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2nd International Conference on Sustainable civil engineering and Architecture, ICSCEA 2021

作者： Saludung, Apriany Azeyanagi, Takumu Ogawa, Yuko Kawai, Kenji Department of Civil and Environmental Engineering Graduate School of Engineering Hiroshima University 1-4-1 Kagamiyama Higashihiroshima City Japan Civil and Environmental Engineering Program Graduate School of Advanced Science and Engineering Hiroshima University 1-4-1 Kagamiyama Higashihiroshima City Japan

ISBN: (纸本)9789811933028

Designing a building material with high fire resistance is crucial for minimizing the impact of catastrophic fire. Geopolymer, a new type of binder synthesized by the reaction of aluminosilicate sources with an alkaline solution, has been extensively studied as it offers comparable or even high durability when compared to ordinary Portland cement (OPC). The concentration of the alkaline solution is one of the important factors that affect the durability;however, there is very little data on the heat resistance of geopolymer activated with potassium hydroxide. Thus, this study aims to investigate the effect of molarity of potassium hydroxide on the heat resistance of fly ash-slag blended geopolymer paste. The potassium hydroxide (10, 12, and 14 M) and sodium silicate solutions were prepared as activator solutions. The initial heat curing at 70 ºC for 24 h was applied. In addition, an OPC specimen was also prepared for comparison. After curing for 28 days, some specimens were exposed to high temperatures (500, 750, and 950 ºC). The compressive strength of unexposed and exposed geopolymer and OPC paste specimens was measured. The results showed that the increase of molarity of potassium hydroxide solution increased the heat resistance of geopolymer in terms of retained compressive strength. Moreover, the geopolymer specimens could maintain higher compressive strength than that of OPC paste when exposed to high temperatures up to 950 ºC. This is attributed to the mineral composition of geopolymer, which is different from OPC paste, as studied by X-ray diffraction analysis. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Potassium hydroxide

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The Effect of EPS Addition to Soil Stabilized with Fly Ash as Lightweight Fill Materials for Embankment Construction 1

The Effect of EPS Addition to Soil Stabilized with Fly Ash a...

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2018 1st Workshop on engineering, Education, Applied Sciences, and Technology, WEAST 2018

作者： Syahril Somantri, Andri Krisnandi Febriansya, Aditia Civil Engineering Department Politeknik Negeri Bandung Bandung Indonesia Post-Graduate Stud. of Infrastructure Engineering Study Program Applied Master Program Politeknik Negeri Bandung Bandung Indonesia

Design and construction of road embankment presents several challenges, including the possibility of bearing capacity failure, large total settlement, differential settlement, and slope instability, which may result from the weight of the embankment construction itself, and/or weak foundation. A number of techniques have been developed and can be used to overcome these problems, one of them is by modifying the weight of the embankment itself with the use of lightweight materials, such as soil-EPS mixture. The use of soil-EPS mixture as lightweight material provides several advantages, among which can achieve the same volume or elevation requirement with a significantly lighter weight compared to ordinary materials, improving slope stability, embankment over high compressibility soil, and to reduce soil pressure to soil retaining structures, abutment or bridge pillar. Fly ash also added to act as binder to increase shear strength of mixture. The result of the compaction test shows that the addition of a small amount of EPS to the mixture can significantly reduce the maximum dry density of the mixture. Triaxial UU and UCS test results show a reduction in mixture strength as EPS contents increase, but due to the presence of fly ash increases the strength of mixture as the number of day increases, so that the use of lightweight materials has the potential to be one of soil improvement solutions. © Published under licence by IOP Publishing Ltd.

关键词： Mixtures

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Study of Hybrid Steel Fibers Effects on the Workability and Compressive Properties of Non-proprietary UHPC 3rd

Study of Hybrid Steel Fibers Effects on the Workability and ...

