İnşaat Mühendisliği Bölümü Koleksiyonu

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Optimizing nutrient content of microbial self-healing concrete
(CRC PRESS-TAYLOR & FRANCIS GROUP, 6000 BROKEN SOUND PARKWAY NW, STE 300, BOCA RATON, FL 33487-2742 USA, 01.01.2019) Ersan, Y. C.; Akin, Y.; 0000-0003-4128-0195; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü
Cracks in microbial self-healing concrete are autonomously sealed through microbial induced calcium carbonate precipitation (MICP). The biogenic production of dissolved inorganic carbon (i.e. CO2) is the main drive for MICP and it is limited by the bioavailability of the nutrients. When added as admixtures bioavailability of the nutrients becomes even more significant for crack sealing as they disperse in mortar and a considerable portion stays far from an individual crack. Therefore, determination of the nutrient bioavailability and optimization of the nutrient content is necessary to enhance self-healing performance of bioconcrete. This study defines an optimum nutrient content range for nitrate reduction based microbial self-healing concrete. Ca-formate and Ca-nitrate were used as nutrient admixtures and their wt/wt ratio was kept constant at 2.50: 1.00 while testing various nutrient doses. Variation in mortar properties and nutrient bioavailability was observed and the optimum nutrient content range was defined as 3.5% to 7% depending on the expectations.
Overlooked Strategies in Exploitation of Microorganisms in the Field of Building Materials
(SPRINGER-VERLAG SINGAPORE PTE LTD, 152 BEACH ROAD, #21-01/04 GATEWAY EAST, SINGAPORE, 189721, SINGAPORE, 01.09.2019) Ersan, Yusuf Cagatay; 0000-0003-4128-0195; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü
Resource efficiency reports released in the last decade point out construction industry as one of the key sectors that needs improvement in terms of ecological sensitivity. Being aware of this unfavorable reputation of construction industry, researchers embarked on replacing the ongoing conventional methods with more sustainable and environmentally friendly ones. One of the approaches for the latter is incorporating microorganisms into construction industry. Popularly investigated strategies can be listed as biocementation, biomasonry, biorepair, and bioconsolidation. Most of these processes are the outcome of a single approach, namely microbial-induced calcium carbonate precipitation (MICP) which was mostly investigated by means of axenic cultures and through one single microbial process, ureolysis. The state of the art about the latter is close to saturation. Moreover, approaching from the ecological wisdom perspective it can be said that some promising microbial strategies to achieve green building materials were overlooked and drawing attention to these strategies became necessary. This review study reveals the overlooked promising microbial strategies in the field of construction biotechnology. The context mainly discusses the potential of five overlooked microbial strategies: (i) heterotrophic and autotrophic MICP pathways, (ii) microbial strategies for surface treatment, (iii) microbial-induced corrosion inhibition, (iv) microbial sequestration of greenhouse gases, and (v) microbial- produced polymers, for their application in the field of construction materials. Further suggestions aim to integrate the microbial resource management approach and non-axenic cultures into the relevant fields of research for the development of environmentally friendly building materials.
Effect of Granulated Blast Furnace Slag and fly ash addition on the strength properties of lightweight mortars containing waste PET aggregates
(ELSEVIER SCI LTD, 2011) Akcaozoglu, Semiha; Atis, Cengiz Duran; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
In this work, the effect of Granulated Blast Furnace Slag (GBFS) and fly ash (FA) addition on the strength properties of lightweight mortars containing waste Poly-ethylene Terephthalate (PET) bottle aggregates was investigated. Investigation was carried out on three groups of mortar specimens. One made with only Normal Portland cement (NPC) as binder, second made with NPC and GBFS together and, third made with NPC and FA together. The industrial wastes mentioned above were used as the replacement of cement on mass basis at the replacement ratio of 50%. The size of shredded PET granules used as aggregate for the preparation of mortar mixtures were between 0 and 4 mm. The waste lightweight PET aggregate (WPLA)–binder ratio (WPLA/b) was 0.60; the water–binder (w/b) ratios were determined as 0.45 and 0.50. The dry unit weight, compressive and flexural–tensile strengths, carbonation depths and drying shrinkage values were measured and presented. The results have shown that modifying GBFS had positive effects on the compressive strength and drying shrinkage values (after 90 days) of the WPLA mortars. However, FA substitution decreased compressive and flexural–tensile strengths and increased carbonation depths. Nevertheless a visible reduction occurred on the drying shrinkage values of FA modifying specimens more than cement specimens and GBFS modified specimens. The test results indicated that, GBFS has a potential of using as the replacement of cement on the WPLA mortars by taking into consideration the characteristics. But using FA as a binder at the replacement ratio of 50% did not improve the overall strength properties. Although it was thought that, using FA as binder at the replacement ratio of 50% for the aim of production WPLA concrete which has a specific strength, would provide advantages of economical and ecological aspects.
