Abstract: A method and apparatus for digging and removing excavated material from a selected site provides a mobile device having a chassis that is movable or self-propelled. The mobile device has an elongated, preferably articulated boom with a free end portion having a digging implement that can include a digging tool, excavating tool or jetting tool. The boom preferably comprises at least three sections. The boom sections are foldable to a storage position on the chassis wherein one boom section stacks upon or is aligned with another boom section. The vacuum line is supported upon the boom wherein the vacuum line extends between the free end portion of the boom and the chassis. The boom attaches to the chassis at a base that can include a rotary or pivotal connection. The vacuum line supported by the boom extends along the boom and above the earth's surface. A selected material is excavated with the excavating implement (e.g., jetting tool or digging tool).

Abstract: A method of stabilizing a blasthole prior to detonation which comprises the step of coating the inner wall of the blasthole with a stabilizing composition. In one embodiment, the invention comprises coating the blast hole with a movable spraying application. The invention further relates to the use of a silicate-containing resin but is also suitable for use with a thermoset resin system. The method can be used to apply the stabilizing composition to both dry and wet blastholes.

Abstract: Cement compositions comprising carboxylated inulin and methods of using the same to cement a workspace. In one embodiment, a method of cementing includes providing a cement composition comprising a carboxylated inulin, for example, in a subterranean formation. The method further includes allowing the cement composition to set. In some embodiments, the cement composition has a thickening time of from about 2 hours to about 11 hours. In other embodiments, the cement composition has a viscosity that is about constant for a period of time after the cement composition is placed.

Abstract: The present disclosure provides a method for reinforcing irregular rock or irregular concrete surfaces such as rock structures in mines as well as other rock and concrete structures. The method includes applying a curable foam composition to at least a portion of a surface, at least partially curing the curable foam composition to form a foam layer adhered to the surface, applying a curable reinforcing composition onto at least a portion of the foam layer, and at least partially curing the curable reinforcing composition to form a reinforcing layer, wherein at least a portion of the reinforcing layer is adhered to the foam layer.

Abstract: The present invention relates to improved bentonite barrier compositions having enhanced low permeability over time in containment applications. Of the many embodiments provided herein, one embodiment includes a method comprising: providing a bentonite barrier composition comprising: bentonite; and a polyanionic low molecular weight polymer; and forming a containment using the bentonite barrier composition to provide at least partial separation for a containment from its environment.

Abstract: The present invention relates to improved bentonite barrier compositions having enhanced low permeability over time in containment applications. Of the many embodiments provided herein, one embodiment includes a geosynthetic clay liner comprising: at least one geosynthetic layer; and a bentonite barrier composition comprising: bentonite and a polyanionic low molecular weight polymer.

Abstract: Device (1) for consolidating soils by mechanical mixing and injection of consolidating fluids is designed to be connected to one or more drilling rods and to carry out operations of drilling and mixing. The device has a main body (10), one or more blades (30) (30?) (30?), which are mobile with respect to the body (10) and are constrained by cams (22) to a central structure (20) internal to the body (10). The device (1) has channels for the flow of fluids (40), which are connected in a liquid-tight way to at least one sprayer; a relative motion is generated between the central structure (20) and the external body (10) as a function of the pressure of a liquid introduced into the channels for the flow of fluids (40), which brings about opening of the blades (30) (30?) (30?).

Abstract: A method of lining an earthen formation pit includes covering at least a portion of the pit with a polymer. A portion of the polymer-covered area may be additionally covered with bentonite. The bentonite and polymer combine, when hydrated, to form a layer that is substantially water impermeable. A portion of the formation may be covered by a protective slurry of water and cement. A portion of the formation may be covered by a water-resistant layer such as, for example, a plastic tarpaulin.

Abstract: A levee, canal or aqueduct wall is internally supported by tensional members such as cables which stretch across the width of the waterway. In embodiments the tensional members may leave a space between the topmost member and the water level, so as to allow for passage of sea vessels above the cables. Vertical or horizontal struts or individual anchors attached to the ends of the cables may be positioned within, partially within or outside of the walls. Due to the strength of the device, the waterway wall may even be constructed at an angle to the vertical, even leaning outwards. External guying tensional members may be anchored and may connect to the wall or the internal tensional members to provide tensional support to prevent motion in the inward direction, either temporarily (such as during construction) or permanently.

