Development of Corrosion-Resistant Wall Ties Using Vitreous Enameled Metal

A wide variety of metal brackets and fittings are used in the construction of brick and masonry walls.  The hardware used in the wall is vital to its structural integrity and in tying brick veneer to the building frame.  Most of the places where masonry hardware or fittings are used leave them vulnerable to corrosion.  For example, metal ties used in brick veneer walls are embedded in the mortar between the bricks and only a short distance from the exterior surface of the wall.  The ties stretch across the damp space behind the bricks.  Conventional steel wall ties are typically furnished with an epoxy coating, a light zinc plating or with a hot dipped galvanized finish.  Typical problems related to the epoxy debonding or the corrosion of the zinc plating often occur.  In addition when the bases of the wall ties have to be attached to the wooden frame behind the brick veneer the acids in the wood often attack the plating. 

Because of the problems with regard to corrosion, work has begun on developing glass enamel coated ties.  Vitreous enameling is one of the most corrosion-resistant coatings that can be applied to steel.  Furthermore a special mortar-bonding enamel made by adding an outer coating of portland cement to the enamel can be applied to the parts of the tie that are buried in the mortar, thereby increasing the bond strength between the mortar and the ties by a factor of two or three over a conventional metal finish.  Corrosion on the outside end of the ties can crack the mortar, weakening the wall and destroying the attachment of the tie to the wall.  The newly developed glass enameled ties can increase the service life of the ties and produce a structurally stronger wall.