The Effects of Different Types of Fly Ash on the Compressive Strength Properties of Briquettes
(HINDAWI LTD, ADAM HOUSE, 3RD FLR, 1 FITZROY SQ, LONDON, W1T 5HF, ENGLAND, 2011) Sola, Ozlem Celik; Yayla, Murat; Sayin, Baris; Atis, Cengiz Duran; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü;
The aim of this study is to evaluate the effect of the different types of fly ash on the compressive strength properties of sintered briquettes. Thermal gravimetric (TG) analysis was carried out. The chemical composition and physical properties of the materials used were determined. Particle size distribution and microstructure elemental analyses of the materials used were carried out by a particle size analyzer (Mastersizer) and a scanning electron microscope (SEM-EDS). Following the characterization of the materials, briquettes were prepared by sintering at different temperatures. Compressive strength test results of the briquette samples indicated that briquettes with a compressive strength value of 47.45 N/mm(2) can be produced. The results obtained exceed the Turkish standard (TS EN 771-1) requirements (9.8-23.54 N/mm(2)). SEM-EDS results showed that briquette samples made with Tuncbilek (T) fly ash had a higher percentage of the glassy phase than the other briquette samples. Due to this microstructure, it results in higher compressive strength value.
Alkali activation of mortars containing different replacement levels of ground granulated blast furnace slag
(ELSEVIER SCI LTD, 2012) Bilim, Cahit; Atis, Cengiz Duran; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
The aim of the present study is to investigate some properties of alkali-activated mortars containing slag at different replacement levels. Ground granulated blast furnace slag was used at 0%, 20%, 40%, 60%, 80% and 100% replacement by weight of cement, and liquid sodium silicate having three different Na dosages was chosen as the alkaline activator. In this research, carbonation resistance measurements and compressive and flexural strength tests were performed on the mortar specimens with size of 40 40 160 mm. The findings obtained from the tests showed that carbonation depth values of the mortars decreased with the increase of activator dosage. Additionally, compressive and flexural strength values increased with the increase in activator concentration and slag replacement level. Portland cement/slag mortars activated by liquid sodium silicate exhibited lower strength than the slag alone activated by the same activator.
Investigation of Properties of Engineered Cementitious Composites Incorporating High Volumes of Fly Ash and Metakaolin
(AMER CONCRETE INST, 2012) Ozbay, Erdogan; Karahan, Okan; Lachemi, Mohamed; Hossain, K. M. A.; Atis, Cengiz Duran; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
This study was carried out to develop engineered cementitious composites (ECCs) incorporating binary blends of high volumes of fly ash (FA) and metakaolin (MK) for the purpose of achieving low drying shrinkage and high composite strength with adequate ductility and improved durability. ECC, an ultra-ductile cement-based composite reinforced with short random fibers, exhibits strain-hardening and multiple-cracking behavior in uniaxial tension and bending. Standard (M45) and high-volume FA ECC mixtures are typically produced by replacing portland cement (PC) with 55% and 70% of FA, respectively (FA-to-cement ratio of 1.2 and 2.2 by weight). In this study, the (FA + MK)/PC ratio was maintained at 1.2 and 2.2 and the FA/MK ratio was maintained at 4.5. Two replacement levels of MK with FA were adopted. The investigation used 10% and 12.5% MK by weight of total binder content, respectively. For the purposes of comparison, standard and high-volume FA ECCs were also studied. To determine the effect of binary blends of FA and MK on the properties of ECC, this study focused on the evaluation of free drying shrinkage, flexural and compressive strengths, porosity and water absorption (WA), sorptivity, and chloride-ion permeability. The experimental results showed that the drying shrinkage, porosity, absorption, sorptivity, and chloride-ion permeability properties were significantly reduced with the use of binary blends of FA and MK, while ECC's ultra-high ductility and strain-hardening properties were preserved at an adequate level.
