New Brighton Pier Earthquake Repairs
Fulton Hogan are carrying out the repair work to the 17 columns on the New Brighton Pier which suffered damage as a result of the 2010 and 2011 Christchurch earthquakes. Allied Concrete is proud to be the preferred concrete supplier for this project and aid in restoring this iconic Christchurch structure.
Repair to the columns require large steel caissions to be inserted deep into the sand to surround the column and provide a dry working environment for workers to carry out repairs. Damaged concrete is removed and the exposed steel reinforcing is primed, with large 5m long steel jackets placed over the exposed area and the cavity then filled with Allied Concrete’s high performance self-compacting concrete to restore the structural integrity to each column.
The environment posed significant challenges surrounding accessibility to pour sites. Initial pours on the columns located close to the beach were relatively straightforward as they could be accessed by a pump located on the beach. As work progressed along the Pier, a pour methodology for accessing columns located in the surf zone that were out of reach of a pump was required to be established.
Weight restrictions to the Pier’s access ramp prohibited a loaded concrete truck from driving onto the Pier as this would exceed the 10tonne weight limit on the access ramp. Line pumping was considered but ruled out due to the environmental risk associated with blowouts and excess concrete leftover within the pump the line.
Allied Concrete worked with project partners to develop a safe methodology of driving an empty mini-mixer onto the Pier’s main platform and executing a relay pump from the beach into the mini-mixer, which then drives along the Pier to discharge into a second pump positioned above the relevant column being repaired within the surf zone below.
Allied Concrete’s highly experienced Technical Team developed a custom concrete mix design at Allied’s industry leading R&D laboratory in Christchurch. The mix was designed to be self-compacting (not requiring external vibration or compaction) and easy to place due to the tight working area inside the steel caissions surrounding each column. High strength and durability were also required to resist the harsh marine conditions for decades to come.
The mix design used for this project meets all of the stringent performance criteria set by the Christchurch City Council who specified the project including:
- 60MPa compressive strength at 28 days
- Shrinkage compensated
NZS3101 marine exposure classification C (tidal splash zones)