Analysing the potential use of a low-grade magnesium carbonate by-product as a filler in hot asphalt mixtures

ABSTRACT

Climate change and the depletion of natural resources are causing society to adopt more environmentally sustainable approaches. In areas such as construction and civil engineering, waste and by-product valorisation could help in the fight against climate change, reducing the consumption of raw materials. Thus, the use of residues or by-products in asphalt mixture manufacturing as road pavement layers has great potential due to their characteristics. This study aimed to characterise a flotation sterile (low-grade magnesium carbonate; LG-MC) generated in the beneficiation process of natural magnesite and to analyse its potential as a filler in asphalt mixture manufacturing. The physical, chemical, and microscopic properties of LG-MC were characterised and its potential use as a filler for asphalt mixtures was evaluated using the UCL (Universal de Caracterización de Ligantes) method. The optimum filler/bitumen ratio for LG-MC was 1.49, higher than the 1.33 of calcium carbonate. Results showed a protective effect of LG-MC against ageing both in the short and long- term, reducing losses from abrasion.

KEYWORDS:

• By-product
• low-grade magnesium carbonate
• filler
• asphalt mixtures
• valorisation
• ageing

Acknowledgements

The authors would like to thank Magnesitas Navarras S.A. for their cooperation in financing and supporting the work (FGB 311127). The authors are also grateful to the Catalan government for the DIOPMA (2017 SGR 118) quality accreditation awarded to their research group. Teresa Lopez-Montero acknowledges postdoctoral fellowship support under the ‘Juan de la Cierva-formación’ Programme (grant FJC-2018-035747-I funded by MCIN/AEI/10.13039/501100011033). Jofre Mañosa is grateful to the Government of Catalonia for his research grant (FI-DGR 2020).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported under Grant FJC-2018-035747-I funded by MCIN/AEI/10.13039/501100011033; under Grant FGB 311127 funded by the Magnesitas Navarras S.A.; and under Grant FI-DGR 2020 funded by the Government of Catalonia.