بررسی آزمایشگاهی و عددی مشخصات رئولوژیکی و مکانیکی بتن‌های خودتراکم حاوی سنگدانه‌های بازیافتی با استفاده از روش باکس‌بنکن

نوع مقاله : علمی - پژوهشی

نویسندگان

1 گروه مهندسی عمران، واحد تبریز، دانشگاه آزاد اسلامی، تبریز، ایران

2 گروه عمران, دانشکده فنی و مهندسی, دانشگاه آزاد اسلامی, واحد تبریز

3 گروه مهندسی عمران، دانشگاه صنعتی سهند، تبریز، ایران

4 گروه مهندسی عمران، واحد تبریز، دانشگاه آزاد اسلامی، تبریز ایران

چکیده

بتن به عنوان یکی از مصالح ساختمانی به طور گسترده در سراسر جهان مورد استفاده قرار می‌‌گیرد، اما به عنوان مصالح سازگار با محیط زیست محسوب نمی‌شود. چون علاوه بر تخریب محیط زیست و استفاده از مقادیر زیاد منابع طبیعی، موجب اثرات زیان‌بار زیست ‌محیطی می-گردد. از این رو ارائه‌ی راهکاری جهت کاهش اثرات آلایندگی سنگدانه‌ی بازیافتی، امری ضروری به نظر می‌رسد. در مقاله حاضر تاثیر سنگدانه-های بازیافتی بر روی مشخصات رئولوژیکی و مکانیکی بتن خودتراکم به صورت آزمایشگاهی و عددی مورد بررسی قرار گرفته است. بدین منظور از دو نوع سنگ‌دانه‌ بازیافتی با منشا مقاومتی مشخص و نامشخص برای نمونه‌های مورد مطالعه استفاده شده است. طراحی آزمایشات در این مقاله توسط روش باکس بنکن که یکی از روش‌های سطح پاسخ بوده، انجام گرفته است. متغیرهای ورودی در مخلوط‌ها، شامل میکروسیلیس در محدوده % 15-5 به عنوان جایگزین درصدی از وزن سیمان، درشت‌دانه و ریزدانه‌ی بازیافتی در محدوده %50-0 برای هر دو سری از مصالح بازیافتی، جایگزین مصالح طبیعی گردیده است. پاسخ‌های مورد مطالعه جریان اسلامپ، قیف V، مقاومت فشاری و مقاومت کششی می‌باشند. نتایج حاکی از آن است که با افزایش سنگ‌دانه‌های بازیافتی مشخصات روانی و مکانیکی مخلوط‌ها کاهش می‌یابد، در حالی که میکروسیلیس به طور موثری مشخصات مکانیکی را بهبود بخشیده است. علاوه بر این حساسیت بیشتر پاسخ‌های مورد مطالعه به ریزدانه-های بازیافتی بوده است. لازم به ذکر است مصالح بازیافتی با منشا مقاومت مشخص در مقایسه با مصالح بازیافتی با منشا مقاومت نامشخص نتایج بهتری از خود نشان داده‌اند. همچنین برای تمامی پاسخ‌ها با استفاده از تحلیل واریانس روابط ریاضی جهت پیش‌بینی مشخصات رئولوژیکی و مکانیکی مخلوط‌ها ارائه گردیده است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental and numerical investigation of rheological and mechanical properties of self-compacting concretes containing recycled aggregates using Box-Behnken method

نویسندگان [English]

  • hiwa mollaee 1
  • taleb moradi shaghaghi 2
  • Hassan Afshin 3
  • reza Saleh Ahari 4
  • saeed Mirrezaei 4
1 Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran
2 Faculty of Civil Engineering, Islamic Azad University, Tabriz Branch
3 Department of Civil Engineering, Sahand University of Technology, Tabriz, Iran
4 Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran
چکیده [English]

Concrete is widely used as a building material all over the world, but it is not considered an environmentally friendly material due to environmental degradation and the use of large amounts of natural resources. Therefore, it is necessary to provide a solution to reduce the effects of recycled aggregate pollution. In the present study, the effect of the strength of recycled aggregates on the rheological and mechanical properties of self-compacting concrete is investigated experimentally and numerically. Hence, two types of recycled aggregates with known and unknown strength origins are utilized for the studied samples. The experimental design in this research is accomplished by the Box Behnken method, which is one of the response surface methods. Input variables in mixtures, including micro silica in the range of 5-15% as a percentage substitute for the weight of cement and recycled coarse and fine grains in the range of 0-50% for both series of recycled materials, are replaced by natural materials. The studied responses are slump flow, funnel V, compressive and tensile strengths. The results indicate that the increase in recycled aggregates reduces the rheological and mechanical properties of the mixtures, while micro silica effectively improves the mechanical properties. In addition, the sensitivity of most of the studied responses is related to recycled fine particles. It should be noted that recycled materials of known strengths are shown better results than recycled materials of unknown strengths. Some mathematical relationships are also provided using analysis of variance for all responses to predict the rheological and mechanical properties of mixtures.

کلیدواژه‌ها [English]

  • self-compacting concrete
  • Recycled materials of specified origin
  • Recycled materials of unknown origin
  • Silica Fume
  • Response Surface Methodology
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