WO2022219483A1

WO2022219483A1 - Cellular confinement system

Info

Publication number: WO2022219483A1
Application number: PCT/IB2022/053339
Authority: WO
Inventors: Izhar Halahmi; Oded Erez
Original assignee: P.R.S Geo Tech Technologies Ltd
Priority date: 2021-04-11
Filing date: 2022-04-09
Publication date: 2022-10-20
Also published as: EP4323589A1; AR125677A1; CL2023003953A1; CN117480300A

Abstract

A cellular confinement system (CCS) includes strips of plastic materials that are welded one to the other at weld regions to form an array of cells. At least the weld regions of the CCS are each coated by a high barrier coating that imparts long term durability to the CCS.

Description

CELLULAR CONFINEMENT SYSTEM TECHNICAL FIELD [001] Embodiments of the invention relate to a cellular confinement system, and in particular to cellular confinement system with improved durability. BACKGROUND [002] Cellular confinement systems, also known as a CCS or geocells are used as structural reinforcement for load support e.g. in earth retention for supporting loads. [003] A cellular confinement system (CCS) is an array of containment cells resembling a “honeycomb” structure that is filled with granular infill, which can be cohesionless soil, sand, gravel, ballast, crushed stone, or any other type of granular aggregate, including different minerals, recycled concrete, recycled asphalt. Also known as geocells, CCSs are mainly used in various civil engineering applications involving granular infill. [004] CCSs differ from other geosynthetics such as geogrids or geotextiles in that geogrids/geotextiles are flat (i.e., two-dimensional) and used as planar reinforcement. Geogrids/geotextiles provide confinement only for very limited vertical distances (usually 1-2 times the average size of the granular material) and are limited to granular materials having an average size of greater than about 20 mm. This limits the use of such two-dimensional geosynthetics to relatively expensive granular materials (ballast, crushed stone and gravel) because they provide hardly any confinement or reinforcement to lower quality granular materials, such as recycled asphalt, crushed concrete, minerals and natural occurring sediments, fly ash and quarry waste. [005] In contrast, CCSs are three-dimensional structures that provide confinement in all directions (e.g. along the entire cross-section of each cell). Moreover, the multi-cell geometry provides passive resistance that increases the bearing capacity. Unlike two-dimensional geosynthetics, a geocell provides confinement and reinforcement to granular materials having an average particle size less than about 20 mm, and in some cases materials having an average particle size of about 10 mm or less. [006] Geocells are traditionally made of polyolefin resins, such as polyethylene (PE). The polyethylene (PE) can be high density polyethylene (HDPE) or medium density polyethylene (MDPE). The term “HDPE” refers hereinafter to a polyethylene characterized by density of greater than 0.940 g/cm^3. The term medium density polyethylene (MDPE) refers to a polyethylene characterized by density of greater than 0.925 g/cm^3 to 0.940 g/cm^3. The term low density polyethylene (LOPE) refers to a polyethylene characterized by density of 0.91 to 0.925 g/cm^3. However, there are also more modern and advanced geocells , made from an alloy of Polyethylene or Polypropylene and a high performance resin such as Polyamide , for Example “tough-Cell^TM” [007] When the granular material is confined by a geocell, and a vertical load is applied from the top by a static or dynamic stress (such as pressure provided by a vehicle wheel or train rail), the horizontal pressure is translated to hoop stress in the geocell wall. The hoop stress is proportional to the horizontal pressure and to the average cell radius, and is inversely proportional to the thickness of the cell wall. [008] A geocell made of HDPE or MDPE for example may have a cell wall thickness of 1-1.5 millimeters, an average diameter (when infilled with granular material) of 230 millimeters, a height of up to 200 millimeters. [009] Geocell, or cellular confinement systems, are manufactured from plastic strips, usually polyethylene, welded together by ultrasonic welding. In order to qualify geocell manufacturing, strip tensile strength, seam welding shear strength, seam welding split strength and seam welding peel strength (all ultimate failure values, not long term strength values), creep resistance and dynamic mechanical properties are measured. [010] In some cases however, the measured values for seams welding strength, fail to predict geocell lifetime, especially when it is exposed to organic or inorganic low molecular weight compounds , for examples acids, salts , oils, detergents , fats, soap , solvents and diluents ,distillates and organic waste that is common in mineral mining, landfills and swamps. [011] The root cause