Abstract: A method of soil improvement work drills the ground with a drilling head arranged at a lower end of a rotary shaft and sends the rotary shaft into the ground. The method mixes pressurized water with compressed air on the ground, to prepare a fluid mixture, feeds the fluid mixture through a feed path arranged along the rotary shaft into an ejector arranged on the drilling head, and ejects the fluid mixture from the ejector toward the ground to drill. An envelope defined by a front end of the drilling head has a conical shape.

Abstract: A liner is the product of reaction of (a) a hydrophilic prepolymer bearing isocyanate groups; and (b) a water-borne polymer dispersion, the polymer bearing groups that are reactive to isocyanate groups; wherein the dispersion has a sufficiently high solids content, and the polymer has a sufficiently high modulus and glass transition or crystalline melting temperature, that the product of reaction exhibits a 24-hour Tensile Strength of at least about 2.5 MPa.

Abstract: A method of treating a metal-contaminated sediment includes capping the sediment with a capping product containing sulfur and at least one component selected from the group consisting of clays, clay-sized materials, bulking agents, sand, sand-sized materials, aggregate, and binding agents. A capping product includes a plurality of manufactured composite particles, each composite particle comprising a relatively dense core and a sealant layer at least partially encapsulating the core, the sealant layer including sulfur and at least one of the above components.

Abstract: A liner is the product of reaction of (a) a hydrophilic prepolymer bearing isocyanate groups; and (b) a water-borne polymer dispersion, the polymer bearing groups that are reactive to isocyanate groups; wherein the dispersion has a sufficiently high solids content, and the polymer has a sufficiently high modulus and glass transition or crystalline melting temperature, that the product of reaction exhibits a 24-hour Tensile Strength of at least about 2.5 MPa.

Abstract: Present in a tail shield (1) for a shield tunneling apparatus are a number of grouting lines (3) that are open to a tail shield end (4) and that can be supplied with filling material for grouting a ring gap (7) with the filling material, such as mortar, for example. In addition, additive material lines (8) that can be supplied with additive material are present, which empty into the grouting lines (3) in an end segment (12) of said grouting lines (3). As a result, an additive material, such as a solidification accelerator, for example, can be added immediately before the mixture is discharged into the ring gap (7), so that the risk of a blockage in the grouting lines (3), which are not accessible in the region of the tail shield end (4), is relatively low.

Abstract: A polyurethane-forming reaction mixture characterized by its ability to be adjusted with respect to its viscosity in response to changing temperature and humidity conditions is achieved with a mixture that includes a liquid polyisocyanate having an isocyanate group content of at least 10% by weight, an isocyanate-reactive component which includes at least one high molecular weight polyol, a urethane catalyst and from 0.2 to 5 parts by weight per 100 parts by weight of isocyanate reactive component of a viscosity adjusting component. The viscosity adjusting component is preferably a diamine, a polyamine and/or an amine-terminated polyol. This reaction mixture is particularly useful for producing polyurethane geotextile composite materials useful as liners for ditches and canals.

Abstract: An improvement in an installation having a continuous water-impervious liner forming a barrier against the entry of water vapor and insects such as termites from the sub-soil into a crawlspace. According to the present invention, the water-impervious liner is provided with one or more access openings to the sub-soil, each covered with a flap, patch or cover which is openable to provide access to the sub-soil, and which is resealable to restore the water-barrier and/or water vapor-barrier properties of the liner in simple fashion as often as necessary.

Abstract: A waterstop, 10 or 11, for restricting or preventing the flow of water across the joints of foundation elements 8, such as between or along individual diaphragm wall panels or between or along individual secant wall piles. The present invention also relates to a method of installing a waterstop at or near the joints between adjacent foundation elements. The waterstop consists of one or more longitudinal strips, 1 or 2, of hydrophilic material, wherein the or each hydrophilic strip extends vertically along the interface between adjacent foundation elements, from a position at or near the top of the foundation elements, to a position at or near the base of the elements.

Abstract: A method of preparing a smooth watertight concrete in-ground pool surface that eliminates the use of a plaster outer surface layer that includes allowing the concrete pool body to cure for at least thirty days at which time a grinder is used to grind the surface to a smoothness and depth that is watertight and that exposes aggregates within the pool surface resulting in an aesthetically desirable permanently finished pool surface.

