What is the primary construction material used for Shasta Dam?

The primary construction material used for Shasta Dam is concrete. This choice is correct because concrete provides the necessary strength and durability required for such a massive structure that holds back large volumes of water. The design of Shasta Dam utilizes a roller-compacted concrete technique, which allows for the efficient building of the dam while ensuring it can withstand the immense pressure of the water it retains. The properties of concrete, including its compressive strength and resistance to environmental factors, make it an ideal choice for large-scale dam construction.

Other materials like steel, wood, and brick do have applications in construction, but they do not offer the same structural integrity and longevity as concrete, especially in the context of a dam where water pressure and potential seismic activity are significant concerns. Steel could be used for certain reinforcement tasks, but it is not the primary material for the dam itself. Wood and brick lack the necessary properties to serve as the main structural component of a dam.