Yes / To realize the sustainable development of concrete, it is vital to mitigate its consumption and environmental footprint (especially CO2 footprint) from prolonging the service life through upgrading mechanical and durable performances of concrete. Incorporating nanofillers can effectively tailor the microstructures and performances of bulk cement paste and cement paste at interfacial transition zone in concrete. The hydrated calcium silicate (C–S–H) gels account for half of the volume of hardened Portland cement pastes, and they are the fundamental source of overall properties of concrete. However, the underlying mechanisms of nanofillers on C–S–H gels remains unclear. Herein, this paper underpinned the role of 5 types of representative nanofillers in tailoring the nanostructure of C–S–H gels in cement composites. The research results demonstrated that through the nano-core effect, nanofillers induce the formation of two new C–S–H gels in outer hydration products, namely nano-core-shell element doped low-density C–S–H (NEDLD C–S–H) and nano-core-shell element doped high-density C–S–H (NEDHD C–S–H). The indentation modulus/hardness of NEDLD and NEDHD C–S–H reaches 25.4/0.80 GPa and 46.7/2.72 GPa, respectively. Such superior performances of NEDLD and NEDHD C–S–H derive from the existence of nano-core-shell elements in C–S–H gels rather than the increase in C–S–H packing density. In a short-range, nanofillers form nano-core-shell elements by adsorbing silica tetrahedrons during the hydration process, improving the mechanical properties of C–S–H basic building blocks. In the long-range, the nano-core-shell elements modify the nano-scale performances of C–S–H gels in outer hydration products due to the increase of C–S–H gels’ integrality. / The authors would like to thank the funding offered by the National Science Foundation of China (52308236, 51978127, 51908103, and 52368031), National Key Research and Development Program of China (2018YFC070560 and 2017YFC0703410), the China Postdoctoral Science Foundation (2022M720648, 2022M710973, 2022M713497). / The full-text of this article will be released for public view at the end of the publisher embargo on 01 Dec 2024.

Using wood produced under forest management in the Amazon has been proposed as a way of preserving the ecosystem, generating jobs and to aid in climate change mitigation by using wood products as carbon stock and through CO2 uptake from the atmosphere during forest regrowth. However, the scarcity of research based on primary data of Amazonian lumber incorporated into construction can unknowingly lead to incorrect forest management and consequently forest destruction. Besides, it is necessary to verify the real environmental impacts. Two approaches were applied in this research to evaluate the wood product chain: material flow analysis and CO2 footprint calculation of managed Amazonian lumber. The research quantified the resource efficiency and CO2 footprint based on residue generation during the raw extraction in 5 forest plots in State of Pará, followed by the lumber production and the end-of-life phases, giving the CO2 balance between the emissions from residue decomposition and the CO2 uptake during forest regrowth, disregarding the energy consumption. Results indicated that the large quantities of logging residues are the main source of CO2 emissions in the material flow from selective logging, ranging from 9% to 36% of the initial forest biomass, while timber logs represented between 4% and 11%. Logging residues ranged from 2.9 t t-1 to 3.1 t t-1 per tonne of log. Combined with an average sawmill lumber yield of 54%, wastage rate values increased to between 5.7 t t-1 and 6.6 t t-1, resulting in a CO2 footprint of managed Amazonian lumber ranging between -6.6 tCO2 t-1 for reduced impact logging as carbon stock, to emissions of 6.1 tCO2 t-1 from cradle-to-gate for conventional logging. From cradle-to-grave the total CO2 footprint of lumber is estimated to range from neutral to 7.5 tCO2 t-1. Resource efficiency ranged from 13% to 15%. In this study, only the forest under reduced impact logging was able to fully recover its initial aboveground biomass, showing that in most cases regulations in the New Forest Code for Amazon forest management may not ensure sustainable logging, leading to forest destruction. Policies need to be improved and integrated with results from empirical research based on primary data to achieve sustainable exploitation of the Amazon forest. / O processo seletivo de utilização da madeira de manejo florestal na Amazônia tem sido proposto como forma de conservação e preservação do ecossistema, associada a geração de empregos e à mitigação de mudanças climáticas, pelo estoque de carbono dada a absorção de CO2 da atmosfera durante o crescimento da floresta. No entanto, a limitação de pesquisas baseadas em dados primários sobre madeiras amazônicas incorporadas na construção civil pode levar, inconscientemente, ao manejo florestal incorreto e, consequentemente, à destruição da floresta no contexto original e de reais impactos ambientais provocadas por ações inadequadas. Duas abordagens foram aplicadas nesta pesquisa para avaliar a cadeia de produtos de madeira: análise de fluxo de material e cálculo da pegada de CO2 da madeira manejada na Amazônia. A pesquisa analisou a eficiência dos recursos e a pegada de CO2 com base na geração de resíduos durante a extração em 5 florestas no Estado do Pará, produção madeireira e o fim de vida, proporcionando o balanço de CO2 entre as emissões da decomposição de resíduos e a absorção do CO2 durante a recomposição florestal, desconsiderando a energia consumida. Os resultados indicaram que o expressivo volume de resíduos florestais é a principal fonte de emissões de CO2 no fluxo de material proveniente da extração seletiva, variando de 9% a 36% da biomassa florestal inicial, enquanto os troncos de madeira representam entre 4% e 11%. Os resíduos de exploração florestal variaram de 2,9 a 3,1 t de resíduos por tonelada de tora. Combinado com um rendimento médio de madeira de serraria de 54%, os valores da taxa de desperdício aumentaram para entre 5,7 t e 6,6 t de resíduos por tonelada de tora e madeira serrada, resultando em uma pegada de CO2 variando entre -6,6 tCO2 t-1 (exploração de impacto reduzido) considerado estoque de carbono e as emissões de 6,1 tCO2 t-1 do berço à porta. No final da vida útil, estima-se que a pegada total de CO2 da madeira entre o berço e o túmulo é de neutra (exploração de impacto reduzido) a 7,5 tCO2 t-1, com uma eficiência de recursos variando de 13% a 15%. Neste estudo, apenas a floresta sob prática de extração de impacto reduzido foi capaz de recuperar totalmente sua biomassa inicial acima do solo, mostrando que as regulamentações do Novo Código Florestal para o manejo da florestal amazônica pode não garantir a sustentabilidade de uso do recurso florestal para aquela exploração que não esteja alicerçada dentro desse contexto de conservação da floresta original. As políticas precisam ser melhoradas, integradas e dinâmicas com base em resultados derivados de pesquisas empíricas baseadas em dados primários garantindo a exploração sustentável na Amazônia.

