بررسی و مقایسه تاثیر زئولیت طبیعی و میکروسیلیس بر رفتار مکانیکی بتن های بازیافتی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشیار، گروه مهندسی عمران، واحد اهواز، دانشگاه آزاد اسلامی، اهواز، ایران

2 دانشگاه آزاد اسلامی واحد اهواز

چکیده

تحقیق حاضر به بررسی مقایسه‌ای تاثیر استفاده از پوزولان‌های زئولیت طبیعی و میکروسیلیس بر مشخصات مکانیکی بتن‌های بازیافتی پرداخته است. بتن‌های بازیافتی، متشکل از سطوح مختلف جایگزینی درشت‌دانه‌های بازیافتی بتنی با درشت‌دانه طبیعی هستند. جهت بهبود کیفیت بتن‌های بازیافتی، پوزولان‌های معرفی شده در سطوح مختلفی با سیمان جایگزین شدند. جهت تعیین و مقایسه مشخصات مکانیکی بتن‌ها، 24 طرح اختلاط ساخته شد و آزمایش‌های مقاومت فشاری در سنین 7، 28 و 91 روزه، مقاومت کششی دو نیم‌‌شدن در سن 28 روزه، ضریب ارتجاعی در سن 28 روزه و سرعت امواج فراصوت در سن 28 روزه انجام شدند. نتایج نشان دادند که به طور کلی در بازه 28 روزه، استفاده از میکروسیلیس می‌تواند باعث شود تا بتن‌های 100% بازیافتی به مقاومت مطلوب 40 مگاپاسکالی دست یابند؛ در حالی که استفاده از زئولیت طبیعی نمی‌تواند منجر به کسب مقاومت هدف طراحی گردد. استفاده از سطح جایگزینی 10 درصدی میکروسیلیس به ویژه در بتن‌های حاوی 25% مصالح بازیافتی باعث گردید تا رفتار مکانیکی بتن‌های بازیافتی به میزان چشم‌گیری به بتن‌های معمولی نزدیک گردد؛ هر چند که سطح جایگزینی 10% زئولیت نیز در تامین برخی از خواص مکانیکی بتن‌های بازیافتی مطلوب بوده ولی خواص مکانیکی بتن‌های بازیافتی حاوی این پوزولان به میزان زیادی از ‌ بازیافتی حاوی میکروسیلیس ضعیف‌تر می‌باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Study and comparison of the effect of natural zeolite and silica fume on mechanical properties of recycled aggregates concretes

نویسندگان [English]

  • Fathollah Sajedi 1
  • Hasan Jalilifar 2
1 Associate Professor, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
2 Islamic Azad University of Ahvaz
چکیده [English]

The present study was conducted to compare the effect of natural zeolite (Z) and silica fume (SF) pozzolans on the mechanical properties of recycled aggregates concrete (RAC’s). The RCA’s made with using different levels of recycled coarse aggregates instead of natural coarse aggregates. To improve quality of RCA’s, the introduced pozzolans were replaced with different levels of ordinary Portland cement (OPC). To determine and compare the mechanical properties of concretes, 24 mix designs were made and different tests done as compressive strength at the ages 7, 28 and 91 days, and the tests as splite cylinder tests (SPT), modulus of elasticity and ultra-pulse velocity (UPV) at the age of 28- day. The obtained results generally showed that in duration of 28 days, the usage of silica fume could results in about 40 MPa compressive strength for RCA’s with 100% of recycled coarse aggregates; meanwhile using natural zeolite was not able to give target strength of design. Using 10% of silica fume instead of OPC in RCA’s specially RCA’s having 25% of recycled aggregates caused in the mechanical properties of RCA’s be rarely like those natural aggregate concretes. Although, using 10% of zeolite in concrete could improve some mechanical properties, but the concretes containing silica fume gave superior mechanical properties than those of zeolite.

کلیدواژه‌ها [English]

  • Recycled aggregates concrete (RAC)
  • Mechanical properties
  • Silica fume (SF)
  • Natural zeolite (Z)
  • Pozzolan
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