2026-05-29T23:29:31Zhttps://riuma.uma.es/rest/oai/request

oai:riuma.uma.es:10630/231992026-02-03T10:50:05Zcom_10630_2254col_10630_37953

The role of sodium and sulfate sources on the rheology and hydration of C3A polymorphs Neto, José da Silva Andrade Gómez-de-la-Torre, María de los Ángeles Campos, Carlos E. M. Gleize, Philippe J. P. Monteiro, Paulo J. M. Kirchheim, Ana Paula Martos, Paulo R. de Reología Hidratación Cemento The higher reactivity of orthorhombic C3A (ort-C3A) in sulfate-containing solutions, compared with cubic C3A (cb-C3A), was previously related to the differences in crystal structure or the sodium in the ort-C3A pore solution. We analyzed the hydration of cb-C3A (in water and NaOH solution) and Na-doped ort-C3A in the presence of gypsum and hemihydrate. Calorimetry, in-situ XRD, TGA, and rheological tests were conducted. NaOH accelerated the hydration of cb-C3A, but ort-C3A still presented higher ettringite formation rate and earlier sulfate depletion. Ort-C3A pastes showed 10-20 times higher viscosities and yield stresses. Replacing gypsum by hemihydrate increased the ettringite precipitation rate and anticipated the sulfate depletion of ort-C3A but did not significantly influence cb-C3A hydration. The crystallization of hemihydrate into gypsum resulted in early (<10 min) stiffing of all C3A-hemihydrate pastes. Overall, the higher reactivity of ort-C3A is related to differences in crystal structure rather than the sodium in the pore solution. 2021-11-11T12:30:08Z 2021-11-11T12:30:08Z 2021 2022 journal article Cement and Concrete Research, Volume 151, January 2022, 106639 https://hdl.handle.net/10630/23199 10.1016/j.cemconres.2021.106639 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier