Concrete Cylinder Strength Testing
Compressive Strength: f = P / A (Load / Cross-sectional area)
6x12 cylinder area: pi x 3^2 = 28.27 in2
4x8 cylinder area: pi x 2^2 = 12.57 in2
ACI 318 Acceptance Criteria
- Average of 3 consecutive tests must exceed f'c
- No individual test may be more than 500 PSI below f'c
- 4x8 cylinders typically test 2-5% higher than 6x12