The aim is to use more concrete aggregates (from used concrete pavements) for the manufacture of new concrete pavements. More than 18 years ago a concrete pavement, made from recycle concrete, was placed at the section Oberriet-Haag on highway A13, which will provide valuable experience. On this section investigations will be carried out on recycled concrete containing different amounts of concrete aggregates and the long-term behaviour examined.
Based on the results, the standards for recycling of concrete (SN 670 143) will be checked and probably revised.
From the recycled concrete road sections and from the adjacent section with concrete from natural aggregates cores are removed, visually, chemically and physically examined and evaluated. In particular, on:
- Capillary water absorption
- Frosttaumittelbeständigkeit (diagnostic and physical determination)
- Chloride entry
- AAR (alkali-aggregate reaction)
- Compressive strength of concrete
The analysis showed that all types of concrete with recycled concrete aggregate were still in a good or very good state. The recycled concrete 1a/1b which’s aggregate consisted of all-in aggregate and not composed of separate size fractions showed slightly worse properties than the other types of recycled concrete that had aggregate made from different size fractions (0/4, 4/8, 8/16, 16/32).
Compared to all recycled concrete, the reference concrete performed slightly better. The (slight) damages of the recycled concrete 1a/1b were caused by difficulties during the placing and compacting. All types of concretes showed a beginning alkali-silica-reaction. There was no influence on the quality of concrete whether the recycled concrete consisted of recycled or natural aggregate in the fraction 0/4.
All investigated recycled concrete pavements made with concrete aggregate can be used further and will reach their estimated service life of 40 - 50 years even though the damages will increase.