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- ArticleAçık Erişim2026Assessment of Low-Temperature Fracture Behavior in Bituminous Mixtures Incorporating Sustainable Waste Additives: SCB Testing and Finite Element Analysis
Keleş, Ömer Faruk; Çolak, Muhammed Ali; Demiriz, Ahmet Oğuz; Baş, Fatih İrfan
In this study, the combined effect of waste lubricating oil (WLO) and waste pine branch ash (WPBA) was investigated to improve the low-temperature fracture behavior of asphalt mixtures. To investigate the low-temperature fracture behavior of the mixtures containing 2%–6% WLO and 3%–12% WPBA, the semi-circular bending (SCB) test was conducted at −15 °C, and the experimental results were analyzed using a statistical approach. Fracture toughness (K(IC)), total fracture energy (GF) and its pre-peak and post-peak components, crack resistance index (CRI), flexibility index (FI), and toughness index (TI) were determined. The findings indicate that the optimal combination depends on the fracture parameter under consideration. The best fracture toughness results, K(IC) = 24.96 MPa·mm0.5, indicating increased resistance to crack initiation, was obtained at 4% WLO and 12% WPBA content. On the other hand, the best fracture energy results, GF = 1.202 N/mm, reflecting an increase in energy dissipation during crack propagation, was obtained at 4% WLO and 9% WPBA content. The highest FI, CRI, and TI values were obtained with 6% WLO and 9% WPBA, corresponding to increases of approximately 66%, 69%, and 16%, respectively, compared with the reference mixture. This resulted in greater crack-initiation resistance, improved post-peak deformation capacity, and higher energy-dissipation capacity, although the greater WLO content led to a decrease in structural integrity. When the results are evaluated overall, it is understood that the use of WLO in the mixtures increases deformation capacity, while the use of WPBA controls crack propagation through its hardening and filling effects. In mixtures containing 4% WLO and 9%–12% WPBA, a balanced behavior was achieved in terms of crack initiation, crack propagation, and stiffness under low-temperature conditions.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2026Effects of maximum aggregate grain size and gradation on roller compacted concrete pavements
Keleş, Ömer Faruk
Roller compacted concrete (RCC) pavements, which stand out as an alternative to conventional concrete and asphalt pavements, are increasingly preferred because of their high strength, fast construction, and low cost advantages. The properties of aggregates directly affect the performance in roller compacted concrete mixtures. In particular, the maximum aggregate particle size (Dmax) and gradation play a determining influence on the mixture's density, compressibility, and mechanical strength. This study aimed to investigate the effects of maximum aggregate particle size and gradation on the mechanical performance of roller compacted concrete pavement mixtures. Within this scope, roller compacted concrete pavement mixtures were produced using three Dmax (12.5, 19, and 25 mm) and three different cement dosages (300, 350, and 400 kg). Tests for physical properties on mixtures were conducted using unit weight and ultrasonic pulse velocity (UPV) tests, while tests for mechanical properties were conducted using compressive strength, flexural strength, and splitting tensile strength tests. Increasing the Dmax to 25 mm significantly improved the compressive and flexural strength of the mixtures. However, the splitting tensile strength increased up to 19 mm and showed a slight decrease when reaching 25 mm. The increase in cement content consistently improved all mechanical properties. Overall, the use of well-graded coarse aggregates with Dmax in the range of 19–25 mm was found to improve the mechanical properties and compressibility of roller compacted concrete mixtures.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2025Fracture behavior of warm mix asphalt mixtures incorporating Cecabase and recycled concrete aggregate: An experimental and numerical assessment
Çolak, Muhammed Ali; Keleş, Ömer Faruk; Baş, Fatih İrfan; Demi̇ri̇z, Ahmet Oğuz
This study investigates the fracture performance of warm mix asphalt (WMA) mixtures modified with Cecabase RT BIO10 and various recycled concrete aggregate (RCA) proportions using laboratory tests and finite element modeling. Semi-Circular Bending (SCB) tests at –15 °C under Mode I loading were performed to measure fracture toughness (KIC), fracture energy (GF, pre-peak and post-peak), stiffness, and flexibility indices. Unlike many prior studies relying on a single approach, fracture toughness was calculated through all major analytical methods and validated with ANSYS finite element simulations. Results showed that increasing Cecabase content notably improved fracture resistance, while higher RCA levels reduced mechanical properties due to the porous nature of RCA. Fracture energy analysis indicated that post-peak deformation parameters correlated more strongly with GF than stiffness indices, highlighting the importance of ductility in asphalt performance. Correlation analyses revealed tensile strength (TS) and tensile stiffness index (TSI) largely evolve independently from post-peak flexibility indicators such as flexibility index (FI), toughness index (TI), and crack resistance index (CRI). Among mixtures tested, the combination of 0.50 % Cecabase and 10 % RCA exhibited the most balanced performance with high TSI, TS, and GF values. These findings emphasize the need to optimize both additive and RCA content to enhance WMA mixtures’ mechanical integrity and sustainability. The proposed approach offers a practical and environmentally friendly framework for designing durable asphalt mixtures suited to low-temperature pavements.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Experimental investigation on mechanical properties of sustainable roller compacted concrete pavement (RCCP) containing waste rubbers as alternative aggregates
