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Öğe ANNFAA: artificial neural network-based tool for the analysis of Federal Aviation Administration's rigid pavement systems(Taylor & Francis Ltd, 2022) Tarahomi, Adel; Kaya, Orhan; Ceylan, Halil; Gopalakrishnan, Kasthurirangan; Kim, Sunghwan; Brill, David R.Three-dimensional Finite Element (3D-FE) stress computations involved in the current rigid airport pavement design methodology, are time consuming when considering top-down cracking failure mode. In this study, Artificial Neural Network (ANN) models are integrated into a tool called ANNFAA to replace such 3D-FE computations. ANNFAA makes use of the best ANN models developed in MATLAB for 156 different airplanes without requiring any additional software installation or cumbersome learning of a new program. Within ANNFAA development, about 4,000 of 3D-FE simulations and many ANN models have been developed for each of these airplanes. Three useful tools were also developed using C# and MATLAB for implementing the 3D-FE analysis, post-processing the results, training the ANN models, and determining accuracy and performance of the ANN models. ANNFAA provides an accurate and rapid procedure for practitioners, engineers, and researchers for computing the critical stress responses associated with top-down cracking in multiple-slab rigid airfield pavements. This should make pavement design and analysis more practical, especially when a significantly large number of different cases that include top-down cracking failure mode are investigated. Also, this will help when currently used bottom-up cracking mode in the FAA standard rigid pavement design procedures is being considered in a design.Öğe Comparative Design and Economic Analysis of Asphalt and ConcreteOverlays for Airfield Pavements(2020) Kaya, OrhanOverlays for airfield pavements are one of the cost effective and efficient pavement rehabilitation options. In this study, the Federal Aviation Administration’s state-of-the-art mechanistic-empirical overlay design methodology (FAARFIELD) was explained, design examples using FAARFIELD version 1.42. for both concrete and asphalt overlays were presented, and the results of these examples were compared. For the overlay design scenarios on existing asphalt surface layers, it was found that, overlay thickness decreases, as existing asphalt surface layer thickness increases, and calculated concrete overlay thicknesses were higher than calculated asphalt overlay thicknesses for the same existing asphalt surface layer thicknesses. On the other hand, for the overlay design scenarios on existing concrete surface layers, both asphalt and concrete overlay thicknesses were found to be very similar to each other. Based on FAARFIELD-calculated overlay thicknesses, an economic analysis was carried out to find out the most economic overlay design options for a variety of design scenarios. Although for some overlay cases concrete overlay design thicknesses were found to be higher than asphalt overlay design thickness, cost of concrete overlays was found to be less than that of asphalt overlays. This is because unit cost for concrete materials is less than that for asphalt materials. Incorporating a state-ofthe-art mechanistic-empirical overlay design for airfield overlay pavements as well as considering local cost in the economic analysis to determine which type of overlay would be a more suitable option for a variety of pavement design cases would be very beneficial to Turkish airfield pavement design practices.Öğe Comprehensive evaluation of transverse joint spacing in jointed plain concrete pavement(Pontificia Univ Catolica Chile, Escuela Construccion Civil, 2022) Kaya, OrhanTransverse joint spacing is one of the fundamental input parameters in structural design of jointed plain concrete pavement (JPCP). It has to be determined considering many factors to produce a well-performing and cost-effective JPCP. In this study, a comprehensive evaluation of transverse joint spacing in JPCP was carried out based on the followings: (1) guidelines based on previous studies, the Federal Highway Administration and the American Concrete Pavement Association recommendations were summarized; (2) empirical and mechanistic-empirical (M-E) pavement design methodologies were reviewed; (3) current state highway agency practices in USA were surveyed as part of this study and the survey results were documented; (4) effects of joint spacing on JPCP performance were evaluated based on field observations; and (5) lastly, an economic analysis was performed to evaluate effects of joint spacing on life-cycle costs. This study demonstrated that a joint spacing between 15-18 ft (4.6-5.5 m) seems to be provide a safe zone for both performance and cost effectiveness.