What is one of the inspector's duties when engaged as a witness during testing?

One of the inspector's primary duties when engaged as a witness during testing is to observe all sampling and specimen preparation. This responsibility ensures that the testing process adheres to the specified standards and protocols, which are critical for obtaining accurate and reliable results. By closely monitoring these processes, the inspector can confirm that the materials used and the methods employed comply with both the requirements of the project and industry standards.

Observing sampling and specimen preparation allows the inspector to verify that the materials are representative of the batch and that the preparation techniques are correctly executed. This oversight is essential for maintaining the integrity of the testing process, as any deviations could compromise the reliability of the results. Additionally, active observation helps to identify any potential issues or concerns that might arise during the testing phase, enabling timely interventions to uphold quality control.

In contrast, the other options suggest duties that fall outside the typical scope of an inspector's role as a witness. Selecting materials for construction involves decision-making that is usually done before testing begins, while preparing the testing documentation is typically handled by the testing personnel. Conducting the actual tests goes beyond the witness role, as that responsibility is entrusted to qualified technicians who are specifically trained to perform those tests.