METHOD FOR FILLING LARGE VOLUME HOLES

The present disclosure provides methods to fill large holes rapidly with polyurethanes by injecting polyurethanes in a plurality of containers having volumes less than the volume of the hole to be filled, letting the polyurethanes cure in the containers, and using the polyurethane-filled containers to fill the large hole. Additional filling polymers may be added in between and on top of each layer of polyurethane-filled containers.

DETAILED DESCRIPTION

According to one aspect of the present disclosure, there is provided a method to rapidly fill holes of a minimum volume using rigid polyurethanes or other materials that exhibit similar properties. In the preferred embodiment, the volume of the holes to be filled is at least about 8 cubic feet. In one embodiment, the preferred minimum length is about 2 feet and the preferred minimum width is about 2 feet. The holes can be of any shape, be near the surface, or be deeper in the earth.

The holes of a certain minimum volume can be filled rapidly or quickly using polyurethane by providing a faster curing time for the total volume of polyurethanes used to fill the holes. In the preferred embodiment, faster curing is achieved by filling individual containers of certain sizes with polyurethanes to form filling blocks. In one embodiment, the container is a bag which is sized to provide a desired curing time of the polyurethanes contained in the bag. For instance, a polyurethane composition that releases a higher exothermic energy may be filled in bags that are smaller in volume than a polyurethane composition that releases a lower exothermic energy.

Preferably, the containers are bags made of materials that readily accept and contain expanding polyurethane, and also quickly and efficiently dissipate heat. Exemplary materials include paper, mesh, fiberglass, polyester, textile, fabric, and other materials with similar heat dissipation properties. Both synthetic and non-synthetic textiles are contemplated, as well as mineral, plant, and animal textiles. Preferably, the bags can comprise materials used to make sandbags.

Other types of non-rigid, rigid, or partly rigid containers may be used. Preferably, the containers are fashioned, at least in part, of materials that accelerate exothermic heat dissipation by way of conduction, convection, or radiation. For example, in one embodiment characterized inFIG. 4, the container is a rectangle comprising a rigid high-conductivity material30such as thin metal on five sides, with an expandable flexible material32on the sixth side and a hole28on one side in which the polymer is injected. The expandable side stretches as needed to catch the overflow expansion of the expanding polymer and may be made of rubber, rubber-like material, 2-way or 4-way stretch fabrics, or any material capable of stretching to increase the volume of the container. In the alternative or in addition, one or more sides may contain folds34in order to allow for expanded volume of the container as needed.

In another embodiment, a semi-rigid container comprises a rigid skeletal structure with non-rigid material in suspension around said skeletal structure, as contemplated inFIG. 5. The skeletal structure22may be constructed of any rigid or semi-rigid material capable of maintaining integrity at least during initial contact with the expanding polymer. The semi-rigid container may be open at one end26or may be enclosed, with the enclosure having a polymer injection opening28. In one embodiment, non-rigid, heat dissipating material24is suspended around the skeletal structure22to form a shell. Examples of the non-rigid material include paper, mesh, fiberglass, polyester, textile, fabric, and other materials with similar heat dissipation properties. In some embodiments, one or more sides of non-rigid material may be substituted with rigid or partially rigid material. Expanding polymer is injected into the container until full. For a container open at one end, the injection operator gauges the correct amount of polymer such that the polymer will expand to fill the container.

The filling blocks need not be square, rectangular, or spherical. In one embodiment, the container may be uniquely shaped to dissipate heat, such as by maximizing the surface area of the container. A person skilled in the art of heat sinks would understand how to fashion a container of optimum surface area which takes into account the expansion rate, rise time gel time, and tack free time of the polymer.

In certain embodiments, the container or bag need not maintain its integrity through the expansion/injection process. The container need only affirmatively shape the expanding polymer. After the polymer is shaped into the preferred geometric mold, the container may be discarded, and the block of polymer placed into the hole.

For simple shapes, the dimensions of the containers are preferably about 12 inches×14 inches×18 inches. In another embodiment, the dimensions of the containers are preferably 14 inches×14 inches×26 inches, such as those used for making sand bags. Preferably, the containers allow the exothermic heat to dissipate to achieve the desired curing time, such as through perforations, high surface area, material that promotes convection, conductive material, or similar systems to reject heat.

The desired curing time is preferably the quoted curing time of the rigid polyurethane or other expanding polymer. In one embodiment, the desired curing time is about 15 minutes to about 20 minutes. The smaller volume of the containers in comparison with the volume of the hole to be filled, in conjunction with the exothermic heat dissipation qualities of the container materials, allows the polyurethane polymer to cure within the desired time period.

