Comparison between the effects of phosphorous slag and fly ash on the C-S-H structure, long-term hydration heat and volume deformation of cement-based materials

•The addition of 30 wt% PS reduces the 180-day hydration heat by about 9.2%.•The addition of 30 wt% PS reduces the 180-day shrinkage by about 9.0%.•FA is more conductive to reducing the long-term hydration heat and shrinkage.•PS reacts with CH and produces lots of C-S-H with high polymerization degree.•FA increases the polymerization and Al content of C-S-H more noticeable than PS.