Early age hydration of calcium sulfoaluminate (synthetic ye'elimite, ) in the presence of gypsum and varying amounts of calcium hydroxide

Type
Article

Authors
Hargis, Craig W.
Kirchheim, Ana Paula
Monteiro, Paulo J. M.
Gartner, Ellis M.

KAUST Grant Number
KUS-l1-004021

Date
2013-06

Abstract
Suspensions of synthetic ye'elimite (C4A3S̄) in a saturated gypsum (CS̄H2) and calcium hydroxide (CH) solution were examined in-situ in a wet cell by soft X-ray transmission microscopy and ex-situ by scanning electron microscopy. The most voluminous hydration product observed was ettringite. Ettringite commonly displayed acicular, filiform, reticulated, and stellate crystal habits. Additionally, pastes with C 4A3S̄, 15% CS̄H2, and varying amounts of CH were prepared and examined with X-ray diffraction (XRD) and isothermal calorimetry. The XRD experiments showed that increasing CH content caused more solid solution (SO4 2 -/OH-) AFm phases to form at early ages (< 1 d) and more monosulfate to form at later ages (> 1 d). Calorimetry indicated that the increased production of solid solution AFm was accompanied with an increase in the initial (< 30 min) rate of heat evolution, and increasing CH generally reduced the time till the second maximum rate of heat evolution due to the formation of ettringite and monosulfate. © 2013 Elsevier Ltd.

Citation
Hargis CW, Kirchheim AP, Monteiro PJM, Gartner EM (2013) Early age hydration of calcium sulfoaluminate (synthetic ye’elimite, ) in the presence of gypsum and varying amounts of calcium hydroxide. Cement and Concrete Research 48: 105–115. Available: http://dx.doi.org/10.1016/j.cemconres.2013.03.001.

Acknowledgements
C.W. Hargis was supported by the Berkeley Fellowship for Graduate Study and the Carlson-Polivka Fellowship. A.P. Kirchheim acknowledges the financial support of CAPES (Fundacao Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Ministerio da Educacao - Brasil) and CNPq (National Counsel of Technological and Scientific Development). Research at XM-1 is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under contract no. DE-AC02-05CH11231. We thank Peter Fischer and Mi-Young Im for assisting the XM-1 users and maintaining the beamline. This publication was based on work supported in part by award no. KUS-l1-004021, made by King Abdullah University of Science and Technology (KAUST).

Publisher
Elsevier BV

Journal
Cement and Concrete Research

DOI
10.1016/j.cemconres.2013.03.001

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