When the owner of a multi-storey car park in the UK wanted to expand the capacity of the facility by adding extra floors, the challenge was to achieve this structural strengthening works rapidly and without disrupting the operation of the car park and shopping centre it serves.

  • Name of the owner
    Legal & General
  • Name of the client
  • Delivery date of the project
    January 2018
  • Partner of the project
    Architectural precast cladding: Thorp Precast

The concrete structure in Eastbourne had to be strengthened in order to support the load of the additional storeys. This is usually done by increasing the cross-section of existing columns, however this can make the adjacent parking spaces very narrow or even unusable.
It is also disruptive for users, with temporary props necessary to support the building over its full height while the columns are partially demolished and rebuilt.

The presence of these props, and the activities and equipment that are needed for the reconstruction procedure can have a significant impact on operation of the facility, and a corresponding drop in revenue for the owner. The work needed at the Eastbourne car park would have taken a year to complete with this standard procedure.


  • 15
    Weeks on site to strengthen the building
  • 84
    Number of columns strengthened
  • 70
    Reduction in time for site works (%)
Eastbourne Arndale center - Fibre-reinforced concrete ‘shells’

Innovative retrofit system

Freyssinet proposed an innovative retrofit system that used thin, fibre-reinforced concrete ‘shells’ that were made offsite and installed with minimum fuss around the columns that needed strengthening. The ultra high-performance concrete meets the requirements of strength and stiffness even at a thickness of just 40 mm, which also reduces the impact of the strengthening work on adjacent parking spaces.
The Exoleaf system was created specifically for this project, with Freyssinet investing around a year of research and development to prove the system, including building and testing two prototypes.

Easy handling

Installation was quick, simple, clean and quiet. Two full-height, u-shaped elements were connected to one another around each existing column and a cementitious grout was used to fill the voids between the shell and the column, and the gap at floor and ceiling level. Shear key connections were included inside the shell, and the system became fully load-bearing once the new floors were added to the top of the building.

With each shell element weighing around 200kg, they could be wheeled to site on a trolley and manoeuvred into place by two operatives without the need for any heavy, noisy or smelly equipment. The total time on site was just 15 weeks, once design and manufacture of the units had been carried out.

Eastbourne Arndale Centre - Shells installation

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