Project:  Wellington Railway Station Seismic Strengthening

Date:  February 2006

Location:  Wellington

Contractor:  Fletcher Construction

Engineer:  Holmes Consulting Group

Concrete Supplier:  Firth Industries

Type of Unit:  New 6-story shear walls constructed between existing floors.

Reason for choosing SCC:  The top of each wall panel intersected with a particularly complex ceiling profile, including a grid of beams running both across and along (inside) the wall.  Reliably placing conventional concrete in complete contact with such an overhead profile was not possible.  Accordingly, the walls were initially constructed by demolishing a section of each floor.  The noise and dust generated by demolition were unacceptable in a building which houses NZ Rail's network control system and Victoria University lecture rooms.  By using an SCC mix, the floor structure could be left in place.  The concrete for the top 1m of each wall was poured from above through a 150mm hole in the floor until it flowed along and back up through adjacent holes.

Outcome:  Significant reduction in noise and dust nuisance to the occupants of a building during refurbishment.  A very complex-shaped void was completely filled with concrete with no compaction defects or need for remedial work.  Reduction of demolition work achieved time and labour savings for the contractor.  Elimination of noise from compaction (vibration) during SCC pouring was also an advantage.

Submitted by:  Alistair Bennett, Firth Industries