VAA Round Robin — Have You Ever Asked... (Part 1 of 5)
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Have you ever asked yourself these questions: "Am I doing this right? Does my equipment really work? How close is close enough?" The answers to simple questions like these can have a big impact on a company’s bottom line. Yet these questions are faced by contractor’s laboratories every day. In many cases the outcomes determine if a plant produces mix, if a plant is placed on limited production, or if a project is completely shut down.
To assist the industry in answering these questions, Virginia Asphalt Association led a Round-Robin Lab Testing effort during the Summer of 2017. This effort focused on producing mixes to exact specifications (i.e. aggregate gradations and AC content) in a third-party lab, distributing samples to interested labs, collecting the results and analyzing the data against VDOT specifications and limits.
For this effort, four primary lab tests were evaluated: Maximum Theoretical Specific Gravity or Rice, Bulk Specific Gravity from gyratory specimens, Asphalt Content, and Aggregate Gradation. By knowing the exact mix properties, the Round Robin was able to focus on the other variables during testing – people, procedures and equipment. Using this approach versus the common method of bulk sampling from a plant, the study would evaluate, if given the exact same material, whether the participating contractor labs/technicians could reproduce the results of a known reference sample (produced by a third-party reference lab). If variability was identified by the results being outside of an acceptable range, then investigation to determine the potential source was undertaken (equipment, technician, procedures, or material) and adjustment or improvements were made as necessary.
The first VAA Round Robin has been a big success. At last count, 17 Companies participated. Of those, a total of 46 different Technicians were testing samples in 43 different Laboratories. Nine of the 43 labs were AMRL accredited. Overall, the study compared 49 Gmm (Rice), 49 Gmb (Bulk Specific Gravities) and 64 Asphalt Content & Gradations (Furnace). There are still a few samples whose results have not been reported, so these counts may go up.
In future newsletters, more details will be provided on the development of the samples and the analysis of the results. A full article will be included in the Spring/Summer edition of Virginia Asphalt magazine. Also, the VAA has additional samples for technicians and laboratories wishing to participate. If interested, please contact Mike Dudley at mdudley@vaasphalt.com.