The method according to the aspects of the present disclosure further comprises using multiple filling blocks to fill the hole. In the preferred embodiment, the hole is filled layer-by-layer with multiple filling blocks, such as containers filled with cured polymer, like those shown inFIG. 1. InFIG. 1, the bottom part of hole10is filled with a first layer of containers12containing cured polymer. In the preferred embodiment, additional polyurethane14is added to the layer of containers12to fill the open space14between the containers and to cover the layer of containers12. In one embodiment, the additional polyurethane completely covers the layer of containers12to form layer14. Afterward, multiple additional cured polymer containers are then used to fill above that covered container layer. Additional polyurethane is then added to the open space14between those containers, completely covering the container layer. The process is repeated until the large hole is filled to the desired level. Individual containers12act as individual filling units for filling in hole10.

The exothermic heat is dissipated more rapidly through the total surrounding surfaces of containers12via the natural heat sink of adjacent earth, water, or air, as compared to the heat dissipation of the same amount of polymer directly injected into the hole. The total reduction in curing time and the faster achievement of stronger physical characteristics of the polymer used is accomplished by the methods of the present disclosure.

In one embodiment, containers12of cured polymers can be made off-site and transported to the site of the project where hole10is located. In another embodiment, containers12can be made at the site of the project where hole10is located, either outside of the hole or inside the hole itself. In one embodiment, containers12have various dimensions.FIG. 3, for instance, shows containers with smaller dimensions15and various shapes16placed at the edges of hole10whereas containers with larger dimensions17can be placed at the center of hole10. In another embodiment, containers12have uniform dimensions, as inFIG. 2.

Different types of polyurethanes can be used with the method of the present disclosure. Preferably, the polyurethane exhibits compressive strengths of at least about 20 psi, more preferably at least about 30 psi, and most preferably at least about 40 psi, when cured. Hole10can be filled with containers12containing different types of polyurethanes. In one embodiment, materials with compressive strength of at least about 40 psi are used to fill containers12that are placed around the periphery of hole10while materials with compressive strengths of at least about 20 psi or at least about 30 psi are used to fill containers12that are placed near the center or middle of hole10.

In one embodiment, the polyurethane comprises a two-part foam. The first component can be a mixture of polyols comprising a polyether polyol and/or a polyester polyol, a catalyst, and/or water. The water in the composition may be 3.44% by weight. The second component can be an isocyanate MDI. The mixing of these two components produces an expandable polyurethane foam the density whereof, at the end of expansion, varies according to the resistance opposed by the soil adjacent to the injection region.

In another embodiment, the chemical compositions comprise an aromatic isocyanate and a polyol resin blend. The polyol blend is formulated to provide a final rigid polyurethane foam product with a free rise density characteristic of between 5 and 10 pounds per cubic foot. The material is a two component system with a 1/1 ratio by volume. One example of such material is URETEK HRR Polyurethane manufactured by Bayer Material Science.

While polyurethane is mentioned specifically by name as the preferred choice, the use of the term “polyurethane” is not intended to be limiting, but rather exemplary. The methods of the present disclosure are applicable to other substances that exhibit similar properties as polyurethane and suffer from a similar problem of prolonged curing time in a large volume.

The method to fill any large hole with polymer, according to the present invention, substantially consists in first filling smaller containers of various selected sizes with expanded rigid polyurethane. The polyurethane in the container is then allowed to cure to at least about 90% of its fully cured physical strength characteristics for compressive, tensile, elongation, and shear strength, and then the container is placed into the hole.

In one embodiment, the container-filling process uses a liquid proportioner pump. There are a variety of types of liquid proportioner pumps known to those of ordinary skill in the art. It is within the knowledge and skills of a person of ordinary skill in the art to select an appropriate liquid proportioner pump and substance for use according to the aspects of the present disclosure.

Depending on the reaction profile characteristics (rise time, gel time, tack free time) of the substance selected, containers12are preferably injected with an appropriate amount of the liquid polyurethane components to provide sufficient liquid material to fill containers12with the cured polymer, which may have expanded substantially and have a final volume that is significantly larger than the initial starting volume in liquid form. After containers12are filled with polymer, and in some instances, after polymer expansion is completed, the filled containers12are set aside to cure, typically for a minimum of 15 to 20 minutes. For one job, the container-filling process is repeated until the total volume of the multiple expanded small containers is roughly equivalent to the volume of the large hole to be filled, e.g., hole10. According to another aspect, the container-filling process continues to provide “pre-made” containers having already cured polymers for future use. In one embodiment, containers12containing cured and/or expanded polyurethane can be placed into hole10. Containers12can be placed in a pattern or at random.

In one embodiment, a proportioner pump is used to add liquid polyurethane components to the stacked containers12to fill the space between the containers12. The polymers can be added at random layers, in a pattern, or for each layer of containers12, as shown as layer14inFIG. 1. In one embodiment, layer14is allowed to cure for at least about 15-20 minutes before additional containers12are added. As described, hole10is thereby filled with polyurethane without the current problem of longer polymer curing time, longer heat dissipation time, or higher likelihood of the polymer material itself to smolder because of excessive exothermic heat generation of polyurethane compositions, particularly large volumes of expanding polymers.