Öğe Development of Neural Network-Based Asphalt Mix Design Parameters Prediction Tool(Springer Heidelberg, 2023) Kaya, OrhanMix design of asphalt concrete is carried out in order to produce a mixture of asphalt bitumen and aggregate that satisfies both minimum design requirements and cost-effectiveness. Marshall mix design, similar to other mix design methods, aims to determine an optimum mix for a given design criteria, having an optimum bitumen content, and has still been one of the most used asphalt mix design method in the world. Marshall mix design procedure requires significant amount of time and skilled workmanship for lengthy laboratory experiments. Time required for the mix design may negatively affect construction schedule especially during the peak construction season. In Marshall mix design procedure, optimum bitumen content is determined based on Marshall stability and flow test results, and other volumetric properties of the mixes. Prediction models that quickly predict all required Marshall mix design parameters based on very few numbers of input parameters requiring significantly less amount of time to obtain compared to the time needed to obtain all Marshall mix design parameters through lengthy laboratory experiments could be quite useful. In this study, artificial neural network-based prediction models based on the data of 200 asphalt mixes designed for asphalt wearing course, obtained from 5th district of the General Directorate of Highways of Turkey, were developed to predict all required Marshall mix design parameters. As part of the paper, a Microsoft Excel Macro-based tool, to be potentially used by 5th district of the General Directorate of Highways of Turkey, was also developed that makes prediction of all required mix design parameters for any given mix in seconds using the developed models and very few numbers of user-defined input parameters requiring significantly less amount time to obtain so that optimum bitumen content could be quickly determined. This will significantly reduce the amount of time and other resources required to determine optimum bitumen content.Öğe Development of Pavement Performance and Remaining Service Life Prediction Tools for Iowa Jointed Plain Concrete Pavement Systems(Asce-Amer Soc Civil Engineers, 2023) Kaya, Orhan; Citir, Nazik; Ceylan, Halil; Kim, Sunghwan; Waid, Danny R.Moving Ahead for Progress in the Twenty-First Century (MAP-21) requires US state highway agencies (SHA) to utilize performance-based approaches in their pavement management decision-making processes, and use of a remaining service life (RSL) model would be one of such performance-based approaches for facilitating the pavement management decision-making process for SHAs. In this study, statistical and artificial neural network (ANN)-based pavement performance and RSL models were developed for Iowa jointed plain concrete pavement systems (JPCP) using actual pavement structural, traffic, construction history, and pavement performance records obtained from the Iowa Department of Transportation pavement-management information system database. While both models were found to be potentially useful for project and network level performance and RSL predictions, statistical and ANN-based models were respectively found to be more suitable for project and network level analysis. Using these models, efficient Microsoft Excel-based automation tools were created to predict future performance of a JPCP section and estimate RSL values based on predicted future performance and threshold limits for the performance indicators. Consequence analysis was also conducted to investigate the impact of traffic and preservation treatment (diamond grinding) on the RSL of a JPCP. The tool, also capable of estimating realistic pavement pretreatment and posttreatment performance and RSL, could be successfully used as part of performance-based pavement management strategies and helping decision-makers make better-informed pavement management decisions to properly allocate agency resource expenditures. Moreover, this study provides a better understanding of RSL and the factors that influence both the project and network level RSL.Öğe Estimating local pavement performance and remaining service interval using neural networks-based models and automation tool(Taylor & Francis Ltd, 2024) Citir, Nazik; Kaya, Orhan; Ceylan, Halil; Kim, Sunghwan; Waid, DannyThis study introduces an integrated approach to enhance county pavement management, emphasising operational efficiency in determining the Remaining Service Interval (RSI) for rigid and flexible pavements. It establishes a robust methodology for systematically processing raw county road data through dynamic segmentation and summarisation to create a structured pavement database. It also incorporates innovative approaches and input configurations in employing Artificial Neural Networks (ANNs) to predict current and future county pavement performance indicators, including International Roughness Index (IRI), rutting, transverse, and longitudinal cracks, even with limited data. Evaluation of the ANN models on independent county road databases exhibited high prediction accuracies (0.86 < R-2 < 0.99), varying with specific performance indicators. The study results in an automation tool for expediting road performance estimation over multiple years. This tool seamlessly integrates the ANN models, empowering county engineers to make data-driven decisions and optimise resource allocation for effective pavement management, achieving significant cost savings.