for premature seam welding failure in certain cases may be the development of cracks especially near the ultrasonic welding line, where stresses and thermal degradation are maximized. Due to the high ultrasonic power concentrated in welding spots during welding, antioxidants and HALS (hindered amine light stabilizers) may be degraded or diffused outside, leaving polymer in welding area with inferior long-term protection. Moreover – due to the welding peaks, stresses are not distributed evenly in seam, so as premature cracking due to combination of mechanical stress and the chemical nature of the medium in contact with seams is expected there. The result of that is failure that occurs at much shorter time than designed (typically, geocells are designed to 10-50 years outdoors). [012] Such failure near an ultrasonic welding area may occur in certain cases at stresses that are much lower than strip tensile or ultimate seam strength (welding stress to failure) stress to failure or, for example at about 10-50% of said stresses. This phenomenon, may be independent of raw material resistance to stress cracking (usually provided as ESCR by the polymer manufacturer), because of the localized weakness near welding and local depletion of protective additives during welding. [013] In some cases, softer and weaker resins may be useful in lowering the damage due to this phenomenon, however such resins on the other hand may render the geocell inferior from the perspective of its load bearing capability. [014] Therefore, there is a need to improve geocell resistance to failure of seams welding or near seams welding due to cracking during service and inferior protection, possibly without substantial changes being made to raw material and manufacturing technology, and in a way that such improvements do not interfere substantially with the extrusion of strips and with the ultrasonic welding applied to the strips. [015] The ASTM standard D 5397 (ASTM D 5397) is a test method that can be used for evaluating resistance to cracking of Polyethylene materials. This test method measures the time to failure associated with a given test specimen made at a specified tensile load level, by exposing test samples to conditions that include submerging them in IGEPAL® CO-630 solution, under elevated temperature, in order to accelerate cracks initiation and propagation, while applying load to the sample. The IGEPAL® CO-630 is a surfactant, accepted by industry and academy as a standard cracking initiating agent. SUMMARY [016] The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. [017] In one aspect, it is one object of the invention to disclose a method of improving seam welding resistance to long term service conditions (SRSC) of ultrasonically welded geocells, by coating the strips of a geocell after welding. [018] Possibly, the coating may be able to lower the rate of ingress of cracking inducing molecules into the geocell matrix, and function as barrier against HALS (hindered amine light stabilizers) and antioxidant depletion from polymer matrix, out to the environment. [019] In certain cases, the method may include a step of applying a water borne or solvent borne coating on a geocell, so that a welding area or a portion of an area or the total surface of the geocell may be covered. [020] In certain embodiments, the coating may be characterized as having any one of the following: good adhesion to untreated or treated or modified with adhesion promoter polymer selected from polyethyleneor polypropylene, including alloys thereof with high performance polymer such as polyamide (or the like); good barrier properties against migration of salts, acids, and small organic molecules from soil or aqueous or granular material medium into geocell matrix, especially at a welding area of the geocell by small organic molecules having usually of molecular weight less than 800 Dalton or less than 10 carbon atoms in molecule. [021] In an aspect of the invention, a coating according to certain embodiments of the present invention preferably exhibits suitable ‘retention of adhesion’ to a geocell strip matrix (polyethylene or polypropylene , including alloys thereof with high performance polymer such as polyamide (or the like)), which is the typical material from which a cellular confinement system is made from. Such ‘retention of adhesion’ may be assessed by submerging a coated sample for about 7 days in a solution of 10% w/w of IGEPAL® CO-630 and water, at about 65 degrees Celsius, and then washing the sample under tap water, and leaving it to dry at the ambient environment for about 48 hours and then the “adhesion” is tested by applying for up to several minutes 3M™ General Purpose Masking Tape 203 to the coated sample, and then pulling away the tape. If less than about 10% of the coating area is removed, the tested sample qualifies as a coating that may possibly exhibit long term durability according to certain