Decarbonization of the concrete industry has arisen as one of the main priorities for the construction sector in order to mitigate the negative climate impact associated with construction. The carbon emissions of concrete mainly originate from the production of cement, and it is essential to find supplementary cementitious materials (SCMs) to achieve eco-friendly construction materials. The use of tailings as SCMs could reduce the carbon footprint of concrete, as well as improve the environmental impact of waste management within the mining sector. To investigate the effects of using lead–zinc tailings as a partial replacement for ordinary Portland cement (OPC), an experimental study was conducted. Two types of lead–zinc tailings were utilized in the experiments to replace 10% and 20% of OPC. A mechanical activation method was adopted using a vibratory cup mill. The effects of activation on the tailings’ particle size distributions and mineralogy were evaluated. The results indicated that the activation was insufficient to promote the pozzolanic activity in T1 and only partially promoted it in T2. A total of 18 different tailing-based mortar (TBM) specimens were produced from the raw and activated tailings, and their flowability, setting time, and compressive strengths after 7, 28, and 90 days were evaluated. The microstructures of the specimens were analyzed using scanning electron microscopy with energy dispersive X-ray spectroscopy. No alteration of mineralogy was observed in T1 after activation; however, a reduction in muscovite was observed in T2. The TBM specimens with 10% activated tailings exhibited comparable 28-day compressive strengths to the control specimen. For the replacement level above 10%, there was a loss of compressive strength at 28 days, both for the activated and raw tailings and for both T1 and T2. Evaluation of the microstructure showed that the use of tailings caused regions in the cement matrix with high metal concentrations. Microcracks could be observed in or around such grains in several cases. The study demonstrated that 10% of OPC can be replaced by lead–zinc tailings while retaining the compressive strength of the specimens.

The decarbonization of concrete is an urgent goal in sustainable construction because cement is a major contributor to greenhouse gas emissions. Meanwhile, the growing volumes of municipal solid waste (MSW) also require more circular and efficient management strategies. Municipal solid waste incineration bottom ash (MSWBA), generated during MSW incineration, has potential as a partial cement replacement in concrete. However, its practical use as a cement replacement remains uncertain because its properties vary depending on its source, treatment, and chemical composition. Therefore, both technical performance and environmental safety must be considered simultaneously. This study examined the feasibility of using MSWBA as a partial cement replacement in concrete through an integrated mechanical and environmental assessment. Specifically, the present work focused on the long-term performance of MSWBA-incorporated concrete, with compressive strength evaluated at the curing ages of 90 and 180 days, alongside assessments of leaching behavior and cradle-to-gate CO₂ emissions. Five MSWBA samples (denoted B1–B5) were first characterized, of which B3 and B5 were selected for further use in concrete production. The selected MSWBA samples were used in raw and mechanically activated forms at cement replacement levels of 10% and 20% to assess their long-term mechanical performance and environmental implications. The results showed that performance depended strongly on MSWBA type and replacement level, with the 10% replacement mixtures exhibiting more favorable performance. In contrast, the 20% replacement mixtures generally resulted in greater reductions in compressive strength. From an environmental perspective, partial cement replacement reduced cradle-to-gate CO₂ emissions by 9.45% at the 10% replacement level and by 19.27% at the 20% replacement level compared with the control concrete (without MSWBA). Leaching tests further revealed increased release of Al, Ba, Cr, Mo, and chloride ions in mixtures containing MSWBA, although the measured concentrations of individual substances remained below the evaluated limits for the tested concrete specimens. The results also indicated that higher replacement levels led to greater environmental concerns than the 10% replacement level, highlighting the importance of controlling the MSWBA content in concrete mixtures. This study demonstrated that MSWBA can contribute to the decarbonization of concrete when suitable MSWBA samples are appropriately selected and utilized, thereby contributing to both a greener construction sector and a more effective approach to MSW recycling.

