To reflect the phase assemblage of cement paste under drying conditions in PHREEQC, you can modify the water content in the SOLUTION definition to simulate evaporation. By reducing the total amount of water in the solution, you effectively replicate the drying process. Here are key steps and considerations:

1. Adjust Water Content: Decrease the water volume in the SOLUTION definition to represent evaporation. This can be done iteratively to simulate progressive drying.

2. Link Water Content to Degree of Hydration: Use the reduced water content to limit the extent of hydration reactions. You may define constraints or adjust the moles of phases to simulate the inhibited dissolution of clinker due to limited water availability.

3. Include Thermodynamic Data: Ensure that the thermodynamic database (e.g., Cemdata18) accurately reflects the stability fields of phases like C-S-H, AFt, and AFm under varying water activities.

4. Track Water Activity: Use PHREEQC’s -water and -pe options to adjust the water activity, which will influence phase equilibria.

5. Iterative Simulations: Perform simulations iteratively to model different stages of drying and monitor how the phase assemblage evolves.

This approach can provide insight into the interplay between drying, water content, and phase evolution. It would be valuable to validate results against experimental data to confirm the reliability of the simulation.

Dear Dr.Altawil:

Thank you for your kindly reply.

The points you mentioned gave me some inspiration, I will try to simulate it to see how the phase changes under dry conditions by Phreeqc and compare with experimental results.

Best regards,

Liao

Yes, it is possible to simulate the drying condition of cement paste in PHREEQC, but this requires some adjustments in the input model and result interpretation. In drying conditions, you need to adjust the water content in the SOLUTION section of PHREEQC, which will reflect the evaporation of water over time. The reduction in water content will affect the hydration of the cement, which in turn can influence the phase distribution (such as CSH, AFt, and AFm).

To simulate this more accurately, you can:

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