embodiments of the invention. [022] In an aspect, certain embodiments of the invention may be defined as being aimed at disclosing a coated geocell seam able of withstanding a seam welding resistance test, such as in the ASTM standard D5397, so as time to failure is at least about 50% greater than uncoated geocell, made of same polymer at same gauge, welding power, pressure and welding horn and cell height. [023] In certain embodiments, a coated geocell seam welding long term durability may be able to undergo a seam durability test, per a modified ASTM D5397, exhibiting a time to failure that may be at least 2 times or even 3 times greater than the time to failure of an uncoated geocell, made from the same polymer at same gauge, welding power, pressure and welding horn and cell height. [024] In certain cases, a coating thickness may be measured by cutting a geocell and measuring the coating thickness using a microscope coating gauge, in a direction perpendicular to the geocell surface. Such coating thickness in at least certain embodiments may vary e.g. from between about 0.1 to about 100 micrometers. [025] A coating according to at least certain embodiments of the present invention, may comprise at least one barrier polymer (shortly BAPOL) selected from any one of the following: polyvinyl chloride and copolymers of vinyl chloride with ethylene and/or acrylic acid esters; hydrocarbons including aromatics, saturated and unsaturated; polyvinylidene chloride and copolymers of vinylidene chloride with ethylene and/or acrylic acid esters; poly ethylene vinyl acetate copolymers and terpolymers of acrylic acid esters; styrene copolymers and terpolymers; polyamide; polyester; copolymers and terpolymers of acrylic acid esters and methacrylic acid esters and blend thereof. In an aspect, the coating in accordance with at least certain embodiments of the invention may be defined as having any one of the following properties: elasticity with elongation at break of at least about 25% at 23 Celsius to possibly allow retention of adhesion and integrity during geocell installation; long term hydrolytic stability to possibly enable long term protection of up to several years, for example 25 years (or the like) in an outdoor environment; improved adhesion to untreated or treated or modified geocell matrix (and the like). [026] In certain cases, combining such properties may be challenging, since the higher the glass transition temperature (Tg) of a coating polymer, or its crystallinity – the lower the adhesion, but the better the barrier properties. [027] In certain embodiments of the present invention, this may be accomplished by providing a coating that may be formed by blending tacky, low Tg (below about 23 degrees Celsius) polymer or resin or oligomer, with a high barrier polymer (BAPOL) - or by copolymerizing polymers with good barrier (BAPOL) with side chains or block segments of low Tg polymer. [028] Non-binding examples of hydrolytic stable low Tg, tacky polymers or resins or oligomers that that may be blended with BAPOL may be any one of: bitumen, rosin esters, phenolic tackifier and hydrocarbon tackifier, chlorinated polyethylene and chlorinated paraffin. [029] In an aspect of the invention, embodiments of the present invention may be defined as being directed to a geocell wherein durability of the geocell seams may be enhanced on and near welding’s. [030] In one embodiment, a coating may be applied on a welding area (e.g. between about 10 to about 25 mm width, centered on welding), while a remainder or other outer surfaces of the geocell may remain substantially un-coated or coated by coating that may be thinner than the coating on welding area. [031] Such design may allow optimizing protection on the most sensitive area (i.e. the welding area), while avoiding waste of unnecessary costs on areas much more resistant. [032] In an aspect of the invention there may be provided a method of providing a seam welding durability test, which can be based on the modified ASTM standard test D5397. [033] Since a welding may accordingly be a weak point in a geocell structure, instead of notched strips as in original ASTM D5397, two or more ultrasonically welded strips, about 20 to about 50 mm wide, may be tested. [034] In one example, a load of about 10 to about 50 percent of average ultimate weld split load at failure may be applied to the tested strips; and the stripe may be submerged in an aqueous solution having a cracking initiating agent of about 10% w/w IGEPAL® CO 630 in water, at temperature of about 50 to 70 Celsius degrees, in order to accelerate failure rate. [035] Typically, coated samples in accordance with various embodiments of the invention may be expected to last longer that uncoated samples, due to delay of diffusion of agent from solution into weld area. [036] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the figures and by study of the following detailed descriptions. BRIEF DESCRIPTION OF THE FIGURES [037] Exemplary embodiments are illustrated in referenced figures. It is intended that the embodiments and figures disclosed herein are to be considered illustrative, rather than restrictive. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying figures, in which: [038] Figs. 1A and 1B schematically show perspective views of folded and expanded states of a cellular confinement system in accordance with the embodiments of the present invention; [039] Fig. 2 schematically shows a top view of a cellular confinement system in accordance with the embodiments of the present invention; [040] Fig. 3 schematically shows a specimen of a cellular confinement system in accordance with an embodiment of the present invention, with supporting members located within each cell of the specimen; [041] Figs. 4A and 4B schematically show, respectively, perspective and cross sectional views of an embodiment of a test apparatus for testing failure of a specimen such as that seen in Fig.3; [042] Fig. 5 shows a table exhibiting test results obtained by a test apparatus such as that seen in Fig.4; and [043] Fig. 6 shows a table exhibiting various CCS compositions and examples of coatings that may be applied thereto. [044] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated within the figures to indicate like elements. DETAILED DESCRIPTION [045] Attention is first drawn to Figs. 1A and 1B showing a cellular confinement systems (10), also known as a CCS or geocells, in respective folded and expanded states. [046] The CCS 10 is formed from strips 12 of plastic materials that extend each along a respective longitudinal axis L, and are welded one to the other at weld regions 14 to form an array of cells 16 (best visible in the expanded state of the CCS). [047] Each strip 12 has a height H that is measured along an extension that is perpendicular to its longitudinal axis along the width of the strip that extends up from a ground face upon which the CCS is placed in a deployed and expanded state. A distance T is defined between adjacent weld regions 14 within a given strip 12 when the CCS 10 is in a folded state where all the strips are held generally straight one alongside the other. [048] Attention is drawn to Fig. 2 showing a top view of the CCS 10 it its expanded state. [049] The CCS 10 in its various embodiments may be suited for use as a lower foundation beneath sites housing saline and/or chemical rich water. Such sites may be pools, ponds, landfills (or the like). In one example, such a site where the CCS may be used may be evaporation pools where e.g. mineral-rich brine is stored for evaporation. [050] When used in such sites, a CCS may fail due to exposure to concentrated organic or inorganic low molecular weight compounds, for examples acids, salts, oils, distillates and organic waste. The root cause for premature failure may occur especially near the ultrasonic welding line, where stresses and thermal degradation are maximized. Due to the high ultrasonic power concentrated in welding spots during welding, antioxidants and HALS (hindered amine light stabilizers) may be degraded or diffused outside, leaving polymer in welding area with inferior long term protection. [051] In order to increase long term durability, cellular confinement systems (CCS) 10 in accordance with various embodiments of the present invention may be coated at least at their weld regions (seams) 14 with a high barrier coatings 15 to reduce exposure to substances that may be harmful to the welds in these regions, when such harm may be characterized by promoting failure near or at the ultrasonic welding lines of the weld regions 14. [052] In certain embodiments, such coatings 15 may be applied selectively to the weld regions 14 (as illustrated in the enlarged section in Fig. 1B), while in other embodiments the coatings 15 may not necessarily be applied only at or adjacent the weld regions 14 but also to larger areas of the CCS such as to the entire cellular confinement system (CCS). [053] In the enlarged section of Fig. 1B, an example is shown where the coating is selectively applied to the weld region, with a lateral width of the weld region 14 being defined as ‘w’ and a lateral width of the coating 15 being defined as ‘c’. In a non-binding example, lateral width ‘w’ may be between about 10 – 30 millimeter, and lateral width ‘c’ may be designed to be larger than ‘w’ so that it extends between about 5 to 50 millimeters beyond the lateral edges of the weld region 14 on both its lateral sides. [054] In an embodiment, such coating may comprise one or more polymer latex emulsions, such as those available in the Vycar® 460X46, or Vycar® 577, or Vycar® 578, or Permax™ 805 emulsions of the Lubrizol Corporation or the Diofan® PVDC coating of Solvay S.A. [055] For example, a coating suitable for application on a weld region 14 may be based on a 50/50% w/w blend of Polyvinylidene