Stock material or miscellaneous articles – Composite – Of polyamidoester
Patent
1997-02-14
1998-02-10
Nakarani, D. S.
Stock material or miscellaneous articles
Composite
Of polyamidoester
156287, 156294, 4051502, 427202, 427204, 427205, 4273855, 4273936, 4274071, 4274195, 4284231, B32B 2740, C04B 4148, C04B 4152, E21D 1138
Patent
active
057167117
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for providing support to rock surfaces such as found in mine openings and, more particularly, relates to a method for providing gas-impermeable coatings on rock, masonry and concrete surfaces, specifically coatings which are fire retardant, which provide support to mine openings, and which prevent the flow of gases such as radon gas.
2. Description of the Related Art
The application of linings to the walls of mine openings to provide local restraint for rock masses such as by the spraying of a coating of shotcrete/gunite is known. It is believed that the cementing action of the coating on adjacent parts of rock fractures, due to the shear strength of the coating material, a possible "caisson" support effect, and the protection of rock faces from deterioration due to oxidation, strengthens the wall rock. The application of shotcrete/gunite is expensive and the linings are brittle and are lacking in significant tensile strength, and are prone to fracturing upon flexing of the rock such as during mine blasting activities or rock bursting.
It is an object of the present invention to provide a relatively inexpensive, flexible, air-tight coating having good tensile strength on wall surfaces to induce the caisson effect to avoid fracturing of rock and to actively resist spalling, bursting and localized gravity falls of loose rock.
Rock, concrete and masonry walls and floors are sufficiently gas permeable to allow radon gas infiltration driven by air convection (i.e. by pressure-driven air) into quarters such as residential and industrial sites.
It is another object of the invention therefore to provide a tight coating which is substantially gas impermeable to prevent the diffusion of noxious gases such as radon gas into residential and industrial sites.
Gas impermeable coatings such as polyurethane polymers are not strongly resistant to ignition and flame consumption and will burn with substantial smoke production once ignited.
It is a further object of the present invention to provide an inexpensive, flexible, air-tight coating on wall surfaces, such as mine wall surfaces, which is fire resistant.
SUMMARY OF THE INVENTION
In its broad aspect, the method of the present invention comprises applying, such as by spraying, an adherent coating of a plastic material such as polyurethane which has a rapid cure rate and which contains a fire retardant material onto rock and the like surfaces to provide a gas-tight fire resistant lining whereby the rock is supported by the caisson effect and the mechanical strength properties of the adherent coating.
The method of the invention preferably comprises spraying a two-component polymer such as polyurethane as a coating onto a rock surface for curing thereon and spraying a layer of inorganic particulate material such as unexfoliated vermiculite onto the said coating of polymer with or without concurrent application of further layers of said polymer before completion of curing of the coating whereby the particulate material adheres to the polymer coating. An aqueous dispersion of inorganic particulate material such as vermiculite, which may be in the exfoliated form, can be applied onto the initial coating.
The plastic material preferably is a composition which can be applied easily by spraying as a uniform coating at high application rates to form an air-tight membrane, has gap filling and covering capabilities (in excess of 2 mm wide gap coverage), has sufficient elasticity to deform readily under tension (between 5-15% strain without breaking) and is readily adhesive to rock surfaces including rock surfaces that are not totally dry.
In its broad aspect, the composition of the invention comprises a coating or layer of two-component polymer such as polyurethane. The coating preferably includes a layer of inorganic, particulate material such as unexfoliated vermiculite applied to the polymer surface prior to completion of curing of the polymer. The layer of said inorganic, particulate ma
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Archibald James
Calder Peter N.
Maine Frank
Canadian Mining Industry Research Organization--Organisation de
Nakarani D. S.
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