Both gravel and pebbles can be used as coarse aggregates to mix concrete, and their formation processes and properties are different.
Gravel is usually artificially crushed, with rough and angular interfaces, a large specific surface area, and good bonding performance with cement.
Pebbles are smooth surfaces formed by years of erosion and collision under the action of river water.
They are mostly circular or elliptical particles with poor bonding properties to cement.
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