This study explores the feasibility of using municipal solid waste incineration bottom ashes (MSWIBAs) as a partial replacement for cement in concrete with respect to the fresh and hardened properties of concrete. MSWIBA samples from five Swedish incineration plants (BA1–BA5) were collected and analyzed for their mineral composition and particle size distribution (PSD). The samples (BA3 and BA5), exhibiting better pozzolanic behavior and particle sizes closer to those of conventional cement, were selected for further detailed study. Mechanical activation was performed on the BA3 and BA5 samples. Concrete mixes were prepared with 10% and 20% (by mass) cement replacements utilizing raw and activated BA3 and BA5 samples. The resulting concrete specimens were evaluated through slump, density, and compressive strength tests at 7, 28, and 56 days. The results showed that activated MSWIBAs improved the workability of the concrete specimens compared with the control concrete mix, and the density of the concrete decreased with increasing the MSWIBA content. The compressive strength of the concrete mixes generally decreased as the replacement level of MSWIBAs increased. At 56 days, the concrete mix with 10% raw BA5reached about 77% of the compressive strength of the control concrete mix, whereas mixes with 20% raw or activated MSWIBAs reached about 58%. The concrete mix with BA3 performed better than the mix with BA5 at 7 days, while the concrete mix with BA5 showed higher later-age compressive strength. In addition, mechanical activation of MSWIBAs did not significantly improve compressive strength of concrete mixes. Despite the reduction in compressive strength when using MSWIBAs, this sustainable concrete contributes to the development of climate-friendly concrete and offers potential environmental benefits.

Projektet "Bottenaska som ersättare till cement i klimatförbättrad betong" undersöker möjligheten att använda bottenaska, som produceras vid förbränning av kommunalt avfall (municipal solid waste incineration bottom ash, MSWIBA), som en delvis ersättning för cement i betong med avseende på betongens mekaniska egenskaper. Betong är ett oundvikligt material inom byggindustrin och består av cement, vatten, finkorniga och grovkorniga ballastmaterial. Produktionen av cement förbrukar naturresurser, orsakar luftföroreningar och släpper ut växthusgaser, vilket leder till drastiska förändringar i klimatförhållanden. För att motverka detta arbetar betongindustrin mot klimatneutral betong till år 2030, med en strategi som innefattar optimering av bindemedel och minskning av cementinnehållet. En betydande ökning av produktionen av kommunalt avfall har noterats i samband med förändrade levnadsvanor och urbanisering. Bortskaffandet av det genererade avfallet genom förbränning producerar MSWIBA och flygaska från kommunalt avfall (municipal solid waste incineration fly ash, MSWIFA). MSWIBA utgör cirka 90% av restprodukten och innehåller olika oxider, vilket gör askan jämförbar med olika kompletterande bindemedel. I detta projekt samlades in fem olika MSWIBA (benämnda BA1-BA5). De undersöktes avseende kemiska ingredienser, mineralsammansättningar och partikelstorleksfördelning (particle size distribution, PSD). Efter genomförda röntgendiffraktionsanalyser (X-ray diffraction, XRD) och PSD på alla prover valdes de prover (BA3 och BA5) som visade pozzolanska egenskaper och partikelstorlekar närmast konventionell cement för vidare studier.Olika betongblandningar bereddes med 10% och 20% ersättning av cement med rå och aktiverad MSWIBA (BA3 och BA5). Totalt gjöts och analyserades 81 provkuber. Egenskaperna hos färsk och härdad betong jämfördes med kontrollblandningen. Prestanda och hållfasthetsökning för varje blandning undersöktes genom provning av tryckhållfastheten vid 7, 28 och 56 dygn. Betongblandningar med rå MSWIBA uppvisade liknande bearbetbarhet som kontrollblandningen, medan blandningar med aktiverad MSWIBA visade en ökad bearbetbarhet. Betongens densitet minskade med en ökning av ersättningsandelen MSWIBA, vilket innebär att lättare betong kan framställas genom tillsats av MSWIBA. Dock hade aktivering av MSWIBA ingen betydande positiv effekt på tryckhållfastheten hos betongblandningarna. Även om tryckhållfastheten minskade med ökad ersättningsandel av MSWIBA uppnådde betongblandningen med 10% ersättning av rå BA5 cirka 77% av tryckhållfastheten hos kontrollprovet efter 56 dygn. För alla betongblandningar med MSWIBA visade blandningen med BA3 bättre prestanda än blandningen med BA5 efter 7 dygn. Vid längre härdningstider uppvisade dock betongblandningen med BA5 högre tryckhållfasthet än blandningen med BA3. Betongblandningen med 20% rå och aktiverad MSWIBA uppnådde 58% av tryckhållfastheten hos kontrollprovet efter 56 dygn. Trots minskningen i betongens tryckhållfasthet erbjuder denna hållbara betong potentiella fördelar inom avfallshantering. Användning av MSWIBA som en ersättning för cement kan också bidra till utvecklingen av klimatförbättrad betong. Detta projekt kan utökas till två olika faser: (1) Att studera effekten av att blanda MSWIBA med andra kompletterande cementbundna material, såsom flygaska, silikastoft eller mald granulerad masugnsslagg, för att ersätta en del av cementen. På detta sätt kan MSWIBA lägre reaktivitet kompenseras. Följaktligen kan lika bra eller överlägsen tryckhållfasthet för betongen uppnås genom denna synergi, tillsammans med förbättrade hållbarhetsegenskaper. (2) Att undersöka MSWIBA som en ersättning för ballastmaterial i betong. En annan potentiell användning för MSWIBA är som ersättning för ballast i betong, vilket bidrar till utvecklingen av mer miljövänlig betong. Detta minskar efterfrågan på naturliga ballastmaterial och hjälper till att bevara naturresurser.