Öğe Evaluation of the Federal Aviation Administration's Rigid Airfield Pavement Cracking Failure Models(Asce-Amer Soc Civil Engineers, 2022) Kaya, Orhan; Ceylan, Halil; Kim, Sunghwan; Rezaei-Tarahomi, AdelThe Federal Aviation Administration's (FAA's) pavement thickness design software, FAA Rigid and Flexible Iterative Elastic Layer Design (FAARFIELD) uses bottom-up fatigue cracking as the only failure criterion in its rigid pavement design procedure. However, top-down cracking has also been observed in two full-scale experimental studies under some circumstances; therefore, it should be included as one of the failure criteria in the analysis and design of rigid airfield pavement systems. In this study, FAA's current rigid airfield pavement design methodology was reviewed and evaluated in great detail to better identify needs for improvements with respect to cracking failure models and to produce recommendations on how current design methodology could be improved. Critical mechanical loading and pavement response locations for top-down and bottom-up cracking failure modes were also investigated to seek identification of input scenarios where critical pavement responses at slab top are higher than those at slab bottom. The effect of temperature loading in determining which failure mode (top-down or bottom-up cracking) would be dominant in rigid airfield pavement failure was also studied. Slab thickness calculations were carried out using the same slab thickness determination steps as FAARFIELD design software (version 1.42) when top-down cracking and bottom-up cracking are specified as failure modes. Recommendations are made with respect to including the top-down cracking failure mode in rigid airfield pavement design.Öğe EXPERIMENTAL INVESTIGATION OF MECHANICAL AND ELECTROMAGNETIC PERFORMANCE OF ASPHALT CONCRETE CONTAINING DIFFERENT RATIOS OF GRAPHITE POWDER AS A FILLER TO BE POTENTIALLY USED AS PART OF WIRELESS ELECTRIC ROADS(Riga Technical Univ-Rtu, 2023) Kaya, Orhan; Annagur, Hatice merve; Altintas, OlcayThis study experimentally investigates the usability of asphalt concrete pavement containing five different ratios of graphite powder (0%, 1.25%, 2.5%, 3.75% and 5% by weight of the aggregate blend or 0%, 25%, 50%, 75% and 100% of the filler content) as a filler to be potentially used as part of wireless electric roads (ER). As part of the study, first, optimum asphalt binder content for the asphalt mixes without graphite powder was determined as 5%. Then, using the determined optimum asphalt binder content, asphalt mixes containing five different ratios of graphite powder as a filler were prepared and their mechanical and volumetric properties based on Marshall mix design methodology were evaluated. As graphite powder ratios in the asphalt mixes increased, their Marshall stability, flow, voids filled with asphalt and unit weight test results mostly decreased but their air content and voids in mineral aggregate test results increased. Possible reasons for this could be: (1) lower bulk specific gravity of graphite powder, (2) higher asphalt absorbance, (3) having greater surface area compared to that of limestone filler, and (4) weak bonds between sheet-like graphite layers. Furthermore, another batch of asphalt mixes containing five different ratios of graphite powder were prepared and tested in the frequency range of 3-18 GHz for their electromagnetic permittivity properties. It was observed in this study that, except for the specimens with 100% graphite powder ratios, transmission magnitudes of all specimens were above 50% up to 8 GHz, indicating that they had comparably high transmission magnitudes so as comparably low tangent loss values. In the frequency range of 3-13 GHz, transmission magnitudes of the specimens with 25% and 50% graphite powder ratios were consistently higher than that having no graphite powder, the ones with 25% powder ratios had the highest transmission magnitudes in most of the cases in this frequency range. Considering the mechanical, volumetric and electromagnetic property test results of the asphalt mixes with five different ratios of graphite powder, it can be concluded that the use of 25% graphite powder ratio (corresponding to 1.25% of the aggregate blend used in the mixes), has a comparably lower negative effect on mechanical and volumetric properties of asphalt mixes and has a positive effect on electromagnetic permittivity properties of asphalt mixes. Asphalt mixes produced with this graphite powder ratio can be considered to be used as part of wireless ER.