Rose Fitzgerald Kennedy Bridge

The challenge

Extending more than 300m over the River Barrow and with a 36-metre clearance, the bridge is a key link for the surrounding communities and also for shipping navigation to the port of New Ross.

Extrados bridges are noted for their lower tower heights when compared with conventional cable-stayed bridges. While aesthetically pleasing, such an approach puts additional demands on the materials that make up the bridge, with higher strength concretes typically required.

The solution

High strength concrete mixes including C50/60, C60/75 and C80/95 were required to meet these demands. While the use of C50/60 concrete is relatively common, the use of C60/75 and in particular C80/95 concretes in Ireland is rare, and seldom has such concrete been used to the scale required for this bridge.

Through the use of Roadstone’s research and development laboratory in Dublin, a wide range of trials were conducted to assess both the plastic and hardened properties of the concrete mixes, including workability, workability retention and compressive strength. After the laboratory trials, operational trials were conducted to further assess the plastic and hardened properties and their performance in different weather conditions. In addition, Roadstone worked with other parties involved in the construction of the bridge to assess other parameters such as the pumpability of the different mixes.

The outcome

With construction nearing completion, in excess of 4,000m³ of C80/95 concrete has been supplied to the Rose Fitzgerald Kennedy Bridge to date.

Over 90% of the constituent materials were produced locally, with the aggregates sourced from Roadstone’s Kilmacow quarry in south Kilkenny and cements sourced from Irish Cement’s Platin facility.