Cleaner Materials最新文献

Sustainability assessment of ultra-high performance concrete made with various supplementary cementitious materials

Cleaner Materials

Pub Date : 2025-03-01 DOI: 10.1016/j.clema.2025.100301

Leila Farahzadi , Saeed Bozorgmehr Nia , Behrouz Shafei , Mahdi Kioumarsi

Ultra-high performance concrete (UHPC) is widely recognized for its exceptional strength and durability, making it a preferred choice in modern concrete construction. However, the high cement content of conventional UHPC mixtures causes environmental concerns, particularly in terms of carbon footprint. To address such concerns, this study presents a comprehensive sustainability assessment of various UHPC mixtures that incorporate high volumes of supplementary cementitious materials (SCMs), including ground granulated blast furnace (GGBF) slag and fly ash, individually and in combination, as partial replacements for cement. The use of alternative SCMs also addresses the reliance of UHPC mixtures on silica fume. While beneficial for a range of concrete properties, silica fume poses challenges, in terms of cost and potential particulate emission during handling and mixing. A detailed life cycle assessment (LCA) was performed in the current study to evaluate the environmental impacts of alternative UHPC mixture designs, considering key factors, such as resource utilization, energy consumption, water use, raw material transportation, and production processes. In contrast with past research that primarily focused on simple CO₂-equivalent metrics, this study assessed 14 distinct environmental impact categories, offering a unique and holistic contribution to UHPC sustainability research. The findings demonstrated that incorporating up to 50% GGBF slag as cement replacement significantly reduces the UHPC’s environmental impacts without jeopardizing the main mechanical and durability characteristics. This research underscores the critical role of industrial by-products in enhancing sustainable construction practices and offers practical solutions for adopting low-impact concrete production methods.

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引用次数: 0

Mechanical properties, life-cycle assessment, and costs of alternative sustainable binders to stabilise recycled aggregates

Cleaner Materials

Pub Date : 2025-02-18 DOI: 10.1016/j.clema.2025.100302

Luca Tefa , Bartolomeo Coppola , Paola Palmero , Marco Bassani

Cement-stabilised subbases provide superior bearing capacity and durability to road pavements compared to unbound aggregate layers. However, stabilisation reduces the environmental benefits derived when recycled aggregates are used. This research compares alternative binders to Portland cement to highlight mechanical, environmental, and economic advantages and disadvantages in a cradle-to-production scenario. Three low-clinker cements with different proportions of pozzolana and three alkali-activated (AA) binders derived from (i) construction and demolition waste fines, (ii) municipal incinerator bottom ash and (iii) waste clay, were compared to Portland limestone cement. The compressive strength of binder pastes was measured after 7 and 28 curing days.

Pozzolanic cements proved viable alternatives to Portland ones, while AA pastes exhibited lower strengths. The crystallinity of alkali-activated silica- and alumina-rich waste precursors was responsible for their limited strength. The life cycle assessment indicated that the replacement of clinker with pozzolana significantly reduces the environmental impact. AA binders with waste precursors can reduce the environmental impact only with a limited quantity of alkaline solution. If the lower strength achieved by AA binders is compensated by adding higher quantities to recycled aggregate, the increase in environmental impact and cost would make them less competitive. The option of using AA binders would be further strengthened with the production of environmentally friendly alkaline solutions and greater local availability of amorphous precursors. At present, cements are cheaper than AA binders due to the current massive production, widespread availability, and competition between producers.

与未粘结的集料层相比，水泥稳定基层可为路面提供更高的承载能力和耐久性。然而，当使用再生骨料时，稳定化会降低环境效益。本研究对波特兰水泥的替代粘结剂进行了比较，以突出从摇篮到生产过程中的机械、环境和经济优缺点。研究人员将三种不同比例的低熟料水泥、三种碱激活（AA）粘结剂与波特兰石灰石水泥进行了比较，这三种粘结剂分别来自（i）建筑和拆除废物细粉、（ii）城市焚化炉底灰和（iii）废弃粘土。经过 7 天和 28 天的养护后，测量了粘合剂浆料的抗压强度。事实证明，波特兰水泥的替代品是可行的，而 AA 浆料的强度较低。碱激活二氧化硅和富含氧化铝的废物前体的结晶性是其强度有限的原因。生命周期评估表明，用毛石粉替代熟料可显著减少对环境的影响。使用废物前驱体的 AA 粘合剂只能通过有限数量的碱性溶液来减少对环境的影响。如果通过增加再生骨料的用量来弥补 AA 粘结剂所达到的较低强度，则环境影响和成本的增加会降低其竞争力。随着环保型碱性溶液的生产和本地无定形前体供应的增加，使用 AA 粘结剂的选择会进一步加强。目前，由于水泥的大量生产、广泛供应和生产商之间的竞争，水泥比 AA 粘结剂便宜。

