Abstract:
A multi-layer liner system for application to a substrate, comprising a primer layer, a first moisture barrier layer, the first moisture barrier layer being impervious to moisture, a second moisture barrier layer, a foam layer, the foam layer being sandwiched between the first moisture barrier layer and the second moisture barrier layer, and an anchor assembly extending outwardly from the substrate into the multi-layer liner.

Description:
CLAIM OF PRIORITY 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 62/048,868 filed Sep. 11, 2014, and U.S. Provisional Patent Application No. 62/075,475 filed Nov. 5, 2014, the entire disclosures which are incorporated herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to waste water systems. More particularly, the present invention relates to an anchored multi-layer liner system for use in the rehabilitation or repair of waste water system components such as manholes, sewer pipes, lift stations, etc. 
       BACKGROUND OF THE INVENTION 
       [0003]    Deterioration of waste water system components is a severe and growing problem. Originally built of brick, block or concrete construction, these components develop leaks, cracks and holes due to age, erosion, corrosion and ground water intrusion. Leakage from old manholes and sewer lines contaminates the environment and sometimes result in catastrophic damage with respect to clean-up and repair costs. 
         [0004]    Since the cost of repairing the components is typically much less than the cost of replacement, many techniques have been developed to repair and rehabilitate waste water system components. For example, it is known to recast manholes and the like through the use of forms and poured concrete, such as shown in U.S. Pat. No. 5,032,197 to Trimble. Because this process is very labor intensive, many techniques are directed toward spray-applied liners. For example, U.S. Pat. No. 5,002,438 to Strong teaches the use of sprayed cement to form a liner inside the deteriorating structure. Spray-applied epoxy, acrylic or polyurethane liners are also known, as is the use of resin impregnated substrates, such as felt, as taught in U.S. Pat. No. 5,017,258 to Brown et al. 
         [0005]    Note, however, it is not uncommon for current spray-applied systems to suffer from moisture, delamination, shrinkage and structural weakness problems resulting from the typical environment encountered in the repair operation. Moreover, in various instances, it is known for portions of existing liner systems to become separated from the substrate to which they are applied, especially where water intrusion can be expected, accompanied by the subsequent build up of hydrostatic pressure. The joints between pre-cast sections of various waste water components, such as manholes, are known to cause such damage to liners. 
         [0006]    The present invention recognizes and addresses considerations of prior art constructions and methods. 
       SUMMARY OF THE INVENTION 
       [0007]    One embodiment of multi-layer liner system for application to a substrate includes a primer layer, a first moisture barrier layer, the first moisture barrier layer being impervious to moisture, a second moisture barrier layer, a foam layer, the foam layer being sandwiched between the first moisture barrier layer and the second moisture barrier layer, and an anchor assembly extending outwardly from the substrate into the multi-layer liner. 
         [0008]    Another embodiment of a multi-layered liner system is a method of applying a multi-layer liner system to a substrate, including the steps of applying a primer layer, applying a first moisture barrier layer to the primer layer, the first moisture barrier layer being impervious to moisture, applying a foam layer to the first moisture barrier layer, applying a second moisture barrier layer to the foam layer so that the foam layer is sandwiched between the first moisture barrier layer and the second moisture barrier layer, and attaching an anchor assembly to the substrate so that the anchor assembly extends outwardly from the substrate into the multi-layer liner. 
         [0009]    Yet another embodiment of a multi-layered liner system for application to a substrate includes a foam layer, the foam layer being applied to the substrate, a first moisture barrier layer, the first moisture barrier layer being impervious to moisture and disposed on an outer surface of the foam layer, and an anchor assembly including a first portion disposed within the substrate and a second portion extending outwardly from the substrate into the foam layer so that the second portion is embedded in the foam layer. 
