From the design phase and throughout the construction process, everything was conceived and executed with this in mind, including the use of high-performance EXEGY® ultra- and very-low-carbon solutions and their controlled implementation.
The I3F project in La Celle-Saint-Cloud comprises two five-storey residential buildings and an underground car park.
Project
Residential blocks in La Celle-Saint-Cloud
Project owner
Immobilière 3F
Project manager
Sicra Île-de-France
Time frame
March to December 2022
Location
La Celle-Saint-Cloud, west of Paris, France
Environmental performance
C2 (E+C- label)
EXEGY®ULTRA concrete wherever possible
Keen for the project to serve as a shining example of sustainable construction, I3F tasked the external engineering consulting firm CETAB with performing a building life-cycle assessment (LCA) and conducting an audit based on the E+C- label to validate the construction solutions. The use of EXEGY®ULTRA concrete earned the construction project a “C2” rating for its life-cycle greenhouse gas emissions. VINCI Construction subsidiary Sicra Île-de-France’s innovative proposal was selected as it fulfilled all the necessary criteria and its LCA exceeded the expected performance levels. One of its strong points was the use of EXEGY®ULTRA concrete wherever possible.
Developed in collaboration with Ecocem, EXEGY®ULTRA is an ultra-low-carbon concrete that uses the cement-free, alkali-activated binder ECOCEM Ultra. It offers almost a 70% reduction in carbon emissions compared with standard concrete, releasing only 85 kg of CO2e per cubic metre during its production.*
* These figures take account of the carbon footprint of the activated slag at the start of the experiment (prior to reallocation).
Three different types of concrete for different purposes
Three different types of concrete were used for the project, with a total volume of 3,500 m3.
- EXEGY®ULTRA concrete was mainly used, totalling 2,536 m3 and, to be more specific, forming 5,496 m2 of walls. This concrete was produced for and delivered to the site by the Nanterre-based Béton Solutions Mobiles production site – a long-standing Exegy® partner – with an optimised transport time of less than one hour to guarantee optimal pouring conditions on-site. Additionally, the aesthetic properties of exposed EXEGY®ULTRA concrete, including its light colour and smooth finish, were something the architect wanted to showcase on the façades, for which a patterned mould was added to the formwork during pouring.
- A very-low-carbon EXEGY® concrete, having delivered high levels of performance in a laboratory environment, was used for the foundations and paving, which, for technical reasons, could not be made from EXEGY®ULTRA.
- Shotcrete was used for the retaining walls, as no tried-and-tested low-carbon solution was found for this application.
0%
classic
0%
low carbon
25%
very low carbon
75%
ultra low carbon
3396
Volume of EXEGY® concrete in cu. metres
– 47%
Reduction of CO2*
350
Tonnes CO2 equivalent avoided
*compared to an equivalent traditional concrete solution (Type CEM II A)
Less concrete and a more diverse range of materials
To improve the project’s carbon footprint, Sicra Île-de-France also suggested reducing the amount of concrete needed by implementing innovative material substitution solutions. Rather than a traditional apron, a thinner concrete paving layer was chosen – a decision permitted by the soil characteristics. Additionally, the interior load-bearing walls between the housing units were replaced by a support structure composed of posts and embedded beams, along with infill partitions comprising 13 mm plasterboard and fibrous insulation material, with equivalent sound insulation properties. These substitutions helped reduce the amount of concrete needed by 200 m3.
Heated tools needed to set the concrete but used in an optimised and controlled way
The EXEGY® concrete solutions were set using a heated tools-based approach optimised through a collaborative and feedback-oriented process involving various VINCI Construction worksites running at the same time, particularly Universeine (in Saint-Denis, north of Paris) and CESAME (in Saint-Vulbas, eastern France), operated by BATEG and CITINEA respectively.
- The system used for the flooring comprised heated frames (blowing hot air between the concrete and a taut horizontal tarpaulin), already used by BATEG but improved upon by Sicra Île-de-France, with sandwich panels and side extensions, to provide exactly the right coverage.
- The system used for the vertical walls comprised heated formwork, co-developed by SOLUMAT (VINCI Construction’s equipment entity) and its supplier Outinord based on specifications developed by VINCI Construction’s concrete laboratory. Equipped with a power control module, this system provided a slow and gradual release of heat, ensuring the formwork removal times matched those for traditional concrete.
To assess the carbon footprint of these tools, Sicra Île-de-France had a special on-site electrical installation, equipped with counters to accurately measure the exact electrical consumption of the heated equipment – information from which the worksite’s carbon footprint could be deduced. The carbon footprint was found to be 5 kg CO2eq/m3, which is negligible compared with the amount of greenhouse gas emissions avoided through the use of EXEGY®ULTRA concrete.
On this project, VINCI Construction once again showcased its ability to meet its worksite carbon footprint reduction targets, using innovative types of concrete and leveraging the ability of its various entities and their partners to work in close collaboration, from design through to delivery.
VINCI Construction entities involved in the project:
- Sicra Île-de-France (project manager)
- VINCI Construction’s concrete laboratory
- SOLUMAT, VINCI Construction’s equipment entity, with its supplier Outinord (heated tools)
Ready-mixed concrete partner involved in the project:
- Nanterre-based Béton Solutions Mobiles production site (for EXEGY®ULTRA concrete)
