期刊
CRYSTAL GROWTH & DESIGN
卷 19, 期 10, 页码 5850-5857出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.cgd.9b00864
关键词
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资金
- projects Closing the gaps in CO2 well plugging - Research Council of Norway [243765/E20]
- Gassco
- Shell
- Statoil
- Total
- Engie
- Research Council of Norway [193816/S60]
- Research Council of Norway through its Centres of Excellence Funding Scheme [262644]
- FRINATEK Program [275182]
Cement degradation caused by CO2 exposure is an increasingly important environmental challenge that must be understood, for example, if former oil reservoirs are to be used for CO2 storage. When exposed to CO2-saturated brine, cement undergoes a chemically complex carbonation process that influences all the physicochemical properties of the cement. It is known that under favorable conditions, fractures and voids in cement can be occluded, or self-sealed, by precipitation of calcium carbonate. Here, we report a detailed X-ray microcomputed tomography (mu-CT) study on the carbonation of gas pores (macropores) of diameter similar to 1 mm in cement. Specifically, cured class G Portland cement with sub-millimeter spherical disconnected macropores was exposed to CO2-saturated brine at high pressure (280 bar) and high temperature (90 degrees C) for 1 week. High-resolution synchrotron-based mu-CT enabled visualizing the morphology of the precipitates inside the macropores within both unreacted and carbonated regions. Quantitative analysis of the type and amount of material deposited in the macropores during carbonation suggests that the filling of the disconnected macropores involves transport of calcium ions from the cement bulk to the macropore interior. A detailed model describing the chemical processes involved is provided. The present study gives a deeper understanding of cement carbonation by literally shedding light on the complex precipitate structures within the macropores.
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