Soil classification follows AASHTO M 145 (soil classification system). Required tests: moisture content (AASHTO T 265), Atterberg limits (AASHTO T 89/T 90), grain size analysis (AASHTO T 88), compaction (AASHTO T 99 standard or T 180 modified Proctor), CBR (AASHTO T 193), and resilient modulus (AASHTO T 307). NC subgrade characterization includes R-value (AASHTO T 190) where required by the pavement design method.
References: AASHTO current edition, NC Standard Specifications, FHWA Technical Advisories, and applicable federal regulations (23 CFR). Contractors shall maintain current copies of all referenced standards on the project site.
Source: NCDOT Materials Testing Manual, 2024 Edition. Pages 3–4 of 25.