Öğe Experimental Investigation of Usability of 100% Recycled Asphalt Pavement (RAP) as a Cold Patching Material in Turkey(2023) Kaya, OrhanIn this study, the usability of 100% RAP as a cold patching material (CPM) was experimentally investigated. As part of this study, first, the RAP material has been characterized to determine its binder content and particle size distribution of the extracted aggregate. Then, three sets of RAP specimens (each set has three specimens) were prepared. These specimens were conditioned at 22°C, 40°C and 45°C for three hours. Then, the specimens were compacted with 75 Marshall hammer blows. The compacted specimens were then tested for their Marshall stability, and flow at 22°C. Air contents of the test specimens were also determined . It was observed that as conditioning temperatures of the compacted test specimens increased, their Marshall stability test results increased but their flow and air content test results mostly decreased. Marshall stability test results of all three sets of specimens were well above the specification limits. Moreover, all test specimens except for only one specimen conditioned at 22°C met the flow and air content criteria. It could be concluded that 100% RAP could be used as a CPM especially above 22°C. If it is needed to be used at around 22°C, it must be ensured that it is well compacted so that its air content is below 8% for a durable and comparably long-lasting cold patching application.Öğe Experimental investigation of usability of modified asphalt binder with waste expanded polystyrene (EPS)(2023) Kaya, OrhanEPS (Expanded polystyrene) is widely used in construction and packaging industries. Unfortunately, EPS is not mostly recyclable because it might not be economically feasible to store, transport, and process EPS so that it becomes recyclable. Therefore, alternative waste management strategies are urgently needed. The main objective of this study is to experimentally investigate the potential use of waste EPS in asphalt binder modification. As part of this study, a base asphalt binder with a Penetration grade of 70/100 was modified with waste EPS in four different ratios (0%, 1.5%, 3% and 4.5%, by weight of asphalt binder). The modified asphalt binder specimens were tested based on several physical (penetration, ductility, softening points and viscosity) as well as rheological/Superpave binder grading system tests including Rolling Thin Film Oven (RTFO), Pressure Aging Vessel (PAV), Dynamic Shear Rheometer (DSR), and Bending Beam Rheometer (BBR). Based on the tests results, rheological and engineering properties of the modified asphalt binders were compared with the ones of the base binder so that effect of waste EPS addition on the properties of the base binder was evaluated; and how the Superpave binder grades of the modified binders were changed with the additions of waste EPS was discussed. It was found out that modifying asphalt binders with EPS provided them with a better rutting resistance at the expense of lowering their fatigue and low temperature cracking resistance. Overall, it could be concluded that waste EPS can be potentially used in the asphalt binder modification by paying special attention to these factors, and it should be noted that using waste EPS in the asphalt binder modification has many economic and environmental benefits.Öğe Geri Dönüştürülmüş Farklı İnşaat ve Yıkıntı Atıklarının Yol Temellerinde Kullanımının Maliyet ve Esnek Üstyapı Kalınlığına Etkisinin Araştırılması(2023) Kaya, Orhan; Ok, BahadırGünümüzde hem üretiminin sınırlı olması hem de üretim aşamalarının çevreyi tahrip etmesinden dolayı doğal kırma taş agregaya (DA) alternatif olabilecek sürdürülebilir yol malzemelerini araştırmak ön plana çıkmıştır. Bu bağlamda, bu çalışmanın amacı geri dönüştürülmüş agregaların plent miks temel (PMT) olarak kullanımının esnek üstyapı kalınlığına ve yol yapım maliyetine etkisinin araştırılmasıdır. Bu çalışma kapsamında DA ve dört farklı atık agrega PMT’de kullanılacak şekilde AASHTO 93 üstyapı tasarım yönteminde değerlendirilmiş ve üç farklı yol sınıfı, tabi zemin taşıma gücü ve trafik yoğunluğu olmak üzere (5x3x3x3) 135 farklı tasarım senaryosu için üstyapı kalınlıkları ile Karayolları 2023 yılı birim fiyatları kullanılarak yaklaşık yol yapım maliyetleri hesaplanmıştır. DA ile teşkil edilen PMT kullanıldığında toplam kaplama kalınlığının atık agregalarla teşkil edilen PMT’nin kullanılma durumuna göre daha az olduğu görülmüştür. Kaplama kalınlıklarındaki farklılıklara rağmen atık agregalarla inşa edilen yolların yapım maliyetleri DA ile inşa edilene göre daha düşük olmuştur. Kaplama kalınlığında fazla bir artış olmaması, yol yapım maliyetinin DA’ya göre daha az olması ve çevresel faydaları sebebi ile atık agregaların esnek üstyapı PMT tabakalarında kullanılma potansiyeline sahip olduğu sonucuna varılmıştır.