chloride 577 (PVC) and bitumen latex. Blending with bitumen in some cases may assist in the bonding to the material of the strips 12 of a polyolefin or alloy of polyolefin and high performance polymer CCS 10, such as bonding to strips formed from Polyethylene or polypropylene or alloy thereof with high performance polymer (or the like). [056] In another embodiment, bonding of polyvinyl chloride 577 (PVC) may also be performed without blending with bitumen. This may be performed by dispersing a bonding promoting polymer , such as PVC, or chlorinated polyethylene or ionomer resin with CCS matrix outer layers or all layers during extrusion of CCS strips, where a ratio of dispersed bonding promoting polymer to polyolefin or alloy may vary from about 1:100, to about 1:2. [057] In certain cases, determining compliance of an embodiment of a cellular confinement system (CCS) 10 with long term seam welding durability, may be performed by applying a modified ASTM D5397 (MAD) test to a specimen of a tested CCS. [058] Attention is drawn to Fig. 3 showing an example of a CCS specimen 18 that may be tested for determining compliance with long term seam welding durability of in a MAD test. As seen in this example, specimen 18 may include two cells 16 of a tested CCS 10 that are welded together by a weld region 14 that has been coated. Specimen 18 may be cut away from the CCS as seen by the dashed rectangle marked by numeral III in Fig 2. A height H of the specimen 18 may also be reduced e.g. to 20 millimeters. [059] Cylindrical members 20 having a diameter D may be inserted into each one of the cells 16 of the specimen in order to urge the cells to assume an expanded state. The specimen may be defined as having an axis X that generally passes through the centers the two cylindrical members 20 and through the weld region 14 that is located therebetween, and the specimen may be include two coupling members 22 that are attached to the specimen at its opposing axial ends. [060] Attention is drawn to Figs. 4A and 4B showing an embodiment of a modified ASTM D5397 (MAD) test setup 24. The MAD test setup 24 has a test bath 241 filled with IGEPAL® CO-630 solution and one or more (in this example four) CCS specimens 18 that are located within the test bath 241 submerged within IGEPAL® CO-630 solution that is heated to about 65 degrees Celsius (+/- 3 Celsius). [061] Each specimen 18 is aligned with its axis X in an upright position and is anchored via its lower coupling 22 to a lower floor of the test bath 241 and at its upper coupling 22 via a cord to a first end of a lever 242 of the test setup 24. Each lever 242 is hinged generally at its center to rotate about a rotational axis R and is attached as its opposing second end via a cord to a weight 243. [062] The weight stretches the specimen 18, and induces stress concentration in the seams welding in the weld region 14, at a realistic geometry and realistic stress distribution, until failure (possibly due to slow crack propagation (“crazing”) mode of stressed polymer in the seam) occurs and is logged. The time span that lapsed until failure of a tested specimen can then be used to determine compliance with long term seam welding durability of a tested cellular confinement system (CCS) 10. [063] Attention is drawn to the table seen in Fig. 5 that summarizes test results of five coated and five uncoated specimens 18. All tests were performed in a MAD test setup such as that shown and described with respect to the test setup 24 of Figs. 4A and 4B and with CCS specimens such as those seen and described with respect to the CCS specimens 18 of Fig.3. [064] In tests performed by the inventors, it has been found that specimens 18 with coated weld regions 14 when exposed to forces applied by weights of 10 and 15 kilograms, have exhibited a time to failure that is at least about 50% greater than uncoated specimens 18. [065] The loads applied by the 10 and 15 kilograms weights to samples of 20 mm width, are equal to about 4.9 and 7.35 KN/m respectively, which in agreement to the long term design strength of a CCS seam which is about 25 to 33% of ultimate strength, 19-25 KN/m expected for such kind of strips. [066] In the exemplary results in the table of Fig. 5, it can be seen that when exposing the specimens to 10 kilogram, the coated specimen lasted 14 days until failure of seam welding, which is more than 50% greater than uncoated specimens 18 that lasted only 9 days until failure. [067] Attention is drawn to the table seen in Fig. 6 that summarizes various compositions of strips that may be used in a CCS and coatings that may be applied to such a CCS. [068] In the first example tagged ‘1’ in the left hand-side column of the table, the composition forming the strips 12 of the CCS 10 may be Polyethylene (HDPE or MDPE) or an alloy of Polyethylene with high performance polymer. A typical high performance polymer is polyamide 6, blended in HDPE or