When density is referred to in earthworks, it is defined by which of the following?

Density in the context of earthworks primarily relates to the weight of the soil and water in a given volume. When we talk about density, we are effectively discussing how much mass is contained within a specific volume. In earthwork operations, this measurement is crucial because it impacts the stability and strength of soil for construction projects.

The weight of soil and water contributes significantly to the overall density, as both components dictate how compact the material will be when placed or excavated. This understanding helps engineers and construction professionals assess whether the soil can support structures, undergo compaction properly, or identify if it needs treatment to improve its density and load-bearing capacity.

The other options, while they pertain to components associated with earth materials, do not specifically define density in this context. For instance, the volume of air doesn't contribute to the mass of soil and water; rather, it is the spaces between soil particles. Similarly, while the proportion of soil types is relevant for determining properties like permeability and cohesion, it doesn't directly define density. Temperature can affect the moisture content of the soil but is not a defining factor of density itself. Thus, the correct definition of density within earthworks is indeed aligned with the weight of soil and water.