【摘 要】
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The study demonstrates a new method to quantitatively evaluate the complex pore system in cement pastes, via water sorption isotherms.The method is used to illuminate mechanisms that control drying sh
【机 构】
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Department of Civil and Environmental Engineering,Massachusetts Institute of Technology,Cambridge 02
【出 处】
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The 14th International Congress on the Chemistry of Cement (
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The study demonstrates a new method to quantitatively evaluate the complex pore system in cement pastes, via water sorption isotherms.The method is used to illuminate mechanisms that control drying shrinkage, and to compute the original water-to-cement (w/c) ratio;both important to engineering practice.We show that irreversible changes in the nanostructure during first drying are associated with changes in the pores that empty between 85-to-45% relative humidity (RH).Furthermore, water in the interlayer space (e.g., similar to clays) of the binding calcium-silicate-hydrate (C-S-H) phase, does not empty until drying below 25% RH, but this water does not completely re-saturate the pore system even upon rewetting at 100% RH.With a new ability to identify the volume of pores associated with the C-S-H gel, as opposed to the remaining capillary pores, a method for computing the original cement content is proposed.These examples support the validity of a new method of evaluating cement-based materials in terms of mixture formulation, and pore system characteristics.
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