Freyssinet was appointed to undertake concrete repair works to the Portsmouth Hard Interchange structure. Following commencement on site, the concrete was found to be in significantly poorer condition than originally anticipated, requiring extensive additional remedial works.

  • Client
    Portsmouth City Council
  • Principal Contractor
    Osborne
  • Scope
    Concrete repairs
The interchange is constructed on an existing reinforced concrete deck spanning Portsmouth Harbour’s tidal waters, supported by concrete beams, pile caps and columns founded into the seabed. Its exposed marine environment presents ongoing durability challenges, including chloride ingress, corrosion of reinforcement and concrete deterioration.

The scope

The works included:

  • Hydrodemolition and hand break‑out
  • Design and installation of replacement reinforcement
  • Resin injection
  • Concrete reinstatement using spray‑applied concrete

Freyssinet managed all under‑deck activities, including hydrodemolition and concrete repair works, while the Principal Contractor controlled access to the work area through a strict permit system.

Freyssinet’s subsidiary, Aquaforce Concrete Repairs Limited, removed deteriorated concrete using hydrodemolition. We then designed and installed replacement reinforcement, including connectors, splicing and welding to heavily reinforced pile caps, cross‑beams and radial columns. The team reinstated the concrete using spray‑applied Gunite to achieve a dense, durable finish, applying curing and environmental controls in full compliance with Environment Agency requirements.

A challenging marine environment

Freyssinet delivered the works in a challenging tidal environment, with constantly shifting mud banks beneath the structure. The team carefully planned activities and continuously monitored tidal movements to maintain safe working conditions, supported by clear evacuation procedures for all below‑deck works.

Despite the complex conditions, Freyssinet successfully delivered the project, demonstrating its expertise in providing durable concrete repair solutions in demanding marine environments.