Massachusetts Unrestricted Construction Supervisor License Practice Test

Does concrete in a test cylinder, which fails at a load of 70,000 lbs, have sufficient strength to be used in footings in a single-family dwelling with moderate weathering potential?

1. Yes

2. No

3. Only with additional testing

4. It depends on the mixture

The correct answer is: No

In assessing whether the concrete that fails at a load of 70,000 lbs is suitable for use in footings for a single-family dwelling with moderate weathering potential, it is essential to consider the necessary compressive strength for footings. Generally, footings must be designed to handle various loads, including the weight of the building, soil pressure, and any additional live loads. The standard minimum recommended compressive strength for concrete used in footings is typically around 3,000 to 4,000 psi. The failure load of 70,000 lbs must be interpreted in terms of the equivalent compressive strength. For example, without knowing the specific dimensions of the test cylinder from which this load is derived, we can't directly equate this failure load to an appropriate compressive strength without further conversion. However, if this value indicates that the concrete has not met the minimum required strength for its intended application, it cannot be deemed sufficient for footings, especially given the moderate weathering conditions which imply a need for durable, reliable construction. Therefore, since the load indicates that the concrete would likely have lower compressive strength unsuitable for the footings, it leads to the conclusion that the concrete does not have the requisite strength to be safely and effectively used