Synthesis of novel polyelectrolyte sacrifice agents and their effects on the adaptability of polycarboxylate superplasticizer with clay-containing cement paste

Using cheap epichlorohydrin and dimethylamine as monomers in order to introduce cationic groups, acrylamide as another monomer, and ammonium persulfate as initiator through free radical copolymerization in aqueous solution, cationic sacrifice agent (SA1) was synthesized. Similarly, an amphoteric sacrifice agent (SA2) containing both quaternary amine and carboxylate functional group was synthesized. The terpolymers were used as a sacrifice material for polycarboxylate superplasticizer (PCE), and its reactive mechanism in cement–PCE–water with clay system was studied, which is desirable to solve the problem of PCE sensitivity to clay. The flow behavior of cement paste containing PCE in the presence and absence of clay was assessed. It was pointed out that the presence of montmorillonite (MMT) or kaolin significantly reduced the dispersion effect of PCE, eventually decreased the slurry fluidity. Fortunately, the addition of the sacrifice agents hindered this disadvantage. The fluidity of slurry increased with the increase in the amount compared with the lack of sacrificial agent. The sacrifice agent has a positive effect on retaining the fluidity of cement pastes, and to some extent makes up for the poor dispersion of PCE in the presence of clay impurities. The adsorption of SA1 or SA2 by MMT particles was studied by total organic carbon (TOC) analyzer. The results show that SA1 or SA2 can be preferentially adsorbed on particles by MMT compared with conventional PCE which result in more releasing PCE macromolecules and less useless loss. The sacrifice agent provides a possibility for improving the adaptability of PCE in low-quality cementing materials and has a potential application. Graphical Abstract