed to cure for approximately half an hour. Since each filling is built upon a preceding lower level, it is not critical that some of the lowest portion of the epoxy has begun to cure. Upon completion of the filling, the next length of the conduit pipe or tunnel is then prepared, with the filling end at the higher portion of the sloped tunnel to be repaired, and the process repeated.

It is to be noted that, contrasted to some prior art, the instant invention requires the connection of the laterals when the cavity forming vinyl sheet structure is in place before filling. As shown in Figs. 11 and 12, a hole is cut by an operator where the lateral 22 has been going into the old sewer line 10, the site where waste water may very likely enter into the space between the vinyl liner and the original walls of the conduit pipe or sewer line. The operator runs a piece of a tube of vinyl sheet into the lateral, a convenient distance perhaps, half a meter, welds the tube lining the lateral opening to the vinyl sheet lining the main sewer repair. The outer end of this lateral liner is sealed with epoxy putty sealant. Any waste water that entered the main cavity before sealing is picked up and injected upward, then outward through the exhaust tube during the above mentioned process of filling the main cavity with the settable liquid epoxy.

Fig. 13 shows an alternate form of rectangular tubing structure 24 including a channel base element having a bottom segment 26 and an upstanding sidewall 27. This channel shaped segment can be fastened to the cleaned surface of the inside of the sewer line using anchors in a manner similar to fastening rectangular tubes 13 as shown in Fig. 2. The sides of the channel have openings 28 similar to the openings 19 in Figs. 6 and 7 to allow flowing of settable resin. The channel 26 is converted to a rectangular tube by adding a cover 29 which is affixed to the channel by means of snap-on fittings 30. This structure functions similarly to rectangular tubing 13 by allowing the settable resin under pressure to spread out through the openings 28 which are openings defined by the inner wall of the sewer, the plastic sheet to which the now rectangular tube 24 is fastened and the adjacent parallel tube of the same description.

Fig. 14 is a second alternative unitary system combining the functions of the rectangular tubes and the plastic sheeting connecting them. It consists of a channel-like segment 31 having a base 32 which is fastened to the inside of the sewer to be repaired by adhesive 33 or a metal fastener 14. The sidewalls 27 of the channel portion 31 have mating snap-on fittings 30 and 34 which when snapped together form a rectangular tube which can function similarly to the device shown in Fig. 13, tubes 13 in Fig. 2 and openings 19 in Figs. 6 and 7. The center section of the integral tube and plastic sheeting assembly is a plastic sheeting element 35 which connects the cap- forming edge of the assembly 36 with the rectangular tube base assembly forming element 37.

These unitary rectangular tube and plastic sheet forming assemblies can be inserted in the sewer to be repaired, the bases fastened to the inner surface of the sewer by anchors or screws similar to those used to anchor the rectangular tubes in Figs. 2-5, and successively snapped together edge to edge to line the sewer line with settable plastic receiving chambers.

As indicated above, where the width of these integral rectangular tube forming/plastic sheet assemblies do not closely match the circumference of the inner surface of the sewer to be repaired, these assemblies should be put in place with an opening left at the top which can be closed by covering with a strip of plastic sheeting wide enough to cover the opening and which is held in place by an adhesive or plastic welding. Alternatively, the opening can be covered with a piece of the assembly shown in Fig. 14 slit lengthwise down the middle with the mid- portions of the plastic sheeting portions overlapping and fastened together by use of adhesive or plastic welding techniques .

_ The instant invention offers a number of advantages over the prior art. First, the repaired liner offers structural integrity because it will be a single rigid unit which is fixed within the conduit pipe or tunnel being repaired. The added repair portion is the epoxy liquid when cured is literally molded to the inner surface of the conduit under repair and thus conforms to every projection or cavity which existed in the original structure. Further, through the use of metal fasteners which went through the rectangular vinyl tube portion into the concrete or masonry that sewer pipe being repaired, the finished plastic liner is locked into place preventing or strongly resisting longitudinal movement of the repair in the sewer lines or conduit.

Claims

WHAT IS CLAIMED IS:

1. A method for repairing a length of a conduit having a circumferential inner surface, comprising the steps of: anchoring to the inner surface in a direction generally parallel to the length a plurality of sections of tubing of generally rectangular cross-section spaced entirely around the conduit in the circumferential direction along the entire length of the repairing, said tubing having a plurality of openings in a direction parallel to the circumferential direction; anchoring to the tubing on a surface thereof opposite to a surface of the tubing anchored to the inner surface of the conduit a plurality of strips of plastic sheeting, said strips of plastic sheeting extending circumferentially around the conduit along the length of the repair, defining thereby a space between the plastic sheeting and the inner surface, said plastic sheeting being primed on a surface thereof facing the inner surface of the conduit, and the strips being sealed together along adjacent edges thereof to form thereby a lining around the circumferential inner surface; sealing a first end of each of the plurality of sections of tubing and adjacent space between the sheeting and the conduit; pumping into a second end of a plurality of sections of tubing a settable liquid plastic composition, which exits through said openings and fills said space; and - curing said settable liquid plastic composition, thereby repairing said conduit.

