Which material has higher shear strengths, gravels/sands or silts/clays?

Gravels and sands exhibit higher shear strengths compared to silts and clays primarily because of their internal friction angle, which is a key factor in their strength characteristics. The internal friction angle is a measure of the inter-particle friction that occurs when the grains are loaded.

In granular materials like gravels and sands, the particles are relatively coarse and have a rough surface, allowing for better interlocking and friction when subjected to stress. This results in higher shear strength due to the ability of the particles to resist sliding past one another. The nature of these materials enables them to dissipate loads effectively, making them ideal for construction and foundational applications.

In contrast, silts and clays have much smaller particle sizes and tend to exhibit plasticity and cohesion, which can sometimes lead to lower shear strength under certain conditions. The moisture retention in silts and clays can also lead to changes in their effective stress and, consequently, their shear strength. However, while cohesion in silty and clayey soils can provide some strength, it does not typically surpass the shear strength contributed by friction in granular materials.

Thus, the assertion that gravels and sands have higher shear strengths due to their internal friction angle accurately reflects the fundamental properties of these materials in ge