The project ‘‘Bottom Ash as a Replacement for Cement in Climate-Improved Concrete’’ investigates the possibility of using bottom ash, produced from municipal solid waste incineration (municipal solid waste incineration bottom ash, MSWIBA), as a partial replacement for cement in concrete, with regard to the mechanical properties of concrete. Concrete is an indispensable material in the building industry and consists of cement, water, fine aggregates, and coarse aggregates. The production of cement consumes natural resources, causes air pollution, and emits greenhouse gases, leading to drastic changes in climate conditions. To counteract this, the concrete industry is working toward climate-neutral concrete by 2030, with a strategy that includes optimizing binders and reducing cement content. A significant increase in municipal waste production has been noticed due to changes in lifestyles and urbanization. The disposal of the generated waste through incineration produces MSWIBA and municipal solid waste incineration fly ash (MSWIFA). MSWIBA accounts for approximately 90% of the residue product and contains various oxides, making the ash comparable to different supplementary binders. In this project, five different MSWIBAs (named BA1–BA5) were collected. They were examined for their chemical ingredients, mineral compositions, and particle size distribution (PSD). After conducting X-ray diffraction (XRD) and PSD analyses on all samples, the samples (BA3 and BA5) that exhibited pozzolanic properties and particle sizes closer to conventional cement were selected for further studies. Various concrete mixes were prepared with 10% and 20% replacements of cement using raw and activated MSWIBAs (BA3 and BA5). A total of 81 test cubes were cast and analyzed. The properties of fresh and hardened concrete were compared to the control mix. The performance and strength developments of each mix were studied by conducting compressive strength tests at 7, 28, and 56 days. Concrete mixes with raw MSWIBAs showed similar workability to the control mix while mixes with activated MSWIBAs exhibited increased workability. The density of concrete decreased as the MSWIBAs replacement percentage increased, indicating that lighter concrete can be produced by incorporating MSWIBAs. However, the activation of MSWIBAs had no significant positive effect on the compressive strength of the concrete mixes. Although the compressive strength decreased with increasing the replacement ratio of MSWIBAs, the concrete mix with 10% replacement of raw BA5 achieved around 77% of the compressive strength of the control specimen after 56 days. For all concrete mixes containing MSWIBAs, the mix with BA3 showed better performance than the mix with BA5 after 7 days. However, at longer curing times, the concrete mix with BA5 exhibited higher compressive strength than the mix with BA3. The concrete mix with 20% raw and activated MSWIBAs obtained 58% of the compressive strength of the control specimen after 56 days. Despite the reduction in the compressive strength of concrete, this sustainable concrete offers potential benefits in terms of environmental protection and waste management. The use of MSWIBA as a substitute for cement can also contribute to the development of climate-improved concrete. This project can be extended into two different phases: (1) studying the effect of mixing MSWIBA with other supplementary cementitious materials, such as fly ash, silica fume, or ground granulated blast furnace slag, to replace part of cement. In this way, the lower reactivity of MSWIBA can be compensated. Consequently, similar or even superior compressive strength for concrete can be achieved through this synergy, along with improved durability properties. (2) Investigating MSWIBA as a substitute for aggregates in concrete. Another potential application of MSWIBA is replacing aggregates in concrete, contributing to the development of more environmentally friendly concrete. This reduces the demand for natural aggregates and helps conserve natural resources.

