Ronacrete Pointing Mortar Keeps London's Rail Network Running
The brickwork of a 1½ mile long British Rail tunnel has been successfully repointed using a very rapid waterproof mortar formulated from Monoset Powder and Ronafix BBA Approved waterproof additive.
Because water was actually percolating through the old mortar during reinstatement, it was essential to have a fast-setting mortar with good adhesion.
The tunnel, in Farringdon, London is an old brick-built ‘cut and cover’ structure which was closed temporarily while the line was being electrified using the 25Kv A.C. overhead system as part of the British Rail’s plan for the Moorgate - Bedford route. There were many damp areas where water was seeping through the joints and this had made it impossible to repoint with a conventional mortar. The Monoset/Ronafix formulation has a 15 minute initial set, monolithic (“as one”) adhesion to the sides of the bricks and to the old mortar and is waterproof when tested to ISAT standards.
The Main Contractor for the project was Edmund Nuttall who worked to a specification laid down by the Chief Civil Engineer, LM Region, British Rail. The existing mortar joints were raked out to a depth of 10mm deep and wide , cleaned out and washed with clean water. Loose material was removed.
The replacement pointing mortar was a site batched blend of Monoset Powder, medium grade sharp sand, Ronafix liquid, and water. The mortar was hand mixed in the tunnel close to the point of application and trowelled and pointed into the recess and compacted smooth.
Monoset Powder is an ultra-rapid hardening cement replacement. Ronafix BBA Approved admixture for mortars imparts strength, adhesion and waterproofing to cement mortars and concretes.
It will reach an impressive compressive strength of 10N/mm² within one hour, increasing to 50N/mm² after 28 days.