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Rheology and 3D printing of alginate bio-stabilized earth concrete

CEMENT AND CONCRETE RESEARCH 2024年 175卷

作者： Maierdan, Yierfan Armistead, Samuel J. Mikofsky, Rebecca A. Huang, Qiqi Ben-Alon, Lola Srubar III, Wil V. Kawashima, Shiho Columbia Univ Dept Civil Engn & Engn Mech New York NY 10027 USA Columbia Univ Grad Sch Architecture Planning & Preservat New York NY 10027 USA Univ Colorado Dept Civil Environm & Architectural Engn Boulder CO USA Univ Colorado Mat Sci & Engn Program Boulder CO USA

Driven by the need for sustainable construction solutions, there is renewed interest in earth-based materials. Biopolymer stabilizers can enhance the rheological and structural properties of these materials to facilitate their use in 3D printing. This research examined the influence of sodium alginate on the stability, particle interaction, rheology, and 3D printability of kaolinite, a commonly found clay in soils deemed suitable for construction. Findings revealed that sodium alginate could boost electrostatic interactions to enhance the stability of kaolinite suspensions. This rise in repulsive potential energy could reduce storage modulus and yield stress by orders of magnitude. However, as the alginate content increased beyond its critical overlapping concentration (0.12 %- 0.6 %), a reverse trend was observed, which was attributed to the formation of a three-dimensional polymer network. Furthermore, alginate addition shifted the "printability window" of kaolinite mixtures to higher solid contents, which has positive implications on the strength and shrinkage of the printable mixtures.

关键词： Kaolinite Soil Biopolymer Microstructural analysis Additive manufacturing

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A review of utilization of industrial waste materials as cement replacement in pervious concrete: An alternative approach to sustainable pervious concrete production

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HELIYON 2024年第4期10卷 e26188页

作者： Khankhaje, Elnaz Kim, Taehoon Jang, Hyounseung Kim, Chang-Soo Kim, Jimin Rafieizonooz, Mahdi Seoul Natl Univ Sci & Technol Sch Architecture Architectural Engn Program 232 Gongreung Ro Seoul 01811 South Korea Yonsei Univ Sch Civil & Environm Engn Yonsei Ro 50 Seoul 03722 South Korea

Around 8% of the global carbon dioxide emissions, are generated during cement manufacturing, which also involves significant use of raw materials, leading to adverse environmental effects. Consequently, extensive research is being conducted worldwide to explore the feasibility of utilizing different industrial waste by-products as alternatives to cement in concrete production. Fly ash (FA), Metakaolin (MK), Silica fume (SF), and ground granulated blast furnace slag (GGBS) are potential industrial materials that can serve as cement substitutes in pervious concrete. However, there exist conflicting findings in the literature regarding the impact of industrial supplementary cementitious materials (ISCMs) as partial cement replacements on the physical, mechanical, and durability properties of pervious concrete. The aim of this review is to investigate the feasibility and potential benefits of using ISCMs and compare them as partial cement replacements in the production of pervious concrete. The analysis primarily examines the effect of ISCMs as partial cement replacements on cementitious properties, including properties of ISMCs, mechanical properties, and durability of pervious concrete. The influence of ISCMs primarily stems from their pozzolanic reaction and filler characteristics. SF has the highest reactivity due to its high surface area and amorphous structure, resulting in a rapid pozzolanic reaction. GGBS and FA have moderate reactivity, while MK has relatively low reactivity due to its crystalline structure. Results from various studies indicate that the addition of FA, SF, and MK up to approximately 20% leads to a reduction in porosity and permeability while improving compressive strength and durability due to the filler effect of SF and MK. Incorporating GGBS increases permeability slightly while causing a slight decrease in compressive strength. The range of permeability and compressive strength for pervious concrete incorporating FA, SF, GGBS and MK were 0.

