The moisture content curve is primarily used to determine which of the following?

The moisture content curve, also known as the moisture-density relationship or compaction curve, is essential in understanding how moisture affects the compaction of soil or aggregates. The primary aim of this curve is to identify the optimum moisture content, which is the moisture level at which the material achieves its maximum dry density when compacted.

In practical terms, when materials are compacted, their density varies with the moisture content. If the moisture is too low or too high, the density achieved will not be optimal. Thus, the moisture content curve allows technicians to establish that critical point or optimum moisture content where the maximum density is achieved, which is vital for ensuring stability and strength in construction applications.

While compaction density, soil gradation, and plasticity index are important factors in materials characterization and performance, they are not the primary focus of the moisture content curve. The curve specifically provides insight into moisture-related compaction properties, guiding the proper moisture levels required for effective compaction practices.