Oriented aggregation of calcium silicate hydrate platelets by the use of comb-like copolymers

We present an in-depth study of the formation of stable suspensions of low density aggregates of calcium silicate hydrate (C-S-H) particles stabilized by comb-like copolymers. These suspensions exhibit fundamentally interesting properties such as gel formation at 1.4 vol% of particles. Furthermore, they constitute a novel class of hardening accelerators for cementitious systems. Stabilization of C-S-H particles by polyelectrolytes is essential for the synthesis of stable and active C-S-H suspensions. Comb-polymers consisting of charged monomers (acrylic acid or 2-(phosphonooxy)-ethyl-methacrylate) and poly(ethylene glycol) monomers direct C-S-H particle aggregation into fractal structures. The fractal nature of the aggregates has been characterized by TEM and SAXS. Based upon (U)SAXS data of different C-S-H suspensions, it is demonstrated that two-dimensional initial C-S-H particle aggregation favours the creation of structures with a high specific surface area which are particularly active as cement hardening accelerators.