         [0010]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended drawings, in which: 
           [0012]      FIG. 1A  is a perspective cross-sectional view of a portion of an embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0013]      FIG. 1B  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0014]      FIG. 1C  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0015]      FIG. 1D  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0016]      FIG. 2A  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0017]      FIG. 2B  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0018]      FIG. 2C  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0019]      FIG. 3A  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0020]      FIG. 3B  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0021]      FIG. 3C  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0022]      FIG. 4  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0023]      FIG. 5  is a perspective cross-sectional view of a portion of an alternate embodiment of an anchored multi-layer liner system, applied to a waste water system component, in accordance with the present invention; 
           [0024]      FIG. 6A  is a cross-sectional view of a manhole constructed of pre-cast components; and 
           [0025]      FIG. 6B  is a cross-sectional view of the manhole as shown in  FIG. 6A , further including a partial application of the anchored multi-layer liner system shown in  FIG. 4 . 
       
    
    
       [0026]    Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention according to the disclosure. 
       DETAILED DESCRIPTION 
       [0027]    Reference will now be made in detail to presently preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation, not limitation, of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope and spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
         [0028]    As illustrated by the sectional depiction in  FIG. 1A , an embodiment of the present invention comprises a multi-layer liner  10  applied to a concrete, brick, block, metal or the like substrate  20 , and further secured thereto by an anchor system  30 . Typically, the substrate  20  will be a deteriorated manhole or sewer pipe having an irregular surface with cracks or holes. The liner  10  comprises a primer layer  11 , a first moisture barrier layer  12 , a foam layer  13 , and a second moisture barrier layer  14 . Preferably, the liner  10  is applied so as to cover the entire internal surface of the substrate  20 , which is usually generally tubular in configuration, although any shape or configuration is possible and the technique is applicable without regard to the particular shape of the substrate  20 . 
         [0029]    The substrate  20  surface is initially prepared using high pressure water or abrasive sand blasting to remove all hard contaminants, any micro-organisms or living matter such as mold, mildew, etc., and any loose degraded materials of the substrate itself. This abrading step results in a clean surface with an optimized surface for adhesion of the liner  20 . Next the primer layer  11  is spray-applied using conventional compressed air spraying devices. The primer layer is a material capable of adhering to the substrate  20  even if wet, and is preferably an epoxy material. The primer layer  11  is applied to a necessary thickness to insure adhesion of the first moisture barrier  12  to the substrate  20 , and is generally applied to a dry film thickness between 2 and 10 mils, and preferably at a thickness of approximately 5 mils. The primer layer  12  is coated over the entire surface to be repaired. 
         [0030]    The next step is to spray-apply, again using conventional techniques, the first moisture barrier layer  12  onto the primer layer  11 . The first moisture barrier layer  12  is preferably composed of a polymer blend of separate components which are mixed as they exit the spray nozzle, the components reacting to form a hard material upon curing. Preferably, a blend of a polyurea component and an isocyanate component is utilized, with the two components formulated to have similar viscosities. The first moisture barrier layer  12  is applied to a dry film thickness of preferably between 40 to 80 mils, and even more preferably at a thickness of 60 mils. The material used for the first moisture barrier should have a gel time of less than a few seconds and preferably less than 3 seconds, with total cure time of less than 60 seconds and preferably less than 30 seconds, and have minimal shrinkage during curing. This rapid cure is necessary to insure integrity of the first moisture barrier  12  even when applied under non-optimum conditions. The preferred polyurea and isocyanate blend has a tensile strength of greater than 1500 psi, an elongation percentage of 125%, tear strength of 350 psi, a shore D hardness of 55 and an 100% modulus of greater than 1500. The first moisture barrier layer  12  is impermeable to water and other fluids and is a structurally rigid layer adhered to the substrate  20  so as to remain adhered under pull test conditions of greater than 300 psi. The first moisture barrier layer  12  is applied to completely cover the primer layer  11 . 
         [0031]    In the embodiment shown in  FIG. 1A , the next step is to install the anchor system  30  to the substrate  20  prior to applying the foam layer  13 . In this manner, the portion of the anchor system extending outwardly from the substrate  20  will be fully embedded in the foam layer  13 , thereby providing a resistive force to any forces that may tend to cause multi-layer liner  10  to separate from the substrate  20 , such as, but not limited to, hydrostatic pressure due to water intrusion. As shown, anchor system  30  includes a plurality of elongated anchor plates  34  (only one is shown) that are each secured to the substrate  20  by one or more fasteners. In the instant case, the fasteners being used comprise a plurality of threaded bolts  31  and correspondingly threaded nuts  33 . 