2. The method of claim 1, wherein the step of pumping is performed by pumping the settable liquid plastic composition into a first pair of sections of tubing disposed at a lowest point of the second end until the pair of sections and adjacent space is filled, then pumping into a next higher pair of sections of tubing until the pair of sections and adjacent space is filled, and sequentially pumping into a next higher pair of sections of tubing until all sections of tubing and adjacent spaces are filled.

3. The method of claim 2, wherein the conduit is inclined, and the first end is the lower end.

4. The method of claim 1, wherein the plastic sheeting is polyvinyl chloride sheeting.

5. The method of claim 4, wherein the strips are sealed together by hot air welding.

6. The method of claim 4, wherein the strips are sealed together using a sealant.

7. The method of claim 1, wherein the settable liquid plastic composition comprises an epoxy resin.

8. The method of claim 7, wherein the settable liquid plastic composition additionally comprises a filler .

9. The method of claim 8, wherein the filler is Class C or Class F fly ash.

10. The method of claim 8, wherein the filler is present in an amount of 20 to 65% by volume.

11. The method of claim 9, wherein fly ash is admixed into the settable liquid plastic composition prior to said pumping.

12. The method of claim 9, wherein said fly ash contains oxides of calcium, magnesium, aluminum, silicon and iron.

13. The method of claim 9, wherein the fly ash has a weight-averaged particle size of less than 50 microns.

14. The method of claim 1, wherein anchoring of the plurality of strips of plastic sheeting is performed by sequentially adhering to the tubing a strips of plastic sheeting starting from adjacent side and bottom portions of the inner surface, and a final strip of sheeting is cut to a remaining width and adhered adjacent to a top portion of the inner surface.

15. The method of claim 1, wherein each of said strips of plastic sheeting is formed in a unitary manner with a portion of at least one of said sections of tubing, and anchoring said strips to the tubing completes the formation of the tubing.

16. The method of claim 2, additionally comprising connecting an exhaust line to an uppermost section of tubing to, and removing air, water and excess settable Liquid plastic therethrough.

17. A method for repairing sewers or like conduits wherein the conduit to be repaired has one end lower than the other end, comprising the steps of: selecting a segment of conduit to be repaired; forming a cavity within the conduit to be repaired using longitudinally disposed hollow support means holding a plastic sheet in a spaced relationship from the inner surface of the conduit to be repaired, said longitudinal hollow support means having openings permitting settable plastic to flow between the longitudinal hollow tubes throughout the cavity; sealing the end of the support means and the openings in the cavity between the plastic sheeting and the conduit at the lower end; sealing the cavity between the conduit and the sheet plastic means at the upper end leaving the ends of the hollow support means exposed; fixing an exhaust tube for exhausting air and waste water from the cavity, said exhaust tube located at an uppermost portion of the cavity at the higher end of the conduit portion to be repaired; and filling the cavity with a liquid settable plastic resin from the lower portion of said higher end to the upper portion until settable plastic reaches the exhaust tube;

— said filling comprising sequentially filling opposing pairs of longitudinal hollow support tubes in the cavity from bottom to top of the conduit.

18. The method of Claim 17, wherein the longitudinally disposed hollow support means holds a polyvinyl chloride plastic sheet in a spaced relationship from the inner surface of the conduit to be repaired.

19. The method of claim 17, wherein the hollow support means holds a polyvinyl chloride plastic sheet in a spaced relationship from the inner surface of the conduit to be repaired, said longitudinal hollow support means having openings permitting settable liquid plastic composition to flow between the longitudinal hollow tubes throughout the cavity, sealing the end of the support means and the openings in the cavity between the plastic sheeting and the conduit at the lower end, the cavity between the conduit and the sheet plastic means is sealed at the upper end leaving the ends of the hollow support means exposed, an exhaust tube is fixed for exhausting air and waste water from the cavity, said exhaust tube located at the uppermost portion of the cavity at the higher end, and the liquid settable plastic composition comprises an epoxy resin.

20. The method of Claim 17, wherein the settable liquid plastic resin composition contains about 20-65% by volume of a filler comprising Class C fly ash.

21. A method of forming solid plastic resin objects comprising the steps of: a) forming a hollow object having walls at least partially formed of polyvinyl chloride sheet plastic; b) applying a primer to the polyvinyl chloride sheet plastic on an inner surface of the object; c) filling the hollow object with a settable liquid epoxy resin composition containing Class C fly ash; and d) allowing the settable liquid epoxy resin composition to cure to form a solid plastic resin object.

