Which type of device is prohibited for sampling materials?

Shelby tubes are specifically designed for taking undisturbed soil samples, making them unsuitable for sampling aggregate materials. In the context of aggregate sampling, it's essential to use devices that will not disturb the material's properties or alter its moisture content, which Shelby tubes are not designed to do. Their construction and intended use focus on soil sampling rather than aggregate, which may lead to inconsistency in the representation of the material being sampled.

In contrast, loose tubes, open-ended tubes, and core sample tubes are designed for sampling aggregate materials and can accommodate the necessary procedures to ensure accurate results without compromising the material's integrity. This adherence to proper sampling protocols is critical in ensuring the quality and performance of the materials used in construction and engineering projects.