Mainstreaming low-carbon concrete
Decarbonising concrete to open up exciting prospects for this material: this, in a nutshell, is what Exegy is doing by concurrently optimising its products from the technical, economic and environmental standpoints.
— VINCI Construction has been developing Exegy since 2020, in line with its pledge to use low-carbon concretes extensively on its own projects while encouraging their use across the sector. It teamed up with Ecocem to fine-tune Exegy ultra-low-carbon concrete, wherein clinker (cement’s main component) is entirely replaced by an alkali-activated sodium carbonate binder. The formula underwent European technical evaluation in 2021 and Exegy ultra-low-carbon concrete is now certified to meet NF EN 206/CN standards. This product’s carbon footprint is up to 70% smaller than that of traditional concretes. Furthermore, as it uses blast furnace slag in its binders, its technical performance in some cases exceeds that of its standard alternatives: Exegy ultra-low-carbon concrete is less vulnerable to chemical attack and its compressive strength continues to increase significantly after 28 days.
A VARIETY OF POSSIBILITIES
It was used in 2020 to build six structural pillars – a first in France – holding up an eight-storey building in l’archipel, VINCI’s new head office in Nanterre. Soletanche Bachy then used Exegy ultra-low-carbon concrete in 2021 to pour a deep-foundation barrette at a worksite at a port in Le Havre.
In another momentous development, it was trialled, in partnership with Société du Grand Paris, in prefabricated segments for the Grand Paris Express Line 18 underground works project. Following tests at CDB, a VINCI Construction subsidiary that specialises in concrete prefabrication, production scaled up in September 2021. Five full rings, consisting of 40 segments, will be produced.
We are very proud to enable our partners to use our worksites to try out new solutions that can benefit the entire building and civil engineering sector going forward Using ultra-low-carbon segments is a perfect example of our approach to lowering CO2 emissions on our construction projects.
BERNARD CATHELAIN,
Member of the Board of Société du Grand Paris.
70%
lower emissions with Exegy
ultra-low-carbon concrete, compared
to traditional concretes.