Interaction of polycarboxylate-based superplasticizers with cements containing different C3A amounts

This parametric study links the molecular structure of a carboxylate-type of superplasticizer with their performance in cement pastes with different C3A-contents. Beside the variation of the C3A-content, the experimental synthesized superplasticizers have been varied by polyethylene-oxide side chain density and length. The connection between the superplasticizers, their effect on workability properties and retardation phenomenon and the dependency of C3A-content in the cement paste has been investigated. The characteristic interaction phenomenons between different PCE-architectures and different C3A-contents have been examined by calorimetric, rheological, adsorption, and zeta potential measurements. This study shows that with decreasing side chain density the PCE molecules adsorb stronger and thus, lower the yield stress of a cement paste by steric stabilization. It is also shown that PCE molecules with long side chains delaying the setting of the cement paste to less extend than PCE molecules with shorter side chains. Consequently, in terms of optimization of the molecular architecture, good workability can be achieved by addition of highly charged PCE with long side chains. The latter minimizes undesired retardation phenomena.