5.10 : شكل وملمس الركام الخشن

The shape of the coarse aggregate is defined by two characteristics: roundness, which indicates the sharpness or angularity of its edges and corners, and sphericity, which measures how closely it resembles a sphere.

Using simple gauges, the shape of the coarse aggregate can be identified as elongated if its length is considerably larger than other dimensions, flaky if its thickness is smaller relative to the other dimensions, or both elongated and flaky.

The surface texture of coarse aggregate is generally categorized as rough or smooth based on the texture of its parent material and the extent to which forces act on it.

Freshly crushed rocks are angular with sharp corners and a rough texture. Over time, through weathering, the corners break down, forming subangular particles.

Further, as these particles are transported by weathering agents, their corners wear off, resulting in rounded particles with smooth texture.  

Lastly, the shape and surface texture of coarse aggregates influence the ease of packing them into a dense configuration.

Angular and rough-textured aggregates are more difficult to compact than rounded, smooth textures.