CO2REDRES

Financed within the framework of the program Interreg Grande Région (FERDER), the CO2REDRES project aims at the treatment of secondary resources for a reduction of_CO2 emissions in the construction industry. The University of Liège and more particularly researchers of the research unit Urban and Environmental Engineering (Faculté des Sciences appliquées) take part in this project.

 

In order to develop more sustainable processes, the cement and concrete industry is faced with a double challenge: on the one hand, to reduce greenhouse gas emissions and, on the other hand, to reduce the amount of waste sent to landfills.

The CO2REDRES project aims to meet these two objectives: the most important is the reduction of CO2 to mitigate climate change. The production of ordinary Portland cement is responsible for about 8% of global CO2 emissions. In addition, the project focuses on the lack of natural resources in the future and the large amount of waste currently produced. In the near future, there will be a shortage of fly ash and blast furnace slag. The overall goal is to reduce_CO2 emissions from the cement industry by replacing Portland cement with an environmentally friendly, locally produced option. To this end, waste and by-products from local quarries are used and valorized.

With the aim of strengthening cross-border cooperation in the field of R&D in order to make their territory an area of excellence, four European Union Member States - Luxembourg, France, Germany and Belgium (Grande Région) - have set up a project called CO2REDRES

CO2REDRES is a project that aims to demonstrate the feasibility of producing mineral additions with hydraulic/pouzzolanic properties from the thermal treatment of secondary resources from the Greater Region:

• A new way to reduce the clinker content and the_CO2 production in cement and concrete, by incorporating locally produced low_CO2 emitting binder additions, especially from residual clays, sludge and fines from construction and demolition waste;
• An alternative to granulated slag or fly ash, which is on the verge of extinction due to industrial changes in the Greater Region;
• Solutions to reduce the storage or burial of industrial by-products or waste with an interesting technical and economic potential

The mineral resources used in this project are mainly siliceous, clayey, calcareous or dolomitic, and are presented in a wide variety of typologies (sludge, sand, rock, gravel, etc.). These resources come from the 14 industrial partners involved in the project.

Each country has a role to play in the project. The University of Trier in Germany is in charge of identifying industrial by-products or co-products that are not used in the Greater Region, and that could potentially provide, after treatment, new reactive additives that can be used in cement and concrete.

The University of Luxembourg, which has expertise in the treatment of by-products, is in charge of the treatment process applicable to each type of material selected.

The University of Lorraine in France is in charge of evaluating the properties of the new additives for cement and concrete. An evaluation of the hydraulic properties and thus the reactivity of these clay materials is carried out on the basis of a series of tests

Finally, the University of Liège in Belgium is in charge of the study on the life cycle analysis (LCA). The LCA allows to study the environmental impact of the proposed solutions.

Although the scientific and industrial interest of the project is no longer to be proven, since it is a question of finding additions which, locally, take over from the granulated slag of blast furnaces which is on the way out. It is also necessary to verify that the environmental impact of the proposed solutions is not greater than that of conventional additions. This logic is part of a concern for quantifying environmental impacts, even if it is already known that the calcination of clays generates much less_CO2 than the firing of cement raw meal rich in calcium carbonate.

The aim of the environmental assessment is to quantify the impacts of the different productions developed during the project, in terms of_CO2 quantities. This quantification will allow the comparison of the products developed with conventional products (clinker and slag cement). The impact of the elaboration of the products on the environment will be evaluated via a wide range of environmental indicators including global warming but also resource depletion, eutrophication, etc.). These are quantified using the methodology of life cycle assessment (LCA). This is similar to the approach usually used to establish the environmental and health declaration sheets (EDS) for a new product. This study allows to verify the environmental aspect of the solutions developed by the project. The LCAs are based on quantitative and scientific studies respecting the international standards ISO 14040 to ISO 14049. The functional unit, common to all the selected products, defined in the preliminary study of environmental impacts is the production of one kg of dry mortar. All environmental impacts are therefore related to this production (resource extraction, energy consumption, greenhouse gas emissions, etc.). The scope of this study includes the production of all raw materials used, energy consumption (electricity and fuels), packaging of the dry mortar as well as the transportation of the raw materials.

The data used in the LCA is based on the treatment of calcined clays developed by the University of Luxembourg. The drying (temperature, exposure time) and grinding (intensity and quality) parameters were defined in accordance with this treatment. The heat treatment tests followed by characterization allowed to define the optimal temperature and duration of the treatment with respect to the chemical and mineralogical properties of the materials. The LCA is therefore used in the CO2REDRES project as a tool for the evaluation and improvement of environmental performance (eco-design).

The preliminary LCA show encouraging results that dry mortars with a 20% substitution rate of calcined clays would be responsible for lower environmental impacts than conventional mortars. This decrease is explained by the fact that the consumption of clinker is reduced. Indeed, it has been shown during the study of the environmental impacts of the conventional production of dry mortar that clinker is responsible for the major part of the environmental impacts related to this production. This is mainly due to the decarbonation process necessary for the production of clinker. In fact, decarbonation is responsible for significant greenhouse gas emissions and requires a large consumption of fuel.

The research presented has the potential to reduce greenhouse gas emissions and help conserve non-renewable natural resources, as well as reduce the amount of waste going to landfills, which has benefits for the cement and concrete industry

The production of new mineral additions from industrial by-products as developed by the project has three main advantages. First, this production would reduce the use of clinker and thus reduce the environmental impact of mortar production. The second advantage of these new additions is to take over the cementitious materials used in the Greater Region whose stocks are depleting (blast furnace slag and fly ash). Finally, the third advantage is to reduce the quantity of industrial waste sent to landfill by finding an economically advantageous way of recovery

The LCAs associated with this project can be used, for example, by the decision-makers of the Greater Region, when they have to choose new strategies or support new technologies or products, to set a regional waste management policy, etc. The methodological operators and the companies involved in the project will also be able to use the results of this LCA to optimize their current processes and to use the indicators put forward as arguments for the transition to new technologies.

Consult the project website