Browsing by Author "Gürbüz, Ayhan"

Now showing 1 - 7 of 7

Citation Count: 10
Bacteria-Induced Cementation in Sandy Soils
(Taylor & Francis inc, 2015) Gurbuz, Ayhan; Sari, Yasin Dursun; Yuksekdag, Zehra Nur; Department of Civil Engineering
Bacteria-induced calcite precipitation (BICP) is a promising technique that utilizes bacteria to form calcite precipitates throughout the soil matrix, leading to an increase in soil strength and stiffness. This research investigated BICP in two types of sands under sterile and nonsterile conditions. Bacteria formation and BICP in the sterilized sand specimens are higher than those in the nonsterilized sand specimens. The development of calcite with time is initially greater for the sand specimens containing calcite. Scanning electron microscope imaging allowed the detection of cementation from calcite precipitation on the surface and pores of the sand matrix. The effects of injecting nutrient mediums and bacteria into the specimens, as well as pH of soil samples on BICP were investigated. The bearing capacity of biologically treated vs. untreated sand specimens were determined especially by laboratory foundation loading tests.
Citation Count: 11
Cementation in a matrix of loose sandy soil using biological treatment method
(Academic Journals, 2011) Gurbuz, Ayhan; Sari, Yasin Dursun; Yuksekdag, Zehra Nur; Cinar, Berat; Department of Civil Engineering
Man-made materials varying from cement-based to chemical-based have been injected into soils to improve their engineering properties (shear strength, compressibility, permeability, bearing capacity etc.). Soil type in general plays important role in determination of treatment material and method. Materials used for soil treatment might have side effects in terms of air pollution, soil or water contamination etc. during manufacturing or application. An alternative, environmentally friendly soil treatment method that is based on the use of bacteria present in soils and named Biological Treatment Method (BTM) has been used by researchers to bond particles of loose sandy soils via creation of calcite (CaCO3) generated by bacteria using urea to influence the precipitation of calcium carbonate. This study presents the results of bacterial induced cementation (BIC) in matrix of loose sandy soil. A bacterium used in this study is Sporosarcina pasteurii that is naturally present in soils and is aerobic type. The bacteria grown in laboratory environment were injected to the matrix of loose sandy soil. Subsequent nutrient mediums were introduced to specimens to accelerate the development of cementation level. Number of bacteria, pH level, temperature and amount of CaCO3 were measured during the duration of testing. Images of Scanning Electron Microscope (SEM) showed that creation of cementation from precipitation of CaCO3 on the surface and pores of soil matrix were observed for only sand samples into which nutrient was flushed on sequence of arbitrary time.
Citation Count: 15
Cementation in a matrix of loose sandy soil using biological treatment method
(2011) Gurbuz,A.; Sari,Y.D.; Yuksekdag,Z.N.; Cinar,B.; Software Engineering; Department of Civil Engineering
Man-made materials varying from cement-based to chemical-based have been injected into soils to improve their engineering properties (shear strength, compressibility, permeability, bearing capacity etc.). Soil type in general plays important role in determination of treatment material and method. Materials used for soil treatment might have side effects in terms of air pollution, soil or water contamination etc. during manufacturing or application. An alternative, environmentally friendly soil treatment method that is based on the use of bacteria present in soils and named Biological Treatment Method (BTM) has been used by researchers to bond particles of loose sandy soils via creation of calcite (CaCO 3) generated by bacteria using urea to influence the precipitation of calcium carbonate. This study presents the results of bacterial induced cementation (BIC) in matrix of loose sandy soil. A bacterium used in this study is Sporosarcina pasteurii that is naturally present in soils and is aerobic type. The bacteria grown in laboratory environment were injected to the matrix of loose sandy soil. Subsequent nutrient mediums were introduced to specimens to accelerate the development of cementation level. Number of bacteria, pH level, temperature and amount of CaCO 3 were measured during the duration of testing. Images of Scanning Electron Microscope (SEM) showed that creation of cementation from precipitation of CaCO 3 on the surface and pores of soil matrix were observed for only sand samples into which nutrient was flushed on sequence of arbitrary time. © 2011 Academic Journals.
