High titanium heavy slag powder as a sustainability filler and its influence on the performance of asphalt mortar

High titanium heavy slag powder (HSP) is a typical waste with vast reserves but lacks effective disposal. This paper investigated for the first time the potential of reusing HSP as a sustainable mineral filler for asphalt mixtures. Firstly, a comprehensive comparison and analysis of the physicochemical properties of HSP and limestone powder (LSP) were conducted. Subsequently, asphalt mortars were designed, incorporating four filler-to-asphalt ratios (F/A of 0.2, 0.3, 0.4, 0.5) and five levels of HSP substitution for LSP (0%, 25%, 50%, 75%, 100%). Finally, selected properties of twenty types of asphalt mortar were tested. Compared with LSP, the HSP presented a coarser surface, more pores, smaller particle size and larger specific surface areas, which were conducive to the formation of more “structured asphalt”. Moreover, the chemical composition of HSP was complex, but it did not leach toxic elements, and the volume stability, high temperature stability, radioactivity met the requirements. However, its alkalinity was significantly lower than that of LSP, indicating weaker interactions with the asphalt. At F/A ratios of 0.2 and 0.3, the replacement of LSP with HSP resulted in a slight decrease in high temperature properties of asphalt mortars, but an improvement in low temperature performance. However, a further increase in the F/A ratio revealed an opposite trend. The properties of asphalt mortars were influenced by the combined effects of the chemical composition and physical properties of HSP. The FTIR test results indicated that no new functional groups were formed between the HSP and asphalt, suggesting primarily physical interactions.