Abstract: An improved polyurethane/geotextile composite is prepared from a polyurethane forming composition in which a liquefied monomeric diphenylmethane diisocyanate (MDI) is used as the isocyanate component. Such composites may be used to line canals and/or ditches by applying the geotextile soaked with polyurethane forming composition to the surface to be lined before the polyurethane-forming reaction has been completed and allowing the polyurethane to cure in place. These composites are characterized by improved physical and mechanical properties and the ability to withstand dramatic changes in the temperature of the environment in which they are employed.

Abstract: A tool for use with a rotatable drill shaft and a source of pressurized fluidized solidifying agent. The tool member has upper and lower extremities. A coupler is coupled to the upper extremity of the tool member and is adapted to be secured to the drill shaft. A plurality of radially extending arms are secured to the tool member intermediate the upper and lower extremities of the tool member. A plurality of forwardly and downwardly extending teeth are secured to each of the radially extending arms and are spaced apart longitudinally of the arms. A plurality of nozzles are carried by the tool member and are spaced circumferentially of the tool member and are coupled to the source of pressurized fluidized solidifying agent.

Abstract: The present invention relates to a method of limiting the release of organic materials into the environment during the making of foundations, according to which a concrete is used which is based on blast furnace slag ground to a fineness of between about 2,500 and 5,000 Blaine. The invention also relates to a concrete which can be used in said method.

Abstract: A method is provided for forming an interconnected underground structure which avoids settling of adjacent soil structure. A plurality of underground support columns is initially formed, with the support columns being spaced apart in a predetermined pattern. Interconnecting holes are thereafter formed between the underground support columns, wherein the interconnecting holes are formed by mechanically cutting the soil and simultaneously hydraulically mixing the mechanically cut soil with slurry injected at velocities of 200 feet per second or higher while maintaining a positive hydrostatic head in the hole relative to adjacent soil. As the interconnecting holes are being formed, the diameter of each interconnecting hole is extended by positioning a second high velocity slurry nozzle near the outer diameter of the interconnecting hole which injects high velocity into the adjacent soil to hydraulically cut the adjacent soil and mix it with the slurry.

Abstract: A system for preventing upward migration of contaminants in soil having capillary pores defined therein, the system comprising the soil and a hydrophobic substance applied to the soil, the substance being attracted to enter the capillary pores so that a barrier is formed which, under unsaturated soil conditions, prevents the upward migration of contaminants carried by water through the capillary pores in the soil.

Abstract: An apparatus for constructing an underground containment barrier for containing an in-situ portion of earth. The apparatus includes an excavating device for simultaneously (i) excavating earthen material from beside the in-situ portion of earth without removing the in-situ portion and thereby forming an open side trench defined by opposing earthen sidewalls, and (ii) excavating earthen material from beneath the in-situ portion of earth without removing the in-situ portion and thereby forming a generally horizontal underground trench beneath the in-situ portion defined by opposing earthen sidewalls. The apparatus further includes a barrier-forming device attached to the excavating device for simultaneously forming a side barrier within the open trench and a generally horizontal, multi-layer barrier within the generally horizontal trench. The multi-layer barrier includes at least a first layer and a second layer.

Abstract: A flowable material to isolate or treat a surface consists of a plurality of manufactured composite particles. Each composite particle includes a core, and a sealant layer at least partially encapsulating the core. The core is relatively dense compared to the sealant layer, and the composite particle has a specific gravity greater than one. The sealant layer includes a clay mineral, a pozzolanic material and/or activated carbon. A sealant layer formed of a pozzolanic material creates a hardened underwater barrier layer. The sealant layer can also include natural fibers such as cellulose or man-made fibers such as glass, carbon or plastics to mechanically improve the geotechnical properties of the layer when hydrated. The composite particles can also include a material to treat the contaminants or otherwise improve the surrounding environment.

Abstract: A method of sealing the entire surfaces of a crawlspace and other areas difficult to access in a structure is set forth in which a uniformly thick layer of a quick drying and moldable lightweight concrete is flowed over the entire surfaces to be covered in a uniform thickness sufficient to seal the surface.