关键词： Pervious concrete Industrial supplementary cementitious materials Mechanical properties Durability Silica fume Fly ash Metakaolin Slag Waste management

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Normal tensile bond behaviour of CFRP-epoxy laminate to concrete and steel

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INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES 2024年 132卷

作者： Jati, Dinar Gumilang Purnomo, Joko Gan, Buntara S. Leksono, Lintang B. Han, Ay Lie Univ Atma Jaya Yogyakarta Fac Engn Dept Civil Engn Yogyakarta 55281 Indonesia Petra Christian Univ Surabaya Indonesia Nihon Univ Coll Engn Dept Architecture Koriyama 9638642 Japan Univ Diponegoro Fac Engn Dept Civil Engn Semarang 50275 Indonesia Univ Diponegoro World Class Res Program Semarang 50275 Indonesia

The effectiveness of CFRP sheets as external concrete reinforcement is determined by the CFRP-concrete bond behaviour. In this study the normal tensile bond of CFRP-epoxy laminate was assessed through the behaviour of the CFRP-concrete, and CFRP-steel bond. A pull -off apparatus combined with a newly introduced method using a clip -on displacement transducer was employed. The specimen was a field-impregnated single CFRP sheet attached to concrete and steel. The contribution of the epoxy was tested individually. The load-displacement behaviour, the ultimate strength, failure mode and the individual component 's contribution to the CFRP bond, were analysed. The study concluded that for a concrete compression strength as high as 50 MPa the failure was designated by concrete rupture. For the CFRP-steel specimens, the failure was distinguished as adhesive interface failure or CFRP failure, influenced by the degree of epoxy impregnation and steel surface preparation. The load-displacement behaviour of the CFRP-concrete, CFRP-steel and epoxy were characterized by nonlinearity with no post peak. The presence of CFRP sheets enhanced the stiffness of the individual epoxy. The presence of CFRP-epoxy has a negative affected to the normal tensile stiffness of concrete, but postponed the load levels at which first concrete cracking occur, regardless the concrete compression strength.

关键词： CFRP Tensile bond Epoxy Concrete Load-displacement

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Geopolymer Haunch Beam-Column Connection Behavior

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ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2023年第10期48卷 13633-13648页

作者： Purwanto, Purwanto Ekaputri, Januarti Jaya Nuroji, Nuroji Indriyantho, Bobby Rio Gan, Buntara Sthenly Han, Ay Lie Univ Diponegoro Fac Engn Dept Civil Engn Semarang Indonesia Inst Teknol Sepuluh Nopember Fac Civil Planning & Geo Engn Dept Civil Engn Surabaya Indonesia Nihon Univ Coll Engn Dept Architecture Koriyama Japan Univ Diponegoro World Class Res Program Semarang Indonesia

A haunch system improves the performance of a beam-to-column structure, in combination with a geopolymer haunch, the green-concrete concept is supported by reducing the Portland cement use. The energy dissipation, load-deformation behavior, failure mode, residual deformation, and plastic hinge formation under a loading-unloading scheme were studied based on experimental full-scale specimens. The responses of the loading-unloading protocol were compared to the monotonic loading results. A geopolymer and conventional concrete haunch having similar compressive strengths were analyzed. It was shown that the geopolymer haunch performed excellently and that a concrete haunch remarkably improves the performance of a structure regardless of the haunch material. The geopolymer haunch enhanced the load level at first cracking for 10%, and the formation of plastic hinges 0.7% and 4.5% for the monotonic and loading-unloading, respectively, but slightly reduced the ultimate load by 1%. The loading-unloading protocol had a negative impact of 3% to 7% on the overall performance, the reduction was lower for the geopolymer haunch underlining the superiority of this material. The loading-unloading scheme resulted in a monotonic strength degradation and deviation in failure mode. A finite element model was constructed to generate and analyze the relation of the haunch's concrete strength to the load-deformation response. It was found that the haunch's compressive strength had no influence on the behavior of the beam-to-column joint, even for a haunch with a compressive strength as low as 25 MPa.

关键词： Beam-to-column joint Concrete strength Finite element model Geopolymer haunch Loading-unloading

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The role of foreign ions in Portland cement production and properties: A state-of-the-art review on phase formation, polymorphism and hydration

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CEMENT & CONCRETE COMPOSITES 2025年 159卷

作者： Carvalho, Ivo C. Neto, Jose S. Andrade Matos, Paulo R. Lothenbach, Barbara Kirchheim, Ana P. Univ Fed Rio Grande do Sul NORIE UFRGS Dept Civil Engn Postgrad Program Civil Engn Construction & Infrast Porto Alegre Brazil Univ Estado Santa Catarina UDESC Dept Architecture & Urbanism Laguna SC Brazil Santa Catarina State Univ UDESC Ctr Technol Sci CCT Dept Civil Engn Joinville Brazil Empa Swiss Fed Labs Mat Sci & Technol Concrete & Asphalt Lab Dubendorf Switzerland