Öğe Incorporating the Effectiveness of Preservation and Rehabilitation Techniques on Flexible Pavement Service Life Predictions Using Machine Learning Approach(Amer Soc Civil Engineers, 2021) Citir, Nazik; Ceylan, Halil; Kim, Sunghwan; Kaya, OrhanA flexible pavement network may be exposed to traffic changes over time because of detours that may cause unusually high traffic loading on some parts of the pavement sections. Such sections, therefore, need to be preserved earlier than their expected service life. This study focuses on incorporating the effectiveness of preservation and rehabilitation techniques, e.g., functional thin overlay and structural asphalt overlay on flexible pavement service life predictions using a machine learning approach. The developed models are capable of estimating the current and future international roughness index (IRI) and of detecting performance recovery after application of preservation treatment, thereby forecasting the remaining service life. The traffic, pavement structural, and performance data were obtained from the pavement management information system (PMIS) of the Iowa Department of Transportation (DOT). This study describes realistic what-if scenarios considering various treatment techniques to provide a better understanding of the effectiveness of treatments on extending flexible pavement service life. Such outcomes will help facilitate better pavement preservation management strategies.Öğe Incorporating the effectiveness of preservation and rehabilitation techniques on flexible pavement service life predictions using machine learning approach(American Society of Civil Engineers (ASCE), 2021) Citir, Nazik; Ceylan, Halil; Kim, Sunghwan; Kaya, OrhanA flexible pavement network may be exposed to traffic changes over time because of detours that may cause unusually high traffic loading on some parts of the pavement sections. Such sections, therefore, need to be preserved earlier than their expected service life. This study focuses on incorporating the effectiveness of preservation and rehabilitation techniques, e.g., functional thin overlay and structural asphalt overlay on flexible pavement service life predictions using a machine learning approach. The developed models are capable of estimating the current and future international roughness index (IRI) and of detecting performance recovery after application of preservation treatment, thereby forecasting the remaining service life. The traffic, pavement structural, and performance data were obtained from the pavement management information system (PMIS) of the Iowa Department of Transportation (DOT). This study describes realistic what-if scenarios considering various treatment techniques to provide a better understanding of the effectiveness of treatments on extending flexible pavement service life. Such outcomes will help facilitate better pavement preservation management strategies. © ASCE.All right reserved.Öğe Long-term performance evaluation of Iowa concrete overlays(Taylor & Francis Ltd, 2022) Chen, Yu-An; Ceylan, Halil; Nlenanya, Inya; Kaya, Orhan; Smadi, Omar G.; Taylor, Peter C.; Kim, SunghwanThe use of concrete overlays has long been recognised as a cost-effective pavement maintenance and rehabilitation strategy. However, the long-term performance of various types of concrete overlays has not been fully investigated since there has not been enough performance data available to conduct such an evaluation. Concrete overlays have been regularly constructed on Iowa roadways since the late 1970s and many older projects are still in use. Performance-related data for in-service concrete overlays have been acquired from the available resources to evaluate long-term performance of concrete overlays in Iowa. The information collected includes Pavement Condition Index (PCI), International Roughness Index (IRI), overlay type, construction year, overlay thickness, joint spacing, traffic, and other construction and design-related data. Based on an evaluation of PCI and IRI changes during service life, it is observed that concrete overlays can provide at least 20 years of service life. In terms of PCI ratings, 89% of concrete overlays investigated have PCI values greater than 60% as of the time of the analysis. Similarly, 93% of concrete overlays have IRI values lower than 2.7 m/km (170 in/mile). The effects of overlays type and design features on long-term performance of Iowa concrete overlays are also discussed.Öğe Relationship Between Abrasion, Fragmentation and Thermal Weathering Resistance of Aggregates: Regression and Artificial Neural Network Analyses(Springernature, 2023) Goekalp, Islam; Kaya, Orhan; Uz, Volkan EmreFor 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.