Effect of Dosage of Polycarboxylate Copolymer Used in Synthesis Process on Nucleation and Early Strength of Nano C-S-H Seeds
Nano hydrated calcium silicate/polycarboxylate copolymer(C-S-H/PCE)crystal nucleus suspension is a new type of early strength agent for cement concrete.It can shorten the cement hydration induction period and promote the development of early strength of cement through crystal seed nucleation.This article investigated the effect of PCE dosage on the grain size,morphology,and PCE actual combined dosage of nano C-S-H/PCE using dynamic light scattering(DLS),electron transmission microscopy(TEM),organic carbon analyzer(TOC),and thermogravimetric analysis(TGA)during the synthesis process.The effects of different dosages of PCE on the hydration heat release rate,flowability,and early strength of cement with nano C-S-H/PCE seeds were also investigated.The results show that when the PCE dosage accounted for less than 5.0％of the mass fraction of nano C-S-H/PCE seeds suspension,the average particle size of nano C-S-H/PCE seeds gradually decreases with the increase of PCE dosage,and the agglomeration situation improves,gradually presenting a clear tin foil like morphology.When the amount of PCE increases to 10.0％,there is little change in the particle size and morphology of the nano C-S-H/PCE seeds.TOC and TGA tests show that when the PCE dosage is 5.0％,it basically reaches saturation adsorption capacity on C-S-H.Therefore,excessive PCE will reduce the promoting effect of nano C-S-H/PCE seeds on the hydration heat release and early strength of cement.
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