They consist of cold milling asphalt layers from an end-of-life pavement and re-agglomerating them using bituminous emulsions. Slow breaking emulsions, sometimes made with modified bitumens or with rejuvenators, are usually used depending on the nature and characteristics of the milling process used. It is very important to achieve good packing and compaction of the recycled material.
Cold recycling is carried out at room temperature and usually on site, using special machinery that facilitates the application of this technique, which is very effective and economic. The emulsions recommended for this application comply with the specifications of the General Technical Specifications for Road Works and Bridges (PG-3) and those contained in the UNE-EN 13808 (cationic) and UNE 51603 (anionic) standards.
Half-warm recycled mixes with emulsions are generally manufactured at temperatures below 100ºC, with variable proportions of milled material from aged asphalt mixes (RAP) in an aggregate plant and using a bituminous emulsion as a binder. The recommended emulsions meet the specifications set out in the UNE-EN 13808 standard.