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Mechanical and microstructure analysis of mass-stabilized organic clay thermally cured using a ternary binder

ACTA GEOTECHNICA 2024年第2期19卷 741-762页

作者： Nunez, Victor Lotero, Andres Bastos, Cezar Augusto Sargent, Paul Consoli, Nilo Cesar Univ Fed Rio Grande do Sul Grad Program Civil Engn BR-90035190 Porto Alegre RS Brazil Univ Fed Rio Grande BR-96203295 Rio Grande RS Brazil Ulster Univ Belfast Sch Architecture & Built Environm Belfast BT15 1ED North Ireland

The technique of mass soil stabilization using alternative binders to Portland cement (PC) has been used successfully in the past. However, knowledge gaps exist regarding the design of these binders. Ground-granulated blast furnace slag (GGBS) has been widely used as a substitute for PC;however, it requires an alkaline activator (e.g. lime and PC) to promote pozzolanic reaction and strength enhancement. A candidate that presents a less energy-intensive manufacturing and carbon footprint is carbide lime (CL), a by-product of acetylene gas production, rich in Ca(OH)(2). The main problem with the pozzolanic binder in the stabilization technique is its slow reaction kinetics and the long time required for laboratory-scale investigations before in situ application. Therefore, this research presents a dosing study of a ternary binder (TB) comprising CL, GGBS and PC type III (CEM-III) to mass-stabilize a clayey organic soil using thermal curing as an innovative technique to improve the feasibility of laboratory-scale investigations. The effects of binder composition and thermal curing time on the evolution of strength, stiffness, mineralogy, and microstructure were determined. The results, supported by a statistical analysis (ANOVA) and by a multivariate regression analysis (MRA), have shown that the new TB produced a superior mechanical response to soil samples stabilized exclusively with CEM-III. This was evidenced by a less porous microstructure (more reaction products) and mainly the formation of a C-A-S-H gel, as a product of CEM-III hydration and alkaline activation of GGBS (blended cement), whereby the CL content played a key role for the development of the long-term pozzolanic reaction.

关键词： Carbide lime Ground-granulated blast furnace slag Mass stabilization Organic clayey soil Thermal curing

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Strategies for Selecting Infilled Frame Models for Seismic Performance: Meso and Macro Models 7th

Strategies for Selecting Infilled Frame Models for Seismic P...

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7th International Conference on architecture and civil Engineering, ICACE 2023

作者： Hapsari, Isyana Ratna Kristiawan, Stefanus Adi Sangadji, Senot Gan, Buntara Sthenly Doctoral Program Civil Engineering Department Faculty of Engineering Universitas Sebelas Maret Surakarta Indonesia SMARTCrete Research Group Civil Engineering Department Faculty of Engineering Universitas Sebelas Maret Surakarta Indonesia SMARTQuake Research Group Civil Engineering Department Faculty of Engineering Universitas Sebelas Maret Surakarta Indonesia Department of Architecture College of Engineering Nihon University Tokyo Japan

ISBN: (纸本)9789819707508

When laboratory testing is inconvenient, numerical modelling of infilled frames is required in order to represent the elastic and inelastic behaviour of these structures. However, the choice of model is very complex, as an infilled frame is made up of various materials such as bricks, mortar, concrete and reinforcements. The most accurate approach to modelling is a technique that is capable of representing the actual behaviour of the structure. In this study, we carry out numerical analysis and compare two modelling techniques, meso and macro modelling, in terms of the structural response produced. A meso model of an infilled frame has the advantage of capturing the detailed local behaviour of the panels, but has disadvantages such as complexity and high computational load. The accuracy of the structural response modelled with a meso approach is shown to have a similarity of 98% with the test results. In contrast, macro modelling using diagonal struts can significantly reduce the analysis time without compromising the accuracy of the results. This method can also accurately reproduce the nonlinear global structural behaviour. The disadvantage of this type of model is that the resulting structural response cannot represent the local damage to the masonry panel in detail. The similarity between the behaviour of the macro model and the experimental results is shown to be 104%. We find that a meso model of the infilled frame is more responsive to the initial variables derived from test results for the materials used in the structure. This is obvious in the initial stages of creating a meso model based on test data on masonry panels, as the structural response is much closer to the test results than that of the macro model. This may be because the geometric and mechanical behaviour of the meso model is closer to the actual conditions. The damaged states of the infilled frame based on the local behaviour in the meso model are related to the structural-nonstructural elemen

