To enable the construction of two connecting slip roads it was necessary to widen an existing underpass by 20m either side of the existing Edinburgh City bypass. As the original structure had been designed to carry only the fill which formed side slopes, it was necessary to consider the additional imposed loads. Rather than strengthen or replace the existing structure, it proved economical simply to reduce the dead loads by incorporating Fillmaster in the design.

The reduction in dead loads acting on the structure by using a fill with a density of less than 30kg/m³, enabled the live loads to be increased with no detrimental effect to the extended structure.

In all, 2,000m³ of Fillmaster blocks were used in three grades to replace structural backfill on a 30m stretch of the road. The 2440 x 1220 x 610mm blocks were delivered on vehicles carrying 70-100m3 per load enabling rapid construction without the need for compaction.

Client: Scottish Office
Design: W.A. Fairhurst
Contractor: Balfour Beatty
Volume: 2,000m³