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1st Progress in Science and Technology Research Symposium, PSTRS 2019

作者： Adam, Andi Arham Akifa, Sri Nur Siregar, Atur P.N. Mustofa Department of Civil Engineering Tadulako University Indonesia Post-Graduate Program Tadulako University Indonesia Department of Mechanical Engineering Tadulako University Indonesia

The use of lime to produce ambient cured Geopolymer concrete is one of a practical solution to avoid heat curing in the production of geopolymer concrete. The addition of lime in the geopolymer system will add another hardened mechanism, i.e. hydration in addition to condensation-polymerisation. This research aims to determine the influence of air and water curing on the strength of geopolymer concrete which uses class F fly ash and lime as raw materials. The geopolymer concrete was produced by varying the activator (sodium silicate and sodium hydroxide) with the variation of the activator to binder ratio of 0.45, 0.50, 0.55, and 0.60. Five per cent of the fly ash was replaced by slaked lime and the water added to the mix to maintain the ratio of water to solid (activator + binder) to 0.32. The test specimens were 100 mm dia x 200 mm height cylinder. Water-immersion curing was performed for 7, 14, and 21 days and the compressive strength test was done at 28 days. The results show that there is a difference in the curing process between the geopolymer concrete and the normal concrete. In the geopolymer concrete, there is a decrease in compressive strength if soaked for seven days and recovered with the increase in the age of immersion. Whereas for normal concrete, the compressive strength continues to increase with increasing age of immersion. © Published under licence by IOP Publishing Ltd.

关键词： Compressive strength

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Biogas Production from Rice Husk Waste by using Solid State Anaerobic Digestion (SSAD) Method 2

Biogas Production from Rice Husk Waste by using Solid State ...

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2nd International Conference on Energy, environmental and Information System, ICENIS 2017

作者： Matin, Hashfi Hawali Abdul Hadiyanto Master Program of Environmental Science School of Post Graduate Studies Diponegoro University Indonesia Chemical Engineering Department Engineering Faculty Diponegoro University Indonesia

An effort to obtain alternative energy is still interesting subject to be studied, especially production of biogas from agriculture waste. This paper was an overview of the latest development of biogas researches from rice husk waste by Solid State Anaerobic Digestion (SSAD). The main obstacle of biogas production from rice husk waste was the lignin content which is very difficult degraded by microbes. Various pretreatments have been conducted, either physically, chemically as well as biologically. The SSAD method was an attractive option because of the low water content of rice husk waste. The biogas yield by SSAD method gave more attractive result compared to Liquid Anaerobic Digestion (LAD) method. Various studies were still conducted in batch mode laboratory scale and also has not found optimum operating conditions. Research on a larger scale such as bench and pilot scale with continuous systems will be an increase trend in the future research. © 2018 The Authors, published by EDP Sciences.

关键词： Biogas

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Influence of Superplasticizer on Workability and Early Strength of Fly Ash/Blast Furnace Slag Based Geopolymer Mortar 2nd

Influence of Superplasticizer on Workability and Early Stren...

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

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

ISBN: (纸本)9789811933028

Recent studies have shown the presence of ground granulated blast-furnace slag (GGBS) in fly ash based geopolymer induced denser microstructures and better compressive strength. However, the inclusion of GGBS gives rapid setting time despite its benefit in terms of mechanical properties and could cause difficulty in handling the geopolymer in its application such as troubles with delivery time of fresh mix geopolymer concrete. This study aims to investigate the effect of polycarboxylate based superplasticizer, which is commonly used in Portland cement concrete to improve the workability and achieve appropriate compressive strength, on the fresh properties and early strength of geopolymer mortar. Geopolymer mortar was composed of fly ash and GGBS acting as binder with sodium silicate and 12 M of sodium hydroxide solution as alkaline activator. Alkaline to binder and fly ash/GGBS ratios were kept constant at 0.5 and 1.5, respectively. Superplasticizer was added into alkaline solution before casting at various dosages of 0%, 1%, 2%, 4%, and 8% by the binder mass and all the specimens were cured in two regimes of heat curing and 20ºC curing. The results have shown that the inclusion of superplasticizer maintained the workability over the time and may delay the setting of geopolymer mortar. Moreover, the mixture with 8% superplasticizer had dense microstructure and comparable compressive strength to that without superplasticizer at the age of 7 days. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Compressive strength

