Gidday Pete, [#welcome] to the forum.
Here’s links to some recent threads that might help…
http://cs.trains.com/mrr/f/88/p/206188/2255639.aspx#2255639
http://cs.trains.com/mrr/f/11/p/205754/2250790.aspx#2250790
The May 1994 issue of Model Railroader has an article by Bob Foltz entitled “Pour your own city streets.”
Part 3 of “Union Freight” by John Pryke in the November 2000 Model Railroader is on “paving for railroads in streets”, though he mainly uses styrene.
Cheers, the Bear.