Civil Engineering / İnşaat Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/13

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  • Review
    Citation - WoS: 42
    Citation - Scopus: 49
    Utilization of Waste Materials in the Stabilization of Expansive Pavement Subgrade: an Extensive Review
    (Elsevier, 2023) Tanyıldızı, Muhammed; Uz, Volkan Emre; Gökalp, İslam
    Expansive soils, also known as swell-shrink soils, are one of the most problematic soils in highway construction and exhibit significant volume changes by swelling and shrinking while wet and dry, respectively. These changes in soil cause cracks, heaves, differential settlements, and damages to the overlying pavements leading to high maintenance costs. The annual average maintenance cost of structures built on expansive soils ranges from $9 to $15 billion, with 50% of the expenses associated with highways and streets. Chemical stabilization techniques such as cement and lime stabilization are one of the most efficient ways to treat expansive soils. However, there is a need to develop environmentally friendly approaches to stabilize expansive soils due to worldwide growing interest in sustainable developments and concerns about greenhouse gas emissions and climate change. In this context, using waste materials in soil stabilization has been considered an important issue for sustainability concerns. The aim of the current study is to review the relevant studies performed to improve the geotechnical and engineering properties of expansive subgrade soils of pavements by using waste materials arising from industrial, agricultural, and other activities in the last decade. In the organization of this study, characteristics of expansive soils including plasticity, compaction, strength & stiffness, microstructural characteristics, shrink-swell properties, and durability were focused to point out the effect of the waste materials. The overall results obtained throughout the scope of the current study indicated that the use of waste materials in soil stabilization improves the engineering properties of expansive soils, significantly. This paper also provides key information and creates awareness for researchers and sector representatives about sustainable soil stabilization.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 6
    Sustainable Production of Aging-Resistant Bitumen: Waste Engine Oil Modification
    (American Society of Civil Engineers, 2021) Gökalp, İslam; 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.