Cleaner Engineering and Technology最新文献

In today's age, finding harmony between construction endeavors and safeguarding the environment is of utmost importance. Consequently, there is a substantial requirement to explore the feasibility of utilizing waste materials as a replacement for traditional construction substances. Unfortunately, there is a lack of information regarding the possibilities of incorporating recycled glass, rice husk, and sugarcane bagasse ash into concrete production. This study investigated the viability of integrating recycled glass fibres and agricultural waste ash into concrete to bolster its strength and sustainability. When evaluating mechanical and durability properties across five mixtures, the concrete formulations ranged in fibre content percentages from 1% to 3% and in ash content percentages from 10% to 20%. Specifically, Mixtures 1, 2, 3, 4, and 5 contained 1% fibre and 10% ash, 2% fibre and 15% ash, 2.5% fibre and 20% ash, 3% fibre and 12% ash, and 1.5% fibre and 18% ash respectively. Mixture 2 and Mixture 5, boasting heightened fibre and ash content, showcased outstanding compressive strength at 38.5 MPa and 37.2 MPa, respectively, indicating a positive correlation between these materials and concrete strength. Conversely, Mixture 3, burdened with excessive fibre and ash content, witnessed diminished strength, underscoring the necessity for meticulous optimization. In terms of tensile and flexural strength, Mixture 2 and Mixture 5 displayed commendable performance, while Mixture 3 suffered setbacks from excessive content. Durability assessments unveiled Mixture 1 and Mixture 4's superior freeze-thaw resistance, with minimal mass loss (1.5% and 1.8%, respectively) and no visible damage, rendering them favorable choices for sustainable construction. Contrastingly, Mixture 3 exhibited poorer freeze-thaw resistance and higher environmental impact, highlighting the need for careful consideration in material selection. Overall, this study underscores the importance of optimizing concrete formulations through the integration of recycled materials, paving the way for stronger, more durable, and environmentally friendly construction practices.

Permeable pavement is an environmentally beneficial material that can ease urban problems and mitigate the effects of climate change, such as flooding, urban heat islands, and groundwater decrease. However, it is susceptible to clogging, has limited strength, and demands frequent maintenance. To overcome these problems, an untraditional fiber-reinforced permeable pavement with a low tortuosity pore structure that has an excellent infiltration rate and strength while being resistant to clogging has been studied in this research. Straight pore channels of various sizes and quantities were introduced into self-compacting concrete to create this permeable pavement. High-strength pervious pavement (HSP) samples with porosity ranging from 3.60 to 8.30% and 0–0.2% fiber content were tested. In all cases, HSP showed high infiltration rate (>1 cm/s), high compressive strength (>27 MPa) and tensile strength (1.5 MPa), low mass loss in potential resistance to degradation by impact and abrasion (>25%). However, it did not clog despite extensive cyclic exposure to flow containing sand, clay, and combined ‘sand & clay’. PP fiber content of 0.1%. The 3.60% porosity was found to be optimum considering all properties, whereas 8.30% porosity gave a higher infiltration rate with compromised properties. This permeable pavement can maintain sufficient porosity and permeability for stormwater infiltration without frequent maintenance. Adding polypropylene fiber reduces compressive strength marginally but increases split tensile strength, degradation and potential resistance. This novel fiber-reinforced HSP has the potential to expand the material's applicability. The results obtained from this research are expected to lead the way for a broader application of HSP in various contexts and initiatives that were not previously considered appropriate. This will eventually enhance the design and implementation of a new generation of flood-resistant infrastructure and significantly improve the ability to mitigate urban floods.

This study evaluated the potential of sugarcane bagasse fly ash, collected from boiler exhaust stacks via a bypass pipe, as a renewable supplementary cementitious material. The bagasse fly ash was ground into three different particle sizes (D₅₀ of 10, 20, and 30 μm) and characterized in terms of morphology, porosity, specific surface area, and pozzolanic activity. The influence of the ashes on paste hydration was investigated using isothermal calorimetry. Mortars were then tested with 20% cement replacement by fly ash, analyzing packing density, compressive strength evolution, and durability against sulfuric acid. Results indicated the suitability of the fly ash as a supplementary cementitious material, with low contamination and greater pozzolanic activity at smaller particle sizes. This enhanced initial hydration and long-term strength, with finer ashes showing superior mechanical properties when compared to the reference mortar (an 8% increase). Mortars with fly ash exhibited higher packing density and reduced mass loss under sulfuric acid attack, but increased water absorption and capillarity, alongside decreased compressive strength compared to the reference. Briefly, the findings highlighted that the potential of bagasse fly ash as a promising low cost and eco-beneficial material for sustainable construction practices.

