[piercehawkeye45]

Interesting. Keep in mind that lime stabilized Roman roads have lasted 2,000 years as well. We have the technology to stabilize our roads to that degree, however, the cost would be considered much too high.

Hopefully this Roman style concrete is looked further into but it may just end up being that this particular Volcano Ash had optimal chemical properties (pozzolan...alumina especially) which cannot be reproduced on a mass scale. That is the main issues with fly ash; the properties are very inconsistent since they are purely naturally variable products and not manufactured.