The Construction Materials Testing laboratory accreditation program (LAP) began in 1978 as the Concrete LAP. The program gradually expanded beyond concrete testing to include other testing areas such as admixtures, aggregates, cement, geotextiles, road and paving materials, soil and rock, and steel materials.
For information on the requirements of accreditation, see NIST Handbook 150 which contains the general requirements for accreditation of laboratories. In addition, NIST Handbook 150-5 contains specific requirements for construction materials testing laboratories.
Pictured: John Ardinger, AASHTO, is weighing out samples of Coarse Aggregate to be shipped to labs as PT samples.