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    A review on bike-sharing: The factors affecting bike-sharing demand
    (Elsevier Ltd, 2020) Eren, Ezgi; Uz, Volkan Emre
    This paper aimed to address the need for a comprehensive review on the factors affecting bike-sharing demand to bridge the gaps by deepening the knowledge on weather, built environment and land use, public transportation, station level, socio-demographic effects, temporal factors, and safety. This article evaluates recent studies on station-based bike sharing in literature and seeks answers to two main research questions: First, how do the weather conditions, built environment and land use, public transportation, socio-demographic attributes, temporal factors, and safety affect the bike-sharing trip demand? Second, what are the most commonly used factors in literature affecting trip demand? For this purpose, an overview of the factors affecting trip demands has been established to evaluate the performance of Bike-Share Programs(BSPs) comprehensively. The results can provide reliable estimate for planners or decision-makers in understanding the key factors contributing to bike-sharing demand. The information obtained from this overview can also be a guideline for BSP planners, policymakers and researchers to improve the efficiency of BSPs. © 2019 Elsevier Ltd
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    ATIK BİTKİSEL YEMEKLİK YAĞLARIN SAF BİTÜM ÖZELLİKLERİNE ETKİSİNİN ARAŞTIRILMASI
    (2018) Gökalp, İslam; Özinal, Yağmur; Uz, Volkan Emre
    Bitkisel yemeklik yağlar, insanların temel besin öğesinden birisini oluşturmaktadır.Sadece Türkiye’de değil, tüm dünyada insan nüfusu her geçen gün artmakta ve budaha fazla temel besin malzemesine gereksinim duyan insan topluluğudoğurmaktadır. İnsanların kullandıkları yağ miktarındaki artış, beraberinde doğalolarak tehlikeli atık sınıfında yer alan atık bitkisel yemeklik yağlar (ABYY) sorununuortaya çıkarmaktadır. Yönetmenliklerin öngördüğü yöntemlerle toplanmalarının,taşınmaların ve bertaraf edilmelerinin sağlanamaması durumda, ilgili belde veyönetimleri için ciddi çevresel problemlere neden olabilmektedir. Bu çalışmada,ABYY’lerin bertaraf etme yöntemlerine alternatif bir yaklaşımda bulunulmuş vebitümde bir katkı maddesi olarak kullanılabilirliği ve bitüm özeliklerine olan etkisiaraştırılmıştır. Bu kapsamda, 70/100 penetrasyon sınıfına sahip bitüm ve ABYYtemin edilmiştir. % 2, 4, 6, 8 ve 10 (Bitüm ağırlığınca) oranında ABYY bitümeeklenmiş, homojen bir karışım elde edilmesi için standart bir metotlakarıştırılmıştır. ABYY katkılı bitüm ve taze bitüm numunelerine, penetrasyon,yumuşama noktası, parlama noktası, düktilite ve iki farklı sıcaklıkta dönelViskozimetre testleri uygulanmıştır. Sonuç olarak, ABYY’lerin bitüm özeliklerinibelirgin bir şekilde değiştirdiği görülmüştür.
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    Bitumen expanding using bio-oil product of rose pulp's pyrolysis process
    (Elsevier Sci Ltd, 2020) Terzi, Serdal; Saltan, Mehmet; Armagan, Kemal; Kurtman, Akay Kurter; Karahancer, Sebnem; Eriskin, Ekinhan; Uz, Volkan Emre
    Within the study, the usability of rose pulp, which is the common waste of many industrial products produced by using rose, was examined as bitumen modification material. In order to investigate this possibility and potential benefits, waste rose pulp was subjected to the pyrolysis process to obtain the biochar, bio-oil and biogas. Since it has a viscous liquid form, the bio-oil product has been selected to modify the bitumen for this study. Supplied wet rose pulp was first dried until the water content decreases to around 10%. Afterwards, the dried rose pulp subjected to pyrolysis process for one hour at 450 degrees C after 30 min heating period. Used neat bitumen's grade was PG 64-22. Bio-oil product has been mixed 2 and 4% by weight into the bitumen at 160 degrees C for 30 min. After the modification process, bitumen performance tests have been done. Because of the analysis, it was concluded that modification did not change the bitumen grade, reduced the mixing and compaction temperature up to 8 degrees C and so saving energy. In addition, the modification increases the optimum bitumen ratio up to 5%, strength value up to 4.1%, tensile strength ratio (TSR) value up to 2.3%, and the wheel tracking depth up to 95.2% but still remains within the Hamburg wheel tracking test specification limits. (C) 2020 Elsevier Ltd. All rights reserved.
