Static molds – In situ construction engineering type or building type-mold... – Forming building structure
Reexamination Certificate
1997-06-20
2001-11-20
Nguyen, Nam (Department: 1722)
Static molds
In situ construction engineering type or building type-mold...
Forming building structure
C249S048000, C249S051000, C249S05300R, C249S134000, C249S143000
Reexamination Certificate
active
06318700
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an anti-frost concrete mould.
BACKGROUND OF THE INVENTION
The use of forms, casings, moulds and shells is well known in the construction of cast-in-place concrete footings, piers and piles. These footings, piers and piles are used to transfer the loads of buildings, bridges, decks, porches, raised walkways, ramps, mini-home supports, highway sign posts and add-ons of existing structures to the underlying supporting soil. The concrete of a cast-in-place pile or footing is cast inside a mould that usually consists of a tin metal, plastic or paper shell left in the ground. The mould is usually so thin that its strength is disregarded in evaluating the structural capacity of the pile or footing. However, the mould must have adequate strength to resist collapse under the pressure from the surrounding backfill before it is filled with concrete. Similarly, if the mould is filled with concrete without the support of backfill, the mould must have sufficient strength to resist bursting pressures.
In northern latitudes, such as those which encompass Canada, northern Europe and the northern portions of the United States, soils, and particularly fine grained water saturated soils, are susceptible to the formation of ice lenses and frost heave. These phenomena can greatly diminish the stability and integrity of structures embedded in such soils. Therefore, footings are placed at a depth of not less than the depth of normal frost penetration. This prevents damage to the footing from the swelling and shrinkage of the surrounding soil caused by freeze-thaw cycles or displacement from frost heaving. However, while placing the footing below the depth of frost penetration will protect the footing from the effects of frost action, the pier that transfers the loads from the supported structure to the footing remains above the frost line and therefore remains vulnerable to frost and ice action.
The mechanisms of frost heave and frost action are well known to persons skilled in the art. The main phenomenon of concern to the construction industry is the displacement, laterally and vertically, of foundation members due to loads placed upon them from frost action. Where surrounding soil is frozen to a pier connecting a supported structure to a supporting footing, movement of the soil frozen to the pier will displace the pier. This will diminish the stability of the footing and structure to which it is attached no matter the depth of the footing below the frost line. In northern climates, a pier must be of a significant length to connect a footing placed below the frost line to the structure on the surface. Most of the entire length of the pier embedded in frost susceptible soil will be vulnerable to frost action.
Many examples of concrete moulds are known. However, none of these addresses the problem of being able to resist upward displacement due to frost heave in the surrounding soil. The problem is particularly acute in climates where the footing must be placed at a significant depth below the surface to remain unaffected by frost. One example of the known art is described in U.S. Pat. No. 5,271,203 issued to Nagle on Dec. 21, 1993 and entitled “Support Form For A Setable Material”. Nagle recognizes the problems associated with frost heave and compares the advantages of his invention over conventional thin-walled constant diameter moulds, such as the SONATUBE™, which he states are vulnerable to tipping and leaning due to lateral forces caused by frost heave in surrounding soil. While the Nagle invention relies upon its conical shape to resist frost heave, it possesses longitudinal ribs that could permit water to collect and freeze therein thus allowing localized frost action to act detrimentally upon the mould.
Furthermore, the dimensions of the Nagle invention, specifically its height to width ratio, approaches unity. Therefore, for deep frost line applications, where the mould would have to be embedded deeply into the soil and remain connected to the above surface supported structure, the resulting mould of the Nagle design would have to be very large. This would result in greater expense and the mould would require a significant volume of setable material to fill it.
An additional disadvantage of the Nagle invention is that it is of a fixed height and cannot be adjusted at the work site to adapt to the variable depth of excavations. Furthermore, the Nagle invention does not possess anchoring means to prevent the mould from shifting as the concrete is poured. Furthermore, if the Nagle invention is left exposed to the elements for several days before the setable material is poured, there are no means to anchor the Nagle invention to the ground to prevent wind and rain forces from displacing the Nagle invention.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved concrete mould that resists the detrimental action of frost heave.
In accordance with an aspect of the present invention there is provided an anti-frost concrete mould that resists the adhesion of frost, ice and frozen soils. The mould generally resembles a cone and comprises an upper frustoconical portion coaxially aligned with a lower drum portion whose outer surface extends outwardly and downwardly from a transitional shoulder. The shoulder connects the upper portion of the mould with the lower portion of the mould. The mould has opposed top and bottom ends and a continuous and smooth exterior surface. The mould is manufactured from recycled material bound with a binding agent. The bottom end of the mould has an integral anchor flange extending horizontally from it. The anchor flange is apertured at regular intervals for holding anchoring means in the form of pins, nails, dowels and other hold-down devices. The mould is sufficiently resilient and rigid to withstand the pressure from surrounding soil attempting to collapse the mould inwardly. The mould is further able to withstand fluid pressures from the fluid setable material contained therein attempting to burst the mould outwardly. The mould has a smooth outer and inner surface.
In a further aspect of the present invention there is provided an inexpensive and simple method of manufacturing the mould comprising the steps of: determining the appropriate dimensions of the mould to suit the intended purpose; producing a die in obedience to the desired dimensions of the mould; covering said die with a non-stick fabric; applying a plurality of layers of a mixture of binding agent and recycled material to the fabric covering the die until a mould of the desired thickness is formed; finishing the mould with a smooth surface of binding agent.
In a further embodiment of the invention, the mould may be manufactured using injection moulding techniques.
In yet another aspect of the present invention it is contemplated that the mould be manufactured from resilient, rigid and light weight recycled materials, such as, wood, plastic, cloths, fabrics or other synthetic or natural materials bound together using a binding agent. The outer surface of the mould will have a smooth surface with frost and ice adhesion resistant properties.
Yet another aspect of the present invention contemplates a method of using the mould comprising the steps of: excavating a cavity in the earth; placing a mould of desired dimensions into the cavity; anchoring the mould through the anchoring flange using anchoring means; adjusting the height of the mould as necessary by cutting away excess mould along the grooves at the top end of the mould; backfilling the excavation around the mould; if necessary, capping the open top end of the mould with capping means to prevent water from collecting within the mould; when convenient, filling the mould with a setable material, generally concrete; insert the desired structure to be supported by the concrete before setting or alternatively allow the concrete to set and then affix the concrete mould to the structure to be supported; and, leaving the mould in place.
Advantages of the present inventio
Leyson Joseph
Nguyen Nam
Simpson, Simpson & Snyder, PLLC
LandOfFree
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