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引用次数: 0

A comprehensive study on the mechanical properties of natural fiber reinforced stabilized rammed earth using experimental and data-driven fuzzy logic-based analysis

Cleaner Materials

Pub Date : 2025-02-16 DOI: 10.1016/j.clema.2025.100300

Aryan Baibordy, Mohammad Yekrangnia, Saeed Ghaffarpour Jahromi

This study investigated the mechanical properties of rammed earth (RE) stabilized with cement or lime and reinforced with straw. Specifically, the compressive and tensile strengths of 15 different mix designs were analyzed, including unstabilized RE, RE stabilized with lime or cement (at 4 % and 8 % by weight of soil), and RE reinforced with straw (at 0.5 % and 1.0 % by weight of soil), along with various combinations of stabilized and unstabilized RE reinforced with straw. Mechanical properties were further assessed through ultrasonic testing and scanning electron microscopy (SEM). Additionally, a data-driven fuzzy logic model was developed to estimate the mechanical properties of RE, addressing a key gap in the application of fuzzy logic to RE construction. The results showed that stabilizing RE with cement and lime increased its 28-day dry compressive strength by 365 % to 640 % and 109 % to 237 %, respectively. The addition of straw generally reduced compressive strength. The stress–strain curves indicated that the elastic modulus of RE stabilized with cement and lime increased by up to 350 % and 11 %, respectively. The 28-day dry tensile strength of the samples ranged from 0.17 to 0.56 MPa. Furthermore, the addition of stabilizers improved tensile strength by approximately 88 % to 224 %, while straw enhanced the tensile strength of unstabilized RE by about 35 %. Ultrasonic and SEM analyses provided valuable insights into the mechanical properties of RE. Additionally, the fuzzy logic model proved useful, yielding satisfactory results in predicting the properties of RE, particularly when using the centroid defuzzification method. The study concluded that RE materials when properly cured and effectively stabilized with cement, lime, and straw, can achieve acceptable mechanical properties and offer sustainable benefits.

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引用次数: 0

Comparative use of different AI methods for the prediction of concrete compressive strength

Cleaner Materials

Pub Date : 2025-02-04 DOI: 10.1016/j.clema.2025.100299

Mouhamadou Amar

Concrete mix design requires specialized knowledge and techniques for characterization. However, this process is time-consuming, and the mechanical properties, such as strength, can vary due to factors like cement type, water content, aggregates, and curing time. Additionally, analytical mathematical models are often used to estimate concrete characteristics. However, accurately determining concrete properties without laboratory testing is challenging, especially when nontraditional materials, such as certain supplementary cementitious materials, are involved. Recently, artificial intelligence has become a powerful resource that enables machine learning-based forecasting using available data. This study utilized RapidMiner® software to design models capable of analyzing various types of tagged data and performing machine learning predictions. These models were applied to over 5,373 concrete formulations compiled from 137 literature sources. The simulations used artificial neural networks or deep learning, generalized linear, decision tree, random forest, support vector machine, and gradient-boosted tree models to predict the compressive strength of 8 concrete mix designs containing different SCMs. The accuracy of models was estimated using traditional statistical indices such as R², MAPE and RMSE. The most accurate model was found to be a gradient-boosted tree followed by deep learning and random forest. Forecasts were validated with high accuracy by comparing experimental results to numerical data.

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引用次数: 0

Enhancing performance of recycled aggregate concrete with supplementary cementitious materials

Cleaner Materials

Pub Date : 2025-02-02 DOI: 10.1016/j.clema.2025.100298

Abba Fatiha , Ezziane Karim , Adjoudj Mhamed , Abed Farid

The substitution of natural coarse aggregates (NCA) by recycled coarse aggregates (RCA) is part of the environmental approach aimed at reducing waste and preserve natural resources. Unfortunately, RCA is of poor quality due to the presence of old mortar attached to its surface. It is characterized by its low density, high absorption, low rigidity and a poor quality interfacial transition zone (ITZ) which results in a lower quality concrete. This experimental study aims to introduce together with RCA aggregates supplementary cementitious materials (SCM) in order to reduce the decrease in mechanical performance, durability and microstructure of concrete. In a concrete based on RCA aggregates, ordinary cement was replaced with 20% natural pozzolan (NP), 10% limestone powder (LP), 20% ground granulated blast furnace slag (GGBFS) or 10% fumed silica (SF). Concrete was studied in terms of workability, superplasticizer requirements, mechanical strength, water absorption and microstructure. The results reveal that SCM significantly improves the performance of RAC concrete by promoting filling effects, nucleation, pozzolanic reactions and hydraulic activity. In the long term, RAC concrete has a 12% lower strength than OAC concrete. This decrease is reduced to only 3% when using LP and even results in 9% and 28% higher strengths when using GGBFS or SF. Similarly, an improvement in structural porosity up to 28% is observed, which led to a significant reduction in shrinkage strain, ranging from 20% to 44%.