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3rd International Conference on Sustainable civil engineering and Architecture, ICSCEA 2023

作者： Zhang, Ye Ogawa, Yuko Goegre, Riya Catherine Kawai, Kenji Civil and Environmental Engineering Program Graduate School of Advanced Science and Engineering Hiroshima University 1-4-1 Kagamiyama Higashi-Hiroshima Japan

ISBN: (纸本)9789819974337

Non-proprietary ultra-high-performance concrete (UHPC) is renowned for excellent mechanical properties, especially high compressive strength which is generally above 150 MPa. Despite the high compressive strength, the failure mode of non-proprietary UHPC under axial loading is sudden, brittle, and explosive. The undesired compression failure mode is not ideal for structure design and undermines the engineering value of non-proprietary UHPC. This research targets to convert the compression failure mode of non-proprietary UHPC from brittle to ductile with hybrid steel fiber reinforcement and select the most effective reinforcing proportion. In this research, a ground granulated blast-furnace slag (GGBS) based non-proprietary UHPC mix is reinforced with five combinations of two steel fiber types with straight ends. The lengths of the two steel fibers are 6.5 mm and 13 mm. The total volume fraction of steel fibers is 2%. The 28-day compressive strengths and the failure modes of the reinforced samples are compared to select a hybrid steel fiber combination that transforms the failure mode of non-proprietary UHPC and strengthens the compression performance most effectively. The experiment results demonstrate that: (1) with steel fibers presented, non-proprietary UHPC is capable of continuously taking compressive load after matrix cracks;(2) instead of explosive brittle failure mode, fiber reinforced non-proprietary UHPC fails in a ductile behavior under axial compression load and the samples stay in integrity;(3) hybrid steel fiber reinforcement is more effective than single type steel fiber reinforcement in improving the compression performance of non-proprietary UHPC. © 2024, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Compressive strength

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Application of the Updated PSHA on the Stability Analysis of the Meninting Diversion-Spillway Tunnel in Lombok Island—Indonesia 5th

Application of the Updated PSHA on the Stability Analysis of...

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5th International Conference on Rehabilitation and Maintenance in civil engineering, ICRMCE 2021

作者： Agustawijaya, Didi S. Marlaningtyas, Ria R. Murtiadi, Suryawan Wahyudi, Mudji Muhajirah Hartana Agustawijaya, Ausa R. Post-Graduate Study Program Department of Civil Engineering University of Mataram Mataram Indonesia Geo-Engineering Research Group Department of Civil Engineering University of Mataram Mataram Indonesia Department of Geomatics Engineering ITS Surabaya Indonesia

ISBN: (纸本)9789811693472

The Meninting diversion-spillway tunnel is a part of the Meninting dam project located in West Lombok District. The construction commenced in 2017;then, a series of severe Lombok earthquakes halted the construction of the tunnel for a while in 2018, where some landslides occurred around the site. This possibly caused rock masses around the tunnel to be sheared off during the earthquake events. Updated probability seismic hazard analysis shows increased seismic parameters, including peak ground, short spectrum and long spectrum accelerations, which then resulted in increased stresses around the tunnel. Thus, the stability of the tunnel decreased in terms of its factors of safety. Although, the overall factor of safety was about 2.5, the tunnel was still stable in current conditions;the tunnel certainly requires more stability improvements to face possible similar severe earthquakes in future. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Earthquakes

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Effect of treatment of sisal fiber on morphology, mechanical properties and fiber-cement bond strength

Effect of treatment of sisal fiber on morphology, mechanical...

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作者： Santos, Rogério De Jesus Lima, Paulo Roberto Lopes Post-graduate Program of Civil and Environmental Engineering Department of Technology State University of Feira de Santana Av. Transnordestina S/N-Novo Horizonte Feira de Santana Bahia44036-900 Brazil

The dimensional instability of vegetable fibers due to hygroscopicity results in a gradual loss of adherence in cement based composites which, when in service, are submitted to a natural variation of humidity. Such an effect reduces the contribution of the fiber as a reinforcement and can cause the early rupture of the material. In this work, a treatment of the sisal fibers is performed with the applying of wetting-drying cycles in order to alter their crystalline structure and improve the dimensional stability of the fiber to withstand the variation of humidity: 6, 10, 20, 30 and 34 cycles were applied in order to evaluate the effect on the properties of fiber;a tensile test, the morphological characterization (MEV) and the evaluation of the chemical structure of fiber were carried out. The effect of the treatment on fiber-matrix behavior was evaluated using the pull-out test. Embedded lengths of 16, 20, 30, 40 and 44 mm were defined through a factorial design and used in the test. It is verified that the use of 10 wetting-drying cycles causes less damage to the tensile strength and the elastic modulus of the fiber and contributes to a better adherence with the matrix, with an increase of up to 23 % compared with the untreated fiber. The statistical analysis of the interaction effect between the studied factors, using 2K factorial design with central composite design, indicates that the number of cycles can be decreased when using a longer length of the embedded fiber. © (2015) Trans Tech Publications, Switzerland.

