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). CA subgrade characterization includes R-value (AASHTO T 190) where required by the pavement design method.
All work under this section shall comply with Caltrans current standards and applicable AASHTO, ASTM, and federal requirements. The Engineer has authority to accept or reject materials and workmanship that do not conform to the specifications.
Source: Caltrans Materials Testing Manual, 2024 Edition. Pages 3–4 of 25.