بررسی رفتار خاک ماسه اهواز تثبیت شده با متاکائولین

نوع مقاله : مقاله پژوهشی

نویسندگان

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

چکیده

با توجه به رشد جمعیت جهت توسعه زیرساخت‌های کشور، تثبیت و اصلاح زمین‌های نامرغوب به منظور ایجاد بستر مقاوم و مستحکم بیش از هر زمانی مورد نیاز است. تاکنون روش‌های بهسازی زیادی در دنیا پیشنهاد شده است که از عمده‌ترین روش‌های رایج تثبیت شیمیایی با استفاده از آهک یا سیمان است که با محیط زیست سازگاری مناسبی ندارند. لذا امروزه استفاده از پوزولان‌ها و سیمان‌های ژئوپلیمری به جای سیمان پرتلند مورد توجه محققین مختلف قرار گرفته است. در این مطالعه تثبیت خاک ماسه شهر اهواز با کمک متاکائولین به عنوان نوعی ماده افزودنی مورد بررسی قرار گرفته است. در این تحقیق به تأثیر مقادیر متفاوت متغیرهایی همچون مقدار درصد متاکائولن، نسبت سدیم سیلیکات به سدیم هیدروکسید، غلظت سدیم هیدروکسید و نسبت محلول فعال ‌کننده قلیایی به ماده افزودنی در سنین عمل‌آوری 7 و 28 روز پرداخته شده است. نمونه‌ها تحت آزمایش مقاومت فشاری تک محوری محصور نشده (UCS) ارزیابی و جهت بررسی ریزساختاری، از آنالیزهای پراش اشعه ایکس (XRD) و میکروسکوپ الکترونی روبشی (SEM) استفاده می‌شود. نتایج این تحقیق نشان می‌دهد برای رسیدن به مقاومت بهینه باید از اختلاط 20% متاکائولن، نسبت سدیم سیلیکات به سدیم هیدروکسید 2/5، غلظت سدیم هیدروکسید 12 مولار و نسبت محلول فعال ‌کننده به ماده افزودنی 0/5 استفاده کرد. مقاومت نمونه با عمل‌آوری 28 روزه به حدود 5 مگاپاسکال یعنی حدود 3 برابر بیشتر از نمونه‌های سیمانی و 23 برابر بیش از خاک تثبیت ‌نشده می‌رسد که در آنالیز ریزساختاری وجود ژل N-A-S-H به عنوان عامل اصلی افزایش مقاومت در فرآیند ژئوپلیمریزاسیون قابل مشاهده است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of the behavior of Ahvaz sand soil stabilized with metakaolin

نویسندگان [English]

  • Pouria Daneshgar
  • Saeed Ghaffarpour Jahromi
  • Hamed Arzani
Shahid Rajaee Teacher Training University/ Faculty of Civil Engineering
چکیده [English]

Considering the growth of the population for the development of the country's infrastructure, stabilization and improvement of low-quality land in order to create a strong and resistant base are needed more than ever. So far, many improvement methods have been proposed in the world, which is one of the most common methods of chemical stabilization using lime or cement, which are not compatible with the environment. Therefore, nowadays, the use of pozzolans and geopolymeric cements instead of Portland cement has attracted the attention of various researchers. In this study, the stabilization of sandy soil in Ahvaz City with the help of metakaolin as an additive has been investigated. In this research, the effect of different amounts of variables such as the percentage of metakaolin, the ratio of sodium silicate to sodium hydroxide, the concentration of sodium hydroxide, and the ratio of alkaline activator solution to the additive at the curing ages of 7 and 28 days have been discussed. Samples are subjected to unconfined uniaxial compressive strength (UCS) evaluation and microstructural investigation, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses are used. The results of this research show that in order to achieve optimal resistance, it is necessary to mix 20% metakaolin, the ratio of sodium silicate to sodium hydroxide is 2.5, the concentration of sodium hydroxide is 12 Molar, and the ratio of activator solution to additive is 0.5. The strength of the sample with 28-day curing reaches about 5 MPa, which is about 3 times more than cement samples and 23 times more than unstabilized soil, which can be seen in the microstructural analysis of the presence of N-A-S-H gel as the main factor in increasing the strength in the geopolymerization process.

کلیدواژه‌ها [English]

  • Soil stabilization
  • Soil improvement
  • Geopolymer
  • Metakaolin
  • Unconfined compressive strength
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