For pores above 100nm MIP would be the best option

Appropriate BET nitrogen adsorption measurements will allow the pore size distribution to be deduced using the BJH (Barret, Joynner, Halenda) method. The concrete must be dry, which may rule this technique out if you are planning to monitor development in a continually hydrating specimen.

thank you, Dr. Dyer. Im trying to keep the concrete as what it is, or cut some samples for test. So far, most techniques are primarily employed for static tests. I've used CT for concrete scanning, but its only applicable for pores of diameter at mm level.

Thank you, Prof. Aleem, I've try and find out if it works.

As standardized by ISO, the upper limit of BJH method based on nitrogen adsorption is 100nm. Thus it cannot be used for characterization of capillary pores larger than 100nm. You are advised to use numerical method to solve this problem, and use experimental methods to test the degree of hydration. Please see my paper "realistic pore structure of cement paste..."

For pores above 100nm MIP would be the best option

You could also try to develop desorption isotherms and relate each RH (%) to the pore size (i.e., radius) through the Kelvin-Laplace equation. This is a more accurate and consistent way of doing it, although time-consuming due to the long drying times especially for the smallest pore sizes. Hope this helps. Best.

Thank you all, dear colleagues.