         [0032]    After a suitable number of anchor plates  34  have been installed, the next step is to spray-apply, again using conventional techniques, a foam layer  13 . The foam layer  13  is preferably composed of a polyurethane blend which rapidly foams and cures upon exiting the spray nozzle of the application equipment. Preferably, the foam material is primarily closed cell and has a rise time of less than 30 seconds and preferably less than 10 seconds. The foam layer  13  is applied preferably to result in a dry thickness of at least 500 mils, although the foam layer  13  can be thicker overall or in selected areas if necessary. The foam layer  13  as applied creates a smoother inner surface, its bulk filling any holes, depressions or cracks in the substrate  20  surface. Additionally, the foam layer  13  encapsulates the exposed anchor plates  34  and associated fasteners, bolts  31  and nuts  33 , so that the anchor system  30  provides a plurality of points at which adhesion of the foam layer  13  to the substrate  20  is enhanced. The foam layer  13  preferably has a density of between 4.5 to 5.5 pounds per cubic foot, a compressive strength of between 105 to 110 psi, a closed cell content of over 90 percent, and shear strength of between 225 to 250 psi. As with the other layers, the foam layer  13  is applied over the entire previous layer. 
         [0033]    Finally, the second moisture barrier layer  14 , preferably composed of the same material as the first moisture barrier layer  12 , is spray-applied over the entire surface of foam layer  13 . Preferably, the second moisture barrier layer  14  is also applied to a dry film thickness of between 40 and 80 mils, and even more preferably to a thickness of approximately 60 mils. If necessary due to circumstances, greater thicknesses of first moisture barrier layer  12  and second moisture barrier layer  14  may be utilized. 
         [0034]    The resulting anchored multi-layer liner  10  is a water impermeable barrier strongly adhered to the substrate  20 , via its own adhesive properties as well as the anchor system  30 , which prevents liquids from leaking out of the waste water system and also prevents ground water from entering the system. More importantly in terms of longevity, the liner  10  is a structural member which strengthens the components of the waste water system no matter to what extent they have deteriorated. Previously used water impermeable liners, whether composed of epoxy, acrylic, polyurethane or resin impregnated substrates, are not strongly adhered to the substrate and tend to delaminate over time. These typical liners do not reinforce or impart any structural strength to the system components. The multi-layer liner  10  of the invention not only creates a liquid barrier, it adds to the strength of the waste water system components by providing a reinforcing member which is structurally rigid due to its multi-layer composition. The liner  10  is a stressed skin panel, comprised of a structurally rigid foam internal layer  13  bounded by two adhered surface layers, first moisture barrier layer  12  and second moisture barrier layer  14 , which are under stress due to the rapid cure rate of the material when applied. This rapid cure time does not allow internal stresses created by the small amount of shrinkage during curing to be relaxed, as occurs in sprayed films with long cure times. The principles of stressed skin panels, well known in the construction industry for walls of large buildings, provide for a structural member with increased structural strength and integrity of multiple factors beyond that of the individual components taken separately. Thus, the combination of the stressed skin panel created by the multi-layer combination of first moisture barrier layer  12 , foam internal layer  13  and second moisture barrier layer  14  adhered to the waste water system component results in a repaired component with exceptional structural characteristics due to the reinforcing properties of the liner  10 , and is a vastly improved system over those in use today. 
         [0035]    Referring now to  FIG. 1B , an alternate embodiment of the anchored multi-layer liner  10  includes, similarly to the first embodiment, a plurality of anchor plates  34  that are secured to substrate  20  by way of bolts  31  and nuts  33 . Additionally, other fasteners may be used such as powder activated fasteners  40 ,  42  ( FIG. 4 ). Note, however, that this embodiment differs from the first embodiment shown in  FIG. 1A  in that each anchor plate  34  is disposed between foam layer  13  and second moisture barrier layer  14  rather than in the foam layer  13 . As shown in  FIG. 1C , anchor plate  34  is disposed on top of second moisture barrier layer  14 . As shown in  FIG. 1D . anchor plate  34  is encapsulated by first moisture barrier layer  12 . 