Abstract: The invention pertains to a process for sealing off ground sites in particular a waste dump, abandoned dumping grounds, pipelines or the like, or also excavated construction sites, using sealants, wherein a fully course-controlled boring technique is used to drive at least one bore underneath the ground site from the surface outside the ground site and the sealant is injected into the soil surrounding the bore. To implement the process, jets for injecting the sealant into the soil are mounted on the steerable remote-controlled boring head.

Abstract: A waterproofing system and method for hydraulic structures which includes rigid sheets of synthetic material connected with flexible hinges made of sheets of synthetic material. Mechanical anchoring hold the rigid sheets in place.

Abstract: An apparatus for building a horizontal underground barrier by cutting through soil and depositing a slurry, preferably on which cures into a hardened material. The apparatus includes a digging means for cutting and removing soil to create a void under the surface of the ground and injection means for inserting barrier-forming material into the void. In one embodiment, the digging means is a continuous cutting chain. Mounted on the continuous cutting chain are cutter teeth for cutting through soil and discharge paddles for removing the loosened soil. This invention includes a barrier placement machine, a method for building an underground horizontal containment barrier using the barrier placement machine, and the underground containment system. Preferably the underground containment barrier goes underneath and around the site to be contained in a bathtub-type containment.

Abstract: An apparatus for building a horizontal underground barrier by cutting through soil and depositing a slurry, preferably one which cures into a hardened material. The apparatus includes a digging means for cutting and removing soil to create a void under the surface of the ground, a shield means for maintaining the void, and injection means for inserting barrier-forming material into the void. In one embodiment, the digging means is a continuous cutting chain. Mounted on the continuous cutting chain are cutter teeth for cutting through soil and discharge paddles for removing the loosened soil. This invention includes a barrier placement machine, a method for building an underground horizontal containment barrier using the barrier placement machine, and the underground containment system. Preferably the underground containment barrier goes underneath and around the site to be contained in a bathtub-type containment.

Abstract: A cellular drainage structure is formed of a predetermined volume of a settable, water permeable, cellular concrete product. A concrete mix is formed of a uniformly graded aggregate in the size range from 1/16 inch to two inches and in a quantity corresponding to the predetermined volume; a cementitious component in the quantity range from 141 to 658 pounds per cubic yard of product; water in quantity sufficient to create a water-to-cement ratio in the approximate range from 0.30 to 0.55 and sufficient to wet the aggregate, establishing a cementitious-component-and-water matrix of determinable volume; a pre-formed surfactant foam, generated from an aqueous surfactant mixture at a dilution of from approximately 3 to 25 grams per liter of surfactant in water, wherein the pre-formed foam is in the density range of from 2.0 to 3.0 pcf, and the foam is added in the quantity range of 5% to 30% of the volume of the cementitious-component-and-water matrix.

Abstract: This invention is an aggregate extruder for the deposition of a multi-layered aggregate bed having layers of differing aggregate material. The extruder is divided into three sections transversely disposed over a defined surface, each of the sections contains a different aggregate material. A front grading baffle is mounted behind a front panel extending intermediate side panels forming the front dispensing section. A second grading baffle is mounted between the first and rear grading baffles forming the middle dispensing section, behind the front dispensing section, and a rear dispensing section. The extruder is self-propelled by a hydraulically operated ram mounted to each side panel. A panel is mounted to the rear of each side panel of the hopper and extends rearward thereof to define channel within which aggregate is maintained as the hopper moves along the surface. When the ram is activated it extends rearward for engagement with a form, and pushes the extruder along the defined surface.

Abstract: A liquid-resistant protective layer which at least consists of a material layer containing clay, has, adjacent at least one edge of the layer, at least one groove or slit which extends into the material layer containing the clay to enable sealed joints to be formed between contiguous protective layers.

Abstract: The remediation of heterogeneous subsurfaces is extremely time consuming and expensive with current and developing technologies. Although such technologies can adequately remove contaminants in the high hydraulic conductivity, coarse-grained sediments, they cannot access the contaminated low hydraulic conductivity fine-grained sediments. The slow bleed of contaminants from the fine-grained sediments is the primary reason why subsurface remediation is so time-consuming and expensive. This invention addresses the problem of remediating contaminated fine-grained sediments. It is intended that, in the future, a heterogeneous site be treated by a hybrid process that first remediates the high hydraulic conductivity, coarse-grained sediments, to be followed by the process, described in this invention, to treat the contaminated low hydraulic conductivity fine-grained sediments.

