For precast concrete beam, the top surface of the top flange is intentionally roughened when the beam is manufactured. This is typically accomplished with a rake after the concrete has set a bit and can hold the shape. The purpose is to facilitate a mechanical interlock on the shear interface between the beam and a cast-in-place concrete slab. This is similar to roughening a cold joint between two concrete placements. Not quite as similar but somewhat like a broom finish applied to a concrete sidewalk.
What are some options for modeling this information? A detailed geometric representation is not required