关键词： Structural frames

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Understanding the Carbonation Phenomenon of C-S-H through Layer Structure Changes and Water Exchange

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JOURNAL OF PHYSICAL CHEMISTRY C 2024年第28期128卷 11802-11816页

作者： Uno, Taiki Saeki, Naohiko Maruyama, Ippei Suda, Yuya Teramoto, Atsushi Kitagaki, Ryoma Ohkubo, Takahiro Chiba Univ Grad Sch Engn Chiba 2638522 Japan Univ Tokyo Grad Sch Engn Dept Architecture Tokyo 1138656 Japan Nagoya Univ Grad Sch Environm Studies Dept Environm Engn & Architecture Nagoya 4648601 Japan Univ Ryukyus Fac Engn Civil Engn Program Nishihara Okinawa 9030213 Japan Hiroshima Univ Grad Sch Adv Sci & Engn Dept Architecture Hiroshima 7398527 Japan Hokkaido Univ Grad Sch Engn Div Human Environm Syst Sapporo 0608628 Japan

The carbonation process of C-S-H in cement-based materials has the potential to capture carbon dioxide from the atmosphere. However, understanding this process has been hindered by the amorphous nature of C-S-H and the various pore structures that result from carbonation. To better understand this phenomenon, we have carefully synthesized and carbonated C-S-H with 100% CO2 for 24 h and then investigated it using solid-state Si-29 NMR and H-1 relaxometry under relative humidity (RH) conditions. We found that the degree of collapse and reconstruction of the silicate chain structure during carbonation strongly depends on the Ca/Si ratio of the C-S-H and the RH conditions. The polymorphism of carbonates resulting from carbonation also varies in their parameters. The collapse of the chain structure produces bridging silicate structures like amorphous glass, resulting in the development of large-sized pores filling with water. Interlayer, gel pore, and capillary pore water in C-S-H can be determined by H-1 NMR relaxometry using spin-spin relaxation time (T-2). Careful T-2 analyses of the decay data determined the T-2 and quantity of the complex pore created by carbonation. The size of the gel pore predicted from T-2 increased with higher RH. C-S-H with relatively small gel pores produced more unstable vaterite than thermodynamically stable calcite, which was linked to pore size. Carbonation experiments in an atmosphere using D2O-saturated salts directly revealed the exchange of water filled with various pores as detected by H-1 NMR. The changes in layer structure and water movement associated with carbonation discovered by a series of experiments shed light on the phenomenon of C-S-H carbonation.

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Comprehensive Geometric Modeling of the Sibayak Geothermal Field

Comprehensive Geometric Modeling of the Sibayak Geothermal F...

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2024 International Conference on Applied Sciences and Material Applications, ICASMA 2024

作者： Qarinur, M. Silitonga, E.M.R. Alvan, S. Ogata, S. Kinoshita, N. Yasuhara, H. Civil Engineering Study Program Universitas Negeri Medan Medan20221 Indonesia Construction Management Study Program Universitas Negeri Medan Medan20221 Indonesia Division of Global Architecture Graduate School of Engineering Osaka University Osaka565-0871 Japan Department of Civil and Environmental Engineering Ehime University Matsuyama790-8577 Japan Department of Urban Management Kyoto University Kyoto615-8540 Japan

Geothermal reservoirs are significant sources of renewable energy. Accurate geometric modeling of these reservoirs is essential for understanding the distribution of heat and fluid dynamics within them. This study aims to develop a geometric model of the Sibayak geothermal field using borehole data. Borehole data provide detailed geological information, which is crucial for constructing a realistic geometric model. The methodology of this research involves several key steps: the collection of borehole data from the Sibayak geothermal field, the construction of a 3D geometric model of the reservoir using COMSOL Multiphysics based on the borehole data, and the validation of the model through comparison with field data and previous research findings. The results indicate that the developed geometric model successfully identifies zones with high geothermal potential and provides an accurate depiction of the reservoir's boundaries and characteristics. Modeling the geometry of geothermal reservoirs using borehole data offers profound insights into the internal dynamics of the reservoir and can serve as a valuable tool for planning and optimizing geothermal energy exploitation. © 2024 Institute of Physics Publishing. All rights reserved.