MDPE, and compatibilized by maleic anhydride grafted polyethylene. The high barrier coating 15 covering the weld regions 14 welding together the strips may comprise between about 50-95% w/w of any one of the following compositions: PVC, vinyl chloride- ethylene copolymer and terpolymers, PVDC, vinylidene chloride-ethylene copolymer and terpolymers, PVDF, vinyl fluoride-ethylene copolymer and terpolymers. [069] Since these compositions may typically have low or no suitably of adherence to Polyethylene or to an alloy of Polyethylene with high performance polymer, the high barrier coating may comprise also a respective amount of between about 50-5% w/w of bitumen or other tacky resins in order to promote the adherence of such a high barrier coating to the strips. Examples of tacky resins may be e.g. low OH terpene phenolics, Rosin esters, Styrenated terpenes, AMS, AMS phenolics, polyterpenes, C5 or C9 or DCPD hydrocarbons, [070] In the second example tagged in the left hand-side column of the table, the composition forming the strips 12 of the CCS 10 may generally comprise a blend of two groups. [071] A first group comprising between about 50-95% w/w of Polyethylene (HDPE or PDPE) or an alloy of Polyethylene with high performance polymer; and a second group comprising between about 50-5% w/w respectively of any one of the following adhesion promoting polymer: PVC, Chlorinated polyethylene, vinyl chloride-ethylene copolymer and terpolymers, ionomer. [072] Presence of the compositions of the second group that may be melt blended together with the materials of the first group during extrusion of the strips of the CCS, may allow the high barrier coating suitable for application on this type of strip, to lower or be substantially devoid of martials such as the bitumen or other tacky resins (or the like) that assisted in the former example (tagged ‘1’) in the adherence of the coating to the strips. [073] This is due to the fact that the compositions of the second group act as so-called dispersed polar inclusions within the strips to which such a coating may be adhered. [074] The third example tagged ‘3’ in the left hand-side column of the table, exhibits an option of use of a multi layered strip in the CCS, here comprising three layers, with an inner core layer of the strip made from Polyethylene (HDPE or MDPE) or an alloy of Polyethylene with high performance polymer being sandwiched between outer layers comprising between about 50-95% w/w of Polyethylene (HDPE or MDPE) or alloy of Polyethylene with high performance polymer and respectively between about 50-5% w/w of the compositions of the aforementioned second group, and dispersed phase of polar material allowing adhesion of coating . [075] As already mentioned, such compositions of the second group may assist in adhesion to the high barrier coating, which here again may allow lowering or substantially avoiding presence of materials such as the bitumen or other tacky resins (or the like) that may be needed in high barrier coatings where adhesion may be required directly to Polyethylene. [076] As seen in the table, all coatings may be applied to the strips of the CCS, by dipping or spraying substantially the entire strips of the CCS after welding of the strips - in or with the high barrier coating solution, and then leaving the coating to dry in air or hot air. Alternatively, all coatings may be selectively applied to an area at or near the seams or weld regions, by spraying or brushing or roller coating the high barrier coating on a CCS in its open expanded state (such as that seen in Fig 1B) where the seams/weld-regions are better exposed. The coating may then be left to dry in air or hot air. [077] In the description and claims of the present application, each of the verbs, “comprise” “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb. [078] Further more, while the present application or technology has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and non- restrictive; the technology is thus not limited to the disclosed embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art and practicing the claimed technology, from a study of the drawings, the technology, and the appended claims. [079] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures can not be used to advantage. [080] The present technology is also understood to encompass the exact terms, features, numerical values or ranges etc., if in here such terms, features, numerical values or ranges etc. are referred to in connection with terms such as “about, ca., substantially, generally, at least” etc. In other words, “about 3” shall also comprise “3” or “substantially perpendicular” shall also comprise “perpendicular”. Any reference signs in the claims should not be considered as limiting the scope. [081] Although the present embodiments have been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the scope of the invention as hereinafter claimed.