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Solid waste management in the paper industry 5

Solid waste management in the paper industry

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5th International Conference on Energy, environmental and Information System, ICENIS 2020

作者： Devichi Wibowo, Isabella Purwanto, P. Suherman, S. Master Program of Environmental Science Post-Graduate Studies Universitas Diponegoro Semarang Indonesia Department of Chemical Engineering Faculty of Engineering Universitas Diponegoro Semarang Indonesia

The industry developed rapidly since the Industrial Revolution in the 18th century. The side effect of industrial development was a large amount of non-hazardous waste and hazardous waste. All of this waste must be managed properly so that environmental sustainability is maintained and does not cause harm or problems to the community. A review will be conducted from various research journals in various countries and the types of waste also vary, namely plastic, pulp and paper industry waste, and other solid waste. A comparison of solid waste management will be carried on to reduce the generation of waste in the environment. © The Authors, published by EDP Sciences, 2020.

关键词： Solid wastes

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Applicability of Electrical Resistance Method to Moisture Transfer Measurement in Paste Using Mineral Admixture 2nd

Applicability of Electrical Resistance Method to Moisture Tr...

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

作者： Aoki, Takahiro Ogawa, Yuko Kawai, Kenji Civil and Environmental Engineering Program Graduate School of Advanced Science and Engineering Hiroshima University 1-4-1 Kagamiyama Higashihiroshima Japan

ISBN: (纸本)9789811933028

Concrete is a porous material which has the ability to hold moisture stably inside. Since moisture is closely related to the deterioration of concrete structures, it is important to understand the moisture transfer in concrete in order to maintain the concrete structure appropriately. The electrical resistance method is one of non-destructive methods to investigate the moisture in concrete and the moisture transfer can be assessed with time by using one specimen. However, the electrical resistance may be affected by mineral admixtures in concrete. Although previous studies on the effects of mineral admixtures on the electrical resistance have been conducted, there are still many unclear points. Therefore, the purpose of this study is to assess the applicability of the electrical resistance method to moisture transfer measurement in paste containing mineral admixtures by focusing on the moisture transfer in the drying process. The moisture transfer in the hardened cement paste using fly ash and blast furnace slag with water-to-binder ratios of 0.35 and 0.55 was investigated by the electrical resistance method. Stainless steel rods of 0.9 mm in diameter were placed at an interval of 4 mm in the specimen. The calibration test was also conducted to obtain the relationship between the electrical resistivity and the internal relative humidity of the specimen. The result showed that the specific resistance of the specimen containing mineral admixtures was higher than that of the specimen without mineral admixtures. It was observed that at the drying period of 70 days, the internal relative humidity at a depth of 4 mm from the exposed surface was almost the same as the surrounding relative humidity. It is possible to know the change in the internal relative humidity distribution in the cement paste using mineral admixtures during the drying process by performing the calibration test appropriately. © 2023, The Author(s), under exclusive license to Springer Nature Singapore P

关键词： Concretes

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The Behavior of Recycled Concrete through the Application of an Isotropic Damage Model

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Open Journal of civil engineering 2015年第3期5卷 339-351页

作者： Marcelo Pedreira da Silva Magno Teixeira Mota Anderson de Souza Matos Gadea Monica Batista Leite Koji de Jesus Nagahama Civil and Environmental Engineering Post-Graduate Program State University of Feira de SantanaFeira de SantanaBrazil

The main goal of this paper is to describe the mechanical behavior of the CDW recycled concrete in compression, using an isotropic damage model adapted to the variation of the replacement rate of natural aggregates by recycled ones. The isotropic model by Mazars was used as a constitutive equation for the CDW concrete and its adjustment parameters, A and B, were written as quadratic polynomials according to the aggregates replacement rate. The model was evaluated for conventional and recycled concretes. For the latter ones, the aggregates replacement ratios evaluated were 50% and 100%. The results show good approximation between the analytical and numerical values obtained with the adapted isotropic damage model and experimental concrete results for both compressive and flexural strength.

