The special inspector shall verify that the proportions indicated on the batch ticket for the concrete delivered to the construction site are as per the approved concrete mix design prior to concrete placement (see Table 1704.4 of this code). Concrete that does not meet the requirements of the approved concrete mix design shall be rejected.
Samples for strength tests shall be taken in accordance with ASTM C 172.
The contractor shall be responsible for providing the specified field storage curing facility and for monitoring the temperature of the cylinders as defined in ASTM C 31.
Cylinders shall be placed in final curing conditions meeting the requirements of ASTM C 511. Cylinders shall be transported to final curing conditions by the licensed concrete testing laboratory within 48 hours of casting the cylinders.
The cylinders shall be tested in accordance with ASTM C 39.
The strength level of an individual class of concrete shall be considered satisfactory if both of the following requirements are met:
- Every arithmetic average of any three consecutive strength tests equals or exceeds f'c.
- No individual strength test (average of two cylinders) falls below f'c by more than 500 psi (3.45 MPa) when f'c is 5,000 psi (34.50 MPa) or less, or by more than 0.10 f'c when f'c is more than 5,000 psi (34.50 MPa).
Each time concrete is sampled for strength testing, the tests set forth in Items 1 through 5 shall be performed by the approved agency:
- Temperature in accordance with ASTM C 1064.
- Slump in accordance with ASTM C 143.
- Unit weight in accordance with ASTM C 138.
- Air content in accordance with ASTM C 173 or C 231. Testing in accordance with ASTM C 173 must be used for concretes made with lightweight aggregates, and other instances where ASTM C 231 is not applicable.
- Water content per AASHTO T 318 when required by 1905.6.2.1.
For mass concrete sections identified as requiring monitoring, install temperature devices that are capable of measuring the temperature of the concrete continuously and record temperature data in increments that do not exceed 30 minutes for a minimum period of seven days per ACI 301 Section 8.3 or as otherwise directed by the registered design professional of record.
The approved agency shall immediately report the results of field tests performed to the contractor and concrete truck driver, or other representative of the concrete producer. If at any time during the concrete operations, the concrete is not in conformance with ASTM C 94, this code, or is otherwise compromised, it shall be rejected. If it is placed, the location of the load shall be recorded and a pair of cylinders shall be molded from the load per ASTM C 31 and included in the average f'c. The approved agency shall keep a written record of all field tests at the construction site and make the records available upon request. These results need not be used in calculating the arithmetic average of consecutive test results required by Section 1905.6.3.4.