Due to their sustainability, lightweight qualities, and simplicity of installation, wood slab systems have gained increasing attention in the building industry. Cross-laminated timber (CLT), an engineered wood product (EWP), improves structural strength and stability, offering a good alternative to conventional reinforced concrete (RC) slab systems. Conventional CLT, however, contains adhesives that pose environmental and end-of-life (EOL) disposal challenges. Adhesive-free CLT (AFCLT) panels have recently been introduced as a sustainable option, but their environmental performance has not yet been thoroughly investigated. In this study, the environmental impacts of five slab systems are evaluated and compared using the life cycle assessment (LCA) methodology. The investigated slab systems include a standard CLT slab (SCLT), three different AFCLT slabs (AFCLT1, AFCLT2, and AFCLT3), and an RC slab. The assessment considered abiotic depletion potential (ADP), global warming potential (GWP), ozone layer depletion potential (ODP), human toxicity potential (HTP), freshwater aquatic ecotoxicity potential (FAETP), marine aquatic ecotoxicity potential (MAETP), terrestrial ecotoxicity potential (TETP), photochemical oxidation potential (POCP), acidification potential (AP), and eutrophication potential (EP), covering the entire life cycle from production to disposal, excluding part of the use stage (B2-B7). The results highlight the advantages and drawbacks of each slab system, providing insights into selecting sustainable slab solutions. AFCLT2 exhibited the lowest environmental impacts across the assessed categories. On the contrary, the RC slab showed the highest environmental impact among the studied products. For example, the RC slab had the highest GWP of 67.422 kg CO2 eq, which was 1784.3% higher than that of AFCLT2 (3.779 kg CO2 eq). Additionally, the simulation displayed that the analysis results vary depending on the electricity source, which is influenced by geographical location. Using the Norwegian electricity mix resulted in the most sustainable outcomes compared with Sweden, Finland, and Saudi Arabia. This study contributes to the advancement of low-carbon construction techniques and the development of building materials with reduced environmental impacts in the construction sector.

Detta projekt syftade till att utvärdera den tekniska genomförbarheten och miljökonsekvenserna av att använda bottenaska från kommunal avfallsförbränning (MSWBA) som ett kompletterande cementbaserat material (SCM) i betongproduktion. Det övergripande målet var att främja hållbart byggande genom att minska cementförbrukningen och återanvända industriavfall i enlighet med principer för cirkulär ekonomi. Fem MSWBA-prover utvärderades initialt med avseende på deras kemiska egenskaper, pozzolanpotential och partikelstorleksfördelning. Baserat på de erhållna resultaten valdes proverna B3 och B5 ut och införlivades i betongblandningar med 10 % respektive 20 % ersättningsnivåer av cement, både i rå och aktiverad form, med standard Portlandcement-betongblandningar som referens.

Tryckhållfasthetstester upp till 180 dagar visade att 10 % råa B5-betongprover bibehöll den bästa tryckhållfasthetsutvecklingen (33,3 MPa) bland MSWBA-betongblandningar. Däremot ledde 20 % ersättning av cement med MSWBA till markanta minskningar av tryckhållfastheten, medan aktiverade MSWBA introducerade variationer i betongens tryckhållfasthet vid 90 till 180 dagars härdning.

