Under what condition can damaged core samples be used?

Core samples that exhibit damage can still be utilized for testing, particularly if specific criteria are met. The correct condition for using damaged cores is when the damaged portions are effectively removed while ensuring that the remaining length and diameter comply with established testing standards. This is important because the integrity and consistency of the sample must be preserved to ensure that the results are reliable and representative of the material's characteristics.

When damaged portions are excised, the sample needs to maintain a sufficient size to provide meaningful data for strength and other performance assessments. If the dimensions fall below the requirements, the results may not accurately reflect the material's true properties. Therefore, maintaining the length and diameter within specified limits while removing any damaged parts allows for a valid evaluation of the concrete's quality.

Other options may imply certain situations where damaged cores could be used, but they do not assure the necessary integrity and validity of the test results as option B does. For instance, simply being from the same batch or passing a visual inspection does not guarantee the sample's capability to yield valid results in testing. Therefore, it is crucial to follow established protocols regarding sample integrity when utilizing damaged core samples.