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Microstructural Modelling of Self-Desiccation During Hydration.


pdf icon Microstructural Modelling of Self-Desiccation During Hydration. (628 K)
Bentz, D. P.; Snyder, K. A.; Stutzman, P. E.

TVBM-3074;

Self-Desiccation and Its Importance in Concrete Technology. Proceedings. International Research Seminar. June 10, 1997, Lund, Sweden, 132-140 pp, 1997.

Keywords:

cement hydration; building technology; capillary porosity; computer models; curing; microstructure; percolation; self-dessication

Abstract:

A three-dimensiond cellular automation-based microstructural model has been applied to simulate the process of self-desiccation during the hydration of cement paste. As hydration occurs, the proper amount of empty pore space, corresponding to the chemical shrinkage of the cement paste, is created within the microstructure. This empty pore space in turn influences the future kinetics of the hydration process, as less water-filled space is available for the dissolution and precipitation of cement phases. Model predictions are compared with experimental data, including both SEM images of microstructure and measurements of degree of hydration based on non-evaporable water content. For water-to-cement ratios below 0.40, sealed curing conditions are seen to result in a significant decrease in the achievable hydration, relative to curing under saturated conditions. The addition of silica fume is observed to further increase the self-desiccation and decrease the achievable degree of hydration. The model can also be adapted to other curing scenarios, such as saturated curing until the capillary porosity becomes disconnected, followed by sealed curing, to assess the effects of different curing regimens on the hydration and subsequent performance of cement-based materials.