مقایسه تأثیر پسماندهای صنعتی (غبار کوره سیمان، خاکستربادی و سرباره کوره آهن‌گدازی) بر پارامترهای تراکمی و نسبت باربری کالیفرنیا در خاک‌های رسی

نوع مقاله : مقاله پژوهشی

نویسنده

استادیار، دانشکده مهندسی عمران، دانشگاه صنعتی سهند، تبریز، ایران.

چکیده

هدف از این تحقیق، مقایسه تأثیر پسماندهای صنعتی شامل غبار کوره سیمان (CKD)، خاکستربادی (FA) و سرباره کوره آهن‌گدازی (GGBFS) بر تثبیت خاک‌های رسی است. برای تثبیت شیمیایی خاک‌ها، مقدار بهینه CKD، 10-20 درصد، خاکستربادی رده C، 20-25 درصد و GGBFS، 20-30 درصد پیشنهاد شده است. با در نظر گرفتن مقدار pH خاک با درصدهای مختلف مواد افزودنی، مقدار افزودنی‌ها برای مقایسه بهتر، یکسان و برابر با 20 درصد انتخاب شد. آزمایش‌های تراکم استاندارد و نسبت باربری کالیفرنیا بر نمونه‌ها انجام شد. جهت بررسی اثر ریزساختاری مواد افزودنی، نمونه­ها تحت آنالیز میکروسکوپ الکترونی روبشی (SEM) و پراش پرتوی ایکس (XRD) قرار گرفتند. نتایج نشان داد که غبار کوره سیمان و خاکستربادی موجب کاهش دانسیته خشک حداکثر و افزایش درصد رطوبت بهینه خاک می­شوند. در حالی که سرباره کوره آهن‌گدازی، درصد رطوبت بهینه نمونه را کاهش و دانسیته خشک حداکثر را افزایش داد. نسبت باربری کالیفرنیا در خاک تثبیت­شده با CKD، FA و GGBFS به ترتیب 7/21، 3/13 و 7/15 برابر خاک خالص بود. منطبق بر نتایج آنالیز SEM و XRD، افزایش مقاومت در خاک تثبیت­شده، ناشی از واکنش­های پوزولانی و ایجاد محصولات سیمانتاسیون و در نتیجه اتصال ذرات خاک و تثبیت­کننده­ها و پُر شدن فضاهای خالی می­باشد. هر چه میزان آهک آزاد در تثبیت­کننده بیشتر باشد، افزایش مقاومت در خاک، بیشتر خواهد بود. در پروژه‌های اجرایی، عواملی مانند زمان تأخیر (زمان بین اولین تماس ماده افزودنی با آب و کوبیدن نهایی مخلوط) و میزان رطوبت که بر پارامترهای مقاومت تأثیر می‌گذارند، باید در نظر گرفته شوند. همچنین مسائل زیست‌محیطی مانند قابلیت واکنش‌پذیری و نفوذ این مواد به آب‌های زیرزمینی، حائز اهمیت است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

A Comparative Study on the Effect of Cement Kiln Dust, Fly Ash, and Ground Granulated Blast Furnace Slag on Compaction Characteristics and California Bearing Ratio of Clay Soils

نویسنده [English]

  • Sadegh Ghavami
Assistant Professor, Faculty of Civil Engineering, Sahand University of Technology, Tabriz, Iran.
چکیده [English]

The objective of this study is to compare the effectiveness of industrial wastes including cement kiln dust (CKD), fly ash (FA), and ground granulated blast furnace slag (GGBFS) for stabilization of clay soils. To chemically stabilize the soil, optimal amounts of CKD (10%-20%), class C FA (20%-25%) and GGBFS (20%-30%) have been suggested. Considering the soil pH value with different percentages of additives, the amount of each additive was considered the same (20%) for better comparison. Standard compaction and California Bearing Ratio (CBR) tests were conducted on the mixtures. To investigate the microstructural effect of additives, the samples were subjected to scanning electrocleen microscopy (SEM) and X-ray diffraction (XRD) analysis. Results showed that CKD and FA decreased maximum dry density and increased optimum moisture content. Meanwhile, GGBFS decreased optimum moisture content of the samples and increased maximum dry density. The CBR in soil stabilized with CKD, FA, and GGBFS was 21.7, 13.3, and 15.7 times that of pure soil, respectively. According to the results of the SEM and XRD analysis, the increase in strength in the stabilized soil is caused by pozzolanic reactions and creation of cementation products, and as a result, binding of soil particles and stabilizers and filling of the pores. The higher the amount of free lime in the stabilizer, the greater the increase in soil strength. In practical projects, factors such as delay time (the time between the first contact of the additive and water and the final compaction of the mixture) and moisture content that affect the strength parameters should be considered. Also, environmental issues, such as potential of these additives to enter groundwater, are important.

کلیدواژه‌ها [English]

  • Cement Kiln Dust
  • Fly Ash
  • Ground Granulated Blast Furnace Slag
  • Compaction Parameters
  • California Bearing Ratio
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