Grand Canal Dock is a 200-year-old basin between the Grand Canal and River Liffey in Dublin. It is an area undergoing massive commercial and residential development and it is also intended to use the upgraded docks for leisure activities.
By using innovative underwater shutters and micro concrete, Freyssinet Makers was able to offer the client considerable savings on their original design. They proposed a sheet pile cofferdam four metres from the wall face to allow the area between to be drained and receive sprayed concrete. Our innovative design reduced time, cost and possible risk of collapse of the existing wall by the removal of hydrostatic pressure. The works consisted of dredging 2000m3 of excess material close to the canal wall over a 240m length, shuttering underwater to a depth of 4m and pumping over 200m3 micro concrete to consolidate the structure. 600m2 of stonework was also repaired and re-pointed both above and below water.
Some peculiarities on this project were: the age of the existing structure and the requirement to carry out the works from the water side; the 200 year old walls contained little or no mortar and great care was required to maintain its integrity; the shutters used were designed with buoyancy aids that allowed them to be filled with air to fl oat them into place than filled with water to sink them into position; the shutter face was fine plastic gauze that meant that water was dispersed through the face while pumping concrete without causing undue pressure on the wall or the shutter fixings.
The result was a high strength concrete wall with an excellent finish. All completed within a 30-week programme.