For recycled aggregates, there are a few types of treatments depending on the surface characteristics: 1) mechanical treatment, such as abrading them to remove weak attachments, also for improving the surface texture, 2) Chemical treatment for surface stability, also dipping or coating into cement slurry.

The main challenge with recycled aggregates (RA) in concrete is that their surfaces are often more porous, rough, and coated with remnants of old mortar, which can weaken the interfacial transition zone (ITZ) between the aggregate and the new cement paste.

Mechanical treatment by abrasion to remove the old cement paste

Treatment by acids - not practicable

Chemical treatment by accelerated carbonation

Anette