BACKGROUND

Steel wire products, such as concrete rebar and other steel structural elements, for example, steel mesh or lattice, are frequently used in reinforced concrete and reinforced masonry structures. Frequently, these steel reinforcing members are subject to corrosive conditions, such as those resulting from deicing salts applied to roadways or marine conditions, in addition to the alkalinity of the particular concrete mixture being used.

Galvanizing is a well-known treatment process to protect steel reinforcing members from corrosion when embedded in a cementitious medium. Galvanization is the process of coating steel or iron with zinc. The zinc preferentially reacts to the conditions causing corrosion (such as in the presence of an electrolyte) and thereby serves as a sacrifice to protect the steel from corroding instead. In particular, the zinc serves as a galvanic anode protecting the steel, known as cathodic protection. Cathodic, or galvanized, protection provides significant corrosion resistance, particularly given that even if the coating is scratched, abraded, or cut, thereby exposing the steel to the air and moisture, the exposed steel will still be protected from corrosion due to the galvanic action of the zinc in contact with the steel—an advantage absent from paint, enamel, powder coating and other methods. As such, galvanizing provides a relatively long maintenance-free service life, even in the event that portions of the coating are damaged.

Galvanization of a steel or iron product can be achieved in a number of ways, and the method of application is typically determined by the product to which it will be applied. Mill galvanizing applies a relatively thin coating during the steel product manufacturing process. In comparison, hot dipped galvanizing is performed by submerging a previously fabricated steel member or fabricated assembly, into a bath of molten zinc typically at a temperature of 860 degrees Fahrenheit. Hot-dip galvanizing deposits a relatively thick coating to the metal, however it is accompanied by certain manufacturing challenges, such as environmental and safety concerns, in addition to handling challenges.

Another means of protecting steel reinforcing members is to create a chemically-resistant mechanical-barrier coating on the steel member, thereby isolating the steel from the outside elements. For instance, fusion bonded epoxy coatings are commonly used to coat rebar used in reinforced concrete. Known techniques include heating the rebar to a melting temperature of an epoxy powder and then spray-coating the epoxy powder onto the heated rebar such that the latent heat of the rebar provides the energy to elevate the epoxy powder to the fusion temperature of the epoxy powder. The epoxy adheres to the rebar and is then cured into a hardened barrier.

However, in a steel lattice or mesh, where multiple steel members are assembled into a wire matrix reinforcement, such as by welding, spray-coating the resulting structure presents challenges. Further, spray-coating the individual components before assembling the wire matrix might not be effective, as welding the wires together afterwards creates discontinuities in the coating. For these reasons, the spray-coating individual components of a wire mesh reinforcement and other similar products is typically highly inefficient, resulting in excessive waste of the coating material, and thus added expense.

SUMMARY

In one aspect, an example method for coating a structure with a fusion bonded material is disclosed. The method includes (a) heating the structure to a melting temperature of the fusion bonded material, where the structure comprises a ratio of a surface area to an enclosed area of less than about 0.5, (b) submerging the heated structure in the fusion bonded material such that the fusion bonded material coats the structure, where the fusion bonded material is contained in a reservoir of a fluidization bed, and (c) removing the coated structure from the reservoir of the fluidization bed.

In another aspect, an example method for coating a wire matrix reinforcement is disclosed. The method includes (a) fluidizing an epoxy-based powder in a reservoir of a fluidization bed, where the fluidization bed comprises a base and a plurality of side walls, (b) heating the wire matrix reinforcement to at least a melting temperature of the epoxy-based powder, (c) submerging the heated wire matrix reinforcement into the fluidized epoxy-based powder such that the heated wire matrix reinforcement melts a portion of the epoxy-based powder, where the melted portion of the epoxy-based powder coats the wire matrix reinforcement, (d) removing the coated wire matrix reinforcement from the reservoir of the fluidization bed, and (e) curing the melted epoxy-based powder coating the wire matrix reinforcement into a corrosion resistant barrier.

In another aspect, an example system for coating a wire matrix reinforcement is disclosed. The system includes (a) a fluidization bed having a reservoir and comprising a base and a plurality of side walls, (b) an epoxy-based powder disposed within the reservoir of the fluidization bed, where the fluidization bed is configured to fluidize the epoxy-based powder, (c) a first heating element configured to heat the wire matrix reinforcement to at least a melting temperature of the epoxy-based powder, (d) a conveyor positioned over the fluidization bed and configured to engage the heated wire matrix reinforcement, where the conveyor is further configured to submerge the heated wire matrix reinforcement into the fluidized epoxy-based powder such that a portion of the epoxy-based powder melts and coats the wire matrix reinforcement, and where the conveyor is further configured to remove the coated wire matrix reinforcement from the fluidized epoxy-based powder; and (e) a second heating element configured to cure the melted epoxy-based powder coating the wire matrix reinforcement into a corrosion resistant barrier.

The features, functions, and advantages that have been discussed can be achieved independently in various examples or may be combined in yet other examples further details of which can be seen with reference to the following description and drawings.