关键词： Tensile strength

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Analysis of synthetic natural gas injection into charcoal blast furnace

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Journal of Materials Research and Technology 2013年第3期2卷 255-262页

作者： Rocha, Elisa Pinto Da Guilherme, Vagner Silva De Castro, José Adilson Sazaki, Yasushi Yagi, Jun-Ichiro Post-Graduation Program in Metallurgical Engineering Universidade Federal Fluminense Volta Redonda RJ Brazil Environmental Metallurgy Laboratory Graduate Institute of Ferrous Technology Pohang University of Science and Technology Pohang Korea Republic of Tohoku University Sendai Japan

Recently, the synthetic natural gas (SNG) has been available for large consumers in the Brazilian domestic market. The SNG is a suitable fuel with potential use to several processes and facilities of the steel industry. This paper investigates the injection of SNG into charcoal blast furnaces as a substitute for granular charcoal charged from the top and pulverized charcoal injections with potential increase of productivity and decrease of specific CO2 emissions. In order to study the effect of replacement of granular charcoal and injection of pulverized charcoal the well known Blast Furnace Five Fluid Model (BF-FFM) is applied to describe detailed phenomena within the process. This model treats the blast furnace as a five-phase reactor, accounting for gas, lump solids (raw iron ore, sinter, pellets and granular charcoal), hot metal, pulverized charcoal, and molten slag. The model is based on conservation equations for mass, momentum, energy and chemical species numerically solved based on the finite volume method (FVM). The SNG has high amount of H2 and strongly affects the inner conditions of the reactor and only a comprehensive model with detailed chemical reaction rates can properly predict the inner parameters of the process and hence furnish useful information to design smooth operational conditions. The simulation results obtained in this study indicated that smooth operations using SNG up to 25 N m3/t of pig iron could be achieved simultaneously by increasing the productivity up to 58% and with a decrease of 40 kg/thm on the granular charcoal charged. © 2013 Brazilian Metallurgical, Materials and Mining Association.

关键词： Steelmaking

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Surface modification of membrane filters using graphene and graphene oxide-based nanomaterials for bacterial inactivation and removal

Surface modification of membrane filters using graphene and ...

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作者： Musico, Yvonne Ligaya F. Santos, Catherine M. Dalida, Maria Lourdes P. Rodrigues, Debora F. Department of Civil and Environmental Engineering University of Houston Houston TX 77204-5003 United States Environmental Engineering Graduate Program College of Engineering University of the Philippines Diliman Quezon City 1101 Philippines

Surfaces of commercially available membrane filters were modified by the dispersion of poly(N-vinylcarbazole) (PVK), graphene (G), poly(N-vinylcarbazole) -graphene (PVK-G), graphene oxide (GO), and poly(N-vinylcarbazole)-graphene oxide (PVK-GO) in order to impart antibacterial properties. The successful coatings of the membranes were demonstrated through scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Investigations carried out on the surface-modified membrane filters using Escherichia coli and Bacillus subtilis showed that the presence of graphene-based nanomaterials significantly improved the antibacterial properties of the membrane filters. One of the mechanisms for this improved antimicrobial property of the filter was attributed to the production of reactive oxygen species by the nanomaterials. Among the nanomaterials used in this study, the PVK-GO-modified membrane filter exhibited the best removal of B. subtilis and E. coli with 4 and 3 log removals, respectively. The different levels of E. coli and B. subtilis removals were attributed to the differences in their cell structures and composition. This study has demonstrated that the use of graphene-based nanomaterials to modify the surfaces of membrane filters is an effective method of imparting antibacterial properties that can find useful application in water and wastewater treatment. © 2014 American Chemical Society.

关键词： Nanostructured materials

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Selection of sensitive features for damage identification in a railway bridge

Selection of sensitive features for damage identification in...

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作者： Meixedo, A. Alves, V. Ribeiro, D. Calçada, R. Faculty of Engineering University of Porto Portugal Post-Graduate Program in Civil Engineering Federal University of Ouro Preto Brazil School of Engineering Polytechnic of Porto Portugal

This paper aims selects sensitive features for damage identification in a railway bridge. For this purpose, a damage identification methodology based on a genetic algorithm and its application to the numerical model of a railway bridge is proposed. The identification method is based on an iterative process that in each iteration compares the values of the dynamic responses of a bridge for a test damage scenario with the response values for a reference damage scenario. The introduction of damage in the test numerical model is based on the modification of preselected numerical parameters values. The genetic algorithm allows the identification of damage by minimizing the residue of an objective function constructed from the responses of the test and reference model, and based on damage indicators. In this study damage indicators, based on the deck accelerations of the bridge subject to the action of the Alfa Pendular train defined as a set of moving loads, are defined and tested. The proposed methodology for identifying damage has been tested using a two-dimensional numerical finite element model of a railway bridge including the railway track. The results enabled the evaluation of the efficiency and reliability of the methodology and of the damage indicators which, in most situations, showed potential for the detection, location and quantification of the severity of the damage. © civil-Comp Press, 2016.