Adopting alternative raw materials and fuels has significantly increased in the last few years. This practice introduces minor constituents (or foreign ions) into cement kilns, influencing the synthesis process and subsequent clinker/cement properties. This paper examined the impact of zinc, titanium, phosphorus, fluorine, and copper on clinker/cement characteristics, focusing on phase formation, polymorphism, and hydration behavior. These constituents often serve as mineralizers or fluxes, modifying melting temperatures and viscosity of the melt in kilns and/or altering clinker mineralogy. A general trend of hydration retardation was identified in the presence of these minor constituents, with threshold incorporation levels underlined. Gaps in the current knowledge were identified, such as the effect of foreign ions in polymorphism, especially C3A. By synthesizing current research, this work provides valuable insights for the cement industry and the academy. Moreover, it proposes research directions to further understand the effects of co-processing and minor constituents on cement production.

关键词： Cement Foreign ions Co-processing Hydration Polymorphs

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Digital Twin Based on CFD Modelling for Analysis of Two-Phase Flows During Pipeline Filling-Emptying Procedures

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APPLIED SCIENCES-BASEL 2025年第5期15卷 2643-2643页

作者： Paternina-Verona, Duban A. Coronado-Hernandez, Oscar E. Fuertes-Miquel, Vicente S. Saba, Manuel Ramos, Helena M. Univ Sinu Sch Civil Engn Cartagena 130014 Colombia Univ Tecnol Bolivar Fac Ingn Cartagena 130001 Colombia Univ Cartagena Inst Hidraul & Saneamiento Ambiental Cartagena 130001 Colombia Univ Politecn Valencia Dept Ingn Hidraul & Medio Ambiente Valencia 46022 Spain Univ Cartagena Civil Engn Program Cartagena 130001 Colombia Univ Lisbon Civil Engn Architecture & Environm Dept CERIS Inst Super Tecn P-1049001 Lisbon Portugal

Pipeline filling and emptying are critical hydraulic procedures involving transient two-phase air-water interactions, which can cause pressure surges and structural risks. Traditional Digital Twin models rely on one-dimensional (1D) approaches, which cannot capture air-water interactions. This study integrates Computational Fluid Dynamics (CFD) models into a Digital Twin framework for improved predictive analysis. A CFD-based Digital Twin is developed and validated using real-time pressure measurements, incorporating 2D and 3D CFD models, mesh sensitivity analysis, and calibration procedures. Key contributions include a CFD-driven Digital Twin for real-time monitoring and machine learning (ML) techniques to optimise pressure surges. ML models trained with experimental and CFD data reduce reliance on computationally expensive CFD simulations. Among the 31 algorithms tested, decision trees, efficient linear models, and ensemble classifiers achieved 100% accuracy for filling processes, while k-Nearest Neighbours (KNN) provided 97.2% accuracy for emptying processes. These models effectively predict hazardous pressure peaks and vacuum conditions, confirming their reliability in optimising pipeline operations while significantly reducing computational time.

关键词： Computational Fluid Dynamics (CFD) Digital Twin (DT) two-dimensional (2D) models three-dimensional (3D) models two-phase flows Machine Learning (ML) hydraulic transients

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Mix design strategies for 3D printable bio-based cementitious composites using rice husk particles as multifunctional aggregates

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JOURNAL OF BUILDING ENGINEERING 2025年 100卷

作者： Tinoco, Matheus P. Cavalcante, Tiago C. de Andrade, Luiza D. de Araujo, Olga M. O. Lopes, Ricardo Tadeu Toledo Filho, Romildo D. Reales, Oscar A. Mendoza Univ Fed Rio de Janeiro Civil Engn Program BR-21941611 Rio De Janeiro RJ Brazil Univ Fed Rio de Janeiro Fac Architecture & Urbanism BR-21941901 Rio De Janeiro RJ Brazil Univ Fed Rio De Janeiro Nucl Engn Program Nucl Instrumentat Lab BR-21941611 Rio De Janeiro RJ Brazil

