In 1995, KYTC let three experimental maintenance-painting projects. Two of those projects involved the painting of multiple bridges along interstate routes. Those projects encompassed four mainline steel bridges on 1-64 in Franklin County, 16 mainline and overpass steel bridges along 1-71 in six counties, and 660 steel rockers on 36 concrete bridges on 1-71. The steel projects included mainline deck girder structures on the 1-64 project and a mix of mainline and overpass deck girder structures and steel bearings on concrete bridges in the 1-71 project. The third project entailed the painting of a single steel truss bridge, KY -22 over the Licking River at Falmouth, KY. All of those bridges had existing lead based paint. The condition of the existing paint varied from extremely poor on the KY-22 bridge to fair-to-good on the 1-64 and 1-71 structures. Each of the projects was awarded to a different contractor.
These projects incorporated the then current KYTC practice of non-invasive painting. Surface preparation procedures were specified that were intended to avoid generation of hazardous wastes. The resulting specifications did not incorporate mechanical surface preparation procedures. However, to provide more efficient cleaning of the existing paint, the washing pressure on the three projects was increased (1,500 psi for the 1-71 project, 2,500-psi for 1-64 project and 3,500 psi for KY-22 project) over previous experimental projects.
Polyurethane paints were employed on all three projects. This was due to the good performance achieved by that type of coating in previous experimental projects. The paint systems used on the 1-64 and 1-71 projects were compositional specifications provided by KYTC. The paint system for the 1-64 project employed both spot and full prime coats of aluminum-pigmented moisture cure polyurethane followed by a two-component aliphatic acrylic high-gloss polyurethane topcoat. The paint system for the 1-71 project used a spot prime coat of an aluminum- and micaceous iron oxide (MIO)-pigmented moisture cure polyurethane and a two-component aliphatic acrylic high-gloss polyurethane topcoat. Different paint manufacturers supplied paint for the 1-64 and 1-71 projects. A proprietary polyurethane coating system from a third manufacturer was used for the KY-22 project. The spot and full prime coats consisted of aluminum-pigmented moisture cure polyurethane paint followed by a two-component aliphatic acrylic high-gloss polyurethane topcoat.
On all three projects, the primer was to be applied by brushing. The contractor on the 1-64 bridges was allowed to apply the intermediate coat by rolling. The contractors could use brushing, rolling or spraying to apply the topcoats. The contractor on the 1-64 project sprayed on the topcoat. The contractor on the 1-71 project brushed and rolled topcoat on the overpass bridges and sprayed topcoat on the mainline ones. The contractor on the KY-22 Bridge elected to use paint mitts to apply all three coats of paint due to the close proximity of houses to the structure.
Digital Object Identifier
Hopwood, Theodore II and Meade, Bobby W., "Experimental Maintenance Painting by Overcoating on the I-64, I-71 and KY-22 Bridges" (1999). Kentucky Transportation Center Research Report. 354.