What is the best way to clean concrete and tarmac?

yes sandblaster would be a good start,as long as the concrete and tarmac are solid if any is loose it will bring it up,if you are worried about this u could try a power washer,or you could always get paint for concret,and tarmac there is special black paint that i used to use on mine and believe me it looks brand new when you have finished hope this helps  more