بررسی فرآیند اندرکنش خاکستر بادی و خاک‌های رسی با دامنه خمیری زیاد از دیدگاه ریزساختاری

نوع مقاله : مقاله کامل پژوهشی

نویسندگان

1 دانشکده مهندسی، دانشگاه بوعلی سینا، همدان

2 گروه عمران، دانشکده مهندسی، دانشگاه بوعلی سینا، همدان

چکیده

خاکستر بادی پسماند سوزاندن زغال سنگ در نیروگاه­های برقی حرارتی است. تولید زیاد این پسماند معضلات زیست­محیطی برای دفن ایمن آن را به­همراه داشته است. خاکستر بادی به دلیل داشتن مقادیر زیادی سیلیسیوم و آلومینیوم دارای خواص پوزولانی است که استفاده از آن را در مباحث بتن، تثبیت خاک­ها و تثبیت و جامدسازی آلاینده­ها امکان­پذیر می­کند. با وجود انجام تحقیقات متعدد، همچنان نوع عملکرد فیزیکی و یا شیمیایی خاکستر بادی در ترکیب با خاک­های رسی بخوبی مشخص نمی­باشد. بر این اساس هدف این تحقیق بررسی نوع عملکرد خاکستر بادی کلاس F در رس متورم شونده بنتونیت است. خصوصیات مکانیکی ترکیبات بنتونیت و خاکستر بادی تا 30% وزنی بنتونیت، با استفاده از آزمایش­های حدود اتربرگ، تراکم، و آزمایش مقاومت فشاری محدود نشده ارزیابی شده است. همچنین از مطالعات ریزساختاری هیدرومتری، XRD و مقادیر کاتیون­های استخراج شده خاکستر بادی تحت شرایط محیطی اسیدی تا بازی، برای بررسی رفتار شیمیایی خاکستر بادی استفاده شده است. نتایج نشان داده است که مقادیر انحلال کاتیون­های Si و Al  خاکستر بادی تابع pH است و در pH حدود 9 با استفاده از آزمایش استخراج به ترتیب 4/0 و cmol/kg-soil 01/0 به دست آمده است. به دلیل غلظت کم انحلال این کاتیون­ها امکان شکل­گیری واکنش پوزولانی وجود ندارد. همچنین مقاومت فشاری محدود نشده نمونه بنتونیت-30% خاکستر بادی با افزایش زمان مراقبت از 7 تا 90 روز با اندکی افزایش به ترتیب از 444 به kPa 515 رسیده است. نتایج بررسی XRD نمونه­ها نشان می­دهد که با افزایش زمان مراقبت نمونه بنتونیت -30% خاکستر بادی، هیچ­گونه محصولات پوزولانی تشکیل نشده است.

کلیدواژه‌ها

عنوان مقاله [English]

Evaluation of Interaction Process of Fly Ash and Clayey Soils with High Plasticity Index from Micro- Structural Point of View

نویسندگان [English]

  • Vahid Reza Ouhadi 1
  • Morteza Deiranlou 2
  • Porya Rasolui 2
1 Faculty of Civil Engineering, Bu- Ali Sina University
2 Faculty of Civil Engineering, Bu- Ali Sina University
چکیده [English]

Fly ash is a coal combustion product that is composed of the particulates (fine particles of burned fuel) (Dayioglu et al., 2017). In many countries fly ash is placed in landfills. Due to the vast production of this type of waste, the safe disposal of fly ash is one of the major concerns. One of the best methods to reduce the side effects of fly ash production is to re-use it in civil engineering projects (Horpibulsuk, et al., 2009). Due to the presence of Al and Si in fly ash, it shows pozzolanic properties (Phanikumar and Shankar, 2017). Therefore, in the recent years fly ash has been used in many soil stabilization or cement production projects. In spite of many researches which have focused on application of fly ash in soil stabilization, there are very limited attentions on the type of mechanism of soil- fly ash interaction (i.e. chemical or physical type). Therefore, the main objective of this paper is to investigate the interaction process of fly ash and clayey coils with high plasticity index from micro structural point of view. In other words, this paper aims to investigate on the dominant type of soil-fly ash interaction and to examine that in what extent this interaction is physical or chemical process. To achieve the above mentioned objectives series of Atterberg limits test, unconfined compression experiments, XRD testing, and digestion test were performed to address the above mentioned objectives.

کلیدواژه‌ها [English]

  • Fly Ash
  • Bentonite
  • pH
  • USC
  • XRD

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نشریه مهندسی عمران و محیط زیست دانشگاه تبریز
دوره 49.4، شماره 97 - شماره پیاپی 97
زمستان 98
اسفند 1398
صفحه 1-14

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