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From page 6... ... NCHRP Project 14-30 6 CHAPTER 2 Laboratory Accelerated Performance Testing of Spot Coating Systems 2.1 Background A major project requirement was to, "develop guidelines for the selection and use of a broad spectrum of protective materials for spot treatment of failed coatings on steel highway bridges," more specifically, "testing protocols to determine the anticipated performance and service life of protective material types for use on rusted, soluble salt-contaminated substrates prepared to SSPC-SP 3 standard." This requirement was addressed by applying accelerated laboratory testing of candidate spot coatings using modifications of ASTM standard accelerated coating performance tests, in particular ASTM D5894, "Standard Practice for Cyclic Salt Fog/UV Exposure of Painted Metal, (Alternating Exposures in a Fog/Dry Cabinet and a UV/Condensation Cabinet) ," and ASTM B117, "Standard Practice for Operating Salt Spray (Fog) Read the entire page →
From page 7... ... NCHRP Project 14-30 7 ASTM promulgating its standard for cyclic weather/corrosion testing ASTM D5894 in the mid1990s, KTC used that method to test overcoating systems. Prior to this research, KTC employed that method to test approximately 100 different coatings/systems-primarily barrier systems used for overcoating. Read the entire page →
From page 8... ... NCHRP Project 14-30 8 some state highway agencies that employed abrasive blasting to SSPC-SP 6/ NACE 3, "Commercial Blast Cleaning," or SSPC-SP 10/NACE 2, "Near White Metal Blast Cleaning," (used with a coating system employing an organic zinc primer) standard ASTM D 5894 testing would probably suffice over properly prepared panels or state highway agencies could use the AASHTO NTPEP steel coatings test results. Read the entire page →
From page 9... ... NCHRP Project 14-30 9 Weathering Testers capable of performing ASTM D 4587, "Practice for Fluorescent UVCondensation Exposures of Paint and Related Coatings" with SOLAR EYE irradiance control (Figure 2) Read the entire page →
From page 10... ... NCHRP Project 14-30 10 To evaluate the potential steel substrates, half of the Type I test panels had initial test surfaces with intact mill scale and the other had the mill scale removed by blast cleaning to an SSPC–SP 5 White Metal Blast Cleaning condition. "Existing" coatings were applied to half of the test surface of each panel with the remainder of the surface consisting of steel or mill scale left uncoated (Figure 3) Read the entire page →
From page 11... ... NCHRP Project 14-30 11 The Type I test protocol was as follows: A A sufficient number of appropriate steel test panels for a total of 336 Type I tests were prepared (Figure 4) Read the entire page →
From page 12... ... NCHRP Project 14-30 12 F Mechanical surface preparation to an SSPC-SP 3 "Power Tool Cleaning" condition was performed using a 4-inch (10.16 cm) Read the entire page →
From page 13... ... NCHRP Project 14-30 13 G Candidate liquid-applied "repair" coatings/systems were applied by brushing (Figure 8) Read the entire page →
From page 14... ... NCHRP Project 14-30 14 The painting work was performed in the KTC paint shop. To perform the painting, 8 ft. Read the entire page →
From page 15... ... NCHRP Project 14-30 15 bonding and readily attached to the existing coatings and the SSPC-SP 3 substrate. A small wallpaper roller was run over the applied tape to ensure that it adhered and that no air pockets were present at the tape/substrate interface. Read the entire page →
From page 16... ... NCHRP Project 14-30 16 of the spot coating and one in the center. As was anticipated, the calcium sulfonate alkyd coating did not harden sufficiently to permit testing. Read the entire page →
From page 17... ... NCHRP Project 14-30 17 by one hour of evaporation (drying) Read the entire page →
From page 18... ... NCHRP Project 14-30 18 Type II-Shaped Panel Tests – At the direction of the project review panel, KTC developed shaped panels to be used to evaluate spot coatings placed over irregular surfaces. The Type II shaped panels were made from two-6 in. Read the entire page →
From page 19... ... NCHRP Project 14-30 19 to rust the heads of the bolts and unpainted test surfaces. The rusted areas were subjected to mechanical surface preparation to the SSPC-SP 3 standard using a needle gun. Read the entire page →
From page 20... ... NCHRP Project 14-30 20 contamination and degradation of existing coatings on bridges. Read the entire page →
From page 21... ... NCHRP Project 14-30 21 2.3 Results of Accelerated Laboratory Performance Testing The results of the accelerated testing for the Type I flat panel specimens are provided in Tables 1-4 below. If no panels in a group failed after a 1,008- hour evaluation by rusting or blistering, that result was noted as a "0" indicating no failures up to that point. Read the entire page →
From page 22... ... NCHRP Project 14-30 22 moisture cure urethane (2 coats) passed 5,000 hours over the acrylic "existing" coating; 4,000 hours over the alkyd "existing" coating; and 3,000 hours over the epoxy-polyurethane "existing" coating. Read the entire page →
From page 23... ... NCHRP Project 14-30 23 Table 1. Type I Test Results for Mill Scale Plates Tested for 5000 Hours per ASTM D5894 Test Durations in Hours vs. Read the entire page →
From page 24... ... NCHRP Project 14-30 24 Table 2. Type I Test Results for Blast Cleaned Plates Tested for 5000 Hours per ASTM D5894 Test Durations in Hours vs. Read the entire page →
From page 25... ... NCHRP Project 14-30 25 * 0 denotes no failures at specific test durations. Read the entire page →
From page 26... ... NCHRP Project 14-30 26 Table 3 Cont. Type I Test Results for Mill Scale Plates Tested for 5000 Hours per ASTM B117 Test Durations in Hours vs. Read the entire page →
From page 27... ... NCHRP Project 14-30 27 Table 4. Type I Test Results for Blast-Cleaned Plates Tested for 5000 Hours per ASTM B117 Test Durations in Hours vs. Read the entire page →
From page 28... ... NCHRP Project 14-30 28 Table 4 Cont. Type I Test Results for Blast-Cleaned Plates Tested for 5000 Hours per ASTM B117 Test Durations in Hours vs. Read the entire page →
From page 29... ... NCHRP Project 14-30 29 * 0 denotes no failures at specific test durations. Read the entire page →
From page 30... ... NCHRP Project 14-30 30 that were anticipated by KTC researchers based upon published field and laboratory performance tests of those generic types of coatings and KTC experience with experimental overcoating projects on over 200 bridges and extensive in-house laboratory testing. The liquid-applied coating rankings were especially instructive. Read the entire page →
From page 31... ... NCHRP Project 14-30 31 considered important in obtaining good correlations between candidate "repair" coating systems, it is likely that one of those substrate options can be eliminated – preferably the mill scale surface. A problem encountered in the laboratory tests was rust bleed from the taped edges of the test panels. Read the entire page →

From page 6...

... NCHRP Project 14-30 6 CHAPTER 2 Laboratory Accelerated Performance Testing of Spot Coating Systems 2.1 Background A major project requirement was to, "develop guidelines for the selection and use of a broad spectrum of protective materials for spot treatment of failed coatings on steel highway bridges," more specifically, "testing protocols to determine the anticipated performance and service life of protective material types for use on rusted, soluble salt-contaminated substrates prepared to SSPC-SP 3 standard." This requirement was addressed by applying accelerated laboratory testing of candidate spot coatings using modifications of ASTM standard accelerated coating performance tests, in particular ASTM D5894, "Standard Practice for Cyclic Salt Fog/UV Exposure of Painted Metal, (Alternating Exposures in a Fog/Dry Cabinet and a UV/Condensation Cabinet) ," and ASTM B117, "Standard Practice for Operating Salt Spray (Fog)