22. The method of claim 21, wherein the primer comprises an isocyanate and a co-reactant polymer.

23. The method of Claim 21, wherein the Class C fly ash is present in the settable liquid epoxy resin composition in an amount of 20 to 65% by volume.

24. A method for repairing a length of a conduit having a circumferential inner surface, comprising the steps of: a) anchoring to the inner surface in a direction parallel to the length a plurality of sections of tubing of generally rectangular cross-section spaced around the conduit in the circumferential direction, each of said sections of tubing having therein a plurality of openings in a direction parallel to the circumferential direction; b) anchoring to the tubing on a surface thereof opposite to a surface of the tubing anchored to the inner surface a plurality of strips of plastic sheeting, said strips of plastic sheeting extending circumferentially around the conduit along the length of the repair, defining thereby a space between the plastic sheeting and the inner surface, said plastic sheeting being primed on a surface thereof facing the inner surface of the conduit, said anchoring of strips starting adjacent bottom and side portions of the inner surface and concluding by cutting a final strip of sheeting to a remaining width and anchoring adjacent a top portion of the inner surface; c) sealing a first end of each of the plurality of sections of tubing and adjacent space between the sheeting and the conduit; d) pumping into a second end of a plurality of sections of tubing a settable liquid plastic, which exits through said openings and fills said space; and e) curing said settable liquid plastic, thereby repairing said conduit.

25. A method according to claim 24, wherein the settable liquid plastic comprises an epoxy grout.

26. A method according to claim 24, additionally comprising cleaning the inner surface prior to said anchoring to the inner surface.

27. A method according to claim 26, wherein the inner surface is cleaned by exposing to high pressure water.

28. A method according to claim 24, wherein said anchoring to the tubing is performed with adhesive or by welding.

29. A method according to claim 24, wherein one of the plurality of sections of tubing, disposed adjacent a top portion of the inner surface, is connected at said second end to an open container, the method additionally comprising terminating said pumping after said settable liquid plastic exits into said container, indicating completion of filling of said space.

30. A method according to claim 24, wherein the conduit comprises an additional conduit perpendicular to the conduit, the method additionally comprising forming a tube from plastic material, cutting a hole in the strips of plastic sheeting adjacent the additional conduit, inserting the tube through the hole into the additional conduit, cutting off any excess plastic material extending into the conduit and sealing the plastic material to the strips of plastic sheeting.

31. A method according to claim 24, wherein each of said strips of plastic sheeting is formed in a unitary manner with a portion of at least one of said sections of tubing, and said step of anchoring to the tubing completes formation of the tubing.

32. A method for repairing a length of a conduit having a circumferential inner surface, comprising the steps of: a) anchoring to the inner surface in a direction parallel to the length a plurality of sections of tubing of generally rectangular cross-section spaced around the conduit in the circumferential direction, each of said sections of tubing having therein a plurality of openings in a direction parallel to the circumferential direction; b) anchoring to the tubing on a surface thereof opposite to a surface of the tubing anchored to the inner surface a plurality of strips of plastic sheeting, said strips of plastic sheeting extending circumferentially around the conduit along the length of the repair, defining thereby a space between the plastic sheeting and the inner surface, said plastic sheeting being primed on a surface thereof facing the inner surface of the conduit; c) sealing a first end of each of the plurality of sections of tubing and adjacent space between the sheeting and the conduit; d) pumping into a second end of a plurality of sections of tubing a settable liquid plastic, which exits through said openings and fills said space; and e) curing said settable liquid plastic, thereby repairing said conduit, wherein each of said strips of plastic sheeting is formed in a unitary manner with a portion of at least one σf said sections of tubing, and said step of anchoring to the tubing completes formation of the tubing.

33. A method according to claim 32, wherein the settable liquid plastic comprises an epoxy grout.

34. A method according to claim 32, additionally comprising cleaning the inner surface prior to said anchoring to the inner surface.

35. A method according to claim 32, wherein the inner surface is cleaned by exposing to high pressure water .

36. A method according to claim 32, wherein said anchoring to the tubing is performed with adhesive or by welding.

37. A method according to claim 32, wherein one of the plurality of sections of tubing, disposed adjacent a top portion of the inner surface, is connected at said second end to an open container, the method additionally comprising terminating said pumping after said settable liquid plastic exits into said container, indicating completion of filling of said space.

38. A method according to claim 32, wherein the conduit comprises an additional conduit perpendicular to the conduit, the method additionally comprising forming a tube from plastic material, cutting a hole in the strips of plastic sheeting adjacent the additional conduit, inserting the tube through the hole into the additional conduit, cutting off any excess plastic material extending into the conduit and sealing the plastic material to the strips of plastic sheeting.