Dehydrated C/M-S-H Cementitious Material Modified by Polycarboxylate Ether (PCE) and its Effect on Physical and Mechanical Properties and Microstructure of Concrete

A novel method of polycarboxylate (PCE) modification based on phosphorus tailings for the preparation of dehydrated calcium hydrated silicate and magnesium hydrated silicate (C/M-S-H) cementitious materials is presented in this paper. The hydration mechanism of dehydrated C/M-S-H under different morphologies was also revealed. The microstructure of dehydrated C/M-S-H progressively changes from particle flocs to foils with a few particles adhered to the surface with rising the relative molecular mass of PCE. It can rapidly hydrate to form C/M-S-H cement when the dehydrated C/M-S-H is added to the concrete slurry. Furthermore, the C-S-H gels formed by the hydration of the regenerated cement of the foil body have a lamellar structure, which improves the uniformity of the C-S-H gels distribution and the compactness of the concrete microstructure. The 1-day and 7-day strength of concrete can be increased by 161.5% and 16.6%, respectively.