Next: Outputs
Up: Three-dimensional Cement Hydration
Previous: Inputs
The 3-D cement hydration and microstructure development model is described in detail elsewhere [1,2]. Once the initial 3-D microstructure and particle ID structures are read in, hydration is executed as a series of dissolution/diffusion/reaction cycles. In dissolution, any pixels of a soluble phase which are in contact with capillary pore space may dissolve and enter solution as one or more diffusing species. These diffusing species then undergo random walks within the pore space until a reaction occurs. After a specified number (typically 500) of diffusion steps have been taken, phase counts are tabulated, empty porosity created to account for the chemical shrinkage (if hydration is under sealed conditions), and another cycle of dissolution is executed. All diffusing species IDs and locations are stored in a dynamically allocated doubly linked list, so that the diffusing species may remain in solution from one dissolution cycle to the next. However, during the last diffusion step of the last cycle of the hydration, all diffusing species are converted into either the phase from which they dissolved or the appropriate hydration products.
In addition, after each dissolution cycle, the heat released by the reactions (as described in the next section) and the degree of hydration which has occurred are used to update the heat capacity and temperature of the system. The heat capacity is a function of degree of hydration, and undergoes about a 10% decrease during the course of hydration due to changes in the state of the water present in the cement paste [20]. Dividing the incremental heat release by the current heat capacity determines the incremental temperature rise of the system. In this way, the adiabatic response of a concrete system may be predicted by estimating temperature as a function of equivalent real time, calculated based on the application of the principles of the maturity method [21] as described in Section 5.3.
Next: Outputs
Up: Three-dimensional Cement Hydration
Previous: Inputs