Abstract: A geosynthetic clay liner with a low permeability or controlled permeability intermediate sheet is provided. The liner includes two outer sheets with two layers of bentonite and an intermediate sheet disposed therebetween. The intermediate sheet may be rippled or deformed to enhance the structural stability of the liner. The intermediate sheet may be chosen from a material with low or ultra-low permeability characteristics or may be chosen from a material with controlled or directional permeability characteristics.

Abstract: A bead for forming a barrier layer over an underwater surface. Generally, a plurality of such beads are required to form an effective underwater barrier layer. Each of the beads comprises a core, preferably formed of a piece of gravel. A sealant layer is provided which at least partially encapsulates this core. The sealant layer includes a clay and a binder. The binder facilitates the adhesion of the sealant layer to the core of the bead. To form such an underwater barrier layer over contaminated sediments beneath a body of water, a plurality of the beads are deposited on top of the contaminated sediments.

Abstract: A clay liner is provided for use in constructing low permeability barriers in the bottom of landfills and man-made bodies of water. The liner is provided in the form of a layer of bentonite preferably disposed between a primary carrier sheet and a cover sheet. At least one outer edge of either the cover sheet or the primary carrier sheet is made with the fabric that is allows substantial bentonite migration while the remaining areas of the cover sheet or primary carrier sheet are fabricated from a fabric that does not permit substantial bentonite migration. When two liners are disposed adjacent to each other in the bottom of the landfill or pond, the two liners are overlapped so that the more open portion of one liner engages the adjacent liner. Upon activation, the bentonite migrates through the more open fabric to create a seal between the two adjacent liners. The result is a self-sealing geosynthetic clay liner system.

Abstract: Soil that is contaminated by hydrocarbons or other deleterious chemicals is processed through a soil shredding apparatus to break the soil into small particles having a substantially uniform maximum size. The particles are then conveyed to a location above a deposit area and directed onto the deposit area to form a growing pile of contaminated particles. Concurrently, a substantially cone shaped spray of an aqueous solution containing anti-contaminating agents, such as bacteriological microbes is sprayed on the pile. The configuration of the conical pile, taken in conjunction with the application of the liquid spray produces a rolling of the particles down the sides of the growing conical pile, thereby insuring the contacting of substantially all of the surfaces of each particle by the liquid containing the decontaminating agents.

Abstract: A process for forming notched irrigation laterals uses a construction laser adapted to propagate radiation along a planar path, and a device that both detects the radiation and is used to manually form notches in the lateral. The laser is positioned relative to the longitudinal axis of the lateral so as to minimize optical interference during the formation process.

Abstract: A liner is disclosed for a waterway of the type adapted to overlie the bottom of the waterway while a cementious layer covers and protects the liner. The liner itself is positioned at the bottom of the waterway by a machine having two elongated and spaced apart guide rails, each having a hollow interior and a longitudinally extending slot open at each end. The liner includes an elongated, flexible and water impervious sheet of a geomembrane material, such as polyvinyl chloride (PVC) or polyethylene material, having two spaced apart side edges. A strand is secured along each edge of the sheet by wrapping a flap of the sheet around the strand so that the flap encircles and then flatly abuts against one side of the sheet. A heat seal between the flap and the sheet bonds the flap and sheet together and the enclosed strand is then longitudinally slidably positioned within the interior of one of the guide rails.

Abstract: The invention relates to a cement-based injection grout for filling-in and consolidating fine cracks.According to the invention, the injection grout is produced from a finely ground Portland cement with removal of all the particles of sizes greater than 30 microns, the said cement having added to it a water-reducing plasticizer or thinner in a proportion not exceeding 2% and being mixed with water, the weight ratio of the quantity of water to the quantity of cement not exceeding 0.6.

Abstract: A canal paving machine is described. The machine comprises an elongated frame which extends transversely across the canal and which is propelled the length thereof while water continues to flow in the canal. A concrete paver is supported on the frame and is designed to lay concrete on one of the sides of the canal and at least a portion of the bottom of the canal as the frame is moved along the length of the canal. Dam members encircle the concrete paving apparatus to protect it from water flowing in the canal during the paving operation.

Abstract: A self-propelled machine for concreting a ditch includes a caterpillar band which contacts and rolls on the bottom of the ditch, a propulsion unit for driving the displacement belt, and a spreading system for spreading concrete on the bottom and sides of the ditch.

