Which type of sampling equipment must have squared-nosed design and built-up back and sides of 1.5 inches?

The type of sampling equipment that must have a squared-nosed design and built-up back and sides of 1.5 inches is a shovel. This specific design is essential for several reasons in aggregate sampling.

Firstly, the squared nose allows for easier penetration and scraping of materials, especially in packed or dense aggregates, ensuring that a more representative sample can be taken. The built-up back and sides of 1.5 inches serve to retain material during the sampling process, preventing spillage and ensuring that the sample collected is both accurate and sufficient for testing purposes. This design promotes efficiency in handling materials, enhancing the technician's ability to gather samples without losing material or compromising the integrity of the sample.

In contrast, while buckets, spades, and picking tools may be useful in various contexts, they do not have the specific design features that a shovel does, which are crucial for adherence to sampling standards and ensuring high-quality sample collection in aggregate testing.