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引用次数: 0

Selected residual biomass valorization into pellets as a circular economy-supported end-of-waste

Cleaner Materials

Pub Date : 2025-01-24 DOI: 10.1016/j.clema.2025.100295

Zane Vincevica-Gaile , Maryna Zhylina , Andrei Shishkin , Linda Ansone-Bertina , Linards Klavins , Lauris Arbidans , Linda Dobkevica , Ivar Zekker , Maris Klavins

Among prospective directions to convert residual biomass into valuable products is pelleting, which can be followed by low-temperature pyrolysis, serving as an economically justified method for reducing the final waste stream. In this study, fresh and biochar pellets were obtained from selected residual biomass – waste derived from widespread industries such as energy production, food processing, and forestry and chemical processing in a mixture with peat processing residues used as a binder. Obtained pellets consisted of woody biomass ashes (ASP3 and ASP5) or coffee grounds (CSP3 and CSP5) at equal proportions mixed with spruce needles biomass (48.5 % or 47.5 %) by adding 3 % or 5 % of peat processing residues as a binder, respectively, as indicated. Biochar pellets were obtained by pyrolyzing fresh pellets at 500 °C with a heating rate of 5 °C/min. Chemical-physical properties (e.g., moisture content, ash content, chemical composition, porosity, density) of pellets were studied. The most promising for further use were assessed CSP3. In turn, ASP5 were characterized by relatively higher carbon framework density, surface area (6.889 m²/g), and water absorption (97.83 %), indicating their use as a sorbent applicable, e.g., for wastewater treatment, while others can be used in soil quality improvement and sustainable agriculture support. The conversion of residual biomass into fresh and biochar pellets serves as an efficient approach in end-of-waste following the targets of circular economy towards zero-waste production.

{"title":"Selected residual biomass valorization into pellets as a circular economy-supported end-of-waste","authors":"Zane Vincevica-Gaile , Maryna Zhylina , Andrei Shishkin , Linda Ansone-Bertina , Linards Klavins , Lauris Arbidans , Linda Dobkevica , Ivar Zekker , Maris Klavins","doi":"10.1016/j.clema.2025.100295","DOIUrl":"10.1016/j.clema.2025.100295","url":null,"abstract":"<div><div>Among prospective directions to convert residual biomass into valuable products is pelleting, which can be followed by low-temperature pyrolysis, serving as an economically justified method for reducing the final waste stream. In this study, fresh and biochar pellets were obtained from selected residual biomass – waste derived from widespread industries such as energy production, food processing, and forestry and chemical processing in a mixture with peat processing residues used as a binder. Obtained pellets consisted of woody biomass ashes (ASP3 and ASP5) or coffee grounds (CSP3 and CSP5) at equal proportions mixed with spruce needles biomass (48.5 % or 47.5 %) by adding 3 % or 5 % of peat processing residues as a binder, respectively, as indicated. Biochar pellets were obtained by pyrolyzing fresh pellets at 500 °C with a heating rate of 5 °C/min. Chemical-physical properties (e.g., moisture content, ash content, chemical composition, porosity, density) of pellets were studied. The most promising for further use were assessed CSP3. In turn, ASP5 were characterized by relatively higher carbon framework density, surface area (6.889 m<sup>2</sup>/g), and water absorption (97.83 %), indicating their use as a sorbent applicable, e.g., for wastewater treatment, while others can be used in soil quality improvement and sustainable agriculture support. The conversion of residual biomass into fresh and biochar pellets serves as an efficient approach in end-of-waste following the targets of circular economy towards zero-waste production.</div></div>","PeriodicalId":100254,"journal":{"name":"Cleaner Materials","volume":"15 ","pages":"Article 100295"},"PeriodicalIF":0.0,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Impact of manufacturing variables on the mechanical performance of recycled glass-enhanced composites

