*2.2. The Recycling Process of Concrete (Thermo-Mechanical Treatment According to PAT.229887)*

The initial crushing of previously disintegrated concrete specimens (100 × 100 × 100 mm) was carried out in a jaw crusher. The concrete was crushed to the grain size *d* ≤ 40 mm. In the next step, the concrete rubble was calcined in a ceramic laboratory furnace. Calcination of the recycled aggregate is necessary in order to dehydrate the cement paste. Dehydration of the cement paste reduces adhesion of the hardened mortar to the aggregate grains and eventually makes it easier to remove it from the surface of the aggregate. After thermal treatment and cooling, the recycled material was mechanically processed in a Los Angeles machine (Merazet, Poland). The grinding time was 15 min. This allowed for the final separation of the recycled cement mortar (RCM) from the surface of coarse aggregate grains. In the last step, the recycled material (fine and coarse fraction) was sieved in order to separate recycled cement mortar (<4 mm) from coarse aggregate (>4 mm). The recycled coarse aggregate and recycled cement mortar after the full process of recycling are shown in Figures 1 and 2. The coarse aggregate (>4 mm) obtained in recycling process can be used in new concrete as a substitute of natural aggregate. The test results of properties of concrete with recycled aggregate were presented in [8].

**Figure 1.** Recycled coarse aggregate obtained after thermal and mechanical treatment.

**Figure 2.** Recycled cement mortar (fine fraction) obtained after thermal and mechanical treatment, used to tests.