Keleş, Ömer Faruk; Bayrak, Osman Ünsal; Bayata, Halim Ferit
Different types of solid waste are generated every year due to global industrialization. With the rapid growth of the automobile industry, the disposal of billions of waste rubbers (WR), which pollute the environment and cannot be disposed of properly, is emerging as an urgent matter of concern. Recycling waste rubbers by using them on pavements will contribute to the elimination of ecological and economic problems. In this study, the effects of waste rubbers on the mechanical properties of roller-compacted concrete pavement (RCCP) were investigated by obtaining sustainable RCCP mixtures using different types of waste rubbers as coarse and fine aggregate substitutes. In this context, waste rubbers with three different sizes (powder, crumb and shredded) were substituted for aggregate by volume at seven levels (0%, 2.5%, 5%, 7.5%, 10%, 20% and 30%) with a maximum of 30% in RCC mixtures. Unit weight, mechanical properties, modulus of elasticity and ultrasonic pulse velocity (UPV) were evaluated and compared according to the waste rubber content in the RCC mixtures. In addition, microstructural analysis of the mixtures was performed through scanning electron microscopy (SEM). The experimental results revealed that the compressive, flexural and splitting tensile strength and modulus of elasticity decreased with increasing waste rubber content in RCC. The utilization of waste rubber increased the ductility of RCC and decreased the density to produce lighter concrete. RCC with a compressive strength of about 30 MPa could be obtained by substituting 10% of waste rubber for aggregate. Thus, the utilization of high waste rubber content in pavements was feasible. This study can contribute to a more sustainable RCCP production by replacing natural aggregates with waste rubbers.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2022Strength properties of roller compacted concrete pavement (RCCP) under different curing methods
Keleş, Ömer Faruk; Akpinar, Muhammet Vefa
The curing of roller compacted concrete (RCC) pavements requires much more attention and importance than conventional concrete pavements due to its very dry consistency. This research was conducted to determine the effects of different curing types and their application times on mechanical properties of RCC. In addition, the effects on physical properties of RCC were determined in the study, as well. In the experimental study, 4 different curing types as the curing compound, burlap, membrane and water that have been widely used in the market, were applied for 15, 30, and 60 min and immediately after casting. Compressive strength, flexural strength, weight loss, ultrasonic pulse velocity and rebound hammer tests were applied to determine the physical and mechanical properties of RCC specimens. According to the results, the best curing method for compressive and flexural strengths of RCC was determined as water curing, providing approximately 29% and 34% increase in strength compared to uncured mixtures, respectively. In terms of weight loss, the best result was obtained with water curing, increasing the amount of moisture, unlike other curing methods.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2020Kentiçi Kavşakların Mikrosimülasyon Yöntemiyle Modellenmesi: Erzurum İli Örneği
Bayata, Halim Ferit; Bayrak, Osman Ünsal; Bas, Fatih Irfan; Çolak, Muhammed Ali; Demiriz, Ahmet Oğuz; Keleş, Ömer Faruk; Mazlum, Yusuf; Gürel, Mehmet Oğuzhan; Demircioglu, Muhammed Sami
Gelişen teknolojiye bağlı olarak dünya genelinde olduğu gibi Erzurum il merkezinde de araç sayısında artış meydana gelmiş veErzurum kent içi ana arter ve ana arterleri üzerinde bulunan kavşaklarda trafik hacminin artmasına sebep olmuştur. Erzurum’da sonbeş yılda motorlu taşıt sayısı 16.762 artarak 119.108’e ulaşmıştır. Artan trafik hacmi özellikle şehrin en merkezi kavşağı konumundaolan Tebrizkapı Kavşağı’nı etkilemiştir. Tebrizkapı Kavşağı kentin en işlek merkezi olan Cumhuriyet Caddesi, Karskapı Caddesi veen önemli alışveriş merkezlerinden biri olan Taş Mağazalar Caddesi arasında kaldığından özellikle sabah mesai başlangıç saatleri veakşam mesai bitim saatlerinde ciddi trafik yoğunluklarına maruz kalmaktadır. Sayım sonuçları doğrultusunda Tebrizkapı Kavşağı’ndasabah zirve saati 07:45 ile 08:45 ve akşam zirve saati 16:45 ile 17:45 arasında olduğu belirlenmiş ve simülasyon yapılırken yoğunlukolan zirve saatlerin trafik hacimleri alınmıştır.Bu çalışmada, AIMSUN yazılımı kullanılarak Tebrizkapı Kavşağı’nın mevcut durum ve farklı kavşak tipleri ile tasarımlarıMikrosimülasyon ile simüle edilmiştir. Üretilen modellerin doğruluğunu ölçmek için trafik hacimleri üzerinde doğrulama testi olarakkullanılan GEH (Geoffrey E. Havers) formülünden faydalanılmıştır. Mevcut durumdaki gecikme süresi 41,10 saniye ve beklemesüresi 26,85 saniye olarak bulunmuştur. Mevcut durumdaki kavşak tipi değiştirilerek Modern Dönel Kavşak ve Farklı Düzey Kavşaktasarlanarak simülasyonları yapılmıştır. Yeni yapılan tasarımların gecikme süreleri Modern Dönel kavşak için 9,21 saniye, FarklıDüzey Kavşak için 5,03 saniye, bekleme süreleri ise Modern Dönel Kavşak için 1,66 saniye ve Farklı Düzey Kavşak için 1,20 saniyeolarak bulunmuştur. Simülasyonlar sonucunda gecikme süresi ve bekleme süresi faktörleri dikkate alınarak en uygun kavşak tipiFarklı Düzey Kavşak olarak bulunmasına rağmen yapım maliyetinin çok yüksek olmasından dolayı Modern Dönel Kavşak yapılmasıen uygun seçim olarak belirlenmiştir.
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