What future for composite materials in construction ?

This year, the Société Française des Ingénieurs des Plastiques (SFIP) organised the 4th edition of its conference dedicated to the building industry on the Champs-sur-Marne campus (France), just a stone’s throw from the Ponts ParisTech, Paris-Est city and regional architecture and Paris urban planning schools. Entitled “Polymer and Composite Materials in Construction and Public Works“, the two-day event, held on 27 and 28 November 2024, featured conferences, tours and discussions with exhibiting companies.

The impact of climate change

Salem Farkh, head of development at the CSTB (Centre Scientifique et Technique du Bâtiment), a french organisation founded after the Second World War to rebuild the country, stressed the importance of taking into account the impact of climate change on construction. “The building stock is slowly being renewed, so we’re must be very vigilant about the ageing of materials. Networks, pipes, foundations and façades are all affected by global warming. This can affect the mechanical resistance of products to wind and temperature increases,” he notes. To remedy this, the CSTB must first undertake a review of all the technical standards for the building industry.

“They date back a long time, and were designed for a past climate. We’re going to have to revise them to enable better product prescription and facilitate the arrival of innovative solutions on the market. We have undertaken to work on a product-by-product basis, mapping out the expected performances, such as the watertightness of a flat roofing membrane or its removal by the wind’, he continues.

Composite reinforcements

Incessant rain and humidity can accelerate the development of rust on metal rebars, textured reinforcements for concrete. The increase in thickness caused by rust then causes the reinforced concrete to crack.
Boris Duchamp, an expert in composite materials at IRTM2P, showed the audience the benefits of using rebars made from thermoplastic composites based on Elium resin as part of a collaboration with Arkema. “The market offers epoxy resin-coated metal rebars, but they are expensive, as are stainless steel rebars. Composite rebars are light and resistant to corrosion, but they are also more expensive to buy than metal rebars and cannot be bent (deformed) on site. However, they are less expensive to maintain. Thermoplastic rebars are an alternative because they can be easily transported and deformed using infrared heating. Pultrusion enables them to be manufactured on a production line. We convinced Arkema’s partner, Wafios, which manufactures bending machines, and the rebars were used by the Italian company Sireg for repairs on sites in the Czech Republic,” he explains.

In response to the problem of natural resource shortages, Agnès Zambon, a teacher-researcher at the ITM Nord Europe Materials and Processes Centre, is working on the use of alternative materials to sand in cement matrices. At the conference, she presented her current research on composites recovered in the form of crushed material incorporated into concrete instead of sand.
” In our study, we worked on mortar. We characterised the grind and carried out various tests (rheology, porosity) on different forms (flakes, powders and fibres of varying thickness). We worked with Plastic Omnium to recover offcuts from their Douai plant. Thermosets account for 71% of the market. For this application, separating the fibre from the resin by pyrolysis or solvolysis is viable for carbon fibre, but not for glass fibre. So we use grinding,” she explains, adding that she still needs to explore a number of other avenues to confirm the conclusions of her research.

Between two conferences, visitors were able to talk to the exhibitors: Composites Recycling, a Swiss start-up offering a process for recycling composites by thermolysis; FRD, an engineering platform for industrial projects offering innovative materials for the construction industry and the integration of biomass-based materials into composites; Olnica, a manufacturer of UV tracers for materials, enabling integrated recycled materials to be tracked, for example; Poly to Poly, a broker in recycled resins; IMT Nord-Europe, a training school in composite polymers; and Prothélios, a manufacturer of transparent blinds made from perforated film.
The SFIP has already announced the dates of its eagerly awaited conference on polymers in sports: 4 and 5 June 2025 at the Espace du Parc in Vichy (France).

Cover photo : SFIP