Cleaner Materials

Pub Date : 2025-01-22 DOI: 10.1016/j.clema.2025.100297

Nathaphon Buddhacosa , Thevega Thevakumar , Everson Kandare , Sujeeva Setunge , Dilan Robert

This study investigated the influence of various manufacturing conditions – including moulding pressure, post-curing, and aging – on the microstructure and mechanical properties (flexural and tensile) of epoxy matrix composites incorporating recovered glass particles at weight fractions ranging from 84 wt% to 90 wt%. The study focused on understanding how these conditions affect the interfacial bonding between the glass particles, epoxy matrix, and void content to establish a correlation between microstructure and mechanical performance before and after ceramification. The findings revealed that increasing moulding pressure from 1.1 MPa to 6.6 MPa reduced void content, increased composite density, and significantly improved flexural properties. The impact of post-curing on the composites’ flexural performance was also examined, and it was found that adjusting the epoxy matrix weight fraction from 6 wt% to 12 wt% further influenced the composite’s mechanical properties. X-ray computed tomography (CT) and scanning electron microscopy (SEM) analyses revealed changes in composite porosity and interfacial bonding, enabling the correlation of these microstructural changes with variations in mechanical properties for both non-ceramified and ceramified composites. Ceramification induced additional microstructural changes, including the formation of voids, which influenced the composites’ mechanical properties. Additionally, the effect of integrating steel wire mesh with 6.5 mm apertures on the mechanical performance of the glass/epoxy composites, both before and after ceramification, was explored.

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引用次数: 0

Carbonation reaction of recycled concrete aggregates (RCA): CO2 mass consumption under various treatment conditions

Cleaner Materials

Pub Date : 2025-01-16 DOI: 10.1016/j.clema.2025.100296

Hossein Sousanabadi Farahani , Amin Hosseini Zadeh , Jiong Hu , Chris Hawkins , Seunghee Kim

Concrete is a key building material around the world due to its excellent strength and durability. Recycling demolished concrete for new construction materials may play a significant role in sustainable development. Producing recycled concrete aggregates (RCA) from waste concrete is one approach for such an initiative. However, using RCA may pose challenges, such as reduced density, lower elastic modulus and strength, and increased water absorption. Recently, the carbonation of RCA has emerged as a method to address those concerns. This study explores the carbon sequestration capacity of RCA through carbonation, examining various parametric conditions, including initial CO₂ pressure, relative humidity, temperature, and pre-treatment approach. Both lab-scale and large-scale carbonation tests were conducted. Additionally, a cost analysis and CO₂ footprint assessment were performed. The findings showed that applying higher initial CO₂ pressures (e.g., 40–60 psi) and optimal relative humidity (∼55 %) could significantly enhance the carbonation efficiency of RCA. Elevating temperature also led to accelerated CO₂ consumption, being more effective on the lab scale. The economic analysis presented potential cost benefits when substituting natural aggregates with CO₂-treated RCA. All in all, these results suggest that the carbonation of RCA may provide significant environmental benefits through carbon sequestration, promoting sustainable construction practices.

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引用次数: 0

Self-cleaning stone Façades using TiO2 Microwave-Synthesised Coatings

Cleaner Materials

Pub Date : 2025-01-11 DOI: 10.1016/j.clema.2025.100294

David Henriques Bento , Maria Leonor Matias , Maria Magalhães , Catarina Quitério , Ana Pimentel , Dora Sousa , Pedro Amaral , Carlos Galhano , Elvira Fortunato , Rodrigo Martins , Daniela Nunes

This study explores the development and characterization of self-cleaning coatings using titanium dioxide (TiO₂) nanoparticles for natural stone façades, particularly limestone. An energy-efficient, eco-friendly, fast (30 min), and low temperature (110 °C) microwave-assisted solvothermal method is reported for synthesising TiO₂ nanoparticles. These nanoparticles were integrated into coatings that were further applied to limestone substrates via spray-coating, maintaining the stone’s appearance while enhancing its self-cleaning properties. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), UV–VIS spectroscopy and Brunauer-Emmett-Teller (BET) surface area analysis were used to fully characterize the nanopowder. The anatase phase of TiO₂ nanoparticles and a band gap energy of about 3.24 eV were confirmed. SEM and STEM observations revealed that the nanopowder is formed by spherical particles with very fine nanocrystals highly agglomerated, however ensuing a high specific surface area of 199 m²/g. The self-cleaning properties of the coated limestone were assessed using static contact angle measurements. The results showed a significant enhancement in hydrophilicity, with the static contact angle of the coated limestone substrate reducing to nearly zero even without UV exposure, indicating complete wettability. The coating was also subjected to adhesion tests, confirming the presence of TiO₂ nanoparticles even after multiple cycles. The photocatalytic activity of the developed coating was evaluated using rhodamine B and methyl orange as model pollutants under solar radiation. The coating effectively degraded both model pollutants, and the photocatalytic cycling tests revealed a stable performance after multiple cycles. This research provides a promising approach for creating sustainable and low-maintenance building materials, contributing to preserving natural stone façades and reducing environmental impact in the construction industry.

