Which type of grading indicates all particles fall within a wide range of sizes?

Well-graded soils are characterized by a broad range of particle sizes, which means they contain a mix of both coarse and fine materials. This diversity allows the soil to achieve greater density and better compaction than soils with a narrower range of particle sizes. The presence of various sizes fills the voids between larger particles, increasing stability and reducing the likelihood of settlement under load.

In contrast, poorly graded soils typically have a limited range of sizes, often composed primarily of particles that are similar in size, which can lead to poor compaction and less stability. Similarly, uniformly graded soils consist of particles that are nearly all the same size, resulting in significant void spaces and less interlocking, which further diminishes stability. Gap-graded soils have a mix of sizes, but they lack some intermediate sizes, leading to large voids that can also compromise stability and load-bearing capacity.

This understanding of grading types is essential in geotechnical engineering, as it directly affects the performance and behavior of soils in various construction scenarios.