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BRIDGE PAINTING RESEARCH PROJECT

THE STEEL STRUCTURES PAINTING COUNCIL EVALUATED A WIDE VARIETY OF COATINGS ON SIX BRIDGES THROUGHOUT THE COUNTRY. AFTER 32 MONTHS OF EXPOSURE WITHOUT A TOPCOAT ON THE GOLDEN GATE BRIDGE, THREE ZINC-RICH PAINTS WERE STILL IN GOOD CONDITION. THIS AREA COMBINES EXPOSURE TO FOG, CONDENSATION, SOME SEA SPRAY, AND SOME WIND-BORNE SAND. SEVERAL OTHER SYSTEMS, ALL REPRESENTING WELL-ESTABLISHED INORGANIC ZINC- RICH COATINGS, WERE IN ALMOST EQUALLY GOOD CONDITION ON THE FLAT SURFACES, BUT HAD BEGUN TO SHOW RUSTING ON EDGES, RIVETS, AND ROUGH AREAS. PAINT AND GALVANIZING TESTS WERE INSPECTED ON THE ROBERT MOSES BRIDGE. THE EFFECT OF SURFACE PREPARATION IS APPARENT ON THE SECTION PAINTED WITH VINYL. THE VINYL SYSTEM APPEARS MORE SENSITIVE THAN THE ALKYD TO SURFACE PREPARATION ON MAINTENANCE REPAINTING. TEST PANELS WERE BRUSH-OFF BLAST CLEANED AND PAINTED OVER WITH FOUR COATS OF A STANDARD ALKYD PAINT. IT WAS OBSERVED THAT BLEEDING HAD TAKEN PLACE ON THE TEST PANELS PREVIOUSLY PAINTED WITH: (1) SSPC-PAINT 12 ASPHALT MASTIC, OR (2) A COAL TAR MASTIC. A MAINTENANCE PAINTING TEST WAS CONDUCTED ON THE CHESAPEAKE BAY BRIDGE. ALL OF THE TEST AREAS ARE STILL IN EXCELLENT CONDITION FROM A PROTECTION STANDPOINT. SEVERAL OF THE SYSTEMS, IN WHICH THE FINISH COAT WAS APPLIED DIRECTLY OVER A SPOT PRIME, ARE BEGINNING TO SHOW SOME RUST INCLUDING STRONTIUM CHROMATE ALUMINUM PAINTS, STABILIZED ONE-PACKAGE ALUMINUM ALKYD PAINT, AND SILICONE ALKYD ALUMINUM PAINT. IT APPEARS FEASIBLE TO USE A CHLORINATED RUBBER BARRIER PAINT OVER THE STANDARD LONG OIL ALKYD PAINT SYSTEM AS A MEANS OF APPLYING A VINYL FINISH COAT. PAINT TEST ON THE FIRST DELAWARE MEMORIAL BRIDGE WERE INSPECTED. THE STAINLESS STEEL PAINT SYSTEM OVER BLAST CLEANED STEEL IS IN GOOD CONDITION ON THE NEW JERSEY APPROACH WHERE IT HAS BEEN EXPOSED FOR ONLY ONE YEAR. ON THE DELAWARE APPROACH, THE SAMPLE WAS IN POOR CONDITION WHEN APPLIED, AND HAS SHOWN DARKENING, STREAKING, AND RUSTING DURING ITS 22 MONTH EXPOSURE. THE ALKYD, THE VINYL-ALKYD, THE CHLORINATED RUBBER AND THE SILICONE-ALKYD ARE ALL IN EXCELLENT CONDITION. INSPECTION WAS MADE OF PAINT TESTS ON THE NEW JERSEY TURNPIKE. PRODUCTS TESTED WERE VINYLS, ALKYDS, EPOXIES, CHLORINATED RUBBER, AND VARIOUS TYPES OF INORGANIC AND ORGANIC TWO-PACKAGE AND SELF-CURING ZINC-RICH COATINGS, WITH A VARIETY OF TOPCOATS. AFTER 16 MONTHS OF SEVERE SALT AND INDUSTRIAL EXPOSURE, ALL OF THE SYSTEMS ARE STILL IN GOOD CONDITION. HOWEVER, PAINT APPLIED OVER WET BLAST CLEANED STEEL OR OVER HAND CLEANED STEEL WAS BADLY BLISTERED. TEST SECTIONS WERE PLACED ON THE BAYONNE BRIDGE AND THE GEORGE WASHINGTON BRIDGE. BLAST AND HAND CLEANING WERE UTILIZED.

  • Authors:
    • Packman, I B
  • Publication Date: 1969-5

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  • Accession Number: 00216903
  • Record Type: Publication
  • Report/Paper Numbers: pp 51-55
  • Files: TRIS
  • Created Date: Nov 11 1994 12:00AM