Construction of a concrete breakwater for the Port of Calais expansion project

The formulation of the various concretes was the subject of close collaboration between Sika and the Constructor Group (Bouygues TP - agent, Bouygues TPRF, Spie Batignolles, Valérian, Malet, Colas and Jan de Nul).

In a context of increased traffic and economic development, the port of Calais is part of an ambitious expansion project: Calais Port 2015.

Blocked to the west by the city, to the east by protected natural areas and to the south by an area of ​​industrial activity, the Port of Calais could only extend towards the sea. The project therefore consists in carrying out a 3 meter long dike, to dredge the bottom of the future basin by dredging, and to use the materials from these dredging to build 260 hectares of new embankments reclaimed from the sea.

The Ports of Detroit company, project owner, signed a design-build contract with the Constructor Group. They made the choice of concrete added by Sika for the artificial riprap of the dyke made using precast concrete blocks: Xbloc®, the deck ramps as well as the Anti-Scouring Mattress (MAAF).

Calais port 2015: a major project on the sea

A technical challenge, the Calais Port 2015 project aims to double the port's current capacities by creating a new basin towards the sea.

These vast development works will allow the port to welcome new generations of ferries, and thus be able to handle the increase in traffic between the continent and the United Kingdom, expected by 2020-2030. .

They will also promote the creation of spaces necessary for the long-term integration of rail-road-sea intermodal infrastructure (rail motorways and motorways of the sea).

This project includes the construction of a 3-meter dyke housing a 260-hectare body of water, 177 hectares of new medians, the creation of a new rail crossing as well as the construction of 65 new large ferry stations.

More than 16 xbloc® to break the energy of the waves

Calais Port 2015 includes the construction of a breakwater intended to block swells coming from the open sea and thus allow docking maneuvers and the protection of ships and docks. The dike consists of a natural riprap, supplemented by the installation of Xbloc® on its upper surface, sea side and therefore the most exposed to swell.

Developed and patented by the Dutch company Delta Marine Consultants (DMC), the Xbloc® are designed, by their geometry, to overlap one another in order to provide a protective rampart on dikes, breakwaters and areas coastal.

Emblem of the Calais Port dam 2015, the Xbloc® is manufactured by the Manufacturer Group, in a prefabrication factory designed by APS - Advanced Precast Systems, department of the company CBE Group. This dam is directly connected to the concrete plant. The factory is organized around a carousel, allowing the transfer of the steel molds, once filled, to a mechanized formwork workshop.

Started in February 2018, the production line has manufactured more than 16 units made up of blocks of 000 m4 (3 tonnes), 10 m6 (3 tonnes), 14 m8 (3 tonnes), 19 m10 (3 tonnes) and the last , 24 m12 (almost 3 tonnes). The blocks are made of X30 C0 / 30 S37 concrete which meets the specifications in terms of resistance while presenting the workability necessary for its implementation in the molds of Xbloc®, with their particular geometry. Manufacturing is now finalized and the Xbloc® are installed as the work progresses.

A protected and reinforced port thanks to concrete

The Constructor's Group has also chosen Sika concretes for bridge ramps and the Anti-Scouring Mattress.

The VSol® system, a trademark registered by VSL, a subsidiary of the Bouygues TP group, was chosen to form the walls of the ridge and the access ramps to this elevated port exit route. It combines backfill material and reinforcing reinforcement. These frames are fixed to the rear of the facing panels. The combination of these three elements (floor, reinforcement, facing panels) of the VSoL® system creates a particularly stable and lasting retaining wall. The facing panels are made, on site, in self-compacting concrete (BAP) XS3 C30 / 45 added with SikaPlast® Techno 90, a new generation plasticizer suitable for concrete using crushed materials.

To avoid sand movements due to boat propellers, a Anti-Scour Mattress (MAAF) will be deposited at the bottom of the harbor basin. In precast concrete, the parts making up the mattress are cast and demolded on site. The concrete used is an XS2 C30 / 37 S4 added with a water-reducing plasticizer, SikaPlast® TechnoFlow, to obtain the necessary workability.

This addition is completed by a hardening accelerator, Sika Set 2, which reduces the formwork time and increases the rotation of the molds.

Close collaboration between the Manufacturer Group and the Sika teams made it possible to define and optimize the formulation of these different concretes at the Sika laboratory in Gournay en Bray (76).

In progress, this site, considered one of the most important of the decade in France, will be finalized in January 2021.