ACI Concrete Strength Testing Technician Practice Test

According to ASTM C1231, what should be the inside diameter of the retaining rings relative to the diameter of the cylinder?

1. Less than 100%

2. Equal to 105%

3. Not less than 102% or greater than 107%

4. Between 101% and 106%

The correct answer is: Not less than 102% or greater than 107%

The requirement in ASTM C1231 regarding the inside diameter of the retaining rings is designed to ensure proper support and stability for the concrete specimens during curing and testing. Specifically, the standard dictates that the inside diameter of the retaining rings should be not less than 102% and not greater than 107% of the diameter of the cylinder. This specification helps accommodate any slight variations in the diameter of the concrete cylinders, ensuring that the rings provide adequate support without being overly tight or loose. If the rings are too small, they may not fit properly around the cylinder, potentially leading to issues with the curing process or compromising the integrity of the test. Conversely, if they are too large, they may not provide sufficient confinement, which could affect the test results. The percentage range set forth (102% to 107%) strikes a balance that promotes reliable testing conditions while allowing for some manufacturing tolerance in the concrete cylinders. This standard is important for achieving accurate and consistent compressive strength test results, which are critical for quality control in concrete production and construction.