Sulfonamide-based polymer grinding aids in slag grinding and their effect on hydration performance of cement

Granulated blast furnace slag (GBFS) is an industrial by-product with high latent activity generated during pig iron smelting, and its unique vitreous structure results in poor grindability. Therefore, activating the latent activity and improving the grindability of GBFS have become research hotspots in the relevant field. In this study, a low-molecular-weight polymer was synthesized using 2-acrylamido-2-methylpropanesulfonic acid (AMPS), hydroxypropyl acrylate (HPA) and diethylene glycol monovinyl ether (DEGVE) as polymerizable monomers, and then compounded with polyhydric alcohol to prepare a polymer grinding aid suitable for GBFS. The effects of the polymer grinding aid on grinding efficiency and hydration properties of GBFS-blended cement paste were systematically investigated. The results showed that the particle size of GBFS ground with the polymer grinding aid was slightly coarser than that of the alkanolamine-treated sample. But the polymer grinding aid could optimize the cross-linked structure of hydration products and improve the early age and long-term strengths of GBFS-blended cement. When the dosages of initiator and chain transfer agent accounted for 1.28% and 5.14% of the total monomer mass, respectively, and the monomer molar ratio satisfied n (DEGVE):n (AMPS):n (HPA) = 1:2.65:0.5, the obtained polymer grinding aid provides a better balance between particle-size distribution optimization of GBFS and strength development of GBFS-blended cement, while the individual fineness parameters remain comparable to or slightly lower than the sample prepared with reference alkanolamine-based grinding aid. Compared with the alkanolamine-based grinding aids, the volume fractions of GBFS particles with particle sizes of 0–3 μm and above 64 μm treated by the polymer grinding aid decrease by 5.4% and 76.0%, respectively, while the volume fraction of particles with particle sizes of 32–64 μm increases by 12.2%. Correspondingly, the 7 d and 28 d compressive strengths of the GBFS-based cementitious materials are increased by 8.4% and 4.3%, respectively.