A test which is used to determine maximum density is called a ___________.

The Proctor test is specifically designed to determine the maximum density and optimal moisture content of soil. This test involves compacting soil at varying moisture contents in a controlled environment and measuring the resulting density. By establishing this relationship, the Proctor test helps engineers and contractors assess soil suitability for construction projects, ensuring proper compaction rates during excavation and grading operations.

This method is crucial in various applications, particularly in the design of road bases, embankments, and foundations, where achieving the correct soil density is essential for stability and load-bearing capacity. The test results help predict how the soil will behave under load and guide the construction process to meet required standards.

Other options may refer to aspects of soil testing, such as compaction or moisture content, but they do not specifically identify the method used to determine the maximum density, which is the focal point of the Proctor test.