Pecora-Deck Deck Coating Field Inspection and Test Procedures

At Pecora, we truly believe that no matter that size of the project, one of the most important aspects of the job is quality control through application testing. Proper testing methods ensure product success, structural endurance, and most importantly, a happy customer. This week we explore Pecora-Deck field inspection and test procedure: Quantitative Test Method – ASTM D4541 Pull Off Adhesion Strength.

The purpose of this test is to measure the adhesive strength of a material to determine whether the installation has been completed properly. Release or separation during the test will occur along the weakest part of the material, or bond between the material and the substrate.

Poor adhesion may be caused by poor substrate preparation, the surface being contaminated by water or dirt, not properly cured or improper primer application to name a few. For a traffic coating to function properly there must be proper adhesion.

To determine whether proper adhesion has been achieved, on-site testing needs to be conducted. The basic principle is very simple:

1. Attach a steel or plywood disc to the coating material.
2. Cut around the material so you are pulling on that specific area (this will allow no damage to material around the area of the test.)

 

When attaching the adhesion tester (test dolly) to the coating material (coating) with the recommended adhesive¹, ensure the specimen is not being pre-stressed by bumping or bending. You may slightly abrade the surface of the material to remove any surface film that could interfere with the recommended adhesive material. Make sure you clean the abraded area with Pecora recommended cleaning agent² as to not affect the material or leave residue. Before conducting the pull test, make sure the deck coating application is fully cured (min 48 hours). It is very important the test area be flat as to achieve proper adhesion to the disc.

After the material has fully cured, perform the following test set up procedures:

1. Apply the adhesive to the dolly and the surface of the coating material, press the disc onto the prepared surface and allow for approximately 1/16” to 1/8” final adhesive thickness removing excess adhesive pressed out from the side of the dolly. Allow the adhesive to cure in accordance to the manufacturer’s instructions.
2. Do not twist or move the dolly as that could result in incorrect values during testing.
3. When a bearing ring is required, place it evenly around the dolly so there is equal support being applied to the tester.
4. To ensure the correct amount of force is being used, apply it in a smoother continuous manner. The force should be applied to the dolly by turning the handle not more than one revolution per minute (rpm) in accordance with ASTM D4541, method B. The gauge will display the force being applied, and the limit stop dial will register the peak force just before there is a separation.

 

Once the test is complete, you will need to analyze the material for maximum force achieve, the type of release, the surface in which the release occurred, and the percentage of release on each surface. This information should be noted in a test report using lbs. from the gauge.

In order to determine the pull-off value calculation:

1. Use table provided by test apparatus manufacturer
2. In the absence of test jog calculation recommendations use the following:
   1. Measure diameter of disc utilized
   2. Record lbs. force from dial indicator at failure
   3. Use the following calculation to determine max pull off value in PSI
      1. Max force from dial indicator / (3.14 * (diameter/2)² = force in PSI

 

Note: A minimum of 200 PSI is required for warranty purposes.

Any errors in the test should be examined to find its cause. If you discover that this error was caused from improper test procedures, do not include it on your report and perform another test. Any material that was damaged in the pull test needs to be replaced in accordance to Pecora’s instructions.

¹The recommended adhesive is Gorilla brand Super Glue (clear)

²Depending on the project location, generally Xylene is recommended as the cleaning agent. Otherwise, an alternative VOC compliant solvent with quick evaporation is recommended.

For more information, testing questions, or deck coating application recommendations, we urge you to contact our Pecora Corporation Technical Services Group. Our expert team is highly qualified to answer any question, recommend the proper solution, or provide testing training. Our Technical Services staff offers training in product technology and use and provides the technical assistance you require in the planning and implementation of your project. They can be reached by email techservices@pecora.com or by phone (800)-523-6688.

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