Fresh, Mechanical, Transport, and Durability Properties of Self-Consolidating Rubberized Concrete
(AMER CONCRETE INST, 2012) Karahan, Okan; Ozbay, Erdogan; Hossain, Khandaker M. A; Lachemi, Mohamed; Atis, Cengiz Duran; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
This paper presents the fresh, mechanical, transport, and durability performances of self-consolidating rubberized concretes (SCRCs). Fresh concrete properties were determined with slump flow, V-funnel, J-ring, and L-box tests. Mechanical, transport, and durability properties were determined by measuring compressive, flexural, and splitting tensile strengths; bond strength characteristics; water porosity; water absorption; water sorptivity; rapid chloride-ion permeability; and freezing-and-thawing and corrosion resistance. SCRC mixtures with a water-binder ratio (w/b) of 0.32; total binder content of 500 kg/m(3) (842 lb/yd(3)); and crumb rubber content of 0, 10, 20, and 30% by fine aggregate volume were produced and tested. Fresh properties testing revealed that the use of crumb rubber as a fine aggregate diminished the filling and passing ability of SCRC. A gradual reduction in mechanical properties was also observed with an increase in crumb rubber content; however, the rate of compressive strength reduction was more evident than that of tensile strength. Despite the fact that water porosity, water absorption, and chloride-ion permeability increased slightly with the use of crumb rubber, a remarkable decrease was observed in the initial and secondary water sorptivity of SCRC. No significant decrease was observed in the freezing-and-thawing and corrosion resistance of SCRC with 10% crumb rubber. Beyond that level, however, durability performance was significantly affected.
The Effects of Pyrite Ash on the Compressive Strength Properties of Briquettes
(KOREAN SOCIETY OF CIVIL ENGINEERS-KSCE, 2012) Sola, Ozlem Celik; Atis, Cengiz Duran; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
The aim of this study is to investigate the utilization of Pyrite Ash (PA) in the production of briquettes as a replacement of clay or soil. To achieve this, first, the characterization of the materials used (clayey soil and pyrite ash) was made using Fourier Transform Infrared Spectroscopy (FTIR/ATR). Particle size distribution and microstructure elemental analyses of these materials were also obtained using a particle size analyzer (Mastersizer) and a Scanning Electron Microscope (SEM). Following the characterization of the materials, the samples of briquettes made with or without addition of PA were prepared and sintered at 950 and 1000A degrees C in the furnace. The PA replacement ratios with clayey soil were 0, 5, 10, 20% in mass basis (w/w). Compressive strength and bulk densities of briquettes produced were measured and the results were presented. Compressive strength results of the briquette samples indicated that pyrite ash containing briquettes with 35 MPa compressive strength, which was higher than the requirements of Turkish Standard Specification (TS EN 771-1), can be obtained. It is also recorded that for each mixture, compressive strength values obtained at 1000A degrees C were higher than that of obtained at 950A degrees C. XRD analyze was performed on sintered briquette sample made with 10% PA which have the highest compressive strength value. The XRD results showed that peaks are Quartz (SiO2), Hematite (Fe2O3), Ortoclase (KAlSi3O8), Albite (Na(AlSi3O8)), Anorthite (CaAl2Si2O8) and Gehlenite (2CaO.Al2O3.SiO2).
Thermal conductivity, compressive strength and ultrasonic wave velocity of cementitious composite containing waste PET lightweight aggregate (WPLA)
(ELSEVIER SCI LTD, 2013) Akcaozoglu, Semiha; Akcaozoglu, Kubilay; Atis, Cengiz Duran; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
In this study, the influence of waste PET as lightweight aggregate (WPLA) replacement with conventional aggregate, on thermal conductivity, unit weight and compressive strength properties of concrete composite was investigated. For this purpose, five different mixtures were prepared (the control mixtures and four WPLA mixtures including 30%, 40%, 50%, and 60% waste PET aggregate by volume). Thermal conductivity (TC) coefficients of the specimens were measured with guarded hot plate apparatus according to TS ISO 8302 [1]. The thermal conductivity coefficient, unit weight and compressive strength of specimens decreased as the amount of WPLA increased in concrete. The minimum thermal conductivity value was 0.3924 W/m K, observed at 60% WPLA replacement. From this result, it was concluded that waste PET aggregates replacement with conventional aggregate in the mixture showed better insulation properties (i.e. lower thermal coefficient). Due to the low unit weight and thermal conductivity values of WPLA composites, there is a potential of using WPLA composites in construction applications.
