The prototype is complete now, I calibrated my sensors with water in the reference vial so this calibration coefficient will work with solution but I will have to re-calibrate it for cement.
The calibration for cement will require filling the reference (inert) vial with Sand or NaCl. Because the specific heat capacity for water is 4182 J/kg while Concrete is 880 J/kg which matches that of Salt and NaCl of 880 J/kg. Sand will be accessible in our Lab, and its specific heat capacity is 830 J/kg.
A PhD student at my faculty is using the device now to perform the heat of hydration of cement experiment over an interval of 7 days. The data is being logged to a micro SD card into a CSV file every 5 seconds (which can be opened via libreOffice Calc or any spreadsheet program).
I'll be adding more specific details about the build and the calibration process.