IN 2020

T A B L E O F I N D I C A T O R S

F O C U S 7

Launch of the “low-carbon

concrete challenge” In 2020, Société du Grand Paris reinforced

its ambition by launching an “low-carbon

concrete challenge”. The aim is to work with

the construction companies and create the

appropriate conditions for using low-carbon

concretes that are specific to each Grand

Paris Express contract. A dedicated team

has been set up within the Strategy and

Innovation division to manage and monitor

the implementation of this ambition.

This team is working on the eco-design of

concrete structures and is aiming to develop

various solutions that can be implemented at

an equivalent or lower cost by reusing some

of the spoil from the Grand Paris Express in

the production of these low-carbon cements.

Use of processed spoil as

a binder in concrete In September 2020, Société du Grand Paris

co-funded an experiment with ADEME to

evaluate whether clay materials from the

Grand Paris Express could be converted into

an alternative binder that could be used in

concrete formulations to partially replace

traditional cements that emit high levels of

CO2. The results showed that by using this

binder in Grand Paris Express concretes,

carbon emissions could be reduced by a

factor of five.

Environmental innovation

bonus Société du Grand Paris is convinced that

the carbon footprint of concrete can be

reduced even further in public procurement

contracts already awarded, particularly

with regard to the manufacture of stations’

internal structures and tunnel linings and

aprons. In December 2020, it therefore

introduced an environmental innovation

bonus to financially incentivise contractors

to develop solutions that use less concrete

and/or replace traditional concretes with

low-carbon concretes, while maintaining

the quality of the structures built.

ACTION 16 Encourage greenhouse gas emissions reduction initiatives

The construction of the Grand Paris Express will generate nearly 4.5 million tonnes of CO2,

half of which is linked to the concrete used on its worksites. Aware that during the construction

phase, the use of concrete is the main source of greenhouse gas emissions, Société du

Grand Paris is doing its utmost to find alternative solutions that emit less CO2.

Optimising infrastructure sizing and environmental performance

As part of an ambitious eco-design approach, the volume of structures has been optimised

to reduce the amount of materials required to build them.

Promoting the use of “low-carbon” construction materials

Due to the mainly underground nature of the works, Société du Grand Paris requires contractors,

via the specifications, to use slag-based concretes known as “low-carbon concretes ” in the

manufacture of moulded walls, aprons, cover slabs and voussoirs. These concretes produce

significantly less CO2 emissions during their manufacture. Four years after the start of civil

engineering works, more than 70% of the Grand Paris Express is built with low-carbon concrete

containing CEM III cement or an equivalent binder.

Convinced that it is possible to do still more, Société du Grand Paris is encouraging existing

and potential contractors to use innovative materials to reduce the carbon footprint of building

the infrastructure and its real estate projects as much as possible (fibre-reinforced concrete,

wood and bio-based materials, etc.).

Société du Grand Paris has also launched the “designed concrete” process, which is a

requirement in the latest calls for tender. Contractors are encouraged to propose concrete

formulations based on sustainability and carbon emission criteria to meet the objectives set.

RISKS AND CHALLENGES

2020 ACTIVITY

CSR APPROACH

Actions

IDENTITY