High-volume coal gasification fly ash–cement systems: Experimental and thermodynamic investigation

•CGFA could be used as a supplementary cementitious material (SCM) in OPC.•The reactivity of CGFA was relatively low, although it primarily contained amorphous phases.•The incorporation of 10% CGFA into OPC did not significantly influence the mechanical properties.•The drying shrinkage increased with increasing CGFA content.•The phase assemblages over time were generated by thermodynamic simulation.