Flat glass waste from building demolition is an underused resource with potential to reduce the climate impact of construction materials. This study compares two recycling pathways for flat glass waste: the first is closed-loop recycling into new glass, and the second is the use of glass in concrete as a replacement for cement. The comparison is based on life cycle, circularity assessment and experimental evaluation of concrete performance. Recycling flat glass into new glass can reduce emissions by 945 kg CO2eq per ton of recycled glass when the production mix contains 65 percent recycled content. However, only between 1 and 3% percent of demolition flat glass is suitable for this process because of contamination and quality limitations. As a result, the practical climate benefit of demolition glass in new glass production is limited to about 38 kg CO2eq per ton of demolition glass. Concrete offers a much larger waste sink. Replacing 20% of cement with milled glass powder results in emission savings of 776 kg CO2eq per ton of glass. A concrete mix containing 33% glass shows the same compressive strength as a reference mix.

Concrete waste is utilized in Sweden mostly for backfilling in road applications and building landfills. The techniques for recycling concrete to replace natural aggregates are in place and makes it possible to produce circular and climate reduced concrete. This paper explores concrete crushed aggregates (CCA) from rest concrete, produced using industrial crushing methods. Also, the regulatory framework supporting recycling has been discussed. The Swedish concrete standard is implementing to a lower grade the use of CCA in new concrete in comparison to other European standards specially regarding the use of fine CCA fractions. Results for CCA water absorption and apparent density from lab scale and industrial crushing are shown. The CCA fulfills claims for aggregates for indoor concrete. With further improvements in the crushing process, CCA is fit for applications in outdoor concrete.

Concrete waste is underutilized in Sweden, being used for backfilling in road applications and constructing landfills. When it shows the potential for use in load-bearing applications, as an alternative to natural aggregates, to produce circular and climate reduced concrete. This paper explores concrete crushed aggregates (CCA) from reclaimed concrete, produced using industrial crushing methods. The regulatory framework supporting recycling has been discussed. The Swedish concrete standard is less adopting to the use of CCA in new concrete in comparison to other European standards specially regarding the use of fine CCA fractions. Results for CCA water absorption and apparent density from lab scale and industrial crushing are shown. The CCA fulfills claims for aggregates for indoor concrete, with improvements in the crushing process, CA can suit requirements for outdoor concrete. 

A recycling pathway using flat glass waste as a supplementary cementitious material (SCM) leads to circularity in concrete production through industrial symbiosis. By incorporating glass waste, the environmental impact of cement can be reduced, contributing to the goal of climate-neutral concrete by 2045. This review study highlights the pozzolanic, chemical and physical properties of glass powder (GP) activated through mechanical process. The relationship between the strength activity index and particle size of GP as well as the hydration phases and the mitigation effect of alkali-silica reactions (ASR) is discussed.

A recycling pathway using flat glass waste as a supplementary cementitious material (SCM) leads to circularity in concrete production through industrial symbiosis. By incorporating glass waste, the environmental impact of cement can be reduced, contributing to the goal of climate-neutral concrete by 2045. This review study highlights the pozzolanic, chemical and physical properties of glass powder (GP) activated through a mechanical process. The relationship between particle size of GP and the strength activity index as well as the hydration phases and its potential to reduce alkali-silica reactions (ASR) are discussed.

This study examines the benefits and limitations of different supply chain models for recycled concrete aggregates (RCA), a highly resource- and CO2-intensive material. Focusing on Sweden, it combines material science insights with policy analysis and logistics modelling to assess the potential of RCA in construction. RCA demonstrate strong reuse potential in both bound (new concrete) and unbound (road and backfilling) applications, with life cycle assessments indicating lower climate impacts than virgin aggregates. However, barriers to achieve circularity persist, including fragmented regulations, limited infrastructure, and weak market demand. Using qualitative data from industry actors and quantitative modelling, three scenarios are developed: high-utility reuse of elements, consolidated recycling into bound and unbound applications, and low-utility recycling for backfilling. Results highlight the importance of selective demolition, traceability, procurement models, and strategic placement of concrete material terminals. The study concludes that coordinated policy, logistics planning, and procurement practices are critical to scaling RCA adoption. 

Cirkulärt klimatreducerat betongelement i nybyggnation är ett 2-årigt Vinnova projekt som kom till som ett led i utvecklingen av cirkulära fastigheter med avsikt att återvinna betong och fönsterglas samt återbruka prefabricerade betongelement från fabrik eller rivningsobjekt.

Projektet har varit ett samarbete mellan Högskolan i Borås som projektledare, fastighetsägarna Riksbyggen och kommunala bostadsbolaget Bostäder i Borås, Borås Stad, krossmaskintillverkaren Sandvik, ballastproducenten NCC Industri, fabriksbetongtillverkaren Sweock, prefabelement tillverkaren UBAB och konstruktionskonsulten Stiba.

Projektet har skapat fördjupad kunskap om återvinning och återanvändning av restmaterial och resulterar i följande ny teknik och innovationer för cirkulära materialflöden:

• en cirkulär ballast från betongrester har tagits fram på industriell skala med tillämpningsområdet ballast i ny betong; lämpligheten har visats med petrografisk testning, krossningsteknik, fysikaliska och frys och tö egenskaper har visats genom tester
• ett cirkulärt glaspulver från planglasavfall har tagits fram och används som cementersättning; bestämning av innehåll, malning och potentialen med glasersättning visas genom tester
• nya betongmix med cirkularitetsgrad upptill 90 vikt% har tagits fram med en klimatreduktion i nivå 3 från Svensk Betong
• transport och logistikinfrastruktur har optimerats för att säkra klimatfördelarna med cirkulära material.

Doktorander och postdoc samt forskare från Högskolan i Borås har varit delaktiga i projektet och publicerat vetenskapliga artiklar.

Studenter från Byggingenjörsprogrammet, Affärsutveckling Bygg och Fastighet samt Affärsingenjörsprogrammet Bygg vid Högskolan i Borås har deltagit i projektet och dokumenterat delar av resultaten genom sina examensarbeten.

Circular climate-reduced concrete elements in new buildings is a 2-year Vinnova project that was initiated as part of the development of circular properties with the intention of recycling concrete and window glass as well as reusing prefabricated concrete elements from factories or demolition sites. 

The project has been a collaboration between Borås University as the project leader, property owners Riksbyggen and the municipal housing company Bostäder i Borås, Borås City, crusher manufacturer Sandvik, aggregate producer NCC Industry, readymix concrete manufacturer Sweock, prefabricated element manufacturer UBAB, and structural consultant Stiba.

The project has created in-depth knowledge about recycling and reuse of rest materials and results in the following new technologies and innovations for circular material flows:

• a circular aggregate from concrete waste has been developed on an industrial scale with the application area of aggregate in new concrete; its suitability has been demonstrated through petrographic testing, crushing technology, and physical and freeze and thaw properties have been shown through tests
• a circular glass powder from flat glass waste has been developed and is used as a cement replacement; determination of content, milling, and the potential with glass replacement is demonstrated through tests
• new concrete mixes with a circularity degree of up to 90 weight% have been developed with a climate reduction of level 3 from Svensk Betong.
• transport and logistics infrastructure have been optimized to secure the climate benefits of circular materials.

Doctoral students and postdocs as well as researchers from the University of Borås have participated in the project and published scientific articles.

Students from the Building construction and technology program, Business Development in Construction and Real Estate, and the Business Engineering program in Construction at the University of Borås have participated in the project and documented parts of the results through their theses.