Photo courtesy of Holcim
Holcim, the France-based global producer of aggregates and cement that includes the operations of the former Lafarge company, has been focusing on “upcycling” recyclable concrete by deploying a Metso crushing plant the company says enables the recovery of all demolition concrete and the creation of recycled products with high added value.
At the installation site in Saint-Laurent-de-Mure, which is near Lyon, France, the Holcim plant combines what Metso a variable pressure crushing system (a Metso HRC8 crusher) with an air flow system (Metso Air Classifier AC30), making it possible to separate and recover the cement paste during the crushing operation without grinding the original aggregate.
“With this proprietary processing technology, Holcim can upcycle 100 percent of construction and demolition materials into new building solutions, from aggregates and sand to decarbonized cement paste," Holcim says. "With this advanced circular system, we aim to scale up our ECOCycle solutions to lower the CO2 footprint of new building solutions while closing the material loop to save virgin resources.”
The recycling plant, located at a quarrying site, makes it possible to produce a superior quality of recycled construction aggregates for high-end applications, Holcim notes, adding that the technology also helps produce cement-rich fractions that can be used to replace limestone in cement making, therefore helping decarbonize cement manufacturing.
The setup, which began operations last September, is focused in part on isolating very fine materials with a high concentration of cement in demolition concrete. This provides carbon-free additions to the manufacturing of new cements, Metso says.
The plant will serve as a pilot for Holcim to deploy this equipment in France from 2024. If the technology goes global, Holcim has a considerable recycled aggregates presence in the United States, and in the late 2010s the company announced it intended to “multiply by four our volume of recycled aggregates from C&D [materials] and reclaimed asphalt paving” as one of its two main circular economy targets to reach by 2030.
In Saint-Laurent-de-Mure, the cementitious materials separation plant consists of two independent lines: the first line receives concrete demolition material as infeed (sized from about one-third of in inch 1.2 inches) into the HRC8, which separates the aggregates from the cement paste and creates the final products. A second line helps further separate and refine material, creating the final products.
According to Metso, cement fines, which in most existing crushing processes remain attached to the sand-like residue, is becoming a sought-after alternative source material to supplement clinker (a limestone-rich cement material), making it possible to reduce clinker’s share in the final composition of the cement and therefore reduce its carbon weight.
Holcim expresses hope the technology will play an expanding role in its ability as a corporation to reduce its carbon footprint.
“Concrete is the most widely used construction material in the world thanks to its durability, affordability, versatility and strength,” the company says. “That’s why at Holcim we are putting our innovation to work to scale up ‘low-carbon, circular and smart’ concrete applications to decarbonize construction.”
“Construction [materials] generated worldwide represents a great opportunity to accelerate circularity to close the loop in construction, while decarbonizing building," adds Vincent Teissier, head of circular construction at Holcim.
“Holcim is a world leader in recycling. Building new from old, we recycle nearly 7 million tons of C&D materials each year into new building solutions. That represents over 1,000 truckloads of materials every day. We are working to double down on that as soon as possible.”
Metso, citing the Paris-based organization Recybeton, says in France, 80 percent of end-of-life concrete currently is recycled, primarily in road applications such as pavement base course. “By choosing upcycling and reintroducing these demolition concretes into the cement and concrete manufacturing chain, Holcim is able to increase demolition material value and advance its circular ambition,” Metso says.
“The development of circulars is a major pillar of our strategy,” says François Petry, CEO of Holcim operations in France and Belgium. “This new [plant] is a decisive step in developing the reuse of demolition materials by utilizing all the value they have to offer.
“Recovering the fines from crushed concrete to reuse them as a carbon-free addition to the cement process is a first in Europe and a giant step forward in the ecological project of building the city of tomorrow with the materials of the city of yesterday.”
