ESR 05

Objectives:

The objective is:

• To explain previously inexplicable and contradictory features of sorption in cement hydrates that show deviations from the t^0.5 dependence expected from pure diffusion / capillary action control. The project starts from the premise that water sorption hysteresis arises from both “conventional” concepts of pore blocking (“ink-bottle effect”) and also from “new effects” associated with the reversible and irreversible changes in nano porosity (Projects 2 and 4). These processes will be separated by careful measurement of porosity evolution around water drying and wetting fronts passing a fixed depth in a sample using GARField MRI (spatial resolution 10-50 microns).

Progress of the project

Documents

• Presentation mid term [PDF]
• Factsheet [PDF]

Publications

• Sorption, anomalous water transport and dynamic porosity in cement paste: A spatially localised 1H NMR relaxation study and a proposed mechanism, Peter J. McDonald, Ors Istok, Magdalena Janota, Agata M. Gajewicz-Jaromin, David A. Faux,
  Cement and Concrete Research,
  Volume 133, 2020,106045,ISSN 0008-8846,
  https://doi.org/10.1016/j.cemconres.2020.106045.

Factsheet

Expected Results:

• Month12: Construction of a probe for GARField able to hold thin cement samples for the spatially localised measurements of transport while maintaining a water concentration gradient across the sample;
• Month 21: Spatially localised data of porosity and pore size distribution as a function of wetting time in a hydrate sample across which a water concentration gradient is maintained;
• Month 30: Comprehensive data set around a full sorption loop;
• Month 39: Analysis and interpretation of the data in conjunction with Projects 2 and 3.

Planned Secondments

• 4 months at Chryso: Sorption measurements in additive modified hydrates; start month 27.
• 2 months at MR Solutions: Application Scientist: NMR of oil well encasement cements; start month 31.