Method to bond concrete slab to metal

Abstract

The method of bonding concrete to a metal substrate eliminates the additional costs in time and labor involved in providing a mechanical bond between concrete and metal surfaces (e.g., construction steel). The method involves the use of an adhesive bonding agent applied between the concrete and metal components that cures to bond the two components together. The method may be used to form a laminar composite deck formed by a concrete slab bonded to a metal deck, a composite joint formed by bonding a concrete slab to a metal beam or joist, and other composite structures.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/694,700, filed Jun. 29, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to construction methods and composite construction materials. More specifically, the present invention comprises methods of adhesively bonding concrete to a metal substrate, e.g., construction steel, to form a composite material by chemical bonding, precluding the need for mechanical attachment. The present invention extends to a composite construction material formed by the method, e.g., a composite deck having a concrete slab chemically bonded to a metal deck or substrate.

2. Description of the Related Art

Steel (or other metals) and concrete have relatively poor adhesion to one another when fresh concrete is poured upon a metal substrate (e.g., steel construction members, etc.). The relatively weak bond generally separates in short order due to differential thermal expansion between the materials, surface corrosion of the metal, etc. No adhesion between the materials exists at all, when a cured concrete element is placed upon a metal substrate. Accordingly, it is conventional in the construction trade to provide some form of mechanical attachment between the concrete and steel elements, in the form of indentations, protrusions, and/or small passages formed in the steel members that the concrete can flow around and through in its plastic state to adhere to the metal. Such metal elements are known as “Hi-Bond” steel. Alternatively, concrete may be conventionally secured to a metal substrate by studs, anchor bolts and the like passing through the concrete (either before or after curing) and secured to the metal construction member.

Both of these general methods of mechanically securing concrete to a metal substrate increase construction costs. In the case of “Hi-Bond” steel, there is additional expense involved in forming the indentations, protrusions, and/or other elements in the steel material in order to provide the steel with sufficient “tooth” for the concrete to adhere thereto. Where such specialized steel is not used, additional materials and labor are required to set bolts or other anchors into the concrete and steel to attach the concrete and steel components mechanically to one another.

The present inventor is aware of various methods and systems for adhesively securing construction materials to one another. An example is found in French Patent No. 2,678,658, published on Jan. 8, 1993, describing (according to the drawings and English abstract) different embodiments of composite panels formed of polystyrene cores having “rock wool” (asbestos) insulation applied to the faces thereof. The polystyrene-asbestos composite panels are then adhesively bonded or mechanically secured to a cured concrete slab to provide acoustic and thermal insulation.

None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a method of bonding concrete to a metal substrate solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The method of bonding concrete to a metal substrate is applicable for adhesively bonding either uncured concrete slurry in its wet, plastic state or hardened, cured concrete to a metal substrate, e.g., construction steel. The method involves the application of a bonding agent to the metal substrate and then applying the concrete to the bonding agent coating before the bonding agent cures. In the case of wet concrete, the bonding agent is allowed to cure partially before the concrete is poured. In the case of cured concrete, the bonding agent is applied to the metal substrate (and/or to the surface of the concrete), and the concrete and metal are joined immediately after the application of the bonding agent to one or both of the components. The bonding agent develops its full adhesive strength between the two materials as it cures. The bonding agent may comprise a two-part epoxy mixture that is mixed immediately before application, the two parts reacting chemically with one another for curing. The cured bonding agent may have sufficient resilience to accommodate any differential expansion between the materials.

These and other features of the present invention will become readily apparent upon further review of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially broken away perspective view of a metal panel having an adhesive bonding agent applied thereto in accordance with the method of the present invention, with a concrete slab partially overlying the metal panel.

FIG. 2 is a partially broken away perspective view of a cured concrete slab applied to an I-beam and bonded thereto according to the method of the present invention.

FIG. 3 is a partially broken away perspective view of a prior art mechanical method of securing concrete to a metal panel.

FIG. 4 is a partially broken away perspective view of a prior art mechanical method of securing a cured concrete slab to an I-beam.

FIG. 5 is a flowchart describing the basic steps in the method of adhesively bonding a wet, plastic concrete slurry to a metal substrate.

FIG. 6 is a flowchart describing the basic steps in the method of adhesively securing a hardened, cured concrete panel to a metal substrate.

Similar reference characters denote corresponding features consistently throughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention comprises various embodiments of a method for adhesively bonding concrete to a metal substrate (e.g., metal deck panel, I-beams, etc.). The method may be applied to either a hardened, cured concrete slab or element, or to the adhesive bonding of a wet, uncured concrete slurry to the metal substrate. The present methods eliminate need for mechanical fastening of the metal to the concrete, thus providing greater economy in the manufacture of the metal and/or the labor involved in the construction of the metal and concrete structure. While the present methods are particularly well adapted for use with construction steel, they may be applied to other metals, e.g., aluminum, copper, etc., as well, for adhesively bonding concrete thereto.