This work compares two mix design strategies for 3D printable cementitious composites using rice husk particles as multifunctional aggregates. The first strategy involves directly replacing sand with rice husk while keeping the cement paste volume constant. The second strategy introduces rice husk as an extra component, thereby increasing the solids content while maintaining a constant sand-to-cement ratio. Different volume fractions of rice husk (10 %, 15 %, 20 %, and 25 %) were used. Replacing natural sand with 15 % bio-aggregates leads to a 53 % decrease in yield stress and a 62 % decrease in structuration rate, due to the lubricating effect of pre-wetted bioaggregates and a decrease in system interlock. Adding rice husk as extra component, however, increases both yield stress and structuration rate, which is related to the reduced paste volume and increase in internal friction. With 25 % rice husk, the initial yield stress increases from 1.21 kPa to 5.55 kPa, and the structuration rate increases from 26.9 Pa/min to 105.2 Pa/min. The second strategy effectively improved buildability and reduced cement consumption, making it the most suitable choice for producing printable mixtures. Mechanical tests indicate that rice husk has limited effect on anisotropy and interlayer bond adhesion. However, at higher fractions, increased porosity and particle debonding at interfaces pose new challenges for enhancing composite performance. The results highlight the potential rice husk as a multifunctional aggregate in 3D-printed cementitious composites, providing insights for the development of sustainable construction materials with optimized fresh and mechanical properties.

关键词： 3D concrete printing Bio-aggregates Water absorption Fresh properties Mechanical properties Interlayer bond adhesion X-ray microtomography

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Traffic noise assessment in urban Bulgaria using explainable machine learning

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SUSTAINABLE CITIES AND SOCIETY 2025年 120卷

作者： Helbich, Marco Hagenauer, Julian Burov, Angel Dzhambov, Angel M. Univ Utrecht Fac Geosci Dept Human Geog & Spatial Planning Utrecht Netherlands Med Univ Plovdiv Strateg Res & Innovat Program Dev MU Plovdiv Hlth & Qual Life Green & Sustainable Environm Res Plovdiv Bulgaria Med Univ Plovdiv Res Inst Environm Hlth Div Plovdiv Bulgaria Univ Architecture Civil Engn & Geodesy Fac Architecture Dept Urban Planning Sofia Bulgaria

Fine-grained noise maps are vital for epidemiological studies on traffic noise. However, detailed information on traffic noise is often limited, especially in Eastern Europe. When acoustic noise propagation models are unavailable, rigid linear noise land-use regressions are typically employed to estimate noise levels;however, machine learning likely offers more accurate noise predictions. We innovated by comparing the predictive accuracies of supervised machine learning models to estimate traffic noise levels across the five largest Bulgarian cities. In situ A-weighted equivalent continuous sound levels were obtained from 232 fixed-site monitors across these cities. We included transport- and land-use-related predictors using 50-1,000 m buffers. Extreme gradient boosting (XGB) had the highest ten-fold cross-validated fit (R2=0.680) and the lowest root mean square error (RMSE=4.739), insignificantly besting the random forest-based model (R2=0.667, RMSE=4.895). Support vector regression (R2=0.633, RMSE=5.358), elastic net (R2=0.568, RMSE=5.625), and linear regression (R2=0.548, RMSE=5.569) performed significantly worse. Shapley values for the XGB showed that the length of major roads within 100 m buffers, footways within 50 m buffers, residential roads within 50 m buffers, and the number of buildings within 50 m buffers were important non-linear predictors. Our spatially resolved noise maps revealed striking geographic noise variations and that, on average, 96.8 % of the urban population experiences harmful noise levels.

