Using an 80 mm high trapezoidal steel profile alongside a lower volume of poured concrete, Cofraplus® 80 outperforms a traditional precast slab in a greener and more environmentally conscious package.

A new flooring solution for construction companies that want to build differently

With an estimated 25% reduction in overall slab weight, the Cofraplus® 80 flooring system has a positive impact on surrounding load bearing beams, columns, and even foundations, leading to more cost effective, lower mass, and ultimately more sustainable construction. Cofraplus® 80 reduces CO2 emissions by 15% compared to a traditional precast slab.

The cost savings and environmental benefits extend into efficient transportation, storage, and installation. For a 1400 m² floor, Cofraplus® 80 requires only one truck delivery to site and 12 crane movements to unload (as the lightweight profiles can be efficiently stacked) compared with 8 deliveries and 96 crane movements for a prefabricated slab.

Similarly, during installation, a single Cofraplus® 80 profile weighs only 52 kg whereas the equivalent precast slab weighs 1875 kg. A single team can manually install up to 600 m2 safely in just one day while a crane is needed to install the same surface of precast slab.

Thus, logistics is one of the key areas where Cofraplus® 80 really scores over the prefabricated concrete alternative.

Flexibility and long spans

Cofraplus® 80 is flexible enough to be adapted to specific project requirements and detailed design drivers. It can be used alongside all structural materials – including steel or timber beams and concrete - and with any kind of modern build method.

ArcelorMittal Construction has developed a new range of dedicated system accessories that provides a complete solution for installing the slab and pouring the concrete.

Suspended elements such as tubes, ducts, and suspended ceiling fixtures can be anchored using a specific accessory so there is no need for drilling of the concrete during installation or refurbishment. This saves time and cost on floor adaptations and reduces noise levels for those living or working nearby.

In standard mode, the system is compatible with through-deck welding connectors, or it can be supplied in a pre-punched version to suit shear connectors welded to the beam.

The Cofraplus® 80 system can span up to 4.5 m without props and more than 6.5 m with props. The geometry of the prefabricated steel means that it can serve both as shuttering during the pouring phase and reinforcement during the service phase. Its specific geometry means that composite action with the concrete is optimal.

Text:
ArcelorMittal Construction
Constructalia

Images:
ArcelorMittal Construction

Text & photos: ©ArcelorMittal Construction

The site of the Martin's Patershof Hotel – the result of renovating and transforming a church into a four star hotel – was the first to implement an innovative solution combining composite flooring with lightweight concrete, namely Cofraplus® 77 LS, with Argex concrete consisting of expanded clay aggregates. This project was the culmination of nearly two years of research and development by ArcelorMittal Research Centre and the close attention paid by the engineers to ArcelorMittal Construction's prescription to meet the needs of the builder-promoter.

The aim of the Martin’s Patershof Hotel project was unique: to create, within the heart of a nineteenth century church in Mechelen, Belgium - a five-storeyed hotel with 77 rooms in a single framework. The renovation and transformation of the site was the first to apply composite flooring with lightweight concrete. 

Composite flooring

Composite floor slab is a mixed construction system consisting of a steel sheet which serves as shuttering for concrete and reinforces the slab, totally or partially replacing the tensile reinforcements.

It is essential to achieve a bond between the steel and concrete that is stronger than the horizontal stresses to which the slab is exposed.

In this system, the concrete-steel bonding is achieved thanks to the special design of the steel sheets. These sheets are embossed with frustum-shaped projections, repeated indefinitely, both on their horizontal surfaces and on the sloping sides.

During assembly and concrete grouting, the self supporting steel deck constitutes a working platform.

A new solution for renovation

In new constructions, light flooring is particularly useful in multi-storeyed buildings because it significantly reduces the dead weight and lightens the structure and the foundations. But this product has also proved to be useful in renovation works where it is advisable not to overload the existing masonry beyond its limited bearing capacity. In addition, it enables increase in span length without forestay during the concrete grouting.

A solution suited for the Martin’s Patershof Hotel project

ArcelorMittal’s decision to use ArcelorMittal Construction's composite floor Cofraplus® 77 LS combined with Argex concrete is justified for several reasons. First, the configuration of the site required the manual transfer of all the materials through the entrance gate which was only 1.4 m wide.

Then, the thickness of the slab had to be 23 cm, taking the permissible dead weight by adding lightweight concrete up to 1.5 kN / m², which amounted to 450 tonnes for a floor space of 3000 m². The last reasoning was considered decisive by the contractor as the land on which the church is based does not allow the use of conventional composite floors.

The ultimate load bearing capacity was weak. Furthermore, the contractor wanted to avoid the use of concrete props in the middle of this dense structure with five floors.

Despite its well-known rigidity within the range of composite floors, Cofraplus® 77 did not have the permit to cross the limit of 3.2 m with 23 cm of normal concrete. The Argex concrete had the permit to do so. The project technicians used structural concrete with density ranging between 16 and 18 kN/m3 instead of 25 kN/m3. Hence, for a 15 cm thick slab, there was a reduction of about 1 kN / m².

An innovation that met all the objectives: stability and fire resistance for engineers in addition to approved planning and financial savings for the developer-contractor.

Related link(s)

Martin's Patershof Hotel