Proficiency Sample Program
The AMRL Proficiency Sample Program (PSP) was introduced in March 1966, when samples were initially distributed only to state Department of Transportation and Federal Highway Administration testing laboratories. At that time, four basic material types were included in the scope of the program: fine aggregate, coarse aggregate, soil, and asphalt binder. Over the past 45 years, the proficiency sample program has grown tremendously and now includes fourteen specific material types
. The samples are distributed all over the world to laboratories including federal, state, independent, and research facilities.
AMRL’s Proficiency Sample Program is the largest of its kind, with a customer base of approximately 3,000 testing laboratories. Several accrediting bodies, such as the AASHTO Accreditation Program, require participation in the AMRL Proficiency Sample Program. An Extra Proficiency Sample Program
(XPS) is also available, which began in January 2004. At that time, AMRL began to offer extra proficiency samples, in limited quantities, for various uses, such as training or certification of technicians, testing or equipment verification, inter-laboratory studies, and for addressing accreditation issues related to proficiency sample testing.
There are many benefits to participating in the AMRL Proficiency Sample Program. Testing laboratories can judge their testing results by comparing them to a large body of results. The quality of test results can be demonstrated, thereby reducing the risk of disputes due to testing errors. The program also provides laboratories with the means to check both the testing apparatus and the operator under actual testing conditions.
Processing the raw proficiency samples materials is a complex process. Several weeks are typically needed to process each material type before it is shipped to participating laboratories. Homogeneity of the samples is controlled during the production process. Materials are selected from known suppliers and are inspected when received. After any impurities are removed, the materials are thoroughly blended in accordance with established schemes. The individual samples are then obtained through a carefully monitored multiple-sampling process.
Distribution of Samples
Proficiency samples are typically distributed to participants once per year, with a pair of samples provided each time. Viscosity graded asphalt cement and performance graded asphalt binder samples are distributed every six months. Participating laboratories are given approximately six weeks to conduct the testing on the samples. Testing can be performed in accordance with AASHTO or ASTM standard test methods. When testing is complete, laboratories submit their testing results on-line through the AMRL website. Along the way, laboratories receive multiple notifications via email of upcoming shipments, deadlines, and other important information.
Reports and Charts
A final report of the testing analysis is issued approximately two weeks after each testing deadline. Participating laboratories can access their individual report by logging into the AMRL website. The report includes specific information such as the laboratory’s test data, the total number of participating laboratories, the grand average for each testing parameter, standard deviations, the laboratory’s rating in comparison to all other participating laboratories, and repeatability results. Youden diagrams are also available, which illustrate the individual laboratory’s result, in the form of a red dot, as well as the results of all other participating laboratories. Additionally, performance charts are available to track the laboratory’s proficiency sample testing results over time. Specific testing trends may be uncovered by analyzing the performance charts, allowing an opportunity for corrective action before major issues may arise.
Results of Optional Special Study for Surface Dry Penetration of Asphalt Emulsion Residue
The 2010 round of testing for Emulsified Asphalt (samples 51 and 52) included an optional study regarding the effect of surfactant interference when testing the penetration of the residue of emulsified asphalt. Results can be viewed by clicking on the following links: