Dodin Campenon Bernard and its partners Soletanche Bachy International, Balineau and Freyssinet are building a new bridge close to the existing Larivot bridge and succeeding in reducing the project’s concrete-related carbon emissions despite the transport and reduced availability of clinker substitution materials.
The new bridge will carry road traffic heading from Cayenne towards Kourou, with two traffic lanes and a two-wheeled vehicle lane as well as a two-way greenway. The scope of work includes the construction of the access embankments, as well as the construction of the new bridge – a 1.3-kilometre-long structure with 20 spans and a precast prestressed concrete deck installed in segments using a launching gantry.
Project
New Larivot bridge
Project owner
Prefect of French Guiana, General Directorate of Territories and the Sea (DGTM)
Main contractor
EGIS
Consortium
Dodin Campenon Bernard (lead company), Soletanche Bachy International, Balineau and Freyssinet
Local concrete partner
SGRB
Location
Le Larivot, French Guiana
Time frame
Start of work in March 2022
This project takes a broad approach to optimising its environmental and social impact, with:
- preference given to local economic stakeholders for services, supplies and subcontracting;
- the creation of local jobs, reflecting a desire to go well beyond the contractual requirement of 54,000 hours of work for people participating in integration programmes;
- a solid environmental strategy to limit the impact of the work on flora and fauna in an ecosystem that is dense due to the presence of the river and the mangrove zones; and
the use of low-carbon concrete on the basis of a performance-based approach, despite the difficulties encountered in an overseas context differing greatly from the usual mainland frame of reference.
The EXEGY® solutions used
The consortium worked in close collaboration with VINCI Construction’s concrete laboratory to develop formulations that would minimise the structure’s carbon footprint despite the project-specific constraints outlined below.
- The strength of the aggregate available in French Guiana is low, making it necessary to seek out specific working faces for the project and use large quantities of binder.
- The clinker is imported from Colombia, making its carbon footprint higher than that of clinkers produced and used in mainland France.
- The clinker substitutes are imported from mainland France and Panama.
- All the admixtures are imported from Europe.
The solutions developed in this context reflect the decision to replace some of the clinker with two available additives: fly ash and silica fume.
This entire approach was made possible by the local concrete supplier SGRB and its commitment to this highly technical project.
88%
classic
12%
low carbon
0%
very low carbon
0%
ultra low carbon
3,800
m3 of EXEGY® concrete
21%
reduction in CO2*
*compared to an equivalent traditional concrete solution
Project specifics
Only 12% of the concrete used for the project is low-carbon, due to the intrinsically high level of carbon emissions associated with importing materials. If the same formulations were produced in mainland France with the ingredients available locally, 61% of the concrete would be low-carbon.
Optimising the formulations helped reduce the project’s concrete-related emissions by 21%.
