The minimum size sample for making strength test specimens is _____.

The minimum size sample for making strength test specimens is _____.

• A. 5 L (0.2 ft^3)
• B. 28 L (1 ft^3)
• C. 100 L (3.5 ft^3)
• D. 1 L (0.04 ft^3)

Answer: (B)

The key idea is that the sample used to make strength test specimens must be large enough to yield the standard test specimens and to handle practical needs like mixing, placing, curing, and any retests. Standard strength tests use cylinders on the order of 6x12 inches, which hold about 5.5 liters of concrete. To be able to cast several cylinders from a single batch and still have material for handling and potential test needs, a practical minimum is about a cubic foot of concrete, roughly 28 liters. That size ensures the batch is representative and provides enough material to produce the required specimens without running short. The other options don’t provide a realistic, practical amount for creating the standard strength specimens.

The key idea is that the sample used to make strength test specimens must be large enough to yield the standard test specimens and to handle practical needs like mixing, placing, curing, and any retests. Standard strength tests use cylinders on the order of 6x12 inches, which hold about 5.5 liters of concrete. To be able to cast several cylinders from a single batch and still have material for handling and potential test needs, a practical minimum is about a cubic foot of concrete, roughly 28 liters. That size ensures the batch is representative and provides enough material to produce the required specimens without running short. The other options don’t provide a realistic, practical amount for creating the standard strength specimens.