C–S–H-PCE nanoparticles and anionic surfactants as nucleation agent in cement based materials: Focus on the antagonism

The small solid particles and surfactants inclusion have the potential to furnish abundant nucleation sites, yet the concurrent operation mechanisms in cement remain unclear. Thus, calcium-silicate-hydrate-polycarboxylate ether (C–S–H-PCE) nanoparticles and calcium stearate (CaSt₂) all were introduced as composites nucleation agents in this work, and then the properties of fresh cement paste, hydration process and microstructure of hardened pastes were especially investigated. Experimental results demonstrated that C–S–H-PCE and CaSt₂ enhanced cement hydration by utilizing their ability to provide nucleation sites, but they were less compatible. Therefore, the combination showed the antagonistic effects: a decrease in fluidity and compressive strength. The decrease in fluidity was mainly attributed to the lowered particle dispersion. The decrease in compressive strength was associated with a lower overall density and increased cumulative porosity of the C–S–H gels. This work establish the theoretical foundation for selecting components of green composite nucleation agents.