Quality improvement of mixed and ceramic recycled aggregates by biodeposition of calcium carbonate

- The biodeposition of CaCO3 on RMA was proposed to reduce their water absorption.
- Commercial recycled mixed aggregates obtained from recycling plants were tested.
- CaCO3 effect on water absorption, weight and consolidation of RMA was analysed.
- Characteristic appearance of precipitate from B. sphaericus was observed by SEM.
- Biodeposition had positive influence on RMA waterproofing.

This research focuses on improving the quality of mixed and ceramic recycled aggregates by microbially induced carbonate precipitation (Bacillus sphaericus). The precipitation contributed to a weight increase and unleashed a waterproofing response. The roughness of the ceramic particles created a more uniform layer compared to natural or concrete particles. For the concrete fraction, which had a higher macroporosity, the consolidation effect was more pronounced. High ceramic content aggregates profited from a greater biodeposition, leading to a remaining amount of precipitates after sonication which was still greater than in cementitious materials. Pore-filling effect was detected by SEM, supporting the waterproofing result.

198