Abstract: A continuous structural laminate includes a plurality of continuous generally parallel spaced integrally bonded porous blankets with a continuous polymeric matrix extending through each porous blanket. The polymeric matrices include solidified polymeric mixtures with each mixture including a polymer forming material, a gas foaming agent, a catalyst and a major portion of a particulate reinforcement. The polymeric matrices include compatible polymer forming materials. At least two of the blankets include polymeric matrices with differing particulate reinforcements. The continuous structural laminate is formed and applied with mobile apparatus including a support portion, a raw material supplying portion, a mixing portion, a matrix forming portion and a control portion. The support portion includes at least two base sections with carriages depending from a first base section including a plurality of spaced transverse axle assemblies and wheels mounted on free ends of each axle assembly.

Abstract: A method for forming cementitious material, such as gunite or the like, to a desired cross-sectional profile for an interior structure such as a swimming pool, skateboard bowl or the like. A forming assembly includes a cutting edge, which is formed so as to correspond to the final desired profile of the structure. The forming assembly is mounted so as to be pivotable about a pivot axis substantially coincident with the center of the structure being formed. In this manner, when the cementitious material is applied to the side walls and bottom of the excavation to a depth slightly greater than that as finally desired, and the forming assembly pivoted 360.degree. about its pivot axis, the final desired cross-sectional profile of the structure is attained due to the action of the forming assembly striking off the excess material applied to the excavation.

Abstract: A canal trimming machine is disclosed which is designed to trim the bottom and sides of an earthen canal so that the canal may be lined and paved. The machine comprises a frame which extends across the width of the canal and which has propelling tracks at the opposite ends thereof which are driven along the canal in the proper direction and at the proper grade. A trimmer is longitudinally movably mounted on the frame and trims at least one-half of the bottom and a majority of one side of the canal. The trimmer is automatically positioned at the proper grade to ensure that the bottom and sides of the canal will be properly prepared for the lining and paving operation. A rock spreader is also mounted on the frame and trails behind the trimmer to fill low spots in the canal so that an even surface will be provided for the lining and trimming operation.

Abstract: A method for lining or relining a sewer manhole, apparatus comprising an improved leak resistant manhole, and a cementitious mixture for lining/relining manholes. A homogeneous, monolithic, cementitious liner is spray applied in place within a concrete or brick-and-mortar manhole infrastructure without forms, webbing, or re-bar. A manhole to be serviced is first located and spray cleaned with water. Loose concrete and mortar fragments of the original structure are forcibly removed. A cementitious mixture is spray-applied to the interior surfaces of the manhole to create a continuous, monolithic interior liner. This lining is configured substantially identically to the internal shape and geometry of the manhole. When the liner sets after installation, a substantially impervious water and chemical resistant barrier prevents manhole ingress/egress by ground water.

Abstract: Apparatus is provided for introducing and joining diaphragms in slotted walls. The slotted inner connecting pipe of one diaphragm is introduced into the slotted outer connecting pipe of another diaphragm. Furthermore apparatus for fusing together the two connecting pipes is placed within the interior of the inner pipe and can move through the latter. The apparatus has a heating device for heating and fusing the two connecting pipes together.

Abstract: An apparatus for lining a canal is described as well as the method for lining the canal. The apparatus comprises an elongated frame which extends transversely across the canal and which is propelled the length thereof. A concrete paver is supported on the frame and is designed to lay concrete on one of the sides of the canal and at least a portion of the bottom of the canal as the frame is moved along the length of the canal. A flexible sheet material is positioned on the canal sides and bottom just prior to the concrete being positioned thereon. The PVC is positioned on the canal in a substantially wrinkle-free and untensioned condition. The method of lining the canal is also described.

Abstract: A method of constructing a swimming pool by laying a concrete shell of 80 mm thickness without any substantial reinforcement. A glass reinforced plastic of 5 mm thickness is then laid over the concrete once the concrete has cured. This particular combination between the fiberglass and the concrete shell allows the shell to crack and move in relation to the reinforced plastic layer, without transmitting any stresses to the reinforced plastic layer. This results in a pool which allows any stresses due to soil subsidence, movement, etc. to be transmitted to the concrete shell and not the reinforced plastic layer thereby leaving the plastic layer free of cracks.