Yazar "Gokalp, Islam" seçeneğine göre listele

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    Comparative laboratory evaluation of macro texture depth of surface coatings with standard volumetric test methods
    (Elsevier Sci Ltd, 2017) Uz, Volkan Emre; Gokalp, Islam
    In this research, macro texture depth of surface coatings including chip seals and slurry seals were evaluated with two volumetric test methods. Chip seals and slurry seals, one hundred in total, were manufactured with different aggregate types and grading sizes. Mean texture depths (MTDs) of each sample were computed via sand patch and outflow meter tests according to ASTM E 965-12 and ASTM E 2380-12, respectively. Applicability of both test methods was examined and relative differences in MTDs for chip seal and slurry seal samples were determined as 21% in average. As a result, each test method is able to specify the MTDs with increasing aggregate sizes; whereas 6 mm MTD can be identified as a threshold for implementation of outflow meter test. (C) 2017 Elsevier Ltd. All rights reserved.
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    Effect of Aggregate Microtexture Losses on Skid Resistance: Laboratory-Based Assessment on Chip Seals
    (Asce-Amer Soc Civil Engineers, 2020) Ergin, Basri; Gokalp, Islam; Uz, Volkan Emre
    Skid resistance has long been recognized as one of the most important pavement surface characteristics for safer roads. Evaluation of skid resistance of pavement is crucial but it is not an easy task. Moreover, it depends on numerous parameters such as pavement type, materials and tire properties, and environmental conditions. Aggregate texture changes significantly according to its origin and affects the skid resistance performance of the road surfaces. In the current study, chip seal samples were produced with different aggregate types at different polishing levels to evaluate the effect of aggregate microtexture on skid resistance performance. The Micro-Deval (MD) test device was utilized to obtain polished aggregates. Different polishing levels were provided by distinct revolutions of the MD drum. To monitor the change in aggregate surface with the polishing process, aggregates were monitored by scanning electron and optical microscopes at each level. Mean texture depths (MTDs) of chip seals were determined with outflow meter test. On the other hand, dynamic friction tester (DFT) and British pendulum tester (BPT) were implemented for assessment of skid resistance according to the relevant ASTM standards. Skid resistance and texture measurements were further used to identify the International Friction Index (IFI) for each sample. In addition, a correlational analysis was conducted between DFT and BPT results, and variable relationships were set for different speeds. Consequently, better skid resistance values were observed for chip seals produced by slags than the ones with natural aggregates at each polishing level. After fulfilling the economic and environmental requirements, using metallurgical by-products is recommended for long-lasting skid-resistant pavement surfaces. Additionally, it can be concluded that MD apparatus may be considered an easier, more cost-effective, and faster way to assess the polishing resistance of aggregates.
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    Feasibility of Using 4th Power Law in Design of Plastic Deformation Resistant Low Volume Roads
    (Elsevier Science Bv, 2016) Uz, Volkan Emre; Saltan, Mehmet; Gokalp, Islam
    A low volume road (LVR) structural design has two phases: first one is selection of appropriate construction materials and second is the determination of layer thicknesses under the certain traffic and environmental conditions with considering the subgrade bearing capacity. Pavements are prompted to serve the traffic without reaching the terminal serviceability index over its design life. Rut accumulation (plastic deformation) is the most common pavement deterioration type of flexible pavements. Therefore the main goal of the design is prevent rutting. Many low volume road design manual assume that plastic deformation occurs only in subgrade. Construction of overlying layers by selective high performance materials according to the related material and construction specifications is the reason of this assumption. In fact, the assumption is not much reasonable especially for with no, or thinly overlaid low volume road pavements, where the major structural strength is comprised of unbound granular pavement materials and where the principal distress mechanism is rutting in the aggregate layers. Subgrade bearing capacity and the traffic are the main input parameters in the design stage of low volume roads. Subgrade bearing capacity is expressed with California Bearing Ratio (CBR) or Resilient Modulus (Mr). The traffic term is determined by Equivalent Standard Axle Load (ESAL) repetitions which is often admitted as 80 kN single axle load. Although it is not too difficult to determine an axle load for an individual vehicle, it becomes quite complicated to determine the number and types of axle loads that a particular pavement will be subjected over its design life. For calculation of Load Damage Factors of different vehicle types, which have various axle load and configurations, a generalized fourth-power law has been used for more than a half century. The objective of this study is to indicate the limitations and difficulties faced on reliably applying a power law relationship in design of LVRs with no, or only thin seals. If a power law relationship to be used due to its simplicity, several parameters must be considered in selection of the power value. Such as stress dependent behavior of unbound granular materials and the selected distress type.