关键词： Geothermal fields

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Slack in production planning and control: a study in the construction industry

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CONSTRUCTION MANAGEMENT AND ECONOMICS 2023年第3期41卷 256-276页

作者： Fireman, Marcus C. T. Saurin, Tarcisio Abreu Formoso, Carlos Torres Koskela, Lauri Tommelein, Iris D. Univ Fed Rio Grande do Sul Construct & Infrastruct Postgrad Program Porto Alegre RS Brazil Univ Fed Rio Grande do Sul Ind Engn Postgrad Program Porto Alegre RS Brazil Univ Huddersfield Dept Architecture & 3D Design Huddersfield W Yorkshire England Univ Calif Berkeley Civil Engn Berkeley CA 94720 USA

Although buffers of inventories, time, and capacity are commonly recommended to mitigate variability in construction, they abstract away the role played by human agency. This study argues for slack as a socio-technical complement to buffers for dealing with variability. The investigation is based on two case studies conducted in construction projects that adopted the Last Planner (R) System. Data collection focussed on understanding how slack practices and resources (SPR) were used in production planning and control, and was based on observations, analysis of documents, and interviews. Findings revealed 57 instantiations of slack practices and 8 types of slack resources. Several of these SPR diverge from what are traditionally called buffers, highlighting how the concept of SPR gives visibility to a wider range of variability coping mechanisms. Thus, it is important to make SPR explicit so that managers can reflect on why SPR are necessary, understand how they relate to each other, and assess their unintended consequences. Five propositions are presented, encompassing: how to identify SPR;the variety and general- or context-specific nature of SPR;and the value of maintaining SPR. These propositions contribute to risk management in production planning and control.

关键词： Slack buffers variability production planning and control Last Planner (R)

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Performance of Green Areas in Mitigating the Alteration of Land Surface Temperature in Urban Zones of Lima, Peru

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REMOTE SENSING 2025年第8期17卷 1323-1323页

作者： Cano, Deyvis Cacciuttolo, Carlos Rosario, Ciza Barzola, Renato Pizarro, Samuel Ramirez, Damaso W. Freitas, Marcos Bremer, Ulisses F. Univ Huanuco Acad Program Environm Engn Huanuco 10001 Peru Fed Univ Rio Grande Do Sul UFRGS Postgrad Program Remote Sensing PPGSR BR-91501970 Porto Alegre RS Brazil Catholic Univ Temuco Dept Civil Works & Geol Temuco 4780000 Chile Univ Huanuco Acad Program Architecture Huanuco 10001 Peru Univ Nacl Toribio Rodriguez Mendoza Amazonas Ctr Invest Geomatica Ambiental CIGA Inst Invest Desarrollo Sustentable Ceja Selva INDE Chachapoyas 01001 Peru Univ Cient Sur Fac Ciencias Ambientales Ave Antigua Carretera PanamericanaKm 19 Villa Sal Lima 15842 Peru

Urbanization in large cities has altered the urban thermal balance, creating urban heat islands. In this context, green areas are crucial in regulating the urban climate. This study uses remote sensing data to evaluate their performance using the fractional vegetation cover (FVC) and its impact on land surface temperature (LST) in Metropolitan Lima, Peru, between 1986 and 2024. The spatial and temporal relationship between FVC and LST is analyzed, and districts are classified based on their effectiveness in thermal regulation. The Mann-Kendall test was applied to identify trends along with a Spearman correlation analysis and a clustering analysis to group districts according to the cooling effectiveness of their urban green areas. The results show that urban expansion has increased LST by an average of 6.43 degrees C since 1990, and there is a significant negative correlation (p < 0.001) between FVC and LST, indicating positive impacts of vegetation regulating LST at a spatial level. However, it does not reduce LST at a temporal level. This suggests that, while effective locally, green areas are insufficient to counteract the overall warming of LST over time. Based on FVC and LST characteristics, the districts have been classified into four groups: those with well-preserved green areas, such as La Molina and San Isidro, which have a lower LST, compared to areas where urbanization has replaced vegetation, such as Carabayllo and Lurigancho (Chosica). Finally, this study highlights the importance of integrating green area management into urban planning to mitigate urban warming and promote sustainable development.