关键词： Genetic algorithms

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Production of Biogas from Organic Fruit Waste in Anaerobic Digester using Ruminant as the Inoculum 24

Production of Biogas from Organic Fruit Waste in Anaerobic D...

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24th Regional Symposium on Chemical engineering, RSCE 2017

作者： Budiyono Manthia, Firliani Amalin, Nadya Hawali Abdul Matin, Hashfi Sumardiono, Siswo Department of Chemical Engineering Engineering Faculty Diponegoro University Semarang50275 Indonesia Master Program of Environmental Science School of Post Graduate Studies Diponegoro University Semarang50275 Indonesia

Organic waste, fruit waste and vegetable waste are the best substrate to produce biogas. Waste management system for producing biogas can be used as a solution with the waste problem by converting the wastes into biogas. This study is expected to review of the effect of substrate type and substrate composition for the volume of biogas produced. In this study, materials consist of fruit wastes (oranges, apples, papayas, and tomatoes), cow ruminant, urea, cow dung, Na2CO3 buffer, NH4HCO3 buffer, and distilled water with variations of the substrate materials, F/ W, and the buffer types. The addition of cow manure and Na2CO3 buffer with 1:2 of F/W, production of biogas is greater than variable which is used NH4HCO3 buffer and without the addition of cow dung. Variables with addition of cow dung with 1:1 of F/W and using Na2CO3 buffer, the result is greater than the variable using the same buffer but without the addition of cow dung and variables with 1:1 of F/W with the addition of cow dung and Na2CO3 buffer and variables with the same feed and without the addition of cow dung produce more biogases than variable which is the using NH4HCO3 buffer, 1:1 of F/W and without the addition of cow dung. © The Authors, published by EDP Sciences, 2018.

关键词： Biogas

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Study of Biogas Production from Cassava Industrial Waste by Anaerobic Process 24

Study of Biogas Production from Cassava Industrial Waste by ...

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24th Regional Symposium on Chemical engineering, RSCE 2017

作者： Budiyono Primaloka, Arindra D. Ardhannari, Listi Matin, Hashfi H.A. Sumardiono, Siswo Department of Chemical Engineering Engineering Faculty Diponegoro University Semarang50275 Indonesia Master Program of Environmental Science School of Post-Graduate Studies Diponegoro University Semarang50275 Indonesia

Biogas production processes from tapioca wastewater have several problems that cause the biogas production is not optimal, such as pH drop at beginning of the process because the rate of acid formation is too fast and the rate of starch wastewater degradation is too slow. Therefore, to obtain optimal biogas production it is required two-stage reactor. The purposes of this research were to (i) study the influence of one stage fermentation and two stage fermentation on biogas production, (ii) study the effect of buffer Na2CO3 on biogas production, and (iii) study the effect of methanogenic bacteria concentration on biogas production from cassava starch effluent. The first method of our research was hydrolysis process by "Saccharomyces cereviceae" as substrate activator. The second is the arrangement of pH and the last is process of methane production. The results showed that the highest biogas production is achieved at concentration of methanogenic bacteria 20% (v/v) that is equal to 2458 ml. At concentration of 8% (v/v) and 15% (v/v), biogas production was 2105 ml and 2117 ml. The addition of Na2CO3 can extend to 16 days with accumulation of 372 ml. While without the addition of buffer, biogas production period was only 9 days with accumulation of 620 ml. In semi continuous process, the analysis carried out every 3 days. Highest biogas production achieved in the variable addition of yeast with the accumulation 9329 ml. Without yeast, accumulation of biogas was 6831 ml. Yeast is use as substrate activator so it can accelerate the hydrolysis process and increased biogas production. The addition of Na2CO3 is increase the alkalinity so the pH drop did not occur early in the process. © The Authors, published by EDP Sciences, 2018.

关键词： Yeast

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