Concrete Manual & ACI 318

Question 1

What happens to slump and air entrapment as the drum spins?

Answer 1

Both decrease

Question 2

Acceptance Criteria for standard-cured specimens:

Answer 2

Strength level of concrete mix shall be acceptable if (1) and (2) are satisfied:
(1) every arithmetic average of any three consecutive strength tests equals or exceeds f’c
(2) no strength test falls below f’c by more than 500 psi if f’c is 5000 psi or less; or by more than 0.10f’c if f’c exceeds 5000 psi.
(26.12.3.1)