All landscapes are temporary. The earth changes.
What is a "long time"? Is it one human lifetime? The time period in which these blocks will be a blight is a whole lot longer than the time period where they make a nice landscape, it's just that the nice landscape part comes first. Should we do anything we want assuming that what happens after we're dead is irrelevant?
I replied to your comment because I agree with you but I couldn't find any information online to support it. I cited research where they studied foam that's been in place for 40+ years and it's fine. I was hoping you had data that would support what we both want to hear.
Well, I find it questionable to build roadway/infrastructure foundations out of something vulnerable to structural degradation from exposure tp petroleum products.
One wreck involving a fuel tanker without sufficient containment and the entire subgrade starts to dissolve and buckle and sink?
It looks more like a national security issue. If we're ever at war then the enemy can always tip over a jug of petroleum ether to turn our deeply embedded geofoam foundations into glue, which I imagine would cause everything built on top to crumble too. It would appear they're mostly building highways using this stuff (rather than skyscrapers) so that shouldn't be too much of a vulnerability but it probably isn't what Dwight Eisenhower had in mind when he built the interstates.
[1] Aabøe R, Frydenlund TE (2011) 40 years of experience with the use of EPS geofoam blocks in road construction. Paper presented at the 4th international conference on geofoam blocks in construction applications, Lillestrøm, Norway, 6-8 June 2011