Abstract
Influences of alkali or alkaline earth sulfates on the hydration of cubic tricalcium aluminate (C3A) were evaluated by in situ dissolution rate measurements, by ex situ near-surface composition measurements with secondary ion mass spectrometry, and by in situ synchrotron X-ray diffraction to monitor precipitation of hydration products. Both slight reductions in dissolution rate and cation-specific interactions with the solid were observed. The near-surface Ca/Al ratio is significantly lower after some dissolution and the electrolyte cations are incorporated within the surface with different affinities (Mg2+ > K+ > Na+). An interfacial dissolution-reprecipitation mechanism may explain the observations as well as, or better than, a simple cation exchange. The sulfate concentration in solution affects the rates of both C3A dissolution and precipitation of hydration products. Sulfate ions likely adsorb at the hydrous Al-rich surface layer, thereby reducing the dissolution rate of aluminates and delaying the precipitation of aluminate hydration products.
Original language | English |
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Article number | 105989 |
Journal | Cement and Concrete Research |
Volume | 130 |
DOIs | |
State | Published - Apr 2020 |
Funding
The in situ X-ray diffraction is based upon research conducted at the Cornell High Energy Synchrotron Source (CHESS), which is supported by the National Science Foundation under award DMR-1332208. The surface chemical mapping was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility, using instrumentation within ORNL's Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. For the research conducted in Sections 3.1 and 3.3, ASB acknowledges the National Research Council (NRC) for funding through an NRC Postdoctoral Research Associateship at the National Institute of Standards and Technology (NIST). LaKesha Perry and Max Peltz (NIST) performed the inductively coupled plasma optical emission spectroscopy and particle size distribution analyses, respectively. The authors thank Roland Hellmann (Institute for Earth Sciences, Université Grenoble Alpes) and J. Donald Rimstidt (Department of Geosciences, Virginia Tech) for useful discussions. The in situ X-ray diffraction is based upon research conducted at the Cornell High Energy Synchrotron Source (CHESS), which is supported by the National Science Foundation under award DMR-1332208 . The surface chemical mapping was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility, using instrumentation within ORNL's Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. For the research conducted in Sections 3.1 and 3.3 , ASB acknowledges the National Research Council (NRC) for funding through an NRC Postdoctoral Research Associateship at the National Institute of Standards and Technology (NIST). LaKesha Perry and Max Peltz (NIST) performed the inductively coupled plasma optical emission spectroscopy and particle size distribution analyses, respectively. The authors thank Roland Hellmann (Institute for Earth Sciences, Université Grenoble Alpes) and J. Donald Rimstidt (Department of Geosciences, Virginia Tech) for useful discussions.
Keywords
- CaAlO (D)
- Dissolution
- Hydration (A)
- Kinetics (A)
- X-ray diffraction (B)