AASHTO Accreditation Program

 The American Association of State Highway and Transportation Officials (AASHTO) established the Accreditation Program in June of 1988. Technical support and administrative coordination for the Accreditation Program is provided by the AASHTO Materials Reference Laboratory as a research associate program of the National Institute of Standards and Technology under the sponsorship of AASHTO. The objective of the accreditation program is to provide a mechanism for formally recognizing the competency of a testing laboratory to perform specific tests on construction materials. The program is structured as such, so as to verify that participating laboratories comply with the appropriate ASTM and AASHTO Standards or Recommended Evaluation Practices. The fields of material testing include soils, asphalt cement, cutback asphalt, emulsified asphalt, bituminous mixtures, aggregates and portland cement concrete. The Materials and Testing Laboratory participates fully and is accredited in all available areas of accreditation.

Accreditation is dependent upon meeting several respective parameters. The first being the development of a Laboratory Quality Systems Manual, in accordance with AASHTO R 18, Establishing and Implementing A Quality System for Construction Materials Testing Laboratory. The manual documents the activities associated with laboratory policies such as standard operating procedures, employee qualifications, standard forms, charts, equipment listings, in-house calibration procedures and test reporting. The Laboratory Quality Systems Manual serves primarily as a record-keeping method designed to assist the accredited laboratory in achieving their quality objectives.

The second parameter is on-site inspections. These inspections are performed routinely, every 18 to 24 months. AMRL performs the inspection for soils, asphalt cement, cutback asphalt, emulsified asphalt, bituminous mixtures and aggregates. The Cement and Concrete Reference Laboratory performs the inspection for cement, concrete and steel bars. CCRL is also a Research Associate Program of the National Institute of Standards and Technology under the sponsorship of ASTM. The inspections consist of a review of the Laboratory Quality Systems Manual, an examination of the laboratory's facilities, equipment and test apparatus, and calibration records as well as an evaluation of the ability of laboratory technicians to conduct the specified tests on construction materials in accordance with ASTM and AASHTO standard methods of test. If any deficiencies are noted during the inspection, the accredited laboratory must provide AMRL with satisfactory evidence within 90 days noting that all deficiencies were either corrected or that action is currently being taken to correct the deficiency. Failure to respond or correct deficiencies can result in having accreditation revoked.

Proficiency testing is an additional parameter used to evaluate the laboratory's performance. Proficiency samples for soils, aggregates and bituminous materials are prepared by AMRL, cement and concrete proficiency samples are prepared by CCRL. The samples are forwarded to all participating laboratories. The specific tests are performed and results returned to AMRL or CCRL for analysis and ratings. Our laboratory later receives a final report indicating how our laboratory's results and ratings compare with the other participating laboratories. If low ratings are obtained on proficiency samples, the accredited laboratory must attempt to determine the cause of the low ratings and report the finding and the actions taken to AMRL within 60 days. As with inspection, failure to respond to low ratings, can result in having accreditation revoked.

Accreditation status is active for a one-year period. Prior to expiration, the laboratory must reapply for accreditation and provide verification that the laboratory remains in compliance with the specified parameters.

The AASHTO Accreditation Program is available to all laboratories, including independent laboratories, manufacturers' in-house laboratories, university laboratories and governmental laboratories.

The Louisiana DOTD became the first state transportation agency in the country to have its main testing laboratory (the Materials and Testing Section) accredited under this nationwide program in September 1988.


The Louisiana DOTD currently holds certificates of accreditation to signify that the Materials and Testing Section's laboratories have demonstrated proficiency in the tests listed below and have met the minimum requirements set forth by the AASHTO Highway Subcommittee on Materials for the testing of:



Portland Cement Concrete:


    ASTM: C31, C39, C138, C143, C173, C192, C403, C617
Portland Cement Concrete Aggregate:
    AASHTO: T11, T19, T21, T27, T84, T85, T96, T104, T112, T248, T255
    AASHTO: T87, T88, T89, T90, T99, T100, T134, T135, T176, T180, T193, T208, T216, T236, T265, T296
Asphalt Cement/Cutback Asphalt:
    AASHTO: T44, T48, T49, T50, T51, T53, T78, T179, T201, T202, T228, T295
    ASTM: D4402
Emulsified Asphalt:
    AASHTO-T59: Residue by Distillation, Residue by Evaporation, Particle Charge, Saybolt Viscosity, Settlement, Cement Mixing, Sieve Test, Storage Stability
Hot-Mix Asphalt:
    AASHTO: T30, T164, T166, T170, T209, T245, T269
Hot-Mix Asphalt Aggregate:
    AASHTO: T11, T19, T21, T27, T84, T85, T96, T104, T112, T248, T255
Hydraulic Cement (Physical Tests):
    ASTM: C109, C114, C151, C185, C187, C191, C204, C266, C305, C430, C451, C1222
Hydraulic Cement (Chemical Tests):
    ASTM: C114, C1222
      Reference Method (SiO2, Fe2O3, CaO, SO3, LOI), Atomic Absorption (AL2O3, MgO, NA2O, K2O)