Öğe Sensitivity Index comparison of pavement mechanistic-empirical design input variables to reflective cracking model for different climatic zones(Taylor & Francis Ltd, 2021) Gopisetti, Leela Sai Praveen; Ceylan, Halil; Kim, Sunghwan; Cetin, Bora; Kaya, OrhanOne of the main types of distress observed in Asphalt Concrete (AC) overlays is reflective cracking, and a reflective cracking model has been recently incorporated into the latest released version of AASHTOWare Pavement ME Design (PMED) software. This study documents the complete results of the sensitivity with respect to the design inputs and material properties of reflective cracking distress predicted by the PMED software. Six representative locations distributed across different climate zones of the United States were considered for studying the effects of climate extremities on changes in predicted reflective cracking distress. One-at-a-time (OAT) sensitivity analyses was performed to determine the Normalized Sensitivity Index (NSI), with two scenarios considered for OAT analyses: (i) sensitivity of short-term reflective cracking prediction (i.e., the year when predicted distress reached 4000 ft/mile) and (ii) sensitivity of long-term reflective cracking prediction (20-year design life). The summary of NSI ranking for varying traffic levels are presented.Öğe Türkiye’deki Belediyelerin Sorumluluk Sahasındaki Yollar için bir Derzli Donatısız Beton Yol Dizayn Kataloğu ve Modeli Önerisi(2023) Kaya, Orhan; İgit, AbdullahBeton yollar yapısal ömürlerinin fazla oluşu, ekonomik, dayanıklı ve çevre dostu oluşları, her mevsimde uygulanabilir oluşları ve gece görüşünü olumlu yönde etkilemeleri gibi avantajları olan ve ülkemizde yerli imkanlarla üretimi gerçekleşen çimentonun en pahalı bileşeni olduğu ve dolayısıyla maliyet açısından da ön plana çıkan bir yol üstyapısı tipidir. Belediyelerin sorumluluk sahasındaki düşük hacimli yollarda kullanılabilecek Derzli Donatısız Beton Yollar (JPCP) için bir dizayn kataloğu ve modeli geliştirilmesinin birçok pratik faydası olacaktır. Bu çalışmanın amacı ülkemizde belediyelerin sorumluluk sahasındaki düşük hacimli JPCP yolların (hem sokak ve cadde gibi yollar (residential roads) hem de bulvar gibi daha yüksek hacimli yolların (collector roads)) tasarımında kullanılmak üzere: (1) farklı tasarım senaryoları ve parametreleri için PavementDesigner web programı kullanılarak beton yol plaka kalınlıklarını belirleyerek bir “Beton Yol Dizayn Kataloğu” oluşturmak ve (2) bu katalog kullanılarak çoklu regresyon modelleri geliştirerek alternatif senaryolar için hızlı bir beton plaka kalınlığı tahmin modeli geliştirmektir. Çalışmada 432 tasarım senaryosu belirlenmiş ve herbir senaryo için ilgili tasarım değerleri PavementDesigner’a girilerek beton plaka kalınlıkları elde edilmiştir. Farklı dizayn parametrelerinin beton plaka kalınlıklarına etkileri detaylı olarak sunulmuştur. Bununla birlikte bu 432 tasarım senaryosu kullanılarak hem sokak ve cadde gibi yollar (residential roads) hem de bulvar gibi daha yüksek hacimli yolların (collector roads) kalınlık tasarımında kullanılabilecek ve PavementDesigner çıktılarına başarılı bir şekilde benzer sonuçlar veren iki çoklu regresyon modeli geliştirilmiştir. Bu modeller kullanılarak belediyelerin sorumluluk sahasındaki yollar JPCP olarak hızlı bir şekilde tasarlanıp vakit ve kaynak verimliliği sağlanılabilir.Öğe Use of GRP Pipe Waste Powder as a Filler Replacement in Hot-Mix Asphalt(Mdpi, 2020) Beycioglu, Ahmet; Kaya, Orhan; Yildirim, Zeynel Baran; Bagriacik, Baki; Dobiszewska, Magdalena; Morova, Nihat; Cetin, SunaThere is an increasing global trend to find sustainable, environmentally friendly and cost-effective materials as an alternative to limited natural raw materials. Similarly, the use of waste materials has been gaining popularity in the production of hot-mix asphalt (HMA). In this study, the sustainable use of glass-fiber-reinforced polyester (GRP) pipe waste powder (GRP-WP), gathered from the cutting and milling process of GRP pipe production, utilizing it in asphalt mixes as a filler, is evaluated based on lab testing to find out: (i) if it produces similar or better performance compared to the most conventionally available filler material (limestone) and, (ii) if so, what would be the optimum GRP-WP filler content to be used in asphalt mixes. For this reason, an experimental test matrix consisting of 45 samples with three different amounts of binder content (4%, 4.5% and 5.0%), and a 5% filler content with five different percentages of the GRP-WP content (0%, 25%, 50%, 75% and 100% replacement by weight of the filler), was prepared to figure out which sample would produce the similar Marshall stability and flow values compared to the control samples while also satisfying specification limits. It was found that the samples with 4.5% binder content, 3.75% GRP-WP and 1.25% limestone filler content produced the results both satisfying the specification requirements and providing an optimum mix design. It is believed that use of GRP-WP waste in HMA production would be a very useful way of recycling GRP-WP.