This research explores the usage of sustainability in literature and presents ‘three environments’ for addressing sustainability in the Civil and Construction Engineering (CCE) disciplines. Scholars have increasingly studied sustainability and sustainable development across CCE disciplines as the importance of sustainability awareness and action in society has increased. However, the vastness of its conceptual breadth and depth in CCE research is difficult to holistically evaluate. As a result, CCE researchers often focus on specific aspects of sustainability applied to discrete contexts, or address sustainability in broad aspirational terms and guiding motivations. This research utilized a rigorous analytical corpus linguistics approach for investigating CCE-based research published between 1989 and 2021 to capture a full view of the academic discourse surrounding sustainability in CCE. The research employed collocational network analysis to enable an expansive and comprehensive study of the concept of sustainability and how it is addressed by CCE researchers. The authors created a 25,920,583-word corpus from papers published in top CCE journals related to sustainability. Significant collocates of the word sustainability were then identified using collocational analysis, and their relationships mapped through collocational network analysis to uncover dominant research areas in CCE. Observations from over 30 years of sustainability research suggests that the CCE disciplines have largely anchored to generalized notions of sustainability, such as ‘the three pillars of sustainability.’ However, deeper analysis provides a more nuanced view. We propose an alternate paradigm of three interconnected environments where CCE professionals operate, highlight criteria for decision-making, and identify primary actions for sustainability.

Lithium, a vital element in lithium-ion batteries, is pivotal in the global shift towards cleaner energy and electric mobility. The relentless demand for lithium-ion batteries necessitates an in-depth exploration of lithium extraction methods. This literature review delves into the historical evolution, contemporary practices, and emerging technologies of lithium extraction. It scrutinizes environmental and economic impacts, identifies research gaps, and underscores sustainable extraction’s imperative. It examines conventional methods like spodumene mining and brine extraction, highlighting their advantages and challenges. Emerging technologies, particularly Direct Lithium Extraction (DLE) and geothermal brine recovery, are evaluated for their potential to revolutionize the industry. Environmental considerations, including water usage, chemical disposal, and habitat disruption, are assessed alongside economic implications. The review also identifies critical research gaps, beckoning the scientific community to develop solutions that meet lithium’s surging demand while safeguarding the environment. In conclusion, this literature review emphasizes the need for sustainable lithium extraction to facilitate a future powered by cleaner energy sources and sustainable transportation.

The relatively high concentration of thorium and uranium in monazite poses significant environmental issues in the extraction process of rare earth elements from monazite if left untreated. A new process route that recovers both thorium and uranium as oxides has been proposed, and an analysis of its economic feasibility is presented in the current paper, based on analysis and processing of a Korean monazite sample. Comparative evaluations with existing acidic and alkaline routes have also been carried out. It was estimated that the largest proportion of the operational cost for the new process related to the materials and reagent costs. Sensitivity analysis predicted that the value of neodymium oxide followed by Heavy Rare Earth Oxides (HREO) and praseodymium oxide affect the revenue significantly. Increasing the average basket price of the total rare earths oxide by 1.5 times would result in revenues of US$158.8 million/year for the proposed route, compared to US$161.5 and US$156.3 million/year for the alkaline and acidic routes, respectively. The discounted cash flow analysis and the resulted Net Present Value (NPV) suggested that the proposed processing route was in fact the only process estimated to be economically feasible with the payback period expected to be around 4.5 years. The sale of thorium oxide and uranium oxide by-products of the proposed route contributed to the positive discounted NPV. It was also estimated that a minimum sale price of US$20/kg total rare earth oxide is required to ensure all the processes generate a positive discounted NPV. These results shown that the proposed new processing route is estimated to be economically feasible.

