Phase development in conventional and active belite cement pastes by Rietveld analysis and chemical constraints

Journal Article · Thu Oct 15 04:00:00 EDT 2009 · Cement and Concrete Research

DOI:https://doi.org/10.1016/j.cemconres.2009.06.017· OSTI ID:21260481

Cuberos, Antonio J.M.; De la Torre, Angeles G; Martin-Sedeno, M Carmen; Moreno-Real, Laureano ^[1]; Merlini, Marco ^[2]; Ordonez, Luis M ^[3]

---

1. Departamento de Quimica Inorganica, Universidad de Malaga, 29071 Malaga (Spain)
2. European Synchrotron Radiation Facility, ESRF, BP220 F-38043 Grenoble (France)
3. Unidad Tecnica de Investigacion de Materiales, AIDICO, Avda. Benjamin Franklin, 17 Paterna, Valencia (Spain)

High belite cements may be an alternative to reduce CO{sub 2} emissions. Although CO{sub 2} emissions may be depleted up to 10%, unfortunately, the hydration reactivity of belite phases is slow which leads to low mechanical strengths at early ages. In order to enhance their hydraulic reactivity, the activation of these cements by doping with alkaline oxides has been proposed. Here, we have synthesised a laboratory belite clinker without activation (47 wt.% of {beta}-C{sub 2}S and 19 wt.% of {alpha}{sub H}'-C{sub 2}S) and two alkaline oxide activated clinkers (one with 13 wt.% of {beta}-C{sub 2}S, 24 wt.% of {alpha}{sub H}'-C{sub 2}S and 19 wt.% of {alpha}-C{sub 2}S; and the second with 12 wt.% of {beta}-C{sub 2}S, 42 wt.% of {alpha}{sub H}'-C{sub 2}S and 5 wt.% of {alpha}-C{sub 2}S). We have also developed a methodology to analyse quantitatively the phase evolution of cement pastes and we have applied it to these high belite cements. Rietveld quantitative phase analysis of synchrotron X-ray powder diffraction data, together with chemical constraints, is used to determine the phase development up to 1 year of hydration in the belite cement pastes. {beta}-C{sub 2}S almost does not react during the first 3 months, meanwhile {alpha}{sub H}'-C{sub 2}S reacts on average more than 50% in the same period. Moreover, the degree of reaction of {alpha}-C{sub 2}S is slightly larger (on average about 70% after three months) than that of {alpha}{sub H}'-C{sub 2}S. Full phase analyses are reported and discussed including the time evolution of amorphous phases and free water.

• OSTI ID: 21260481
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Journal Issue: 10 Vol. 39; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARBON DIOXIDE
CEMENTS
EMISSION
HYDRATION
PHASE STUDIES
REACTIVITY
X-RAY DIFFRACTION