Samples that drive quality

"I don’t think we would have the quality of the AB program that we do [without] having their involvement, maintaining the standard that we do. I think it’s helped us immensely."

New Hampshire Department of Transportation

Alan Rawson, Bureau of Materials & Research Administrator

55+ years of experience
PSP participants
samples shipped per year
laboratory assessments per year
accredited labs

Proficiency Sample Program

AASHTO re:source’s Proficiency Sample Program (PSP) is the largest construction materials sample program in the world, with a customer base of approximately 3,000 testing laboratories.  Samples are distributed  to federal, state, independent, commercial, and research  testing laboratories. In 2017, the PSP became accredited for ISO/IEC 17043:2010, “Conformity assessment-General Requirements for Proficiency Testing”.  

Our Proficiency Sample Program 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.  Currently, the sample program has grown to 18 different sample types ranging from traditional base materials to top-layer preservation treatments. 


The sample program can be utilized as a useful tool for a company, association, or entity to monitor the quality of its services. Participating laboratories have the capability to:
  • compare individual testing results to a large pool of results from their peers.  
  • verify both the testing apparatus and the operator under actual testing conditions. 
  • show evidence of conformance to testing procedures and protocols as set forth by specifying agencies or internal QA/QC programs.
  • receive individualized reports with performance charts to track testing results over time.
  • use the Extra Proficiency Sample Program (XPS) for training of technicians, testing or equipment verification, inter-laboratory studies, and for addressing accreditation issues related to proficiency sample testing. 

Sample Types

  • Soil Classification and Compaction (SOL)
  • Soil Resistance R-Value (RVL)
  • Soil California Bearing Ratio (CBR)
  • Aggregate Gradation and Gravity (AGG)
  • Aggregate Degradation (AGD)
  • Viscosity Graded Asphalt Cement (BAC)
  • Performance Graded Asphalt Binder (PGB)
  • Slurry and Micro-Surfacing Systems (SMS)
  • Unmodified Emulsified Asphalt (EML)
  • Polymer-Modified Emulsified Asphalt (PME)
  • Asphalt Mixture Solvent Extraction (HMS)
  • Asphalt Mixture Gyratory Design (HMG)
  • Asphalt Mixture Marshall Design (MAR)
  • Asphalt Mixture Hveem Design - California Kneading Compaction (HCA)
  • Asphalt Mixture Hveem Design - Gyratory Shear Compaction (HTX)
  • Asphalt Mixture Hveem Design - 4-in Superpave Gyratory Compaction (HCO)
  • Asphalt Mixture Ignition Oven (HMI)
  • Traffic Paint (PNT)
Testing can be performed in accordance with AASHTO,  ASTM, or designated standard test methods. Participating laboratories have approximately six weeks to conduct the testing on the samples. When testing is complete, laboratories submit their testing results on-line. Throughout the process, laboratories receive notifications 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. 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
  • the standard deviation of each sample in the round
  • the laboratory’s z-score and assigned rating in comparison to all other participating laboratories
  • within-lab repeatability and inter-laboratory reproducibility
Youden diagrams are also provided, which illustrate the individual laboratory’s result, in the form of a red dot, compared to the results of all other participating laboratories. Additionally, performance charts are available to track the laboratory’s proficiency sample testing results over time. Specific trends may be uncovered by analyzing the performance charts, allowing an opportunity for corrective action before major issues arise.

Production Process

Sample preparation and production times vary from days to months.  Raw materials are received from suppliers and are then sieved, blended, or batched using monitored processes ensuring a high level of sample uniformity. Samples are distributed to participants annually, with a pair of samples provided each time. Viscosity graded asphalt cement and performance graded asphalt binder samples are distributed semi-annually.

More Information

Find additional resources for proficiency testing on the Proficiency Sample Documents page or on our re:University pages.