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"They are rigorous, they’re about making sure our labs, personnel, and test methods conform, that they’re in compliance. They’re independent, not driven by a vendor or a construction company.”

California Department of Transportation

Philip Stolarski, Former Deputy Division Chief, DES-METS & GS 

55+ years of experience
PSP participants
samples shipped per year
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Changes to the Aggregate Proficiency Sample Program

Jun 01, 2021

Over the past 56 years, the AASHTO re:source Proficiency Sample Program (PSP) has undergone several changes in our production and packaging processes to align with advancements in the construction materials testing industry, including the addition of many relevant materials and tests within our sample schemes.  Calendar year 2022 will bring yet another rather significant change to the program.  

The existing “Coarse” and “Fine” sample programs will be replaced with “Aggregate Gradation and Gravity” and “Aggregate Degradation” sample programs.

The test method schemes will be reorganized and will include the following tests:

Aggregate Gradation and Gravity

  • Materials Finer Than the 75-µm (No. 200) Sieve by Washing (Fine & Coarse) – AASHTO T11 / ASTM C117
  • Sieve Analysis of Fine and Coarse Aggregates – AASHTO T27 / ASTM C136
  • Specific Gravity (Relative Density) of Fine Aggregates – AASHTO T84 / ASTM C128
  • Specific Gravity (Relative Density) of Coarse Aggregates – AASHTO T85 / ASTM C127
  • Plastic Fines in Graded Aggregates and Soils by Use of the Sand Equivalent Test – AASHTO T176 / ASTM D2419
  • Uncompacted Void Content of Fine Aggregate – AASHTO T304 / ASTM C1252

Aggregate Degradation

  • Resistance to Degradation of Coarse Aggregate by Los Angeles Machine (Coarse) – AASHTO T96 / ASTM C131
  • Soundness of Aggregates by Freezing and Thawing (Coarse Aggregate) – AASHTO T103
  • Soundness of Aggregate by Use of Sodium or Magnesium Sulfate (Fine & Coarse) – AASHTO T104 / ASTM C88
  • Resistance of Coarse Aggregate to Degradation by Abrasion in the Micro-Deval Apparatus – AASHTO T327 / ASTM D6928
  • Resistance of Fine Aggregate to Degradation by Abrasion in the Micro-Deval Apparatus – ASTM D7428

The anticipated schedule will introduce the Aggregate Degradation sample round in January 2022 and the Gradation and Gravity sample will occur in July 2022.  Processing of the sample materials and ordering of the shipping supplies typically occur several months in advance of the shipping dates, and compliance to the enrollment deadlines is critical.  Please ensure that your laboratory is appropriately enrolled.  See details in the next section.

Enrollment Changes
Changes to the enrollment for laboratories that were enrolled in the 2020 Coarse Aggregate samples 209/210 and 2021 Fine Aggregate samples 211/212 will be made automatically by AASHTO re:source.  If your laboratory is not currently accredited by AASHTO and was not enrolled for the rounds above, you will need to request the appropriate changes to fit your testing needs. Should you wish to change your enrollment status, please visit the AASHTO re:source website at to make any changes.  If you have any specific questions regarding the changes, please contact

All changes to enrollment must be completed by August 1, 2021

The 2021 Fee Schedule will be posted on the AASHTO re:source website by July 1st, 2021.  Participants who do not need the Degradation Samples will see a slight decrease in their overall fees.  Participants who need both the Degradation and Gradation and Gravity samples will see a slight increase in overall fees.

AASHTO Accredited Laboratories
The change in the aggregate programs will not affect your accreditation status unless your laboratory chooses not to participate in the new aggregate program(s) applicable to its accreditation scope.  The AASHTO Accreditation Program requirements for participation in proficiency sample programs remain unchanged.  The process for evaluation of accreditation and methods of resolution of proficiency sample program-related issues will also remain unchanged.

Historical Data
There will be no loss of historical data from previous Fine Aggregate and Coarse Aggregate sample rounds.  The Sample Round Analysis and Compilation of Statistics will still be available for use by the industry and members.

Questions or Concerns
If you have any questions or concerns regarding these changes, please do not hesitate to contact us at or