The building comprises a 17-storey shaft with a 4-storey control room sitting on top. The tower is triangular in plan to account for the three modes of vertical circulation from bottom to top: two lifts and a single escape stairway. To achieve the desired elegance in the tower’s shaft, a construction method that had no cold joints and an excellent surface finish was required. To do this, ‘Slipforming’ was selected as the desired construction method – whereby the concrete is poured in a continuously moving form 24/7.
Two CRH companies, Roadstone and Irish Cement, contributed to this significant project at Ireland’s busiest airport. Irish Cement supplied the cement from their factory in Platin, while Roadstone provided concrete for the tower’s construction.
Following close collaboration with the contractor, Roadstone developed a range of mixes for this purpose. The range of mixes was produced with various setting times of slow, medium and rapid set, which allowed:
- The setting characteristics of the concrete to be adjusted to suit the various stages of construction and achieve sufficient concrete strength to allow the formwork to proceed vertically without damaging the extruded concrete below
- No cold joints due to the monolithic nature of construction
- Rapid continuous construction
The main tower structure was constructed in 22 days with over 320 loads and 1,700m³ of Slipform concrete supplied continuously by Roadstone. In addition to meeting construction speed requirements, the supplied mixes also met specified structural and durability requirements.
The completed tower underwent a full internal fit-out and became operational in early 2020.