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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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    Dönel Kavşak Geometrik Elemanlarının Kavşak Güvenliği Üzerine Etkisinin Literatür Işığında Değerlendirilmesi
    (2021) Özinal, Yağmur; Uz, Volkan Emre
    Ulaşım sistemi içerisindeki trafik akımının güvenli ve etkin biçimde işlemesi üzerinde büyük rolü bulunan kavşaklar, faaliyet alanı,geometrik özellikleri ve denetim şekillerine göre farklı kategorilere ayrılmaktadır. Kontrollü eş düzey kavşak kategorisindeki dönelkavşaklar, trafik akımının merkezi ada etrafında yönlendirildiği ve ada içerisindeki araçların ilk geçiş hakkına sahip olduğu kavşaktipidir. Dönel kavşakların her bir geometrik elemanı kavşağın işleyiş, kapasite ve güvenliği üzerinde rol oynamaktadır. İyitasarlanmış bir dönel kavşak, araçların dolaşım yolu boyunca hızlarının sabit kalmasını sağlayarak kavşak güvenliğinin optimizeedilmesine yardımcı olur. Bu makalede, dönel kavşakların geometrik elemanlarının kavşak güvenliği üzerine etkilerinin incelendiğiçalışmalar derlenmiştir. Dönel kavşakların her bir geometrik elemanın literatürde yer alan çalışmalar ışığında kavşak güvenliğiyleolan ilişkileri ve bazı ülkelerin standart/kılavuzlarında yer alan tasarım kriterleri incelenmiştir. Bu çalışmayla amaçlanan, yapılmışçalışmalar doğrultusunda, dönel kavşak geometrik elemanlarının tasarımlarının kavşak güvenliği açısından hayati önem taşıdığınıortaya koymaktır. Ülkemizde bu konuyla ilgili olarak daha önce yapılmış detaylı çalışmalara rastlanılmaması çalışmamızınmotivasyon kaynağı olmuştur. Ülkemizdeki dönel kavşakların hangi standart/kılavuzlara bağlı olarak yapıldığı ile ilgili bilgiyetersizliği olduğu da görülmektedir. Çalışma sonucunda dönel kavşaklardaki güvenliğin sağlanabilmesi için geometrikelemanların birbirleriyle etkileşim içinde ve uygun fiziki boyutlarda tasarlanması gerektiği belirtilmiştir. Ayrıca trafik güvenliğibakımından ülkemizde bu konuyla ilgili ivedilikle çalışmalara başlanılması ve ülkemiz koşullarına özgü tasarım standart/kılavuzuhazırlanması gerektiği ifade edilmiştir.
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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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    Experimental investigation of the stabilization performance trends of two geogrids constructed on low bearing capacity subgrade
    (Korean Geosynthetics Society, 2018) Gökova, Süleyman; Saltan, Mehmet; Terzi, Serdal; Tutumluer, Erol; Uz, Volkan Emre; Karaşahin, Mustafa
    Experiments were carried out on real size samples in the laboratory to investigate the geogrid stabilization performance in highway pavement applications. A moving wheel load was applied on representative pavement samples constructed on low bearing capacity subgrade with and without geogrids. Two types of geogrids were used to construct the pavement sample configurations. Resistance to plastic (permanent) deformation was recorded as a performance indicator to compare structural performance trends of the pavement samples. For this objective, surface deformations were measured after certain wheel load repetitions. Rut depths were calculated from surface profiles measured with a laser profiler. Layer thicknesses were varied to observe differences in the deformation trends. When appropriate conditions were reached in the trial configurations, all layer thicknesses were kept constant during the tests. The two geogrid types constructed with the same granular materials and varying layer thicknesses were used in different layer interfaces to search for the most optimum solution. According to the study findings, the use of geogrid over soft subgrade with low CBR values has been shown to extend the life of the pavement by reducing the rut depth. Copyright © 11th Inter. Conf. on Geos. 2018, ICG 2018. All rights reserved.