Miljöprestandan hos MSWBA-betongblandningar utvärderades genom analys av tungmetallinnehåll och lakningstester. B5 visade sig innehålla lägre halter av farliga ämnen som Cd, Pb, Cr och Hg, och uppfyllde miljösäkerhetskriterierna för lakning. Däremot uppvisade B3 högre föroreningsnivåer, vilket kan begränsa dess tillämpning om den inte behandlas ytterligare. Lakningstester bekräftade att vid 10 % ersättning uppfyllde både råa och aktiverade B3-prover de aktuella miljögränsvärdena för lakning av tungmetaller, vilket visar att de är användbara i begränsande mängder. Emellertid ger den förhöjda glödgningsförlusten (LOI) och spårmetallvariabiliteten i B3 upphov till långsiktiga miljöproblem, särskilt under längre exponeringsförhållanden som karbonatisering eller kloridinträngning. B5:s låga LOI och minimala lakningsbara föroreningar förstärker å andra sidan dess lämplighet inte bara ur ett mekaniskt utan även ur ett miljömässigt perspektiv. Dessa resultat betonar vikten av att noggrant välja MSWBA-källor och den potentiella nödvändigheten av förbehandling för att säkerställa en säker och hållbar implementering av MSWBA i betongapplikationer. Ur ett koldioxidutsläppsperspektiv ledde en ersättning av 10 % cement med MSWBA till en uppskattad minskning av CO₂-ekvivalenter med cirka 10 % per 1 kg betong jämfört med referensblandningen. Denna minskning, som samtidigt innebar godtagbar tryckhållfasthet och säkerhet i både B3- och B5-betongblandningarna, understryker materialets bidrag till att minska betongens koldioxidutsläpp.

Studien visar att rå B5, som används med en ersättningsnivå på 10 %, är ett lovande och miljövänligt SCM-alternativ. Det erbjuder acceptabel mekanisk prestanda samtidigt som det stöder materialåtervinning och utsläppsminskning. Dessa resultat ger en grund för framtida studier av optimerad bearbetning, bredare tillämpningsområden och långsiktig prestanda i hållbara betongsystem.

This project aimed to evaluate the technical feasibility and environmental implications of using municipal solid waste incineration bottom ash (MSWBA) as a supplementary cementitious material (SCM) in concrete production. The overarching goal was to promote sustainable construction by reducing cement consumption and repurposing industrial waste in accordance with circular economy principles. Five MSWBA samples were initially assessed for their chemical properties, pozzolanic potential, and particle size distribution. Based on the obtained results, the samples B3 and B5 were selected and incorporated into concrete mixtures at 10% and 20% replacement levels of cement, both in raw and activated forms, with standard Portland cement-concrete mixtures used as reference.

Compressive strength tests up to 180 days showed that 10% raw B5-concrete specimens maintained the best compressive strength development (33,3 MPa) among MSWBA-concrete mixes. In contrast, 20% replacement of cement by MSWBAs led to marked reductions in compressive strength, while activated MSWBAs introduced variability in concrete compressive strength at 90 to 180 days of curing.

The environmental performance of MSWBA-concrete mixtures was evaluated through heavy metal content analysis and leaching tests. B5 was found to contain lower levels of hazardous elements such as Cd, Pb, Cr, and Hg, and met environmental safety criteria for leaching. In contrast, B3 displayed higher impurity levels, which may restrict its application unless further treated. Leaching tests confirmed that at 10% replacement, both raw and activated B3 samples complied with current environmental leaching thresholds for heavy metals, demonstrating their viability in limited proportions. However, the elevated loss on ignition (LOI) and trace metal variability in B3 raise long-term environmental concerns, especially under extended exposure conditions such as carbonation or chloride ingress. B5’s low LOI and minimal leachable contaminants, on the other hand, reinforce its suitability not only from a mechanical but also environmental perspective. These findings emphasize the importance of selecting MSWBA sources carefully and the potential necessity of pretreatment to ensure the safe and sustainable implementation of MSWBAs in concrete applications.

From the carbon dioxide emission perspective, the replacement of 10% cement with MSWBA resulted in an estimated reduction (production) of approximately 10% CO₂ekv. per 1 kg of concrete compared to the reference mixture. This reduction, while resulted in acceptable compressive strength and safety in the B3- and B5-concrete mixtures, underscores the material’s contribution to lowering the carbon dioxide emissions from concrete.

The study demonstrates that raw B5, used at a 10% replacement level, is a promising and environmentally sound SCM option. It offers acceptable mechanical performance while supporting material recycling and emission reduction. These findings provide a foundation for future exploration into optimized processing, broader application scopes, and long-term performance in sustainable concrete systems.