This research is an attempt to create a comprehensive assessment framework for identifying and assessing potential improvement options of cement production systems. From an environmental systems analysis perspective, this study provides both an empirical account and a methodological approach for quantifying the CO2 footprint of a cement production system. An attributional Life Cycle Assessment (LCA) is performed to analyze the CO2 footprint of several products of a cement production system in Germany which consists of three dierent plants. Based on the results of the LCA study, six key performance indicators are dened as the basis for a simplied LCA model. This model is used to quantify the CO2 footprint of dierent versions of the cement production system. In order to identify potential improvement options, a framework for Multi-Criteria Assessment (MCA) is developed. The search and classication guideline of this framework is based on the concepts of Cleaner Production, Industrial Ecology, and Industrial Symbiosis. It allows systematic identication and classication of potential improvement options. In addition, it can be used for feasibility and applicability evaluation of dierent options. This MCA is applied both on a generic level, reecting the future landscape of the industry, and on a production organization level re ecting the most applicable possibilities for change. Based on this assessment a few appropriate futureoriented scenarios for the studied cement production system are constructed. The simplied LCA model is used to quantify the CO2 footprint of the production system for each scenario. By integrating Life Cycle Assessment and Multi-Criteria Assessment approaches, this study provides a comprehensive assessment method for identifying suitable industrial developments and quantifying the CO2 footprint improvements that might be achieved by their implementation. The results of this study emphasis, although by utilizing alternative fuels and more ecient production facility, it is possible to improve the CO2 footprint of clinker, radical improvements can be achieved on the portfolio level. Compared to Portland cement, very high reduction of CO2 footprint can be achieved if clinker is replaced with low carbon alternatives, such as Granulated Blast Furnace Slag (GBFS) which are the by-products of other  industrial production. Benchmarking a cement production system by its portfolio product is therefore a more reasonable approach, compared to focusing on the performance of its clinker production. This study showed that Industrial Symbiosis, that is, over the fence initiatives for material and energy exchanges and collaboration with nontraditional partners, are relevant to cement industry. However, the contingent nature of these strategies should always be noted, because the mere exercise of such activities may not lead to a more resource ecient production system. Therefore, in search for potential improvements, it is important to keep the search horizon as wide as possible, however, assess the potential improvements in each particular case. The comprehensive framework developed and applied in this research is an attempt in this direction.

Werkstoff- und Prozessgrenzen beschränken unter Beachtung ökonomischer und ökologischer Aspekte den Leichtbau gegossener Fahrwerk-Komponenten aus Al-Si-Legierungen. Zunächst werden Bauteilgewicht und Wärmebehandlungsprozess als beeinflussbare Hauptbeitragsleister für Emissionen im Herstellprozess identifiziert. Zu deren Verringerung werden abhängig von der Belastungsart mögliche Mindestwandstärken abgeleitet, die für den Kokillenguss um 35 % reduziert werden. Dies gelingt durch Einsatz neuartiger, das Formfüllverhalten verbessernder Oberflächenstrukturierungen von Gießwerkzeugen bei Einhaltung von Konstruktionsregeln. Die Gesamtprozesszeit der Wärmebehandlung kann bei gleichbleibenden mechanischen Eigenschaften um 40 % verkürzt werden. Dabei erfolgt die Charakterisierung des Werkstoff- und Bauteilverhaltens unter dynamischer Belastung bei Parametervariation, da keine Korrelation zu den statischen mechanischen Kennwerten vorliegt.

Werkstoff- und Prozessgrenzen beschränken unter Beachtung ökonomischer und ökologischer Aspekte den Leichtbau gegossener Fahrwerk-Komponenten aus Al-Si-Legierungen. Zunächst werden Bauteilgewicht und Wärmebehandlungsprozess als beeinflussbare Hauptbeitragsleister für Emissionen im Herstellprozess identifiziert. Zu deren Verringerung werden abhängig von der Belastungsart mögliche Mindestwandstärken abgeleitet, die für den Kokillenguss um 35 % reduziert werden. Dies gelingt durch Einsatz neuartiger, das Formfüllverhalten verbessernder Oberflächenstrukturierungen von Gießwerkzeugen bei Einhaltung von Konstruktionsregeln. Die Gesamtprozesszeit der Wärmebehandlung kann bei gleichbleibenden mechanischen Eigenschaften um 40 % verkürzt werden. Dabei erfolgt die Charakterisierung des Werkstoff- und Bauteilverhaltens unter dynamischer Belastung bei Parametervariation, da keine Korrelation zu den statischen mechanischen Kennwerten vorliegt.