مقاومت فشاری بتن الیافی حاوی خرده لاستیک تحت آتش

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مازیار، رویان، ایران

2 گروه مهندسی نفت، دانشکده مهندسی شیمی، دانشگاه تربیت مدرس، تهران، ایران

3 گروه راه و ترابری، دانشکده مهندسی عمران، دانشگاه علم و صنعت ایران، تهران، ایران

چکیده

استفاده از ضایعات لاستیکی از جمله خرده لاستیک در مخلوط بتن به عنوان یکی از روش­های موثر جهت کاهش مواد زائد می­باشد. علاوه بر این، امروزه استفاده از مواد ضایعاتی به عنوان جایگزین بخشی از سنگدانه­های طبیعی در بتن، راه حلی موثر برای رفع مشکلات زیست محیطی است که با توجه به تنزل خصوصیات بتنِ حاصل ناشی از حضور مواد ضایعاتی، افزودن الیاف به مخلوط بتن، می­تواند عملکرد مکانیکی آن را بهبود بخشد. از این رو در این مطالعه، مقاومت فشاریِ بتن مسلح شده به الیاف فولادی حاوی خرده لاستیک بازیافتی پس از قرارگیری در دماهای بالا به طور آزمایشگاهی مورد ارزیابی قرار گرفته است. در مجموع 9 طرح مخلوط در طول آزمایش ساخته شد و متغیرهای آزمایش شامل درصد حجمی لاستیک تایر بازیافتی جایگزین ماسه طبیعی(0، 5 و 10 %)، درصد حجمی الیاف فولادی (0، 0.5 و 1 %)، و دمای آتش (25، 200، 400 و 600 درجه) می­باشند. علاوه بر این، مقاومت فشاری با مقادیر پیش بینی آیین نامه­های ACI 216، EN 1994-1-2 مقایسه شدند. نتایج نشان می­دهد که افزودن الیاف فولادی به حجم بتن و اضافه کردن لاستیک تایر جایگزین ماسه به مخلوط بتن منجر به کاهش مقاومت فشاری نمونه­های بتنی حرارت دیده و حرارت ندیده می­شود . همچنین، با افزایش درجه حرارت، مقاومت فشاری کلیه نمونه­های بتنی با یک افت قابل توجهی رو به رو شده است. از این رو، در دمای 600 درجه سانتیگراد، نرخ افت مقاومت فشاری نمونه­ها در مقایسه با سایر دماها بیشتر بود به طوری که مقاومت فشاری نمونه مرجع و نمونه­های بتنی حاوی تایر و الیاف نسبت به مقاومت نمونه متناظر در دمای محیط، با کاهش مقاومت در محدوده 59.5 – 76.9 % رو به رو شدند. همچنین، پیش بینی آیین نامه­ها، نتایج مقاومت فشاری بتن حرارت دیده را اندکی دست بالا تخمین می­زنند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Compressive strength of fibrous concrete containing crumb rubber under fire

نویسندگان [English]

  • Shayan Fakhrian 1
  • Shayan Mashhadi 2
  • Hamid Behbahani 3
1 Department of Civil Engineering, Faculty of Engineering and Technology, Maziar University, Royan, Iran
2 Department of Petroleum Engineering, Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
3 Department of Road and Transportation, School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
چکیده [English]

In Iran, thousands of tons of rubber materials are discarded as wastes each year. Since these waste materials do not have a proper quality to be used for usual life purposes such as household items, thus the best application for these materials is to use them as aggregates in the construction industry. Furthermore, using waste rubber materials such as crumb tires in the concrete mix is regarded as one of the efficient ways to recycle these waste materials. Besides, substituting a fraction of natural aggregates in the concrete mix by waste materials is a promising strategy to deal with environmental problems associated with these materials. Given that the presence of waste aggregate in concrete degrades its properties, adding fibers to the concrete mix has been shown to improve the mechanical performance. Therefore, in the present study, the compressive strength of the concrete reinforced with steel fibers and containing recycled crumb rubber aggregate was evaluated after exposure to fire through an experimental program. Here, a total of nine mix designs were prepared for the experimental phase, with the test variables being the volume percentage of tire rubber aggregate as a replacement for natural sand (0, 5, and 10%), the volume fraction of steel fibers (0, 0.5, and 1%), and temperature (20, 200, 400, and 600 °C). Moreover, the compressive strength values were compared with those predicted by the ACI 216 and EN 1994-1-2 codes. The results showed that adding steel fibers together with tire rubber aggregate in the concrete mix led to a decrease in the compressive strength of the heated and unheated concrete specimens. Also, as temperature increased, the compressive strength of all the concrete specimens saw a considerable reduction. In this regard, after exposure to 600 °C, the compressive strength loss rate was higher compared to that after exposure to other temperatures, such that the compressive strength of the reference specimen and those containing tire aggregate and fibers decreased by 59.5-76.9% relative to that of the corresponding specimens at ambient temperature. ACI 216 and EN 1994-1-2 provide a relatively good estimation for the normalized compressive strength of all the concrete specimens containing tire rubber and steel fibers at 200 and 400 °C; however, they give an overestimation for the reference concrete. Besides, the above codes give a relatively good prediction for the normalized compressive strength of the specimens exposed to 600 °C (except for specimens ST0TR10, ST0.5TR10, and ST1.0TR5).

کلیدواژه‌ها [English]

  • Compressive strength of fibrous concrete containing crumb rubber under fire
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