关键词： Recycled Concrete Construction and Demolition Waste Isotropic Damage Mazars Isotropic Model

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Seismic Response of Variable Section Column with a Change in Its Boundary Conditions

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Buildings 2025年第9期15卷 1456-1456页

作者： de Macêdo Wahrhaftig, Alexandre Eisenberger, Moshe Baptista Elias, Castro Malheiros Filho, Luiz Antônio Department of Construction and Structures Polytechnic School Federal University of Bahia 5º Andar Rua Aristides Novis 02 FederaçãoBA Salvador40210-910 Brazil Faculty of Civil and Environmental Engineering Technion—Israel Institute of Technology Technion City Haifa32000 Israel Department of Geophysics Institute of Geosciences Federal University of Bahia Rua Barão de Jeremoabo s/n OndinaBA Salvador40170-290 Brazil Young Researcher Program Vice-Rectorate for Research and Graduate Studies Federal University of Bahia Rua Basílio da Gama 6/8 CanelaBA Salvador40110-040 Brazil

The end conditions of columns constitute an important design parameter as they change their stiffness. The degree of restraint of the column modifies its fundamental frequency and mode of vibration. The rotational stiffness at its ends may transform from zero (hinged) to infinite (clamped). For intermediate values, the rotational movement is partially restricted, and it is classified as semi-rigid. In this work, the seismic response for a linearly variable section column and with gradual change in the rotational fixity is studied. A parametric solution is developed using the Rayleigh method, derived for cases of non-prismatic columns, and considering the axially distributed force along the column height. The obtained generalized stiffness and mass are used to perform approximate seismic evaluation at low effort and examine the influence of the changes to the structure. The analysis indicated that with a spring coefficient of 5 EI/l, the displacement drops by 50%, meaning that this range can produce significant influence on the structural response. The relationship between the top load and the column self-weight equal to 0.3 defines the limit for the hinged–hinged boundary condition to exist. As research recommendations, analysis of columns with variable cross-sections and different shapes, different distributed loadings, applying the rotational spring for both ends and over the shape functions, and analysis of buildings by an equivalent system are suggested. Experimental activity is indicated as a possibility for future investigations. © 2025 by the authors.

关键词： Structural analysis

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Seasonal Inflow Forecasts Based on Non-Homogeneous Hidden Markov Models: The Case of Orós Reservoir, Northeastern Brazil 18

Seasonal Inflow Forecasts Based on Non-Homogeneous Hidden Ma...

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18th World environmental and Water Resources Congress 2018: Watershed Management, Irrigation and Drainage, and Water Resources Planning and Management

作者： Hernández, Luis Carlos Hernández Reis, Dirceu Silveira Environmental Technology and Water Resources Graduate Program Dept. of Civil and Environmental Engineering Univ. of Brasilia Brasília Brazil Dept. of Civil and Environmental Engineering Univ. of Brasilia Brasília Brazil

ISBN: (数字)9780784481400

ISBN: (纸本)9780784481400

This study explores the use of non-homogeneous hidden Markov models (NHMMs) to forecast streamflows into the Orós Reservoir, located in the State of Ceará, Northeastern Brazil. These models employ hydro-climatic information from a given year to predict the next year inflow. The Orós Reservoir is a key infrastructure in the water resources system of the state, where most rivers present very high temporal variability, which is a challenge for water managers. Streamflow forecast systems at the climate scale (months ahead) can be very useful for the challenging process of water allocation in the region. This paper explores the use of NHMMs to provide a probabilistic one-year ahead forecast of the mean annual flow for the Orós Reservoir. Results based on a forecast verification study based on 60 years of independent data show that NHMMs with two or three hidden states, employing the NINO3 climate index as exogenous variable, provides forecasts with an average value of the continuous ranked probability skill score of about 0.2-0.25, meaning that they are better than climatology. It is also evident that those models performed much better during dry years than during wet years, which may be related to lack of other climate indices. © 2018 American Society of civil Engineers.

