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Hydration Reactions and Mechanical Strength Developments of Iron-Rich Sulfobelite Eco-cements
journal contribution
posted on 2013-11-27, 00:00 authored by Gema Álvarez-Pinazo, Isabel Santacruz, Laura León-Reina, Miguel A. G. Aranda, Angeles G. De la TorreBelite calcium sulfoaluminate (BCSA)
cements are low-CO2 building materials. However, their
hydration behavior and its effect
on mechanical properties have still to be clarified. Here, we report
a full multitechnique study of the hydration behavior up to 120 days
of nonactivated and activated BCSA laboratory-prepared clinkers, with
β- or αH-belite as main phase, respectively.
The effects of the amount of gypsum added were also studied. The hydration
and crystallization processes are reported and discussed in detail.
Finally, shrinkage/expansion data are also given. The optimum amount
of gypsum was close to 10 wt %. Our study has demonstrated that β-belite
reacts at a higher pace than α′H-belite, irrespective
of the gypsum content. The hydration mechanism of belite determines
the development of the mechanical strengths. These are much higher
for activated BCSA cement, ∼65 MPa at 120 days, against ∼20
MPa for nonactivated BCSA cement, with the latter having larger amounts
of stratlingite.