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


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

KAUST Grant Number


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.

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.

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).

Elsevier BV

Cement and Concrete Research


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