AASHTO PP 55:06(2012) Standard Practice for Overcoating Field Test Program for Evaluating Protective Coatings on Existing Bridges or Salvaged Beams.
1.1. This field testing program has been established to provide the end user with test results that can be used to make performance judgments on one-, two-, or three-coat systems for maintenance overcoating previously painted steel structures.
1.2. This field testing program is intended to apply to maintenance overcoating. herein defined as the practice of cleaning and painting over an existing coating that is largely intact but has areas of corrosion or peeling paint in need of repair. This practice usually includes the spot preparation of rusted or degraded areas, feathering edges of existing paint, power washing the entire structure, priming bare or repaired areas, applying an intermediate coat over the repaired areas or entire structure, and the optional step of applying a full topcoat over the entire structure, or a similar variation of these procedures.
1.3. This field testing program evaluates the performance of protective coatings applied to existing painted steel surfaces with various degrees of surface preparation and condition, including surfaces hand tool cleaned (SSPC SP 2), surfaces cleaned by conventional power tools (SSPC SP 3), surfaces power tool cleaned to bare metal (SSPC SP 15). and industrial blast (SSPC SP 14).
1 .4. The coating materials in the field testing program are applied to previously painted steel surfaces of existing bridges or salvaged bridge beams after proper surface preparations, as described herein, and thereafter evaluated annually, unless otherwise agreed, for a period of 3 years.
1.5. All of the elements of this field testing program shall be performed in accordance with applicable local, state, and national regulations governing environmental and worker protection. Specific references to material, environmental, and worker protection rcquircmdnts are not necessarily made in this document since these regulations are widely known and compliance with these regulations is standard practice in the bridge painting industry.
3.1. The purpose of this program is to provide a basis for comparing the performance of coating systems applied with existing painted structures under similar conditions of weathering exposures. There are a number of variables, issues, and risks involved with overcoating an existing painted structure. The intent of this test is not to address all of these issues, but rather to create test conditions tinder which coating systems can be applied and evaluated to provide a basis for evaluating coating performance.
3.2. To provide comparability of field testing and results, all test sites shall use the same testing methods described herein and all field testing and evaluation shall be administered by a qualified representative of the specifying agency selected by and reporting to the agency.AASHTO PP 55 pdf download.