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    Sustainable Production of Aging-Resistant Bitumen: Waste Engine Oil Modification
    (Asce-Amer Soc Civil Engineers, 2021) Gokalp, Islam; Uz, Volkan Emre
    Using waste engine oil (WEOIL) within bituminous binders might be one of the most energy-efficient and sustainable means of producing aging-resistant bitumen due to the antioxidative properties of WEOIL. In this paper, the use of WEOIL to obtain aging-resistant bitumen and its optimum rates for short and long terms were investigated. In this regard, a base bitumen was modified with WEOIL in certain rates ranging from 1% to 5% by weight of bitumen. Then base and oil-modified bitumen samples were subjected to aging. To define the changes in rheological properties of bitumen based on rutting, fatigue, and thermal cracking resistance, dynamic shear and bending beam rheometer tests were performed on each sample. Furthermore, an aging index (AI) analysis was performed for both the short- and long-term aging conditions to express the effect of WEOIL on aging resistance of the bitumen. According to the AI analysis, short-term-aging-resistant bitumen is obtained by adding 3.5% WEOIL to the base bitumen, while a 5.8% contribution rate is required to avoid the long-term aging effect. Moreover, the increase in rate of WEOIL content improved the low-temperature cracking resistance. Consequently, utilizing WEOIL for production of aging-resistant bitumen can provide environmental and economic benefits based on conservation of natural resources and waste recycling.
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    Sustainable recovery of waste vegetable cooking oil and aged bitumen: Optimized modification for short and long term aging cases
    (Pergamon-Elsevier Science Ltd, 2020) Uz, Volkan Emre; Gokalp, Islam
    [Abstract Not Available]
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    Technical and environmental evaluation of metallurgical slags as aggregate for sustainable pavement layer applications
    (Elsevier, 2018) Gokalp, Islam; Uz, Volkan Emre; Saltan, Mehmet; Tutumluer, Erol
    The paper examines physical, mechanical and chemical properties of slags, by-products of the metal industry, and evaluates their suitability for use as aggregates in pavement layers for the sustainability to be achieved in road construction. Samples of both metallurgical slags (steel and ferrochromium slags) and natural aggregates (limestone, basalt, and boulder) were obtained to determine their physical, mechanical, chemical properties through laboratory testing. Leaching tests and Inductive Coupled Argon Plasma Mass Spectrometry analyses were also conducted on the slags to determine whether they posed any detrimental effects on the environment. In addition, scanning electron microscope was utilized to determine the surface roughness of aggregates. The slag properties determined were compared to certain limits provided in the Highway Technical Specifications (HTS) and Waste Disposal Regulations (WDR) of Turkey. In conclusion, physical and mechanical properties of slags satisfied the HTS requirements and leaching test results showed that the slags studied were inert materials based on WDR. Therefore, not only economic and environmental but also technical benefits can be provided by utilizing slags in pavement construction as a sustainable alternative. (C) 2017 Elsevier Ltd. All rights reserved.
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    Testing the abrasion resistance of aggregates including by-products by using Micro Deval apparatus with different standard test methods
    (Elsevier Sci Ltd, 2016) Gokalp, Islam; Uz, Volkan Emre; Saltan, Mehmet
    Structural and functional performance of a pavement is affected by aggregate properties; therefore, characterizing the aggregate properties is crucial. Series of tests are conducted on road construction aggregates, not only for selection of appropriate aggregate which meets related specifications, but also for estimation of the long-term performance of aggregates particularly for economic and safety reasons. Micro-Deval (MD) test is the most common test used for qualifying aggregates on behalf of resistance to wear. This paper compares the European (EN) and US (ASTM) standard methods for the MD test. For comparison, MD tests were conducted on six different natural aggregates and four different by-products according to different standards. Three types of limestone, two types of basalt and one boulder were used as natural aggregates, and three types of Electric Arc Furnace steel slag and one Ferrochrome slag were selected as by-products. Physical, mechanical, and chemical properties of the aggregates were also determined. The test results show that both methods produce different mass losses with different aggregate type and grain size. The percentage loss in mass which is referred to as Micro Deval Coefficient MDC with EN 1097-1 method is higher than all gradations of ASTM method except for Ferrochrome slag. Moreover, the results obtained with ASTM test method show that MDC values are increasing with increase of grain size in natural aggregates but, this tendency is not observed in slags. (C) 2016 Elsevier Ltd. All rights reserved.
