{"id":50723,"date":"2026-05-28T14:47:32","date_gmt":"2026-05-28T12:47:32","guid":{"rendered":"https:\/\/www.uni.lu\/fstm-en\/?post_type=news&p=50723"},"modified":"2026-05-29T08:00:53","modified_gmt":"2026-05-29T06:00:53","slug":"how-geology-and-engineering-can-improve-construction-recycling","status":"publish","type":"news","link":"https:\/\/www.uni.lu\/fstm-en\/news\/how-geology-and-engineering-can-improve-construction-recycling\/","title":{"rendered":"How geology and engineering can improve construction recycling"},"content":{"rendered":"\n
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This research has been selected for a presentation at the press conference <\/a>of the European Geosciences Union (EGU) General Assembly<\/a>, the world\u2019s largest conference in geosciences. The abstract<\/a> was chosen from more than 20,000 submissions.<\/em> <\/p>\n\n\n

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Every year, Luxembourg generates large volumes of construction and demolition waste as buildings are renovated, replaced and rebuilt. At the same time, the country relies heavily on imported natural aggregates for concrete production. <\/p>\n\n\n\n

New research by Dr. Natascha Kuhlmann<\/a> and Prof. Dr. Markus Sch\u00e4fer<\/a> explores how materials from demolished buildings can be identified, classified and reused by tracing their geological origins. <\/p>\n\n\n

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\nGiving old buildings a second life<\/h2>\n\n\n\n

Concrete is everywhere: in homes, schools, bridges and roads. But producing it requires enormous amounts of natural raw materials such as sand and gravel. In Luxembourg, these resources are limited. At the same time, construction activity continues to generate large quantities of waste.  <\/p>\n\n\n\n

Reusing materials from demolished buildings could help reduce waste and lower dependence on imported materials. In this context, existing buildings can be seen as a valuable source of future raw materials. This idea was first explored within the European Interreg project UniGR-CIRKLA<\/a> and served as the starting point for this research. <\/p>\n\n\n\n

The challenge, however, is consistency. Materials recovered from old buildings are often mixed and can behave very differently once reused in new concrete, impacting its quality and reliability. “Therefore, knowledge about their properties is essential. Especially for buildings constructed with rubble stone masonry, this can significantly increase the potential for reuse.<\/em>\u201d explains Prof. Dr. Sch\u00e4fer. <\/p>\n\n\n\n

For Dr. Natascha Kuhlmann, geology offers part of the answer. \u201cBefore the 1940s, many buildings in Luxembourg were constructed using locally sourced stones such as sandstone, limestone, dolomite and slate<\/em>\u201d explains Natascha. \u201cThese materials all have different properties, which affect how they react when recycled.<\/em>\u201d <\/p>\n\n\n\n

From an engineering perspective, Prof. Sch\u00e4fer highlights that some stones absorb more water than others. Some are more resistant to frost or mechanical stress. Understanding where these materials originally came from can therefore help predict whether they are suitable for reuse in concrete production. <\/p>\n\n\n

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\n \u201f<\/span>\n With its high construction activity, limited natural resources and diverse geology, Luxembourg offers a particularly valuable real-world setting for this type of research\u201d\n<\/blockquote>\n
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Dr. Natascha Kuhlmann<\/p>\n\n\n

Postdoctoral researcher<\/p>\n\n

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\nNot all stones behave the same way<\/h2>\n\n\n\n

Despite these differences, many recycling facilities still treat recycled mineral-based construction materials in the same way.<\/p>\n\n\n\n

Dr. Natascha Kuhlmann and Prof. Markus Sch\u00e4fer aim to change that by developing a classification approach that links different local rock types to the way they react in concrete. This could help recycling facilities to sort and process materials more precisely before<\/em> they reuse them in future construction projects.<\/p>\n\n\n

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\n \u201f<\/span>\n By linking demolition materials to their geological origins and historical quarry locations, we aim to improve the classification of recycled aggregates and strengthen their future use in concrete production for more resource efficiency and a circular economy in construction\u201d\n<\/blockquote>\n
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Prof. Dr. Markus Sch\u00e4fer <\/p>\n\n\n

Full professor in Structural engineering and composite structures<\/p>\n\n

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But how does this actually work? Recycling construction materials starts on the demolition site itself. Materials such as metal, wood, glass and plastics are first separated from concrete and masonry. The remaining mineral materials are then crushed, cleaned and sorted before they can be reused as recycled aggregates for new concrete production. <\/p>\n\n\n\n

But recycling is only part of the process. An important step is assessing whether the recovered materials are suitable for reuse. Before recycled aggregates can be incorporated into new concrete, they must meet strict quality requirements regarding their composition, strength, durability, frost resistance, and potential contamination. <\/p>\n\n\n\n

European and national regulations therefore limit how and where recycled aggregates can be used, depending on their quality. This is where the researchers\u2019 approach becomes particularly relevant. By improving the identification and classification of recycled materials, they hope to support more reliable quality assessment and increase confidence in their use in future construction projects. <\/p>\n\n\n

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The researchers are currently developing a geological-engineering approach for recycled mineral construction materials with the support of the Master Thesis project of Uni.lu student Nicola Simoes and the Service G\u00e9ologique de l’\u00c9tat du Luxembourg<\/a>. The project combines geological maps, historical quarry locations, local building traditions, and material testing. In parallel, a database of local rock types and their engineering properties is being established to support future reuse strategies in construction. <\/p>\n\n\n

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\nLearn more<\/h2>\n\n\n\n

This project brings together universities, research institutions, and public authorities. Markus Sch\u00e4fer and Natascha Kuhlmann (糖心Vlog, Department of Engineering<\/a>) initiated the study and served as the main authors.<\/em><\/p>\n\n\n\n

Other contributors:<\/p>\n\n\n\n