         [0036]    The embodiment shown in  FIG. 2A  is similar to that of  FIG. 1A . with the exception that, the anchored multi-layer liner  10  does not include first moisture barrier layer  12 , The embodiment shown in  FIG. 2B  is similar to that of  FIG. 1B  with the exception that anchored multi-layer liner  10  does not include first moisture barrier layer  12 . The embodiment shown in  FIG. 2C  is similar to that of  FIG. 1C  with the exception that anchored multi-layer liner  10  does not include first moisture barrier layer  12 . 
         [0037]    The embodiments shown in  FIGS. 3A through 3C  are similar to those shown in  FIGS. 2A through 2C , with the exception that primer layer  11  has been replaced with a layer of cementitious material  21  that is sprayed on substrate  20  as described in U.S. Pat. No. 5,002,438 to Strong, the entire contents of which are incorporated herein by reference. 
         [0038]    As shown in  FIG. 4 , in an alternate embodiment, wire mesh  36  can be used rather than anchor plates. As shown in  FIG. 4 , wire mesh  36  is preferably secured to the substrate after first moisture barrier layer  12  is applied so that wire mesh  36  is embedded in foam layer  13  when it is applied. Note. various types of wire mesh, of varying gauges, such as galvanized hardware cloth, can he used in the anchor system. 
         [0039]    As shown in  FIG. 5 , reinforcing bar  38 , commonly known as rebar, may also be used in alternate embodiments of the anchor system. As shown, the fasteners used to secure rebar  38  to the substrate  20  include a pair of ears  37  that are connected by a metal band which forms a loop  39  around the rebar  38 . The ears  37  are then secured to substrate  20  by a shaft  35  passing therethrough. Preferably, rebar  38  is secured to the substrate  20  after the first moisture barrier  12  is applied and prior to the application of foam layer  13  and second barrier layer  14 . In yet another embodiment, fiberglass netting, matting strips, etc., (not shown) may be secured to the substrate  20  and serve to anchor the multi-layer liner  10  thereto. 
         [0040]    Referring now to  FIGS. 6A and 6B , an example use of an embodiment of the present anchored multi-layer liner system  10  is discussed. Specifically, the wire mesh  36  embodiment shown in  FIG. 4  is utilized in a pre-cast waste water component, specifically a manhole  50 . As shown in  FIG. 6A , the manhole  50  is constructed of a plurality of pre-cast concrete sections  52 ,  54 .  56  and  58  that extend down to a sewer pipe  60 , A first section  52  and a second section  54  meet at a first joint  53 , the second section  54  and a third section  56  meet at a second joint  55 , and the third section  56  and a fourth section  58  meet at a third joint  57 , Note, however, more or fewer sections may be used. As previously discussed with regard to waste water components constructed of pre-cast sections, they are often susceptible to water intrusion, etc., at the joints between the various sections. Therefore, with prior art liner systems, the liners are often susceptible to separation from the substrate  20  at the joints due to hydrostatic pressure. 
         [0041]    Referring now to  FIG. 6B , to help prevent such separation, the anchor system  30  according to the present disclosure can be applied at the joints  53 ,  55  and  57  after water intrusion, etc., is detected or during original construction, As shown, the wire mesh  36  anchor system  30  is secured to the inner surface of the manhole  50  at each of the joints  53 ,  55  and  57 . Alternatively, the wire mesh  36  can be secured to substantially the entire inner surface of the manhole  50  where necessary, i.e., where excessive leakage may be expected, As previously discussed, wire mesh  36  is preferably applied after a primer layer  11  and a first moisture barrier layer  12  ( FIG. 4 ), but prior to the foam layer  13  and the second moisture barrier layer  14  ( FIG. 1A ).  FIG. 6B  shows only a partial application of the multi-layer liner  10  so that the anchor system  30  is more readily seen. 
         [0042]    While one or more preferred embodiments of the invention are described above, it should be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit thereof. It is intended that the present invention cover such modifications and variations as come within the scope and spirit of the appended claims and their equivalents.