Concrete strength testing per AASHTO T 22 (compressive strength of cylinders). Cylinder fabrication per AASHTO T 23 in the field. Standard curing: lime-saturated water at 73.4°F ±3°. Testing frequency: one set of cylinders (4 minimum) per 50 CY or per day of placement. 28-day strength required for acceptance. 7-day strength for information. TDOT uses statistical evaluation: f'c represents the specified strength; individual tests shall not be more than 500 psi below f'c.
References: AASHTO current edition, TN 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: TDOT Materials Testing Manual, 2024 Edition. Pages 11–12 of 25.