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Making Quality Your Top Priority

posted 03.24.2019

Using an accredited laboratory adds confidence the work being performed is completed in accordance with nationally recognized standards and procedures, and with proper equipment.  The accreditation process involves an on-site laboratory assessment including staff certifications and training records inspection, equipment calibration and maintenance, checking records and documents, and quality manual evaluation. Firms must have management and technical staff that meet accreditation body requirements.  When a company chooses a laboratory to become accredited, it is not an easy path to take.  The firm must make quality a top priority.

An accredited laboratory is one that has taken the steps by an independent accreditation agency to gain formal recognition of technical competence in certain types of testing, calibration, and measurements.  These steps can vary by agency, but typically include an on-site assessment, test procedure demonstrations, management and technician credential evaluations, and a corrective action response to any nonconformities noted during the audit process.  After corrective action response, submission and resolution, the laboratory is added to the agency’s list of accredited labs, and may mention its accreditation in marketing materials. Most projects require third-party testing laboratories to be accredited.

How does a laboratory become accredited?

The accreditations a laboratory chooses to obtain can depend on several factors. The scope of tests the laboratory performs may dictate what accreditations are best suited. The scope can include various subfields of Construction Materials Testing (CMT) to include cement, concrete, masonry, soil, rock, aggregate, asphalt mixtures, and steel. The accreditation required by local jurisdiction or project specifications may drive the selection of the agency as well.  Some of the accreditation agencies include AASHTO re:source, CCRL (Cement and Concrete Reference Laboratory), A2LA (American Association for Laboratory Accreditation), NVLAP (National Voluntary Laboratory Accreditation Program), CMEC (Construction Materials Engineering Council) and USACOE (United States Army Corps of Engineers).  These agencies are typically used by laboratories performing testing for geotechnical and materials engineering services.

How does a laboratory maintain Its accreditation?

To maintain their accreditations, laboratories are required to perform proficiency testing of samples for which they are accredited, continue to participate in periodic, on-site assessments, and complete any required corrective actions.  Proficiency samples consist of material samples from the same lot sent to each participating laboratory. Each laboratory completes the required testing and submits their results to the agency. The sample results are compared, and a final report is issued with a summary of all results. The laboratory then gets a score showing how submitted results compare to other laboratories statistically. The benefit of proficiency sample testing is a laboratory can compare its results with peers who are performing the same testing procedures.  Low ratings can be an indicator of a problem with a laboratory’s procedure or associated equipment.

With more than 140 laboratories serving all 50 states, Terracon owns, operates, and maintains the largest network of accredited and validated laboratories of any geotechnical engineering firm in the U.S. Terracon can consistently produce reliable, repeatable, and accurate test data on projects anywhere in the U.S.


Terracon’s national laboratory resources allow us to process large volumes of test specimens quickly, reducing risk of delays to your critical project schedule. And, with a local presence, we have in depth familiarity with materials and specifications of numerous local, state, and federal agencies.

Linda G. Dobkins, P.E., P.G., is a Senior Engineer in Terracon’s Cheyenne, WY office. She has more than 17 years of experience in construction materials testing services in the western region of the U.S.  Linda also performs Internal Quality Audits for Terracon’s laboratories throughout the Western Operating Group.