Ruislip Ballast Yard - London Underground Ballast Transfer Slab

 

Concrete Design and Supply: Tarmac
Principal Contractor: Balfour Beatty Rail Projects Ltd
Contractor: Hennelly's Utilities Ltd
Consulting Eng: White Young Green
Client: Metronet Rail SSL Ltd

Project Brief

The client wanted to replace their badly worn ballast transfer facility at Ruislip, North East London. The slab area to be replaced was 4200m2 at 300mm depth and the yard was to be reconstructed in two phases with 50% of the yard to remain available to Metronet for ballast transfer activities at all times.

The new slab was also to be trafficked at an early age to minimise disruption to the client and to minimise program time.

Toproc ES microsilica concrete was specified by White Young Green to achieve a high abrasion slab to  comply with Class AR0.5 (Special) BS8204-2: 2003.

The existing, very worn concrete slab was to be removed, crushed and then used as sub-base for the new construction.

Tarmac Proposal

Toproc ES microilica concrete to be utilized to achieve an abrasion resistant cast insitu concrete. Toproc ES is one of a range of 14 end use specific formulations. Its typical 24-hour strength is in the range of 30 to 40N/mm2 and its typical 28-day strength is 70 to 90N/mm2. Whilst it is perfectly acceptable to traffic Toproc ES at 24-hours we recommend avoiding use of the slab in conjunction with the impact and abrasion from loading machines until it is at least 7 days old and has therefore achieved a compressive strength substantially in excess of 50N/mm2. It is the high compressive strength of Toproc ES that gives excellent abrasion resistance to resist damage. The long-term wear resistance of our Toproc ES microsilica concrete has been well proven in many high abrasion applications.

Tarmac ES Performance

1250m3 of Toproc ES microsilica concrete was supplied into the project in February/March 2005 and the Toproc ES performance was confirmed through the cube testing carried on the deliveries made to site the results of which averaged 81.3N/mm2 at 28 days. The concretes insitu performance was also confirmed
through visual assessment of the first phase slab area following its return to use.

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Last updated: 19 September 2008

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