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    The effect of aggregate type, size and polishing levels to skid resistance of chip seals
    (Springer, 2017) Uz, Volkan Emre; Gokalp, Islam
    The objective of this study was to investigate skid resistance performance of chip seal samples, which were produced at laboratory conditions, with different aggregate types, sizes and polishing levels. Three different origins such as limestone, basalt and boulder and four by-products including electric arc furnace and Ferrochrome slags were supplied to prepare chip seals. Physical, mechanical and chemical properties of each aggregate were determined. Micro-Deval test device was utilized to obtain polished aggregates at different levels with five different revolutions changing from 5250 to 52,500. Following the polishing process, aggregates were sieved into four different particle sizes ranged from 4.00 to 12.50 mm to manufacture single size chip seals. The aggregate surface at certain polishing levels was monitored via scanning electron microscope. Sand patch method and British Pendulum Test method were used to measure the surface macro-textures and skid resistance performance of each chip seal sample according to ASTM E 965 and ASTM E 303, respectively. In this study, skid resistance performance of each chip seal sample was evaluated with macro and micro textures. The results showed that micro-texture is more significant feature than the macro-texture in skid resistance. The chip seal samples produced with slags show better skid resistance than those produced with natural aggregates. Dependently, utilizing slags in surface coating applications does not only ensure environmental and economic benefits, but also provides high skid resistant pavement.
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    The waste transparent nylon modified bitumen properties: Experimental assessment on physical, rheological properties and storage stability
    (Elsevier Sci Ltd, 2021) Gokalp, Islam
    The populations consume considerable amount of plastic based materials and accordingly the waste of them increases on daily basis. It is possible to recycle plastic waste with using different technological processes that require excellent energy, cost, labor, and produce significant amount of greenhouse gas. However, the reverse of this situation can also be possible. Using the waste as a modifier in bitumen to improve their characteristics may be an eco-friendly and cost-effective alternative method for recycling. In this regard, this study was established on investigation the effect of Waste Transparent Nylon (WTN) with different rate from 0.5% to 3.0% by weight in bitumen with 0.5% increment to be used a modifier for sustainable recycling. To achieve it, series physical and rheological test were performed on the bitumen samples to determine the changes occur in properties of them. Physical test methods including penetration, softening point, viscosity and flashing point were conducted on the unaged samples. On the other hand, rheological test methods including dynamic shear resistance and bending beam rheometer tests were performed on the unaged and aged samples. To determine compatibility between the WTN and bitumen, storage stability tests were conducted. Testing results showed that modifying bitumen with WTN changes bitumen characteristics, significantly. It was found that there are certain increase in softening point, viscosity and flashing point, while decrease in penetration values. Rheological assessment, on the other hand, indicated that there are obvious increase in rutting and thermal cracking resistance, while reduce in fatigue resistance of the bitumen sample. However, WTN modified bitumen samples did not show storage stability except of the one done with 0.5%. Overall, the results pointed out that bitumen modification with WTN can be one of sustainable solution for both recycling of WTN and improvement of bitumen properties. While it is used in bitumen, certain benefits to economy and environment can be achieved
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    Utilizing of Waste Vegetable Cooking Oil in bitumen: Zero tolerance aging approach
    (Elsevier Sci Ltd, 2019) Gokalp, Islam; Uz, Volkan Emre
    Aging is simply the oxidation of bitumen and as a result of aging significant changes are observed in physical, rheological and chemical properties of bitumen binders. However, aging can also be prevented by using some anti-aging agents in bitumen. The main question addressed in this paper is assessment the effect of using Waste Vegetable Cooking Oil (WVCO) as an anti-aging agent in base bitumen. The response of WVCO modified bitumen against both short (SHT) and long-term (LOT) aging and high and low temperature behavior of base and aged samples are evaluated with physical and rheological tests including penetration, softening point, viscosity, dynamic shear rheometer and bending beam rheometer. To determine the optimum WVCO rate to prevent SHT and LOT aging, a novel approach is specified based on Aging index (AI), which is calculated for each aging case and test method, individually. Zero value of AI is defined as Zero Tolerance Aging (ZTA) and the rate of WVCO corresponding to that value is determined as Zero-Tolerance Aging Dosage (ZTAD) for SHT and LOT aged bitumen. The results showed that different ZTAD values are obtained for each aging cases and evaluation methods. When considering the evaluation methods, higher ZTAD values are observed in physical tests than the rheological ones. Moreover, higher amount of WVCO is required to prevent long term aging in physical assessment, while aging term effect is not apparent in rheological tests. (C) 2019 Elsevier Ltd. All rights reserved.