Dual effectiveness of freezing-thawing and sulfate attack on high-volume slag-incorporated ECC
(ELSEVIER SCI LTD, 2013) Ozbay, Erdogan; Karahan, Okan; Lachemi, Mohamed; Hossain, Khandaker M. A.; Atis, Cengiz Duran; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
This study investigated the dual effect of freeze–thaw cycles with sodium sulfate solution on the performance of non-air-entrained Engineering Cementitious Composites (ECCs) with high volumes of slag. ECC specimens containing three different levels of slag content as a replacement for cement (55%, 69% and 81% by weight of total cementitious material) were exposed to aggressive sodium sulfate solution under freezing–thawing cycles. The load–deflection response associated with ultimate mid-span deflection and flexural strength/stiffness was determined, along with crack development behavior. For comparison purposes, the freezing–thawing resistance (in water) of control ECC specimens was also evaluated. Modified point count method air-void parameters, compressive strength, porosity, water absorption and sorptivity tests were also conducted on the virgin ECC specimens (those not exposed to freezing–thawing cycles in water or aggressive sodium sulfate solution). The test results for the virgin specimens revealed that increased slag content (S/PC) improved the ductility, hardened air content, water absorption, porosity and sorptivity of ECC, while marginally decreasing the compressive and flexural strengths. Freeze–thaw cycles in water or sodium sulfate solution showed that the ductility of ECC specimens decreased remarkably, irrespective of slag content and applied freezing–thawing process. Reduction in mass loss was at minimal levels and no significant behavior change was monitored between the specimens undergoing freeze–thaw cycling in water and the aggressive sodium sulfate solution. Moreover, the decrease in flexural stiffness was more evident than the reduction of the flexural strength for all ECC mixtures.
Influence of admixtures on the properties of alkali-activated slag mortars subjected to different curing conditions
(ELSEVIER SCI LTD, 2013) Bilim, Cahit; Karahan, Okan; Atis, Cengiz Duran; Ilkentapar, Serhan; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
This paper presents the influence of shrinkage-reducing (SHR) and superplasticizing and set-retarding admixtures (SSRe) on the properties of slag pastes and mortars activated by liquid sodium silicate with different dosage and modulus ratio. Properties in the fresh and hardened state for these binders were investigated by means of measuring some properties including setting time, flowability, flexural strength, compressive strength, carbonation and shrinkage. In this study, fifteen pastes and mortars were prepared. Liquid sodium silicate was used to activate the slag at two sodium concentrations, 4% and 6% by mass of slag. Liquid sodium silicate and sodium hydroxide were blended to obtain 0.75 and 1 modulus ratio of SiO2/Na2O. Results showed that although the higher percentage of sodium in the activator produced a higher strength, workability and setting times rapidly decreased with the higher sodium concentration due to instantaneous reaction and quick hardening of slag activated by liquid sodium silicate. None of the admixtures generally had an impact on the setting times of alkali-activated slag (AAS) pastes. SSRe admixture increased the flow rate of AAS mortars while SHR admixture partially affected the flow values of AAS mortars. SHR admixture exhibited a slight decrease in the carbonation depths of AAS mortars. SSRe and particularly SHR chemical admixtures reduced the shrinkage of AAS mortars. However, the shrinkage values of AAS mortars still were higher than those of ordinary Portland cement (NPC) mortars. Curing conditions had a significant effect on the mechanical behavior in the hardened state of AAS mortars compared to NPC mortars
Rehabilitation of water and environment of the TKI - GELI/YLI opencast mine lakes
(Chamber of Mining Engineers of Turkey, 2013) Delibalta, Mahmut Suat; Uzal, Niğmet; https://orcid.org/0000-0002-0912-3459; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Uzal, Niğmet
During the search, production and enrichment process of mining operations the air, soil, water resources and living organisms are affected adversely. In coal opencast production, with the rise of surface water and ground water level large or small ponds are composed. The most important environmental problems of these ponds are low pH (acidic characteristic) and high metal concentrations (Fe, Mn, Al, Cu, Pb, Zn etc.) of these ponds, besides the sulfide minerals containing (S04) and the waste materials. These ponds needed to be rehabilitated for is one the sustainability of natural resources. In this study, the average pH values 6.22-7.79, turbidity (NTU) 0.63-6.71, sulphate content 840-1720 mg/L, KOI 2.27-61.5mg/L and electrical conductivity 1.72 -2.71 mS/cm have been measured during the monitoring study of three different lignite opencast mine post-production lakes of the TKI -GELI and YLI. The results were evaluated within the framework of relevant laws and regulations. Analyses were performed in three-month periods.