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    Farklı Tür Agregalarla Üretilen Yüzeysel Kaplamaların Kayma Direnci Performanslarının İncelenmesi
    (2017) Uz, Volkan Emre; Gökalp, İslam
    Bu çalışmada, doğal agregalardan ve cüruflardan oluşan farklı agrega tür ve tane boyutlarında ve gradasyonunda üretilen yüzeysel kaplamaların kayma direnci performansı araştırılmıştır. Bu amaç doğrultusunda, öncelikle her bir agreganın fiziksel, mekanik ve kimyasal özelikleri TS EN standartlarına göre belirlenmiştir. Sathi kaplama örnekleri; 2-19 mm aralığında değişen yedi farklı tane boyutunda hazırlanırken, harç tipi kaplama örnekleri ise üç farklı gradasyonda üretilmiştir. Üretilen yüzeysel kaplama numunelerinin, kayma dirençleri ve makro dokuları sırasıyla ASTM E 303 ve ASTM E 965 standartları göre belirlenmiştir. Yüzeysel kaplamaların kayma direnci karşılaştırıldığında, her boyut ve gradasyonda cüruflar ile üretilmiş olan numunelerin, doğal agrega ile üretilmiş olan numunelerden daha iyi performans gösterdiği gözlenmiştir
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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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    Investigation of chip seal performance under cold climate conditions
    (Walter De Gruyter Gmbh, 2016) Karasahin, Mustafa; Guerer, Cahit; Saltan, Mehmet; Taciroglu, Murat V.; Uz, Volkan Emre
    The chip seal is an economical type of asphalt pavement that was constructed for single-or double-layer aggregate-bitumen. Chip seals are applied to prime-sealed granular pavement surfaces in order to waterproof the surfaces of sub-layers, produce smooth and high-skid-resistance surfaces for vehicles and protect pavements against the detrimental effects of traffic and climate. Unlike bituminous hot mixtures, numerous factors can affect the performance of chip seal. One of the most important factors is climate. The aim of this study is to determine the performance variation of chip-sealed pavements under cold climate conditions. Three different chip-sealed roads in Erzurum, which is in one of the coldest regions of Turkey, were examined with non-destructive tests. Sandpatch, British pendulum, light weight deflectometer and dynamic cone penetrometer tests were performed. Chipsealed pavements' densities and surface temperature variation and base courses layer's thicknesses were also measured, and deteriorations were observed and scored by researchers. Test results showed that flushing due to the higher temperatures during the short summer season, deficiency of the base course's bearing capacity and moisture in the base course are the most important causes of deterioration in this type of chip seal, and the chip seals in this region must be resealed in <1 year because of the premature deterioration.
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    Pürüzlendirme Uygulamasının Kaplama Yüzeyi Makro Dokusu Üzerine Olan Etkisinin Araştırılması
    (2017) Gökalp, İslam; Uz, Volkan Emre
    Türkiye Karayolları Teknik Şartnamesi (KTŞ), taş mastik asfalt (TMA) ve asfalt betonu (AB) tabakalarında yüksek cilalanma direncine sahip (PSV>=50) agregaların kullanılmasını zorunlu kılmıştır. 2013 yılında, KTŞ'de yüksek cilalanma direncine sahip agregaların temininde yaşanan zorluklardan dolayı belirli bölgeler için ayrıcalık tanınmış ve yukarıda belirtilen kaplama tabakaların inşaatında PSV>=40 değerine sahip agregaların kullanımına izin vermiştir. Ancak bu durumda, 1-3 mm boyutuna sahip magmatik agregalar ile kaplama üzerinde yüksek kayma direncine sahip yüzey elde etmek için pürüzlendirme uygulama yapılması zorunlu tutulmuştur. Bu uygulamada, pürüzlendirme malzemesi 1,5-2 kg/m2 olacak şekilde sıcak karışım üzerine birinci ve ikinci silindiraj arasında uygulanılması istenmiştir. Ancak, KTŞ'de farklı yüzey dokularına sahip TMA ve AB kaplama tabakaları için de aynı uygulama önerilmektedir. Bu çalışmada, farklı oranlarda serpme miktarının (1,75, 2,50 kg/m2) ve agrega boyutunun (1-3, 2-5 mm) kaplama makro dokusuna olan etkisi araştırılmıştır. Dere malzemesi ve metal cürufu gibi farklı agrega türlerinin kullanılabilirliği de ayrıca incelenmiştir. Tüm agregaların özelikleri belirlenmiş ve KTŞ limitleri ile karşılaştırılmıştır. TMA ve AB yüzey dokusunu temsilen, Tip-II ve Tip-III harç tipi kaplamalar kullanılmıştır. Sonuç olarak, pürüzlendirme uygulamasının kaplama makro dokusunda belirgin değişiklere yol açtığı ve bu değişim oranının kullanılan agrega türüne, uygulama miktarına ve boyutuna bağlı olarak farklılık gösterdiği görülmüştür
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    Relationship Between Abrasion, Fragmentation and Thermal Weathering Resistance of Aggregates: Regression and Artificial Neural Network Analyses
    (Springernature, 2023) Goekalp, Islam; Kaya, Orhan; Uz, Volkan Emre
