Phosphorus slags
Structural insights, dissolution behavior, and potential as sustainable supplementary cementitious materials
Yu Zhang (Southeast University)
Shuai Nie (Wuhan University of Technology)
Chen Liu (TU Delft - Materials and Environment)
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Abstract
Phosphorus slags, abundant industrial by-products, hold significant potential for use as supplementary cementitious materials (SCM). To explore its application, phosphorus slags with varying contents of P2O5 were synthesized, and their network structure, dissolution behaviour, and hydration products in cementitious systems were investigated. The results showed that the pozzolanic reactivity initially decreased and then increased with increasing P2O5 content from 3.11 to 8.32 wt%. This behaviour was attributed to the competition between silicate network repolymerization and distortion of aluminium polyhedra. Furthermore, the incorporation of phosphorus increased the fractions of AlV and AlVI in the glass network, which promoted the incongruent dissolution of Al over Si. Thermodynamic simulation predicted the formation of hydroxyapatite, as the main phosphorus-containing hydration product, which was further confirmed by XRD and NMR results, although with low crystallinity. These findings suggested new perspectives on adopting phosphorus slag as a SCM in cement and concrete production.