Golden Bay Cement is the only cement manufacturer in New Zealand and was established, in the 1870’s in Portland, 2 hours north of Auckland. Cement has been produced on site since 1917, with the plant delivering an annual production capacity exceeding 850,000 tons.

  • Name of the owner and client
    GBC Winstone
  • Delivery date
    June 2020
  • Partners of the project
    Beca (design partner)

Unexpected silos’ recovery

The manufacturing complex included 5 silos that were in such a poor condition that all previously consulted designers and contractors had concluded that no remedial solution would ever salvage the storage installations. In contrast to their competitors, Freyssinet teams proposed a solution that would not only reinstate the silos’ capacity but also extend their service life by at least 25 years.

Effective repair strategy

To cover the overall scope of the project, Freyssinet New Zealand’s teams designed a global repair strategy, from silos’ concrete investigation to implementation of a remediation plan for the whole industrial complex.
The silos’ restoration was eventually carried out in 3 stages.
Remediation of Silo 2 was successfully performed within a year’s time, between 2016 and 2017; Based on this achievement, we were awarded a design-build contract, to restore the storage capacity of Silos 3 and 4, up to 1,300 tons of cement and extend their design life by at least 25 years.
After completion of this new phase, demonstrating efficient remedial methodology, we were eventually awarded the final stage of the scheme to conduct the same repair and life extension works on Silos 5 and 6.

  • 230
    Thickness of concrete walls (mm)
  • 7.7
    Diameter of each silo (m)
  • 33
    Height of silos (m)

Heavy repair works

While engaging in continuous works at Golden Bay Cement for nearly 5 years, Freyssinet New Zealand’s teams demonstrated their expertise and repair capabilities and technologies.

Prior works included the removal of all existing surface coatings using ultra-high-pressure water blasting, completion of defect mapping and removal of defective concrete and corroded reinforcement -based on technical specifications covering 3 specific scenarios: corrosion deteriorated concrete repair, non-corrosion deteriorated concrete repair, filling of blowholes and surface imperfections.

Strengthening of the silos was obtained with additional, external post-tensioning using Freyssinet anchored tendons (European Technical Approval ETA 06/2026) -with grout injection before stressing to ensure a perfect strand embedment and the application of a uniform pressure to the concrete surface.
Reinstatement of reinforcement and of concrete was performed with dry shotcrete, to achieve excellent bond between the substrate and the new materials.

Uninterrupted on-site operations

Despite the extensive scope of works and demanding remediation plan, the teams’ strategy also made it possible to maintain the storage silos in operational conditions, which was a true challenge, given their deteriorated, initial state. One of our major achievement was to keep the production process and the supply of cement to the New Zealand market up and running.


The Golden Bay Cement life extension work has been a milestone in the development of Freyssinet New Zealand.
This project is a perfect example of collaboration between our cross-border teams. Freyssinet Australia was heavily involved in the first stages of the project, and Freyssinet New Zealand managed to take over and complete the works successfully.

Freyssinet Australia & New Zealand Zone Director