关键词： Hidden Markov models

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GIS-Based Methodology for Crash Prediction on Single-Lane Rural Highways

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Journal of Geographic Information System 2021年第2期13卷 98-121页

作者： Márcia Macedo Emilia Kohlman Rabbani Maria Maia Marlos Macedo Bianca Ferreira Post-Graduate Program in Civil Engineering UPE Recife Brazil Post-Graduate Program in Systems Engineering UPE Recife Brazil Graduate Program in Architecture and Urban Planning UNICAP Recife Brazil

Due to the need to update the current guidelines for highway design to focus on safety, this study sought to build an accident prediction model using a Geographic Information System (GIS) for single-lane rural highways, with a minimum of statistically significant variables, adequate to the Brazilian reality, and improve accident prediction for places with similar characteristics. A database was created to associate the accident records with the geometric parameters of the highway and to fill in the gaps left by the absence of geometric highway plans through geometric reconstitution or semi-automatic extraction of highways using satellite images. The Generalized Estimating Equation (GEE) method was applied to estimate the coefficients of the model, assuming negative distribution of the binomial error for the count of observed accidents. The accident frequency and annual average daily traffic (AADT) were analyzed, along with the spatial and geometric characteristics of 215 km of federal single-lane rural highways between 2007 and 2016. The GEE procedure was applied to two models having three variations of distinct homogeneous segmentation, two based on segments and one based on the kernel density estimator. To assess the effect of constant traffic, two more variations of the models using AADT as an offset variable were considered. The predominant correlation structure in the models was the exchangeable. The principal contributing factors for the occurrence of collisions were the radius of the horizontal curve, the grade, segment length, and the AADT. The study produced clear indicators for the design parameters of roadways that influence the safety performance of rural highways.

关键词： Roads GEE Single-Lane Rural Highways GIS Crash Prediction

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Fundamental study on impact factor for fatigue design of highway bridges based on moving vehicle response analysis 5

Fundamental study on impact factor for fatigue design of hig...

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5th International Conference on New Dimensions in Bridges, Flyovers, Overpasses and Elevated Structures

作者： Nakano, Kazuya Nakamura, Shozo Nishikawa, Takafumi Civil and Environmental Engineering Program Graduate School of Engineering Nagasaki University 1-14 Bunkyo-machi Nagasaki852-8521 Japan Department of Civil and Environmental Engineering Graduate School of Engineering Nagasaki University 1-14 Bunkyo-machi Nagasaki852-8521 Japan

ISBN: (纸本)9789810727291

Fatigue design was newly included in Japanese design code for highway bridges in the recently revised edition as one of the limit states of structures to be verified in design. The current Japanese design code specifies the impact factor as a function of only span length. Details of analysis method for fatigue of steel highway bridges are described in the fatigue design recommendation, and impact factor is specified to be a half of the value determined in the design code based on the judgment that its average value should be used for fatigue design. However, it is not clearly shown that this value represents adequately dynamic influence on fatigue damage. This paper suggests a calculation method of impact factor for fatigue design. In this method, dynamic response analysis of a bridge against a running vehicle is combined with the Monte Carlo simulation. Impact factor is decided from the ratio of fatigue damages based on dynamic and static analyses. Moreover, impact factors of three simply supported composite girder bridges with different spans are calculated by this method. Three types of roughness on road surfaces are considered in the analysis. The main findings can be summarized as follows: (1) The impact factor becomes smaller when the span length becomes shorter;(2) When road surface condition is average or poor, the impact factor in the recommendation underestimated the dynamic influence for fatigue damages;(3) The vehicle speed has certain influence on the value of impact factor. The influence is not monotonie, but it reaches maximum when the speed is 40km/h.

关键词： Highway bridges

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