Properties of concrete with high-volume pozzolans
(ELSEVIER, 2013) Uzal, Burak; 0000-0002-3810-7263; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Uzal, Burak
This chapter focuses on the materials and properties of high-volume natural pozzolan (HVNP) concrete. The characteristics of natural pozzolans used in high-volume pozzolan mixtures are discussed, together with the fresh and hardened properties of HVNP cementitious systems, their hydration characteristics and their microstructures.
The effects of aerobic/anoxic period sequence on aerobic granulation and COD/N treatment efficiency
(ELSEVIER, 2013) Erguder, Tuba Hande; Ersan, Yusuf Cagatay; 0000-0002-9669-171X; 0000-0003-4128-0195; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Ersan, Yusuf Cagatay
The effects of period sequence (anoxic–aerobic and aerobic–anoxic) on aerobic granulation from suspended seed sludge, and COD, N removal efficiencies were investigated in two sequencing batch reactors. More stable granules with greater sizes (1.8–3.5 mm) were developed in R1 (anoxic–aerobic sequence). Yet, no significant difference was observed between the reactors in terms of removal efficiencies. Under optimum operational conditions, 92–95% COD, 89–90% TAN and 38–46% total nitrogen removal efficiencies were achieved. The anoxic–aerobic period sequence (R1) resulted in almost complete denitrification during anoxic periods while aerobic–anoxic sequence (R2) led to nitrate accumulation due to limited-carbon source and further granule disintegration. NH3–N concentration of 15–28 mg/L was found to inhibit COD removal up to 30%. This study also revealed the inhibitory sulfide production during anoxic periods. Sulfate concentration of 52.6–70.2 mg/L was found to promote sulfate reduction and sulfide generation (0.24–0.62 mg/L) which, together with free-ammonia, inhibited TAN oxidation by 10–50%.
Theoretical and Experimental Analysis of Wave Impact Pressures on Curved Seawalls
(SPRINGER HEIDELBERG, 2013) Mamak, Mustafa; Guzel, Hasan; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Mamak, Mustafa
Experimental model tests were performed in a wave flume with regular waves to measure the magnitude and distribution of impact pressures caused by breaking waves on a curved seawall model having different radii of curvatures. The base structure of the wall has a foreshore slope of 1/10. Theoretical studies based on pressure impulse theory were carried out to obtain the numerical results of breaking wave impact pressures on curved seawalls. The boundary element method was used for the numerical solution of the governing equation. The novel aspect of this study was to investigate the applicability of pressure impulse theory to curved seawalls. The results showed that the pressure impulse model can be used to model the wave impact pressures and their distribution on curved seawall models with good accuracy. A slight decrease has been observed in pressures for increasing radii of curvatures, especially for the case which the water depth at wall was 14 cm. The location of the maximum impact pressure was found to occur above the still water level for all cases tested in this study
Analysis of the probability of failure for open-grown trees during wind storms
(ELSEVIER SCI LTD, 2014) Ciftci, Cihan; Arwade, Sanjay R.; Kane, Brian; Brena, Sergio F.; 0000-0001-9199-6437; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Ciftci, Cihan
Although trees convey important environmental, economic, and sociological benefits on humans and society, they can also cause significant economic and societal disruptions, especially when subjected to wind storms in urban environments. Tools for proper assessment of the risk of these disruptions can be of significant benefit to society. In this research an approach to quantifying the failure probability for trees subject to wind storms is presented and illustrated by application to two specific maple trees in Massachusetts, USA. The approach entails four specific steps: (1) Random wind time history samples were generated using a modified Ochi–Shin spectrum, (2) these wind time histories were used as loading time histories on finite element models of the example trees in both summer (in-leaf) and winter (leafless), (3) maximum bending moments generated by the random wind time histories were compared to the failure (yield) moment of the tree at 1.4 m above ground, (4) the failure/fragility curves of the trees were estimated by Monte Carlo simulation for a range of average wind speeds and for 1000 independent wind time histories at each wind speed.
