The material will be sourced from Lafarge's Mountsorrel Quarry in Leicestershire. Granite will be supplied as 50mm crushed rock for track beds.
The deal enables Lafarge to invest £2m in new processing equipment at the quarry.
The contract continues a 20-year partnership between the quarry and Network Rail, during which more than a million tonnes of ballast have been supplied every year.
"There is a good chance anyone who has ever been on a train and looked down at the track will have seen Mountsorrel granite, as historically, Lafarge have supplied something like 50% of the ballast used by Network Rail," said Lafarge national key account manager John Bradshaw.