Which type of grading includes a good range of all particle sizes?

The correct choice, well graded, refers to a type of grading that encompasses a good range of all particle sizes within a material. This diversity in particle sizes contributes to a denser packing of the soil or aggregate, leading to improved stability and strength. In well-graded materials, the smaller particles fill the voids left by the larger particles, minimizing the amount of air space and enhancing the overall compaction.

For example, when constructing foundations or other structures, well-graded aggregates are often preferred because they can provide better load-bearing properties and drainage compared to other grading types. This characteristic makes well-graded materials essential in a variety of engineering applications, as they facilitate effective construction practices.

In contrast, poorly graded materials feature a limited range of particle sizes and tend to have larger void spaces, which can result in instability under load. Uniformly graded materials consist primarily of particles that are similar in size, leading to poor packing and higher porosity. Gap graded materials intentionally omit certain sizes of particles, which can also diminish the material's strength and compaction efficiency, making well graded the most desirable choice for numerous engineering purposes.