The present invention also extends to a composite material useful in the construction trades formed by chemically bonding concrete to metal. An example of such a composite material is a composite deck formed by bonding a concrete slab to a metal deck. Such a composite deck may form a floor or ceiling in a building or other structure.

The present invention also extends to a joint formed by chemically bonding concrete to metal. An example of such a joint is a joint between a concrete slab and an I-beam formed by bonding the concrete to the I-beam with a bonding agent that forms bonds to both the concrete and the I-beam.

FIG. 1 provides a partially broken away perspective view of a composite concrete panel 10 being adhesively bonded to a metal substrate panel 12. While the concrete panel 10 is illustrated as a solid slab, it will be seen that the continuous, unbroken metal deck panel 12 below the concrete 10 precludes the flow of a wet, uncured concrete slurry through the panel 12. Thus, the concrete material 10 may be provided as a wet, uncured slurry, and is shown broken away in FIG. 1 to show the underlying structure and application of the bonding agent. Reinforcing rods 14 (“rebar”) may be placed over the metal substrate panel 12 prior to pouring the concrete 10 for additional strengthening of the composite assembly as desired or required.

The adhesive bonding agent 16 may be any bonding agent capable of forming a bond to both concrete and the particular metal used as the substrate, usually steel. An example of such an adhesive bonding material 16 is a two part epoxy adhesive material manufactured by the Universal Form Clamp Co., known by the brand name of Unibond MV®. The two parts of this bonding material are mixed prior to application and, once mixed, react chemically with one another to cure to a hardened plastic state. However, the bonding material 16 is in a liquid state prior to and immediately after mixing, prior to its curing reaction. The bonding material 16 is relatively thin, permitting it to be applied by means of a spray gun 18 or the like, or by means of a roller 20 or brush 22.

The bonding strength of the adhesive bonding material 16 in its fully cured state may require coating the contact surface(s) 24 of the construction material(s) over only a portion thereof, as shown by the areas of bonding material 16 being applied in FIG. 1. However, the contact surface(s) of the construction material(s) may be completely coated with the adhesive bonding material 16, as desired or required. The bonding agent 16 is captured between the concrete material 10 and the metal substrate 12, and develops an adhesive bond between the two materials 10 and 12 as the bonding agent 16 develops to a fully cured state, thereby producing a laminar concrete and metal composite panel.

The bonds formed between the concrete and metal layers have sufficient strength and resilience that the concrete and metal are securely bonded together without slippage between the layers, but will have sufficient stretch that the bonds will not break with expansion and contraction of the layers upon variations in temperature within a range that permits use of the material in the building and construction trades. While there is a small degree of bonding that can occur between concrete and metal without the use of adhesive or a bonding agent, such bonds are brittle and are typically destroyed by any differential movement between the two layers, so that no allowance for such bonding is made in the structural engineering design of buildings and other structures. The composite structures formed according to the methods of the present invention, however, are able to withstand normal expansion and contraction without slippage between the two layers.

The method of the present invention is adaptable for adhesively bonding a wet, uncured concrete slurry to a metal substrate, as noted further above. This is accomplished by first coating only the contact surface 24 of the metal substrate 12 with the mixed adhesive bonding agent 16 (either partially or completely coating the contact surface, as noted further above), and allowing the bonding agent material 16 to cure partially. The curing time will depend upon various factors, e.g., the specific bonding agent being used, the temperature, and perhaps humidity and/or other factors. A typical partial cure time might be on the order of three hours or so.

Once the adhesive bonding agent 16 has cured partially to the desired state, the wet concrete slurry 10 is poured over the contact surface 24 of the metal substrate 12 and its adhesive bonding agent coating 16. The partially cured bonding agent material 16 flows slightly and blends with the immediately adjacent concrete slurry, thereby producing a solid adhesive bond between the concrete and the bonding agent when the two materials are fully cured, and with the bonding agent developing a firm adhesive attachment to the underlying metal substrate when the adhesive agent has fully cured.

This process or method is described generally in the flow chart of FIG. 5. Briefly, the method comprises the steps of: coating the metal with adhesive (step 100); allowing the adhesive to partially cure (step 102); applying concrete slurry to the metal (step 104); and allowing the adhesive to cure between the concrete and the metal (step 106). Additional strengthening of the composite concrete and metal structure may be accomplished as required by conventional mechanical attachment (e.g., rivets or bolts 26, or welding) of additional metal supports, e.g., an I-beam 28, to the metal substrate panel 12, as shown in FIG. 1.

FIG. 2 is an illustration of a somewhat different process, in which the concrete is first cured to a hardened state prior to adhesively bonding the concrete to the metal substrate to form a joint between a concrete slab and an I-beam. In FIG. 2, a fully cured, hardened concrete slab 30 is bonded to an underlying or adjacent I-beam 28. The cured slab 30 is supported only by the underlying metal structure 28, with no completely extensive metal substrate panel being provided in the assembly of FIG. 2. The concrete slab 30 may be reinforced using rebar elements 14, as is conventional in reinforced concrete structures.