Claims

CLAIMS: 1. A cellular confinement system (CCS) comprising strips of plastic materials that are ultrasonically welded one to the other at weld regions to form an array of cells, wherein the strips comprise polyolefin, preferably polyethylene (HDPE or MDPE), or an alloy of Polyethylene with high performance polymer, and wherein at least the weld regions being each coated by a coat-blend comprising: a high barrier coating comprising any one of the following barrier compositions: PVC, vinyl chloride-ethylene copolymer and terpolymers, PVDC, vinylidene chloride-ethylene copolymer and terpolymers, PVDF, vinyl fluoride- ethylene copolymer and terpolymers; and bitumen or other tacky resin.

2. The CCS of claim 1, wherein the barrier composition(s) is (are) at between about 50-95% w/w of the total material of the coat-blend and the bitumen or the other tacky resin is respectively at between about 50-5% w/w of the total material of the coat-blend.

3. A cellular confinement system (CCS) comprising strips of plastic materials that are ultrasonically welded one to the other at weld regions to form an array of cells, wherein each strip comprises at least on its outer layers a combination of: polyolefin, preferably polyethylene (HDPE or MDPE), or an alloy of Polyethylene with high performance polymer, and any one of the following adhesion promoting polymer(s): PVC, Chlorinated polyethylene, vinyl chloride-ethylene copolymer and terpolymers, ionomer wherein said adhesion promoting polymer(s) is/are dispersed in the polyolefin, preferably polyethylene (HDPE or MDPE), or an alloy of Polyethylene with high performance polymer matrix. and wherein at least the weld regions being coated by a high barrier coating comprising any one of the following barrier compositions: PVC, vinyl chloride- ethylene copolymer and terpolymers, PVDC, vinylidene chloride-ethylene copolymer and terpolymers, PVDF, vinyl fluoride-ethylene copolymer and terpolymers.

4. The CCS of claim 3 and possibly comprising also bitumen or other tacky resin blended into the coating of the weld regions.

5. The CCS of claim 3, wherein each strip being multilayered with an inner core layer being formed from a polyolefin or an alloy of Polyethylene with high performance polymer, and its outer layers being formed from the combination of: the polyolefin, preferably polyethylene (HDPE or MDPE), or the alloy of Polyethylene with high performance polymer, and the any one of the following adhesion promoting polymer: PVC, Chlorinated polyethylene, vinyl chloride-ethylene copolymer and terpolymers, wherein said adhesion promoting polymer are dispersed in the polyolefin, preferably polyethylene (HDPE or MDPE), or an alloy of Polyethylene with high performance polymer matrix.

6. The CCS of claim 3, wherein in the combination, the polyethylene (HDPE or MDPE), or an alloy of Polyethylene with high performance polymer matrix is at between about 50-95% w/w of the total material of the combination and the adhesion promoting substance(s) is (are) at between about 50-5% w/w respectively of the total material of the combination.

7. A cellular confinement system (CCS) comprising strips of plastic materials that are ultrasonically welded one to the other at weld regions to form an array of cells, wherein at least the weld regions being each coated by a high barrier coating to impart long term seam durability to the CCS.

8. The CCS of claim 7, wherein the high barrier coating is arranged to reduce failure at the weld regions due to cracking.

9. The CCS of claim 8, wherein the strips comprise polyolefin, preferably polyethylene (HDPE or MDPE) or an alloy of Polyethylene with high performance polymer.

10. The CCS of claim 9, wherein the high barrier coating comprises any one of the following barrier compositions: PVC, vinyl chloride-ethylene copolymer and terpolymers, PVDC, vinylidene chloride-ethylene copolymer and terpolymers, PVDF, vinyl fluoride-ethylene copolymer and terpolymers.

11. The CCS of claim 10, wherein the high barrier coating comprises also bitumen or other tacky hydrophobic resin.

12. The CCS of claim 11, wherein the barrier composition(s) is (are) at between about 50-95% w/w of the total material of the high barrier coating and the bitumen or the other tacky hydrophobic resin is respectively at between about 50-5% w/w of the total material of the high barrier of the coating.

13. The CCS of claim 9, wherein each strip comprising in addition any one of the following adhesion promoting substances: PVC, Chlorinated polyethylene, vinyl chloride-ethylene copolymer and terpolymers.

14. The CCS of claim 9, wherein each strip is multilayered with an inner core layer being formed from the polyolefin or the alloy of Polyethylene with high performance polymer, and its outer layers being formed from a blend of the polyolefin or the alloy of Polyethylene with high performance polymer and any one of the following adhesion promoting substances: PVC, Chlorinated polyethylene, vinyl chloride-ethylene copolymer and terpolymers.

15. The CCS of claim 13 or 14, wherein the polyolefin is at between about 50-95% w/w of the total material of the strip or layer and the adhesion promoting substance(s) is (are) at between about 50-5% w/w respectively of the total material of the strip or layer.

16. The CCS of claim 9 or 10, wherein high barrier characteristic of a coating is defined by a test comprising: submerging a coated sample of the CCS for about 7 days in a solution of about 10% w/w of IGEPAL® CO-630 and water at a temperature of about 65 degrees Celsius, and then washing the coated sample under tap water, and then leaving the coated sample to dry at the ambient environment for about 48 hours, and then testing the adhesion by applying 3M™ General Purpose Masking Tape 203 to the coated sample and then pulling away the tape, wherein the high barrier characteristic is defined if less than about 10% of the coating area is removed and remains upon the tape.

