Page 46 - New Trends in Green Construction

Circular Economy
room temperature. A Field Emission Scanning Electron Microscopy (FESEM) analysis was also carried out on fragments of hardened samples.
3. Results and conclusions
A strength test on small-scale prismatic specimens revealed that fines (constituents and UND) react well in an alkaline environment, achieving acceptable strength values without any thermal treatment (Figure 2). RC, and UND were the most reactive powders, achieving 14.0 and 12.0 MPa compressive strength values, respectively.
Compacted cylindrical specimens revealed that when the AS-100% content increases, the UCS decreases (Figure 3). The mechanical properties of AS-stabilized mixtures were significantly higher than those for the reference material (CDW aggregates compacted with water only) and improve with curing time, thanks to the AA process. The RM (Figure 4) and UCS values for AS-CDW aggregates are comparable to those of reference stabilized granular materials from literature. FESEM images (Figure 5) confirm the presence of a thin layer of alkali-activated products enwrapping larger aggregate particles, with the presence of the former being responsible for the stabilization of the full CDW aggregate mixture.
The results of this multiscale laboratory investigation revealed that the finer particles in CDW mixtures react in accordance with the alkali-activation theory. The proposed stabilization method demonstrates that CDW aggregates achieve mechanical properties similar to those of cement-stabilized granular aggregates. Moreover, it avoids the use of cementitious products and promotes the sustainability of road infrastructures.
4. Acknowledgment
CAVIT s.r.l. and INGESSIL s.r.l. are greatly acknowledged for the provision of CDW aggregates and sodium silicate respectively
5. .References
Bassani, M., Riviera, P. P., & Tefa, L. (2016). Short-Term and Long-Term Effects of Cement Kiln Dust Stabilization of Construction and Demolition Waste. Journal of Materials in Civil Engineering, 29(5), 04016286.
Jiménez, J. R., Ayuso, J., Agrela, F., López, M., & Galvín, A. P. (2012). Utilisation of unbound recycled aggregates from selected CDW in unpaved rural roads. Resources, Conservation and Recycling, 58, 88–97.
Mohammadinia, A., Arulrajah, A., Sanjayan, J., Disfani, M. M., Bo, M. W., & Darmawan, S. (2014). Laboratory Evaluation of the Use of Cement-Treated Construction and Demolition Materials in Pavement Base and Subbase Applications. Journal of Materials in Civil Engineering, 27(6), 04014186.
46