However, rather than attaching the cured concrete slab 30 to the metal support structure 28 by conventional mechanical means, an adhesive bonding agent 16 is used. The bonding material 16 is applied to the contact surface 24 of either the cured concrete slab 30 or the metal support 28, or both, as both materials provide a hard surface for the application of the liquid adhesive material 16. The adhesive material 16 may be applied to a part of the contact surface 24 or to the entire surface by any conventional means, e.g., spray, roller, or brush, as shown in FIG. 1. In this case, it is not necessary to allow the bonding agent 16 to cure partially, as both structural elements 28 and 30 are in a fully hardened state. Thus, the two elements 28 and 30 may be assembled to one another immediately after the bonding agent 16 has been applied to one or the other, or both, of the elements.

It will be noted that the juncture of the cured concrete panel 30 and metal support structure 28 is devoid of any form of mechanical attachment or connection, with the adhesive bonding agent 16 providing all of the attachment strength between the two components 28 and 30. This process of adhesively bonding a fully cured concrete slab or element to a metal structural member is described generally by the flowchart of FIG. 6. Briefly, the method comprises the steps of: coating the metal with adhesive (step 110); applying cured concrete to the freshly coated metal substrate (step 112); and allowing the adhesive to cure between the concrete and the metal (step 114).

FIGS. 3 and 4 illustrate conventional prior art means of securing concrete and metal elements to one another. In FIG. 3, a “Hi-Bond” construction steel panel S having a series of indentations, protrusions, and/or other irregularities I therein, has a poured reinforced concrete slab C1 resting thereon. The indentations and/or other irregularities I of the construction steel panel S provide a mechanical grip or “tooth” for the concrete slab Cl to adhere to the panel S as the uncured, fluid concrete flows around and into the irregularities I as it is poured on the panel S. Additional mechanical attachment strength between the concrete slab C1 and the underlying metal panel S may be provided by studs, bolts or pins P, which pass through the concrete slab C1 and are anchored in the metal panel S, and/or to the underlying I-beam B.

FIG. 4 is an illustration of a prior art assembly of a cured reinforced concrete slab C2, which has been mechanically attached to an underlying I-beam B by means of, studs, bolts or pins P. While the reinforced concrete slab C2 is self-supporting in its cured state, conventional construction relies upon mechanical means for the attachment of concrete elements to structural steel elements, generally as shown in FIG. 4.

In conclusion, the present method of adhesively bonding concrete to a metal substrate, greatly simplifies the construction process where concrete and steel structures are formed. This simplification of the construction process results in various economies during construction, as less costly structural steel may be used and less labor is involved due to the elimination of mechanical fasteners. The adhesive bonding agents which may be used in accordance with the present method have been found to provide more than sufficient strength in such applications, and their physical properties can accommodate the thermal expansion and contraction of the adhesively joined or bonded materials as well as other adverse effects. Accordingly, the present method of bonding concrete and metal elements together will prove to be quite beneficial to the building and construction trades, and to other fields where concrete and metal composite structures are used.

It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.

Claims

1. A method of bonding concrete material to a metal substrate material, comprising the steps of:

(a) coating at least a portion of the surface of either material with a liquid adhesive bonding agent;

(b) applying the concrete material to the metal substrate material before the bonding agent has cured, capturing the bonding agent coating therebetween; and

(c) completely curing the bonding agent coating between the metal substrate material and the concrete material, thereby forming a concrete and metal composite.

2. The method of bonding concrete to a metal substrate according to the method of claim 1, further including the steps of:

(a) applying the bonding agent coating only to the metal substrate material;

(b) allowing the bonding agent coating to cure partially;

(c) pouring a wet concrete slurry onto the coated metal substrate material; and

(d) allowing the bonding agent to blend with adjacent concrete slurry as the bonding agent and concrete slurry cure completely together.

3. The method of bonding concrete to a metal substrate according to the method of claim 1, further including the step of applying the concrete material to the metal substrate material in a hardened, fully cured state.

4. The method of bonding concrete to a metal substrate according to the method of claim 1, further including the step of applying the bonding agent to the entire contact surface of the material.

5. The method of bonding concrete to a metal substrate according to the method of claim 1, further including the step of mixing the adhesive bonding agent from two separate parts before application.

6. The method of bonding concrete to a metal substrate according to the method of claim 1, wherein the step of applying the adhesive bonding agent coating comprises spraying, brushing, or rolling the bonding agent onto the material.

7. The method of bonding concrete to a metal substrate according to the method of claim 1, further including the step of attaching a metal support component to the metal substrate material.

8. The method of bonding concrete to a metal substrate according to the method of claim 7, wherein the step of attaching the metal support component to the metal substrate material comprises bolting, riveting, or welding.

9. A laminar composite material, comprising:

a layer of concrete;

a layer of metal; and

a bonding agent joining the layers of concrete and metal, the bonding agent forming adhesive bonds to the concrete and adhesive bonds to the metal.

10. A composite joint, comprising:

a slab of concrete;

a metal beam; and

a bonding agent joining the slab of concrete and the metal beam, the bonding agent forming adhesive bonds to the concrete slab and adhesive bonds to the metal beam.