In 1972, Illinois built a highway embankment with 246,000 cubic yards of coal ash. It’s still holding up even after 50 years

In 1972, a groundbreaking highway project in Illinois incorporated coal fly ash as a structural fill, challenging traditional practices. This innovative tactic not only revealed the material's impressive structural capabilities but also held up remarkably over fifty years without significant settlement or frost heave issues. The project's success led to other states establishing guidelines for fly ash use, and contemporary initiatives now prioritize both structural integrity and environmental safeguards.