Eliminating thousands of tons of CO² in the construction of major complex in Monaco

What is post-tensioned concrete and how does its use eliminate such colossal quantities of CO₂? Tractebel civil engineering supervisor Mohamed Ali Mansouri explains.

Post-tensioned concrete slabs are a combination of conventional slab reinforcement and additional high-strength steel cables which are placed in plastic sleeves and positioned inside the concrete formwork before the concrete is poured. Once the concrete has set, the cables are tensioned by using a hydraulic cylinder.

In addition to functional and economic advantages, post-tensioned concrete slabs enable a reduction of materials and thus a reduction in greenhouse gases. Compared to a traditional reinforced concrete solution, 16 cm of slab thickness per level and 24Kg/m² of steel were saved. During construction, the CO₂ saved on the private housing part of TESTIMONIO II is estimated at more than 3,350 tons.

The use of post-tensioned concrete allows for maximum volume and surface area

Post-tensioned concrete in action in Monaco

After nine months of work, the concrete structural works of the private housing of the TESTIMONIO II project in Monaco was completed in April 2022. Around 20,000 m² of post-tensioned concrete slabs were produced. A total length of ducts of approximately 21,000 m was installed with an altimetric laying tolerance of 5 mm. Each duct had 4 wire strands (4T15S).

Tractebel, as part of the project management team, carried out a work supervision mission, including breakpoints before concreting. At each stopping point, the altimetric profile of the ducts at the high and low points was checked. We also made sure that the hooping at the active and passive anchors was correctly performed.

Tractebel also carried out unannounced checks on the tensioning of the ducts and the duct injection operations.

Monitoring the slabs

The topographic monitoring implemented has allowed us to follow the deformation of the slabs after removing concrete forms and until the installation of the fragile elements. The monitoring, still in progress, concerns several points distributed throughout the private housing area. Monitoring allows us to control the actual behaviour of the slabs and to ensure that any deformation remains lower than the design values.

Post-tensioned concrete floors of the private housing in the TESTIMONIO II project made it possible to offer maximum volumes and surfaces by eliminating a large part of the columns and reducing the thickness of the floors by 16 cm.

Mohamed Ali Mansouri, Civil Engineering Supervisor, Tractebel in Monaco

Discover our Buildings and Complex Structures solutions