Direct air capture (DAC) is a promising technology that can help to remove carbon dioxide (CO₂) from the air. One application of DAC is indoor CO₂ direct air capture (iCO₂-DAC). A wide range of materials with unique properties for CO₂ capture have been investigated, including porous materials, zeolites, and metal-organic frameworks. The selection of suitable materials for iCO₂-DAC depends on several factors, such as cost, CO₂ adsorption capacity, and stability. The development of new materials with improved properties for iCO₂-DAC is an active research area. The captured CO₂ can serve as a renewable carbon source to produce biofuels for internal use (e.g., for heating purposes), decreasing the environmental impact of buildings. This review article highlights the importance of iCO₂-DAC to improve indoor air quality in buildings and boost the circular economy. We discuss the available carbon capture technologies and materials, discussing their properties and focusing on those potentially applicable to indoor environments. We also provide a hypothetic scenario where CO₂ is captured from different indoor environments and transformed into sustainable fuels by using an emerging carbon capture and utilization technology (microbial electrosynthesis). Finally, we evaluate the economic feasibility of such an innovative approach in comparison to the use of traditional, fossil-based fuels.

The pursuit of sustainable and eco-friendly materials has fuelled research into enhancing composite materials using bio fillers derived from renewable sources. This study investigates the incorporation of bio filler - biochar produced from cashew nut shell, in hemp fibre composite to achieve a balance between performance and environmental sustainability. Hemp fibre composites were fabricated with four different weight percentages of biochar such as 5, 10, 15, and 20 wt%. Hemp fibre composites with biochar showed enhanced mechanical strength and water resistance when compared to composite without biochar. The composites containing 10 wt% biochar added showed the maximum tensile, impact, and hardness, ca. 94%, ca. 38%, and ca. 7% increase compared to composite without biochar, respectively. The highest flexural strength (ca. 71 MPa) was observed at a biochar addition of 15 wt%. The integration of biochar improved the filler-matrix interaction by enhancing adhesion, creating effective stress transfer within the vinyl ester matrix, thereby reinforcing the composite's structural integrity. In the water absorption test, the biochar acted as barrier to the water molecules and reduced the water absorption by ca. 32–63%. These findings highlight the potential of biochar-based fillers in advancing the field of composite materials, providing a more nuanced understanding of their applications in addressing both environmental concerns and bio waste accumulation.

The shells of molluscs are a common by-product of the aquaculture industry, and their management represents a significant environmental challenge. Although mollusc farming is considered a low-impact food production, improper shell management could make bivalve farming less environmentally efficient. To address this issue, research is exploring new approaches to reduce waste accumulation and convert shell waste into a valuable resource. The shells of bivalves are functional materials from biological waste, composed mainly of CaCO₃, and can be used as secondary raw materials in various applications. In order to meet the demanding environmental target, the road sector is increasing the use of recycled materials in new construction or maintenance of old ones. The present work illustrates the results of several laboratory tests carried out to determine the physical and chemical properties of three different crushed bivalve shells waste for the application as filler in asphalt concretes. The present study highlighted the similarity of these materials with the limestone filler since no significant discrepancy between the mechanical (or technical) performance of the biofiller and the traditional limestone filler are detected through the test carried out, promoting their use in new asphalt concrete mixtures.

Productive use of energy is recognized as a pathway to economic and sustainable development. Indeed, there has been deliberate effort to promote productive use of energy, particularly, electricity by policy makers and international organizations. However, limited understanding of what constitutes productive use and factors that potentially influence uptake of productive uses at micro level continue to undermine existing efforts to promote productive use of energy in developing countries. Using a systematic literature review approach, a total of 54 out of 997 articles were selected following the criteria for inclusion and exclusion for further analysis. We find that majority of studies define productive use of electricity as application of electricity energy services to activities that generate income or enhance productivity. Regarding conceptualization, we found that productive use of electricity is conceptualized along three dimensions, which are (1) improved performance of existing income generating activities, (2) use of modern electrical productive use appliances and (3) creation of new enterprises and job opportunities after electrification. Furthermore, the review found that majority of studies identify electricity related factors as important drivers of productive use of electricity. However, these should be bundled with other non-electricity related variables including financial, technological, human capabilities, institutional, infrastructural, social, demographic characteristics. The paper has also identified various research gaps that may inform future studies in productive use of electricity.