Technological Centre

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Research on new sustainable concretes made from CDW and steel mill wastes progresses successfully

CETIM is researching the production of more sustainable cements and concretes from construction and demolition waste, as well as steel slag from electric arc furnaces, within the framework of the KEOPS project.

KEOPS offers the potential to close the circle within the construction sector, making its waste the raw material with which to manufacture cements and concretes.

The initiative, supported by CETIM, brings together five business agents from the entire value chain of the construction sector: ADEC Global, Cromogenia, Cementos Cruz, Extraco and Prefhorvisa.

Construction sector accounts for a third of the waste and 35% of the greenhouse gas emissions generated mainly by Portland cement. For this reason, studies on the development of more sustainable cements, mortars and concretes are currently increasing, although the solutions that advocate the total substitution of Portland cement are very scarce.

Among the most relevant solutions are geopolymers, which use different aluminosilicate-based materials that give rise to sustainable cementing materials. These are usually generated from fly ash and blast furnace slag, and their manufacture based on other wastes is a field that is currently little explored.

KEOPS, an alternative to Portland cement
In response to this technical and environmental need to replace Portland cement and natural aggregates with alternative materials, the KEOPS project has arisen. To this end, research is being carried out into completely sustainable, high added-value cementing solutions based on geopolymers (alkaline cements).

These new materials are being developed thanks to the valorization of high environmental impact and high-volume waste, mainly from the construction industry, Construction and Demolition Waste (CDWs), as well as slag (white and black) from the steel production industry, in a clear example of circular economy.

The KEOPS consortium, formed by ADEC Global, Cromogenia, Cementos Cruz, Extraco and Prefhorvisa, covers the entire value chain of the construction sector. It also has the support of CETIM in research.

The KEOPS project is a very interesting, novel and promising avenue for future research. With more than half of the project completed, it is worth highlighting the successful results obtained to date, which are promising for all the companies in the consortium.

Together with Adec Global, a blockchain application is being developed to record the traceability of precursors and aggregates, thus being able to verify their origin and the processes they have undergone, certifying their sustainable origin. In addition, Adec Global conveniently generates the precursors and aggregates conditioned for each application.

Screenshot of the blockchain application developed by CETIM to record the traceability of materials developed for ADEC Global.

The company Cromogenia is developing specific additives that, on the one hand, improve the grinding process of the precursors and, on the other hand, change and optimize the fluidity and workability of the pastes and concretes generated for each end-user.

With Cementos Cruz, several formulations of geopolymer type cements have been developed and optimized for the proposed applications; among them, some suitable for 3D printing of geopolymers, of interest to the company itself, complying with all the necessary technical characteristics.

With Extraco, geopolymers have been successfully formulated for sprayed concrete, high chemical resistance and environmental remediation, with excellent results, highlighting the very high chemical resistance of KEOPS concretes.

With Prefhorvisa, the requirements of the prefabricated material meant that the design of the mixes had to be carried out independently. After the identification in the laboratory of the optimal formulations, it was found that the concrete blocks made in the industrial scaling maintained the good properties achieved in the laboratory.

Preparation of geopolymer concrete specimens (left) and heavy metal absorption test (center) carried out in CETIM’s laboratories, and vibro-compression process output mold of one of the mold mixtures, carried out at Prefhorvisa’s facilities.

CETIM expertise
In this project, CETIM technically supports the five companies that form the consortium. CETIM’s Advanced Materials Area participates in the development of the geopolymeric cementitious base material and the various geopolymeric concretes, optimizing the formulations for their subsequent manufacture. For its part, the Digital Industry Area is participating in the development of the blockchain application thanks to its expertise in traceability and reproducibility of manufacturing processes of different materials and products.

Finally, CETIM also participates in the economic and environmental evaluation of the products and processes developed, in order to guarantee their viability from both points of view.

Thus, in order to generate a product with a lower environmental impact and to valorize waste from the sector itself and other related sectors, KEOPS seeks to promote the circular economy in the construction industry, converting the waste generated into new raw materials, used again in the sector in which they were generated.