关键词： remote sensing urban thermal environment spatial correlation climate change sustainable development urban heat islands trend Mann-Kendall

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Leaching behavior of sustainable concrete made with coal ash wastes as replacement of cement and sand

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Environmental Science and Pollution Research 2024年第52期31卷 61437-61450页

作者： Rafieizonooz, Mahdi Kim, Jang-Ho Jay Khankhaje, Elnaz Rezania, Shahabaldin School of Civil and Environmental Engineering Yonsei University Yonsei-Ro 50 Seodaemun-Gu Seoul03722 Korea Republic of Architectural Engineering Program School of Architecture Seoul National University of Science and Technology 232 Gongneung-Ro Gongneung-Dong Nowon-Gu Seoul01811 Korea Republic of Department of Environment and Energy Sejong University Seoul05006 Korea Republic of

The coal-fired power plant fly ash (FA) and bottom ash (BA) are gradually used as alternative materials in the concrete. However, knowledge of the leaching characteristics of using both incinerator ashes in concrete production is lacking. This work aimed to evaluate the leaching behavior of the FA and BA used in concrete production by employing batch and tank leaching tests. The outcomes of both leaching tests showed that there was no considerable leaching of any trace elements to the environment, and it remains much lower than standard limitations for utilization as construction materials. The results of cumulative mass discharge showed that the slope of flux time for all elements was less than 0.4 and because of that, primary surface wash-off was the main discharge process of all the heavy metals. Strength test results revealed that there was not much difference between coal ash concrete (CAC) and the control mix at the initial age of curing time. Despite that, at a long period of curing time (180 days), the compressive strength of CAC containing 20% FA as cement replacement and 100% BA as fine aggregate replacement increased by 76% due to the pozzolanic reaction of BA and FA in comparison to the normal concrete, while, due to the high porosity of BA, the workability of CAC decreased by 50%. The outcomes of the current work revealed that the combined use of FA and BA can be counted as a promising alternative in the production of sustainable concrete for structural applications toward sustainable development. Graphical abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.

关键词： Trace elements

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Pyrolysis: a promising technology for agricultural waste conversion into value-added products

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ENVIRONMENT DEVELOPMENT AND SUSTAINABILITY 2024年 1-35页

作者： Ferrari, Valdecir Nazari, Mateus Torres da Silva, Nathalia Favarin Crestani, Larissa Raymundo, Lucas Manique Dotto, Guilherme Luiz Piccin, Jeferson Steffanello Oliveira, Luis Felipe Silva Bernardes, Andrea Moura Fed Univ Rio Grande Do Sul UFRGS Grad Program Met Mat & Min Engn PPG3M Porto Alegre Rio Grande do S Brazil Univ Passo Fundo UPF Fac Engn & Architecture FEAR Grad Program Civil & Environm Engn PPGEng Passo Fundo RS Brazil Fed Univ St Maria UFSM Grad Program Chem Engn PPGEQ Santa Maria RS Brazil Fed Univ Rio Grande Do Sul UFRGS Grad Program Chem Engn Porto Alegre RS Brazil Univ Costa Calle 58 55-66 Barranquilla 080002 Atlantico Colombia

Agricultural waste management poses a significant challenge due to increasing generation rate of this residue, necessitating the development of solutions to minimize various problems in this context. Among the potential possibilities, pyrolysis stands out as a promising technology due to its low operational costs, simplicity of operation, and the production of several value-added products, including solids (biochar), liquids (pyroligneous extracts: pyroligneous acid and bio-oil), and gaseous (non-condensable gases). This work aimed to synthesize the recent advances and potential uses for the products obtained from the pyrolysis of agricultural wastes, with a particular focus on the emerging applications of the liquid fraction. To achieve the purpose of this review, a bibliographic portfolio was created using a state-of-the-art approach, utilizing Scopus as the database. The yields and uses of pyrolysis products vary according to operational parameters, such as temperature, heating rate, residence time, reactor, agro-waste characteristics, and others. These products have diverse potential applications, including environmental uses (soil remediation, wastewater treatment, and bioenergy), pharmaceutical purposes (antimicrobials, antioxidants, anti-inflammatories), food industry uses (preservatives and smoke flavor), and applications in agriculture and livestock (plant growth promotion, pest and disease control, feed additive, and soil conditioner). Therefore, pyrolysis is a promising technology for the valorization of agricultural wastes, promoting various aspects of the circular economy and providing a sustainable solution to obtain several value-added products with diverse applications from this thermochemical conversion process.

