تاثیر افزودنی‌‌های زئولیت و سیمان بر رفتار مکانیکی و شاخص واگرایی خاک رسی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی عمران، دانشگاه تربیت دبیر شهید رجایی، تهران ، ایران

2 گروه مهندسی عمران، دانشکده فنی، دانشگاه گیلان، رشت، ایران

چکیده

خاک‌های واگرا عموما دارای پتانسیل بالای انقباض و تورم، نفوذپذیری کم و مقاومت اندک در برابر فرسایش بوده و لذا از نوع خاکهای مسئله دار شناخته می شوند. در این تحقیق تغییر در پتانسیل واگرایی به روش تثبیت شیمیایی با سیمان و جایگزینی بخشی از سیمان با زئولیت (به عنوان یک افزودنی دوستدار محیط‌‌زیست) در تثبیت نوعی خاک رس مورد ارزیابی قرار گرفته است چرا که استفاده از سیمان مشکلات زیست محیطی متعددی دارد. نتایج این بررسی نشان داد با جایگزینی بخشی از سیمان با زئولیت، حداکثر وزن مخصوص خشک افزایش و رطوبت بهینه کاهش می‌‌یابد که روند متفاوتی در مقایسه با تثبیت سیمانی است. همچنین رفتار نمونه در آزمایش تک محوری تحت تاثیر درصد جایگزینی سیمان با زئولیت است. نتایج آزمایش هیدرومتری مضاعف نیز نشان داد ترکیب 5 % سیمان و جایگزینی 30 % زئولیت پتانسیل واگرایی خاک را کاهش می‌‌دهد. همچنین در آزمایش‌‌های ته‌‌نشینی مشاهده شد با افزایش نسبت جایگزینی زئولیت، میزان ته‌‌نشینی افزایش می‌‌یابد که با کاهش ضخامت لایه دوگانه رس قابل توجیه است و کاهش پتانسیل واگرایی را تایید می‌نماید. آنالیزهای ریزساختاری SEM  نیز بیانگر تشکیل ژل کلسیم سیلیکات هیدراته در مخلوط بوده که باعث بهبود مشخصات مکانیکی و مقاومتی و کاهش پتانسیل واگرایی خاک رس متورم‌‌شونده شده است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

The effect of zeolite and cement additives on the mechanical behavior and dispersive index of clay soil

نویسندگان [English]

  • Saeed Ghaffarpour Jahromi 1
  • Meghdad Payan 2
  • Zeynab Amraee 1
1 Department of Geotechnical Engineering and Water Engineering, Shahid Rajaee Teacher Training University
2 Assistant Professor, Department of Civil Engineering, Faculty of Engineering, University of Guilan, Rasht, Iran
چکیده [English]

Some natural clay-rich soils are highly erodible by flowing water both at and below the land surface. These soils contain an abundance of clay particles that disperse (slake) and deflocculate when relatively pure water is added. Dispersive soils can cause great damage to various structures, so geotechnical engineers propose different methods to modify and stabilize these types of soils. Chemical stabilization with cement or lime is the most common method to improve the properties of dispersivity and swelling soils. Word environmental problems such as producing large amounts of heat-trapping greenhouse gases for the production of cement or lime made engineers replace them. This paper investigated the effect of replacing part of cement with zeolite (as an environmentally friendly additive) to stabilize a type of clay and the change in dispersivity potential has been evaluated. The results of this study showed that by replacing a part of cement with zeolite, the maximum dry density increases and the optimum moisture decreases, which is a different process compared to cement stabilization. The behavior of the sample in the uniaxial test was influenced by the percentage of replacement of cement with zeolite. The results of the double hydrometer test also showed that the combination of cement and zeolite reduces the potential of soil dispersion. It also observed in the sedimentation experiments that increase in the zeolite ratio, the sedimentation rate increases, which can be justified by the decrease in the thickness of the double layer of clay so confirming decrease the dispersion potential. SEM microstructural analysis also indicated the formation of hydrated calcium silicate gel in the mixture, which improved the mechanical and resistance characteristics and reduced the swelling clay dispersivity potential.

کلیدواژه‌ها [English]

  • Chemical Stabilization
  • dispersivity potential
  • zeolite
  • cement
  • clay

مراجع

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نشریه مهندسی عمران امیرکبیر
دوره 55، شماره 8
آبان 1402
صفحه 1645-1660

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