In Roller Compacted Concrete (RCC), cement is mixed with aggregates and compacted to its final form at the optimum moisture content (OMC) in order to achieve maximum dry density (MDD). However, at the time when compaction starts, cement has already begun to hydrate and we cannot control or predict the hydration.
How to account this moisture loss?
Can we model hydration of cement using a software?
Considering the variability of RCC mixture ingredients in terms of water absorption, moisture content, etc., maybe a good experimental program would be more informative than using software. It sounds like the issues you are facing may be due to absorption rather than cement hydration. As for cement hydration, your statement that we cannot control or predict the hydration may not that deterministic. We can indeed control cement hydration using chemical admixtures and we can assess it and predict it using for instance calorimetric tets.
You can for example look at this study: Article Optimum moisture content in roller-compacted concrete pavement
Calorimetry, as suggested by Dr. Nehdi, either isothermal or semi-adiabatic should be a good way to follow the hydration progress. Chemical shrinkage measurements can also be employed on the paste component if calorimetric equipment is not available, although a "coffee cup" semi-adiabatic calorimeter only requires a thermometer or thermocouple and a well insulated container holding a known amount of the cementitious materials....
Dear Moncef L. Nehdi and D. P. Bentz,
I really appreciate your informative response!
Thank you.
Dear D. P. Bentz and Moncef L. Nehdi
Since RCC is a dry mix, there might be a residual cement percentage which has not been hydrated due to the low moisture content. And I just need the moisture content used for hydration within a specific time (let's assume - within 0.5hrs).
Can I measure it using calorimetry?
Perhaps, it will depend on the sensitivity of your equipment, etc. Is this the 0.5 hours just after first mixing the materials together? Quite often, the calorimeter requires some time to equilibrate after the materials are added to it and thus the data during the first 30 minutes or so are unreliable.
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