关键词： Biochar Bio-oil Wood vinegar Pyroligneous acid Syngas Waste valorization

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Unveiling the Formation Pathway of Vaterite from Amorphous Calcium Carbonate Using Metadynamics Simulations

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ACS OMEGA 2025年第17期10卷 17948-17959页

作者： Saito, Takumi Maruyama, Ippei Suda, Yuya Teramoto, Atsushi Kitagaki, Ryoma Ohkubo, Takahiro Chiba Univ Grad Sch Engn Chiba 2638522 Japan Univ Tokyo Grad Sch Engn Dept Architecture Tokyo 1138656 Japan Nagoya Univ Grad Sch Environm Studies Dept Environm Engn & Architecture Nagoya 4648601 Japan Univ Ryukyus Fac Engn Civil Engn Program Nishihara Okinawa 9030213 Japan Hiroshima Univ Grad Sch Adv Sci & Engn Dept Architecture Hiroshima 7398527 Japan Hokkaido Univ Grad Sch Engn Div Human Environm Syst Sapporo 0608628 Japan

Calcium carbonate is a compound that is widely distributed throughout the Earth as a natural mineral and a material produced by biological activities. The crystal structure of calcium carbonate has three polymorphs: the most thermodynamically stable calcite, followed by aragonite and vaterite. Of the three crystalline phases, the formation process and structure of the most unstable, vaterite, remain mysterious. In this study, the pathway for forming the vaterite crystal structure from amorphous CaCO3 (ACC) is reproduced using well-tempered metadynamics molecular dynamics simulations. The structures sampled at multiple minima on the energy landscape are refined through first-principles calculations based on density functional theory. The sampled structures are assigned space groups and classified as calcite- and vaterite-like structures according to the arrangement of CO3 2- and Ca2+ sheets. The initial crystal structure produced from ACC is a monoclinic crystal with Ca2+ sheets and CO3 2- lying in the interlayer;however, it does not exhibit the 3-fold symmetry of calcite. Calcite structures with 3-fold symmetry, or orthorhombic crystals with rotated CO3 2- units, as found in vaterite, can be derived from this structure. The orthorhombic structure then transitions to the more stable monoclinic form, which is likely vaterite. The understanding of phase transitions based on the diverse crystal structures of calcium carbonate revealed in this study provides a predictive view of biomineralization and carbonation reactions of cementitious materials.

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Introducing reservoir sustainability indexing to investigate reservoir operations and piloting it at the basin of Lake Urmia with sparse data

ENVIRONMENTAL AND SUSTAINABILITY INDICATORS

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ENVIRONMENTAL AND SUSTAINABILITY INDICATORS 2025年 25卷

作者： Sadeghfam, Sina Fahmfam, Navid Khatibi, Rahman Crookston, Brian Mark Vadiati, Meysam Moazamnia, Marjan Univ Maragheh Fac Engn Dept Civil Engn Maragheh East Azerbaijan Iran Azerbaijan Architecture & Construct Univ 5 Ayna Sultanova St AZ-1073 Baku Azerbaijan Utah State Univ Dept Civil & Environm Engn Utah Water Res Lab Logan UT USA Univ Calif Davis Hubert H Humphrey Fellowship Program Global Affairs Davis CA USA Univ Bonab Fac Engn Dept Civil Engn Bonab East Azerbaijan Iran

Reservoir sustainability indexing/estimation is introduced in this paper, capable of handling sparse data. It innovates by interconnecting a set of three variables: estimating Environmental Water Requirements (EWRs) by conceptual rules;estimating Reliability, Resilience and Vulnerability (RRV) criteria by using EWRs;and thereby calculating Sustainability Indexes (SI), which are either satisfactory or unsatisfactory. These together transform reservoir studies into an innovative capability, implemented by a strategy at three levels: Level 1 scopes critically the research direction setting up a rule engine. Level 2 calculates the EWRs, RRV and SI metrics. Level 3 addresses the defensibility of the results. The capability is piloted on 9 major reservoirs with available data out of 44 in the basin of Lake Urmia for a proof-of-concept. The subsequent knowledge discovery uncovers that: (i) Of 5.3 Billion Cubic Metres (BCM/Annum) lake inflows, 3.1 BCM/annum is required to maintain the lake, but cut off unwarrantedly, instigated the catastrophe. (ii) SI-values verify that the basin is fragile against unwarranted operations;conversely, evidence is given that restoring Lake Urmia is feasible by overhauling reservoir management. (iii) The emerging retrospective explanation is that reservoir operations are the single root cause instigating the catastrophic disappearance of Lake Urmia.

关键词： Environmental flows Lake vulnerability Mismanagement and desiccation of salt lakes Restoration of lake Urmia

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