There are many factors that will influence the final porosity, such as, additives, water content,  environment, curing time, ... , unfortunately there is no straightforward answer to your question as it depends strongly on which pores your interested in and why. I think you will find the answer here: 

http://iti.northwestern.edu/cement/monograph/Monograph7_2.html

These articles might help: 

Hongyan Ma,  Zongjin Li, Realistic Pore Structure of Portland Cement Paste: Experimental Study and Numerical Simulation, Computers and Concrete, Vol. 11, No. 4 (2013), 317-336  

P. Pipilikaki, M. Beazi-Katsiot The assessment of porosity and pore size distribution of limestone Portland cement pastes, Construction and Building Materials, Volume 23, Issue 5, May 2009, 1966–1970

There are many factors that will influence the final porosity, such as, additives, water content,  environment, curing time, ... , unfortunately there is no straightforward answer to your question as it depends strongly on which pores your interested in and why. I think you will find the answer here: 

http://iti.northwestern.edu/cement/monograph/Monograph7_2.html

These articles might help: 

Hongyan Ma,  Zongjin Li, Realistic Pore Structure of Portland Cement Paste: Experimental Study and Numerical Simulation, Computers and Concrete, Vol. 11, No. 4 (2013), 317-336  

P. Pipilikaki, M. Beazi-Katsiot The assessment of porosity and pore size distribution of limestone Portland cement pastes, Construction and Building Materials, Volume 23, Issue 5, May 2009, 1966–1970

Thank you Sebastian and Niloufar!

The hypothesis to fill gaps in tissues using cement slurry in emergency situations (the detail is subject to patent), however to communicate effectively with the tissue the so called concrete needs to be porous, and the idael size of pores would be about 100 µm.

Being a surgeon and unaware of the complicated nature of SCC, I thought there should be data on the "range" of possible pore sizes. It seems that I must consult a material science specialist.

Thanks again, and I would appreciate your further advice having the above info on board.

Thanks heaps Niloufar!

Regards,

Eb