The A1 is expected to remain closed until this afternoon between Colsterworth and Stamford after a lorry carrying sulphuric acid overturned shortly after 5am.
The chemical load did not spill on the road but special assistance with recovery is needed.
The driver of the HGV was unhurt as he escaped from being trapped. The tanker overturned after hitting the barrier on the other side.
The road remains closed in both directions between the A606 (Rutland Water Turn Off) and the A151 (Colsterworth Services Junction).
There are delays through to the A43 (Wothorpe / Easton Hill Turn-off).
Local diversions are in place. Follow police directions and signage.
Inspector Mark Gee said: “The truck has got 23 tonnes of sulphuric acid in it, however it is fully intact, there are no leaks what-so-ever from the vehicle.
“The main issue was the worry that it could leak but it hasn’t at the moment and we do not believe that it will do.”