    For being used in pavement construction, properties of aggregates must satisfy the minimum requirements specified by highway agencies or institutions. The properties of the aggregates are determined by many tests lasting anywhere between a couple of hours to a few weeks depending on the type of the test. If good correlations can be established between the tests taking longer time and the ones taking comparably shorter time, there might be no need to conduct these longer time-taking tests for the sake of time. The aim of this study is to investigate the relationships between abrasion, fragmentation, and thermal weathering resistances of different aggregate types. To accomplish this aim, aggregates with different origins (natural and slags) were tested and correlative analyses utilizing regression analysis and artificial neural network (ANN) models were performed to establish relationships between the results of these test methods. It was found that good correlations can be established especially with ANN models and significant amount of time and effort can be saved with these developed models.
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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 and gradation on fragmentation resistance performance: Testing and evaluation based on different standard test methods
    (Elsevier Ltd, 2020) Gökalp, İslam; Uz, Volkan Emre
    Aggregates used in construction works must be sufficiently durable in that long-lasting performance. Aggregates are exposed to external loads and harsh environmental conditions in all processes from manufacturing to use in the field. These cause fragmentation, abrasion, polishing of aggregates. Aggregates in different origin show distinct characteristics based on their chemical formation and the physical features at that moment such as shape and size. To make the properties of aggregates clear, series of test are implemented. Fragmentation resistance (FR) test using Los-Angeles apparatus is one of test in the series used to identify the strength of aggregate. This test can be performed based on different standard test methods such as the standard by American Society for Testing and Materials, ASTM and European Committee for Standardization, CEN, which are focused on in the current study. However, these two standards differ from each other in a few aspects such as aggregate size and mass of aggregate and charges. Based on these fundamental differences, a question has arisen about the effect of the aggregate size on the FR based on different origin. Respectively, this study was established on this case by using related ASTM and CEN standard. To achieve the answer, different sources of aggregates including metallurgical slags were supplied and a series of tests were performed on them to identify their physical, mechanical and chemical properties. Thereinafter, FR tests were performed in five different grain size distributions ranging from 2.36 to 37.50 mm according to ASTM C131 and CEN 1097-2. The results showed that aggregates in different origin, as expected, exhibited different FR values. However, there exist significant differences between FR values of aggregates tested in different grain size although the materials are the same. Considering the grain size of aggregate being used in the related works, testing and evaluation of FR performance of aggregate will be more accurate and robust. Therefore, the authors recommended that following ASTM standard for testing FR due to the optional grading will give more precise vision about aggregate's performance. © 2019 Elsevier Ltd
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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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    Use of glass waste as mineral filler in hot mix asphalt
    (Walter de Gruyter GmbH, 2015) Saltan, Mehmet; Öksüz, Betül; Uz, Volkan Emre
    The use of resources is increasing due to continuous increase in world population and rapid industrialization, while natural resources are being exhausted day by day. Usage of waste materials or by-products in highway construction has substantial environmental and economic benefits. In this study, the usage of cullet and waste glass bottle dust as mineral filler material in hot mix asphalt as an alternate to traditional crushed stone dust was investigated. Optimum bitumen content was determined by the Marshall mix design method by using six different bitumen contents (4.0%, 4.5%, 5.0%, 5.5%, 6.0%, and 6.5%). With the optimum bitumen content, three different mineral filler types (cullet, glass bottle waste, and stone dust) and six different filler ratios (4%, 5%, 6%, 7%, 8%, and 9%) were used to prepare asphalt mixture samples. Samples were performed using the Marshall stability test, and the results were compared. It is concluded that cullet and glass bottle waste can be used in asphalt mixtures as a mineral filler alternate to crushed stone dust if the economic and environmental factors favor it. © by De Gruyter 2015.
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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.