Effect of side chains on the dispersing properties of polycarboxylate-type superplasticisers in cement systems

摘要

To study the effect of side chains on the dispersing properties of polycarboxylate-type superplasticisers (PCs) in cement pastes, PCs with different side chains were synthesised and used as a superplasticiser for cement suspensions. The effect of side chains of PC on the zeta potential, adsorption, fluidity of the corresponding cement suspensions was investigated systematically, and total interparticle potential energy between particles was calculated. The results show that the higher the short side chains ratio of PC, the larger the adsorption amount of PC. PC with both short and long side chains presents a better dispersing property than PC with short side chains, while PC with long side chains falls in between. The maintaining dispersing ability of PC for cement particles increases as the short side chains ratio increases. The changing rule of total interparticle potential energy produced by PC is in accordance with the changing rule of dispersing property of PC in cement pastes. This indicates that the calculated results of total interparticle potential energy further support the explanation of dispersing property difference of PC in theory. This paper uses the sum of electrostatic energy and steric hindrance potential as the total interparticle potential energy to evaluate the dispersing property of PC for the first time, which is meaningful for the evaluation of dispersing property of polymer dispersant adsorbed on particle surfaces.