关键词： Traffic noise pollution Exposure assessment Land-use regression Machine learning Shapley additive explanations Environmental monitoring

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Multifunctional air filter with enhanced filtration, formaldehyde degradation, and antibacterial properties using PET, PDA, and RGO-TiO2

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PROCESS SAFETY AND ENVIRONMENTAL PROTECTION 2024年 192卷 621-633页

作者： Li, Yunhe He, Weidong Shen, Ruiqing Zhou, Xiaotong Liu, Jingxian Northeastern Univ Filter Test Ctr Sch Resources & Civil Engn 3-11 Wenhua Rd Shenyang 110819 Liaoning Peoples R China Oklahoma State Univ Coll Engn Architecture & Technol Fire Protect & Safety Engn Technol Program Stillwater OK 74078 USA

Currently, most air filters, such as polyester (PET) fiber non-woven fabric, only have a single function of particulate filtration. However, the removal of substances harmful to human health, such as volatile organic compounds (VOCs) and bacteria, is becoming increasingly important in indoor air purification. Herein, based on the biomimetic surface functionalization properties of polydopamine (PDA) and the photocatalytic degradation of organic matter and the antibacterial effect of RGO (reduced graphene oxide)-TiO2, a multifunctional NWP2/PET- PDA-RGO-TiO2(P/PPRT) filter with a sandwich structure was prepared for formaldehyde degradation, aerosol filtration, and bactericidal operation. The P/PP 2 R 0.05 T 20 maintains optimal performance of photocatalytic reaction kinetics and reaches a formaldehyde degradation rate of higher than 79 % within 300 min in the 7th cycle of usage. Compared with the base subtracts, P/PP 2 R 0.05 T 20 has the highest filtration efficiency of 88.57-99.18 % for 0.3-10 mu m particles, respectively, and has a filtration efficiency of higher than 74 % for 0.3 mu m particles in the 7th cycles of usage. The quality factor of P/PP 2 R 0.05 T 20 is improved significantly due to the sandwich structure. The effect of loaded particulate on the catalyst for photocatalytic degradation of formaldehyde was also studied. It was found that the photocatalytic formaldehyde degradation rate of P/PP 2 R 0.05 T 20 is about 81.8 % within 300 min under different A2 particulate load content. In addition, P/PP 2 R 0.05 T 20 has a bioaerosol removal rate of higher than 98 % against E. coli. This study provides a practical approach to preparing a multifunctional air filter with the performance of aerosol filtration, photocatalytic degradation of formaldehyde, and bactericidal function using PET non-woven fabric.

关键词： PET non-woven fabric Photocatalytic degradation Aerosol removal Volatile organic compounds (VOCs) RGO-TiO2 photocatalyst

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Sound absorption estimation using the discrete complex image source method and array processing

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2025年 231卷

作者： Brandao, Eric Fonseca, William D'Andrea Mareze, Paulo Henrique Resende, Carlos Azzuz, Gabriel Pontalti, Joao Fernandez-Grande, Efren Fed Univ Santa Maria UFSM Acoust Engn Program BR-97105900 Santa Maria RS Brazil Fed Univ Santa Maria UFSM Grad Program Civil Engn BR-97105900 Santa Maria RS Brazil Fed Univ Santa Maria UFSM Grad Program Architecture Urbanism & Landscaping BR-97105900 Santa Maria RS Brazil Fed Univ Santa Maria UFSM Grad Program Mech Engn BR-97105900 Santa Maria RS Brazil Univ Politecn Madrid UPM Dept Ingn Audiovisual Madrid 28040 Spain

Estimating the sound absorption of a material under realistic sound-field incidence conditions relies on accurately describing the measured data. Evidence suggests that modeling the reflection of impinging spherical waves is important, especially for compact measurement systems. This article proposes a method for estimating the sound absorption coefficient of a material sample by mapping the sound pressure, measured by a microphone array, to a distribution of monopoles, including the sound source and a series of complex image-sources. The proposed method is compared to modeling the sound field as a superposition of two sources (a monopole and an image source). The sound absorption measurement is tested with simulations of the sound field above infinite and non-locally reacting porous absorbers. The inverse problem estimations are compared to the classical plane-wave absorption coefficient and the one obtained by measuring the surface impedance when a spherical wave impinges on the absorber. Experimental analysis of two porous samples and one resonant absorber is also carried out in a laboratory. Two microphone arrays were tested with different apertures and number of sensors, and it was demonstrated that measurements are feasible even with the more compact array and for frequencies above 250 [Hz]. The discretization of the integral equation led to a more accurate reconstruction of the sound pressure and particle velocity at the sample's surface. The resulting absorption coefficient agrees with the one obtained for spherical wave incidence, indicating that including the source and several complex image-sources is an essential feature of the sound field.

关键词： Discrete complex image sources Absorption coefficient Microphone array

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