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

Abstract

Climate change and natural resources depletion are leading society towards a more environmentally sustainable approach. In areas such as construction or civil engineering, waste and by-products 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 mixtures manufacturing as road pavement layers has great potential due to their characteristics and the large number of natural resources required. Thus, this research aims to characterise a flotation sterile (Low-Grade Magnesium Carbonate, LG-MC) generated in the beneficiation process of natural magnesite and analyse its potential use as filler in asphalt mixtures manufacturing. The characterisation of physical, chemical, and microscopic properties of LG-MC was carried out and then its potential use as filler for asphalt mixtures was evaluated using the UCL (Universal de Caracterización de Ligantes) method. The optimum filler/bitumen ratio for the LG-MC was 1.49, higher than that of calcium carbonate, which was 1.33. Results show a protective effect of LG-MC as filler against ageing, both in the short and long-term, reducing losses due to abrasion.