Citation Count: 4
Evaluation of Boron Ore in Cement Production
(Taylor & Francis inc, 2012) Yesilmen, Seda; Gurbuz, Ayhan; Department of Civil Engineering
A new genre of high belite cement named boron-modified active belite (BAB) cement that was developed using byproduct of boric acid production was investigated. The cement proved superior in compressive strength and permeability characteristics in the previous studies. Long term storage of cement is known to alter the mechanical properties of concrete made with the aged cement. The article investigated the BAB cement in aged condition-stored in silos for about three years-variations of mechanical and physical properties of specimens during a one-year period. An additional comparison is also performed with specimens cast using fresh Ordinary Portland Cement (OPC) of the same grade in order to present the development of mechanical and physical properties in a qualitative manner. Lower 28 day compressive strength values are observed for BAB cement compared to OPC specimens; however, higher rate of strength development of BAB cement resulting from high belite content led to comparable long term strength values with OPC specimens.
Citation Count: 11
Interaction between assembled 3D honeycomb cells produced from high density polyethylene and a cohesionless soil
(Sage Publications Ltd, 2012) Gurbuz, Ayhan; Mertol, Halit Cenan; Civil Engineering; Department of Civil Engineering
Assembled 3D high-density polyethylene honeycomb cells, providing confinement to arrest spreading of the soil in cells and creating relatively stiff bed that redistributes footing pressure over wider area, were used in the present study to enhance load-carrying capacity and to reduce settlement of base materials under a foundation. The effects of various test parameters including width, height, number of layers of the 3D honeycomb cells, vertical distance between layers of the cells and depth of stress zone of the foundation were studied. The test results indicated that considerable improvement in the load-carrying capacity (congruent to 3.0) and reduction in settlement of the foundation (congruent to 62%) were obtained with the implementation of the single layer of the 3D cells into cohesionless soils. The optimum effective distance between two layers of the 3D cells was 0.142 times the width of foundation, the ratio of effective width of 3D cells to the foundation was about 4.2 and the depth of influence stress zone of the foundation was about two times the width of the foundation.
Citation Count: 1
The lateral response of single free headed piles in sandy soils - methods, measurements and reliability
(2009) Gurbuz,A.; Paikowsky,S.G.; Department of Civil Engineering
Piles require withstanding lateral loads from various sources such as wind, waves, traffic, earthquake, soil and water. While the Strength Limit State controls the design of axially loaded piles, serviceability often controls the design of laterally loaded piles, i.e. the applied load is controlled by the magnitude of the limiting lateral displacement. The analysis of laterally loaded piles is complicated due to the pile-soil interaction, where the lateral soil resistance developed along the pile is a function of the pile's deflection being a function of the soil's resistance. Laterally loaded piles are commonly designed using computer-based analysis methods solving the differential equation of a beam on elastic foundation that controls the load-deflection relations, utilizing what is known as p-y curves for the local spring factor-load- deflection relations. Software packages; LPile 5 Plus in which the p-y curves are constituted based on past pile load tests and soil testing results, and the Strain Wedge Model (SWM) in which the p-y curves are derived from the assumption of a wedge failure zone ahead of the pile, were used in this study. Both analyses were employed in a parametric study, calculating the piles' top lateral forces required to obtain given lateral displacements ranging from 0.5 in to 3 in (12.7 to 75.6 mm) in 0.5 in intervals. The results for the two methods are compared and examined against a database of laterally load tested piles. Factors affecting the performance of the analyses are discussed. Copyright ASCE 2009.
Citation Count: 0
Long term behavior of staged construction of a dam on soft clay
(2009) Gurbuz,A.; Dincergok,T.; Department of Civil Engineering
The staged-construction of Alibey Dam on the Alibey Creek near Istanbul in Turkey started in 1968 and ended in 1983 to generate a reservoir to meet up the water requirement of Istanbul. Alibey Dam had a geotechnical challenge of a 29.5 m high zoned earth-fill dam on 33-m-thick soft alluvial foundation and occasional sand bands. Alibey Dam consists of upstream cofferdam, downstream cofferdam, main body and test embankment. Before the construction of Alibey Dam, both extensive field and laboratory tests were performed to determine the engineering parameters of foundation soils. During the construction and approximately 30 years after the construction of the dam, the behavior of the foundation soils and the embankments were monitored using extensive instrumentation placed into the foundation soils and the dam body. All available performed and measured data before the construction, during the construction and approximately 30 years after the construction are collected and presented here to shed light on the staged construction of the dam on soft clay. © 2009 IOS Press.