Hello Claude!
Your construction looks good, nice, solid work!
I don't have the brand name on the stuff I used - I bought it locally and it was cheap, generic stuff. It came in many colours - I took the sand coloured variant for the ground work, and for the concrete I took the white variant and then I applied black wash several times. I have made the wash myself by mixing future and water 50-50 with a very small quantity of acrylic black paint added. This gave a very nice concrete colour.
Hope it helps you - good luck with your build and have a nice day
Paweł