بررسی تاثیر پذیری نمودار تنش-کرنش از خواص رئولوژیکی بتن های خود تراکم الیافی

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه مهندسی عمران، واحد قزوین، دانشگاه آزاد اسلامی، قزوین، ایران.

چکیده

در بتن خودتراکم الیافی، از یک سو الیاف و از سوی دیگر خواصی مانند قابلیت پرکنندگی، سبب ایجاد مخلوطی همگن می گردد. در این پژوهش ۱۰ طرح اختلاط مورد بررسی و آزمایش قرار گرفته که یک طرح آن برای نمونه شاهد و ۹ طرح دیگر شامل درصد های حجمی 0/25 ، 0/5 ، 0/75 الیاف‌هایی از نوع فولادی ، ماکروسنتتیک تک رشته ای (MEX 100) و کربن پلیمری تقویت شده  (CFRP) می باشد.در این تحقیق رفتار رئولوژی بتن تازه خود تراکم به کمک آزمایش رئومتر و همچنین آزمایش های متداول تعیین خواص خودتراکمی بتن تازه که شامل آزمایش های جریان اسلامپ ، حلقه J ، جعبه L ، جعبه U ، قیف V می شود بررسی گردید. در ادامه نیز مدل رفتاری بتن سخت شده بر اساس آزمایش های تعیین خواص مکانیکی (مقاومت فشاری، مدول الاستیسیته) تحلیل شده است. نتایج این تحقیق نشان می دهد که افزودن الیاف به بتن تازه سبب کاهش خواص خود تراکمی و رئولوژیکی بتن می گردد و همچنین با افزایش درصد های حجمی الیاف این تاثیر بیشتر نمایان می گردد بطوری که زیادترین تاثیر را می توان در طرح های حاوی الیاف CFRP مشاهده کرد. نتایج مربوط به خواص مکانیکی بتن سخت شده نیز نشان دهنده آن است که افزودن الیاف ها با مقادیر پایین به بتن خودتراکم سبب بهبود برخی از این خواص می گردد ولی استفاده از مقادیر بالای الیاف سبب افزایش شکل پذیری و در نتیجه کاهش مقادیر مقاومت فشاری و مدول الاستیسیته در بتن های خود تراکم می گردد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigating Effect of Rheological Properties of Fiber Reinforced Self-Compacting Concrete on Stress-strain Curve

نویسندگان [English]

  • Reza Farokhzad
  • Farnam Gervehiee
Department of civil engineering,, Qazvin Branch, Islamic Azad University, Qazvin, Iran.
چکیده [English]

In fiber reinforced self-compacting concrete, fibers and properties such as filling ability create a homogeneous mixture. In this research, 10 mix designs are examined and tested, one of which is related to the control sample and the other 9 designs include steel, macrosynthetic monofilament (MEX 100), and carbon fiber reinforced polymer (CFRP) fibers with volumetric percentages of 0.25, 0.5 and 0.75. The rheological behavior of fresh self-compacting concrete is investigated by rheometer test. Moreover, conventional tests that determine the self-compacting properties of fresh concrete, including slump flow, J-ring, L-box, U-box, and V-funnel tests, are examined. The behavior of hardened concrete is analyzed based on tests to determine mechanical properties (compressive strength and modulus of elasticity). The results indicate adding fibers to fresh concrete reduces the self-compacting and rheological properties of concrete. This effect becomes more visible by increasing the fiber volume ratio so that the greatest effect could be observed in designs containing CFRP fibers. The results of mechanical properties of hardened concrete show adding small amounts of fibers to self-compacting concrete improves some of these properties, while using large amounts of fibers increases ductility and, consequently, decreases compressive strength and modulus of elasticity in self-compacting concrete.

کلیدواژه‌ها [English]

  • Stress-strain
  • fiber concrete
  • SCC
  • modulus of elasticity
  • rheological properties
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