Wagons from a train carrying hundreds of tones of cement have derailed neared Ketton.
Five wagons from the seven wagon train came off the lines on Monday.
No one was hurt in the incident.
Workers from Hanson Cement have been emptying cement from the railway wagons following the derailment, to allow the works to right the wagons with a crane.
A temporary roadway was laid from the A6121 to allow lorries and the crane access to the site.
Each of the railway wagons weighed about 50 tons, including about 38 tons of cement powder, which had to be transferred from the wagons to road tankers and removed from the track.
Hanson Cement communications manager David Weeks said: “We are trying to get these big beasts back on the line.
“We still don’t know what caused the incident to happen and we are carrying out an investigation.”
Mr Weeks said the railway line is also being inspected for damage.
The incident happened on the works’ private branch line when a small shunting locomotive was being used to take the wagons to the main Stamford-Oakham line where they are normally attached to a larger train.
The wagons are still blocking the line and prevented Hanson Cement exporting its product by rail this week.
However, Mr Weeks said the cement works exports a huge amount of cement by road and has silos to store any cement, which can not be immediately shipped so has not slowed down production.
Mr Weeks said the accident was not being investigated by the Health and Safety Executive as no-one was injured.