Why do failed samples not always indicate a defective structure?

Failed samples might not always signal a defective structure because improper sampling techniques can introduce errors that lead to misleading results. When sampling is done incorrectly, it can result in unrepresentative samples that do not accurately reflect the overall quality or integrity of the bulk material or structure. For example, if the sample is taken from an area that has different characteristics than the rest of the structure, or if the sample size is too small, the analysis could yield misleading conclusions about the performance or reliability of the entire structure.

While other factors such as external weather conditions or insufficient mixing time can impact the performance of a material, they do not directly relate to the act of sampling itself. If the sampling method is flawed, it undermines the reliability of all subsequent tests and assessments, making it crucial to ensure correct sampling techniques are used to obtain valid data.