Loss in moment capacity of tree stems induced by decay
(SPRINGER HEIDELBERG, 2014) Ciftci, Cihan; Kane, Brian; Brena, Sergio F.; Arwade, Sanjay R.; 0000-0001-9199-6437; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Ciftci, Cihan
Key message We model varying decay in tree crosssections by considering bending theory to estimate moment capacity loss (MCL) for the sections. We compare MCL with experiments on selected oak trees. Abstract Tree failures can damage property and injure people, sometimes with fatal consequences. Arborists assess the likelihood of failure by examining many factors, including strength loss in the stem or branch due to decay. Current methods for assessing strength loss due to decay are limited by not accounting for offset areas of decay and assuming that the neutral axis of the cross-section corresponds to the centroidal axis. This paper considers that strength loss of a tree can be related to moment capacity loss (MCL) of the decayed tree cross-section, because tree failures are assumed to occur when induced moments exceed the moment capacity of the tree cross-section. An estimation of MCL is theoretically derived to account for offset areas of decay and for differences in properties of wood under compressive and tensile stresses. Field measurements are used to validate the theoretical approach, and predictions of loss in moment capacity are plotted for a range of scenarios of decayed stems or branches. Results show that the location and size of decay in the cross-section and relative to the direction of sway are important to determine MCL. The effect of wood properties on MCL was most evident for concentric decay and decreased as the location of decay moved to the periphery of the stem. The effect of the ratio of tensile to compressive moduli of elasticity on calculations of MCL was negligible. Practitioners are cautioned against using certain existing methods because the degree to which they over- or underestimate the likelihood of failure depended on the amount and location of decay in the cross-section.
Modeling of suspended sediment concentration carried in natural streams using fuzzy genetic approach
(SPRINGER LINK, 2014) Kisi, Ozgur; Fedakar, Halil Ibrahim; 0000-0002-7561-5363; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Fedakar, Halil Ibrahim
This chapter proposes fuzzy genetic approach so as to predict suspended sediment concentration (SSC) carried in natural rivers for a given stream cross section. Fuzzy genetic models are improved by combining two methods, fuzzy logic and genetic algorithms. The accuracy of fuzzy genetic models was compared with those of the adaptive network-based fuzzy inference system, multilayer perceptrons, and sediment rating curve models. The daily streamflow and suspended sediment data belonging to two stations, Muddy Creek near Vaughn (Station No: 06088300) and Muddy Creek at Vaughn (Station No: 06088500), operated by the US Geological Survey were used as case studies. The root mean square errors and determination coefficient statistics were used for evaluating the accuracy of the models. The comparison results revealed that the fuzzy genetic approach performed better than the other models in the estimation of the SSC.
Characteristics of calcined natural zeolites for use in high-performance pozzolan blended cements
(ELSEVIER SCI LTD, 2014) Uzal, Burak; Kucukyildirim, E; 0000-0002-3810-7263; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Uzal, Burak
Two natural zeolites with different characteristics were calcined at various temperatures in order to improve the benefits provided by their use in blended cements as cement replacement material. Natural zeolites were firstly characterized for their crystallinity by X-ray diffraction analysis, specific surface area by nitrogen absorption, and pozzolanic activity by electrical conductivity method, before and after the calcination. In order to assess the performance of calcined natural zeolite as cement replacement material, blended Portland cement pastes and mortars with raw and calcined zeolites were tested for their water requirement, free lime content, pore size distribution and compressive strength. The experimental results indicated that calcined zeolites are more desirable with lower water requirement and higher strength performance as cement replacement material than the raw zeolites. Blended cement with calcined natural zeolite showed higher compressive strength performance, when compared to that with the raw zeolite due to decreased porosity and refined pore structure of the hardened cementitious system
Determining the priority waste in aluminum manufacturing sector using the smaa-2 method: A case study of kayseri
(Computers and Industrial Engineering, 2014) Aydogan, Emel Kizilkaya; Ates, Nuray; Uzal, Nigmet; Ozmen, Mihrimah; 0000-0002-0912-3459; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Uzal, Nigmet
Small and medium-sized enterprises (SMEs) constitute a major part of the Turkish economy, accounting for a large proportion of the country's businesses and total employment. Although the SMEs are known as important contributors to environmental pollution, the relative contribution of SMEs to the total environmental impacts of industrial is unknown. The most important environmental issues related with aluminum industries are emission of gases, wastewater and solid wastes from aluminum production. In multi-criteria decision making (MCDM) problems in some situations, decision makers (DMs) don't or can't express their preferences obviously. In these situations for decision making, stochastic multi-criteria acceptability analysis (SMAA-2) can be applied. In this study, a multi-criteria decision making model is presented to determine higher priority waste types (air and solid wastes, wastewaters) among the three firms. We used stochastic data by applying and the SMAA-2 results are given.

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