Construction materials testing (CMT) comprises an array of licensed-engineer-directed professional services applied principally for purposes of construction quality assurance and quality control. CMT services commonly are provided as a separate discipline by firms like Federal Engineering & Testing, Inc. CMT consists of providing testing on subsurface preparation for foundations of buildings, roadways, and other structures; materials used for subgrade, sub base, and base purposes; site grading; construction of earthen structures and earth-retaining structures (e.g., retaining walls); and so on. Because many of the materials involved, such as concrete, are used in other elements of construction projects and structures, it also encompasses observation and testing of numerous additional materials (e.g., reinforced concrete, structural steel, masonry, wood, and fireproofing). Laboratory services are a major element of CMT operations. Also operating under the direction of a licensed engineer, they are applied in geotechnical engineering to evaluate subsurface-material samples. QC services, which are a major part of CMT services, are those applied by or on behalf of a developer to ensure the contractor has attained conditions that he has contractually agreed to attain. In overall a CMT operation is a laboratory with the equipment and personnel required to evaluate a variety of construction materials.