With concrete’s key role in construction and infrastructure, the reduction of its carbon footprint is critical for addressing global carbon emissions. One strategy to reduce environmental impact from concrete production is to replace cement clinker or fine aggregates in concrete with industrial wastes. Mine tailings, being a high-volume under-utilized resource, possess properties making it suitable for use as a partial substitute for cement or fine aggregates. This review article provides an overview of the recent findings within the topic of tailings-based concrete (TBC). Many of the identified publications aimed to describe the mechanical performance of TBC, and to optimize the concrete mix with respect to the strength and durability. The recommended cement replacement ranged from 5 to 25% and the recommended fine aggregate replacement ranged from 20 to 60%. In general, the compressive strength was decreased with increasing use of tailings as a replacement of cement. For the use of tailings as replacement for fine aggregates, the correlation was more complex, normally the mechanical performance enhanced at low replacement levels, until it reached an optimum after which it decreased. CO2 savings for replacing fine aggregate with tailings were up to 12% and for the cement replacement up to 30%. When assessing the environmental performance, most of the publications did not account for the loss of its mechanical performance, which could lead to the risk of underestimating the environmental impact. This review not only provides a basis for understanding the mechanical, toxicological, and environmental performances of TBCs, but also links the perspectives together, unveiling the connections between them. Moreover, this review presents an organized overview of the topic of TBC and points out topics for future research.

Cross-laminated timber (CLT) is one of the most sustainable, robust, and green building materials nowadays and is normally used for walls, floors, or roofs. The number of studies on CLT has increased significantly since 2010, which shows the acceptance and needs of CLT. Connection systems, rolling shear performance, and sustainability are the popular and main research topics within CLT, including wooden connections, metallic connections, adhesive and rod connections, aspect ratio, bonding performance, life cycle assessment, carbon emission, and environmental impact. Based on these three branches, the current study conducts a literature review on CLT. This review article aims to provide a valuable view and better understanding of CLT, which are linked to (1) promoting the usage of CLT and (2) summarizing the weaknesses of the CLT’s research. This article presents a full background of the CLT research and gives potential research directions for CLT as a structural material. It revealed that the design and analytical methodologies for novel timber and steel connections are the main trends. As for the CLT’s rolling shear performance, standardized testing protocol, environmental impact, and bonding quality need further development. Furthermore, the data collection, selection, and influence of different policies are important for the CLT’s sustainability assessment.

Previous research has shown a lack of studies with comparisons between primary (virgin) and secondary (re-used) building materials, and their embodied emissions. The creation of different scenarios comparing the environmental impact of virgin vs. re-used materials is also motivated by the scarcity of raw materials in the world and the emergency of mitigating greenhouse gas (GHG) emissions from buildings. The aim of this study was to investigate scenarios, including new vs. re-used building products, applying the LCA method for a wooden single-family building. The findings showed a 23% reduction potential for total released (positive) CO2e when comparing the Reference scenario with Scenario I, using re-used wooden-based materials. Further, Scenario II, using all re-used building materials except for installations, showed a 59% CO2e reduction potential compared to the Reference scenario. Finally, Scenario III, which assumes all re-used building products, showed a 92% decreased global warming potential (GWP) impact compared to the Reference scenario. However, when including biogenic carbon and benefits (A5 and D module), the Reference scenario, based on newly produced wooden building materials, has the largest negative GHG emissions. It can be concluded that the re-use of building products leads to significant carbon savings compared to using new building products.

University staff play an important role in the development of a more sustainable world. Their attitudes towards pro-environmental behavior and environmental values likely have an influence on ethics, the current society and future generations. Therefore, this study aims to measure and interpret the ecological worldview among university staff using the validated New Environmental Paradigm (NEP) survey. The mean NEP-score was 3.68. This overall value is of the same magnitude as many samples from diverse geographical areas with representatives and students, but it is considerably lower than for environmentalists. The facet Balance of nature reported the highest score whereas Limits to growth the lowest score. Women had higher mean score, mainly explained by the higher score in the facet Human domination over nature. There is a potential for improving the ecological world-view scores of University staff, who are an unstudied and important group. Values in higher education may influence sustainable development, environmental ethics and society.