Granted Patent
Utility
US 5,702,521 · App. 08/728,026
Air-entrained concrete with lignin-containing air-entraining agent
Inventor:
Richard Robert Suchanec
Patented Case
View Patent ↗
Granted: Dec 30, 1997
Filed: Oct 9, 1996
Inventor
Richard Robert Suchanec
Assignee (at issue)
HERCULES LLC
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.