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The Filler Effect II: The Influence of Filler Content and Type on the Hydration Rate of Tricalcium Silicate



Aditya Kumar, Tandre Oey, Gabriel Falzone, Jian Huang, Magdalena Balonis, Jeffrey W. Bullard, Gaurav Sant


The partial replacement of ordinary portland cement (OPC) by fine mineral fillers accelerates the rate of hydration reactions. This acceleration, known as the filler effect, has been attributed to enhanced heterogeneous nucleation of C-S-H on the extra surface provided by fillers. This study isolates the cause of the filler effect by examining how the composition and replacement levels of two filler agents influence the hydration of tricalcium silicate (T1-Ca3SiO5; C3S), a polymorph of the major phase in ordinary portland cement (OPC). For a unit increase in surface area, C3S reaction rates increase far less than expected. This is because the agglomeration of fine filler particles renders up to 65 % of their surface area unavailable for C-S-H nucleation. By analysis of mixtures with equal surface areas, it is shown that limestone is a superior filler as compared to quartz due to the sorption of its aqueous CO32- ions by the C-S-H - which in turn releases OH- species to increase the driving force for C-S-H growth. This conclusion is corroborated by kinetic data of C3S hydration occurring in the presence of CO32- and SO42- ions provided by readily soluble salts. Contrary to prior investigations, these results suggest that differences in heterogeneous nucleation of the C-S-H on filler particle surfaces, caused due to differences in their interfacial properties, have little if any effect on C3S hydration kinetics.
Journal of the American Ceramic Society


tricalcium silicate, limestone, quartz, filler effect


Kumar, A. , Oey, T. , Falzone, G. , Huang, J. , Balonis, M. , Bullard, J. and Sant, G. (2017), The Filler Effect II: The Influence of Filler Content and Type on the Hydration Rate of Tricalcium Silicate, Journal of the American Ceramic Society, [online], (Accessed July 14, 2024)


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Created April 9, 2017, Updated October 12, 2021