17. The CCS of claim 9 or 10, wherein ability to improve seams welding resistance is defined by a modified ASTM D5397 test that comprises: providing a plurality of test specimens of the CCS that each comprise two cells that are welded together by a coated weld region with a height each specimen being about 20 millimeters wide, providing a plurality of benchmark specimens taken from a benchmark CCS similar to the tested CCS but with un-coated weld regions, wherein a height each benchmark specimen being also about 20 millimeters wide, placing cylindrical members in cells of all of the test and benchmark specimens to expand their cells, wherein each test and benchmark specimen comprises a central axis that extends between the centers the cylinders and through the weld region of the specimen, providing a test bath that is filled with a solution of 10% w/w of IGEPAL® CO-630 and water, and heating said solution to 65 Celsius +/- 3 Celsius, submerging each test and benchmark specimen within the solution of the test bath with its central axis generally aligned in an upright position and with its lower axial side anchored in place, possibly to a bottom of the test bath, providing a lever outside of the test bath above each test or benchmark specimen, wherein each lever being hinged generally at its center to rotate about a rotational axis, attaching a first end of the lever via a cord to a weight of between about 10 to 15 kilograms and a second opposing end of the lever via another cord to an upper axial side of its specimen, and logging the time span that lapsed until failure of each test and benchmark specimen, wherein long term durability is defined by all the test specimens exhibiting an average time to failure or time to transition (Tt) that is at least about 50% greater than an average time to failure of all the benchmark specimens.

18. A method of producing a cellular confinement system (CCS) comprising the steps of: providing strips of plastic materials that are ultrasonically welded one to the other at weld regions to form an array of cells, and coating at least the weld regions with a high barrier coating to impart long term durability to the CCS.

19. The method of claim 18, wherein the high barrier coating is arranged to reduce failure at the weld regions.

20. The method of claim 18, wherein the strips comprise polyolefin, preferably polyethylene (HDPE or MDPE) or an alloy of Polyethylene with high performance polymer.

21. The method of claim 20, wherein the high barrier coating comprises any one of the following barrier compositions: PVC, vinyl chloride-ethylene copolymer and terpolymers, PVDC, vinylidene chloride-ethylene copolymer and terpolymers, PVDF, vinyl fluoride-ethylene copolymer and terpolymers.

22. The method of claim 21, wherein the high barrier coating comprises also bitumen or other tacky resin.

23. The method of claim 22, wherein the barrier composition(s) is (are) at between about 50-95% w/w of the total material of the high barrier coating and the bitumen or the other tacky hydrophobic resin is respectively at between about 50-5% w/w of the total material of the high barrier of the coating.

24. The method of claim 20, wherein each strip comprising in addition any one of the following adhesion promoting substances: PVC, Chlorinated polyethylene, vinyl chloride-ethylene copolymer and terpolymers.

25. The method of claim 20, wherein each strip is multilayered with an inner core layer being formed from the polyolefin or the alloy of Polyethylene with high performance polymer, and its outer layers being formed from a blend of the polyolefin or the alloy of Polyethylene with high performance polymer and any one of the following adhesion promoting substances: PVC, Chlorinated polyethylene, vinyl chloride-ethylene copolymer and terpolymers.

26. The method of claim 24 or 25, wherein the polyolefin is at between about 50-95% w/w of the total material of the strip or layer and the adhesion promoting substance(s) is (are) at between about 50-5% w/w respectively of the total material of the strip or layer.

27. The method of claim 20, wherein the coating is selectively applied only to the weld regions of the CCS or is applied to substantially all regions of the CCS.

28. A high barrier coating for a cellular confinement system (CCS) comprising any one of the following barrier compositions: PVC, vinyl chloride- ethylene copolymer and terpolymers, PVDC, vinylidene chloride-ethylene copolymer and terpolymers, PVDF, vinyl fluoride-ethylene copolymer and terpolymers.

29. The coating of claim 28, wherein the high barrier coating comprises also bitumen or other tacky hydrophobic resin.

30. The coating of claim 29, wherein the barrier composition(s) is (are) at between about 50-95% w/w of the total material of the high barrier coating and the bitumen or the other tacky resin is respectively at between about 50-5% w/w of the total material of the high barrier of the coating.