{"title":"Self-cleaning stone Façades using TiO2 Microwave-Synthesised Coatings","authors":"David Henriques Bento , Maria Leonor Matias , Maria Magalhães , Catarina Quitério , Ana Pimentel , Dora Sousa , Pedro Amaral , Carlos Galhano , Elvira Fortunato , Rodrigo Martins , Daniela Nunes","doi":"10.1016/j.clema.2025.100294","DOIUrl":"10.1016/j.clema.2025.100294","url":null,"abstract":"<div><div>This study explores the development and characterization of self-cleaning coatings using titanium dioxide (TiO<sub>2</sub>) nanoparticles for natural stone façades, particularly limestone. An energy-efficient, eco-friendly, fast (30 min), and low temperature (110 °C) microwave-assisted solvothermal method is reported for synthesising TiO<sub>2</sub> nanoparticles. These nanoparticles were integrated into coatings that were further applied to limestone substrates via spray-coating, maintaining the stone’s appearance while enhancing its self-cleaning properties. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), UV–VIS spectroscopy and Brunauer-Emmett-Teller (BET) surface area analysis were used to fully characterize the nanopowder. The anatase phase of TiO<sub>2</sub> nanoparticles and a band gap energy of about 3.24 eV were confirmed. SEM and STEM observations revealed that the nanopowder is formed by spherical particles with very fine nanocrystals highly agglomerated, however ensuing a high specific surface area of 199 m<sup>2</sup>/g. The self-cleaning properties of the coated limestone were assessed using static contact angle measurements. The results showed a significant enhancement in hydrophilicity, with the static contact angle of the coated limestone substrate reducing to nearly zero even without UV exposure, indicating complete wettability. The coating was also subjected to adhesion tests, confirming the presence of TiO<sub>2</sub> nanoparticles even after multiple cycles. The photocatalytic activity of the developed coating was evaluated using rhodamine B and methyl orange as model pollutants under solar radiation. The coating effectively degraded both model pollutants, and the photocatalytic cycling tests revealed a stable performance after multiple cycles. This research provides a promising approach for creating sustainable and low-maintenance building materials, contributing to preserving natural stone façades and reducing environmental impact in the construction industry.</div></div>","PeriodicalId":100254,"journal":{"name":"Cleaner Materials","volume":"15 ","pages":"Article 100294"},"PeriodicalIF":0.0,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fiber-reinforced geopolymers made with recycled aggregates for screed flooring and repair applications

Cleaner Materials

Pub Date : 2025-01-08 DOI: 10.1016/j.clema.2025.100293

Joud Hwalla , Hilal El-Hassan , Joseph J. Assaad , Tamer El-Maaddawy

The increase in greenhouse gas emissions from cement production, along with limited landfill capacity for construction waste, has driven research into finding sustainable alternatives to replace cement and natural aggregates. While cement replacement with geopolymeric binders in mortar and concrete has been proven feasible, replacing natural aggregates with recycled counterparts has led to performance losses. To offset this drawback, different additives, including fibers, have been incorporated into such construction materials. This study evaluates the feasibility of using steel fiber (SF)-reinforced geopolymer (GP) composites incorporating recycled fine aggregates (RFA) for screed flooring and repair applications. GP mixes were prepared with RFA mass substitution up to 100 %, alongside SF volume of 0.5 % and 1 %. Flow values of 125 ± 25 mm were attained within 35 to 70 min. The 7-day compressive strength of GP composites reached 74.0 % to 96.2 % of their 28-day values. RFA substitution reduced compressive strength, elastic modulus, tensile strength, pull-off bond strength, and energy absorption and increased impact indentation and abrasion mass loss by up to 56, 69, 60, 23, 68, 266, and 2025 %, respectively. Conversely, SF addition improved most of these properties except for compressive and pull-off bond strength, which slightly decreased. GP composites made with 0 %, 25 %, and 50 % RFA satisfied the strength requirements for use in structural repair, while those with higher RFA replacement were suitable for non-structural use. Based on BS 8204, GP mixes were categorized as Category A screed flooring except the plain mix made with 100 % RFA, which was categorized as Category B.

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引用次数: 0