INFRASTRUCTURE RESEARCH PROGRAM
REMOVAL AND VITRIFICATION OF LEAD-BASED PAINTS
Field Demonstration
The TSV process was demonstrated in cooperation with the Triborough Bridge and Tunnel Authority (TBTA) of the Metropolitan Transportation Authority. Sections of the steel structures of the Queens to Bronx span of the Triborough Bridge were used for the demonstration. Glass was applied to an I-beam section 1.5 m X 1.5 m (5 feet x 5 feet) to vitrify the paint. The paint on the overhead upper flange, vertical web and lower flange of the beam were vitrified using the thermally sprayed glass. The paint in these areas ranged from 0.020 inches (0.51 mm) on the overhead flange to 0.020 to 0.090 inches (0.51 to 2.3 mm) on the web to over 0.150 inches (3.8 mm) on the lower flange.
The procedure developed in the laboratory was used to apply the glass on the painted beam. First, the area was heated to approximately 300 oF. After reaching temperature, the glass was applied using the standard parameters. A coating of glass approximately 0.015 to 0.030 inches (0.4 to 0.8 mm) was deposited, which was then fused using the spray flame. The glass with absorbed and contained paint was removed by spalling of the glass/paint layer spalling and then, if necessary, scrapping or sharp hammer blows to the area. Approximately one half of the thickness of the paint was removed in this first glass application. Subsequent applications of the glass coating removed the remaining top coats with the number of passes dependent on the paint thickness.
As well, the same process could be used to remove the red-orange primer. These steps of coating and removal were performed continuously until all the paint was removed. This was done to retain the heat in the substrate to aid in the vitrification. Upon removal of the entire paint system, a polymer coating was readily applied on the substrate.
last updated 03/15/96 by Dr. J. Karthikeyan
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