بررسی مشخصات مکانیکی، الکتریکی و ریز ساختار بتن فراتوانمند حاوی درصدهای مختلف دوده سیلیس و الیاف پلی وینیل الکل

نوع مقاله : علمی - پژوهشی

نویسندگان

1 گروه مهندسی عمران، واحد فومن و شفت، دانشگاه آزاد اسلامی، فومن، ایران

2 گروه مهندسی عمران، دانشکده فنی، دانشگاه گیلان

3 گروه مهندسی عمران، دانشکده فنی، دانشگاه گیلان، رشت، ایران

چکیده

بتن فراتوانمند نوع جدیدی از مصالح مرکب به شمار می آید که با نسبت آب به مصالح سیمانی پایین، توانایی تحمل تنش های فشاری تا 200 مگاپاسکال و تنش های کششی بالایی در حدود 10 مگاپاسکال را دارا می باشد. انرژی شکست بتن فراتوانمند از 8560 تا 40000 ژول بر متر مکعب متغیر است که این میزان تقریبا 220 برابر بزرگتر از انرژی شکست ملات معمولی می باشد. به دلیل خصوصیات برتر مکانیکی و دوام، بتن فراتوانمند توجه زیادی را در بین محققان به خود جلب کرده است. مقاومت فشاری بسیار بالا این نوع بتن منجر به کاهش وزن قابل توجه سازه و همچنین ساخت المان های سازه ای با ابعاد کوچک تر می شود. در این مقاله نمونه های بتن فراتوانمند حاوی الیاف پلی وینیل الکل بعد از عمل آوری در دوشرایط محیطی متفاوت، یکی شرایط استاندارد در دمای 23 درجه سانتی گراد و دیگری قرارگیری در آب گرم 70 درجه سانتی گراد، تحت آزمایش های مقاومت فشاری، خمشی و مقاومت الکتریکی قرار گرفتند. آزمایش های مقاومت فشاری و خمشی در سنین 28 روزه و 6 ماهه و آزمایش مقاومت الکتریکی در سن 6 ماه انجام شدند. با در دست داشتن اطلاعات مقاومت مکانیکی و دوام و ریزساختار، یک دید کلی و جامع از بتن های فراتوامند و قابلیت های آنها به دست آمد. نتایج نشان داد که الیاف PVA در بهبود مشخصات مکانیکی (به دلیل جلوگیری از گسترش ریزترک ها) از یک سو و همچنین افزایش کلی تخلخل ماتریس سیمانی از سویی دیگر تاثیر بسزایی داشت. ولی تاثیر الیاف روی مشخصات الکتریکی به شدت تحت تاثیر میزان جایگزینی دوده سیلیس با سیمان و همچنین نوع عمل آوری بود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

An investigation on mechanical and electrical properties and microstructure of Ultra-High Performance Concrete Containing Silica Fume and PVA Fiber

نویسندگان [English]

  • Mir Alimohammad Mirgozar Langaroudi 1
  • s. Hosein Ghasemzadeh mosavinejad 2
  • Jalil Barandoust 3
  • Ardalan Ghanizadeh 3
1 Department of Civil Engineering, Fouman and Shaft Branch, Islamic Azad University, Fouman, Iran
2 Civil engineering Dept, technical faculty, university of giulan
3 Department of Civil Enineering, Faculty of Engineering, University of Guilan, Rasht, IRan
چکیده [English]

Ultra-high performance concrete (UHPC) is a new type of composite materials that can develop a compressive strength up to 200  MPa and high tensile strength around 10 MPa, given the low water-to-binder ratio (W/B). The fracture energy of UHPC can vary from 8560 to 40,000 J/m2, which is approximately 220 times greater than that of conventional mortar. Due to its superior properties, Ultra-high performance concrete has received great attention among researchers recently. Very high compressive strength leads to a significant weight loss of the structure and makes it possible to build slender structural elements. In this paper, the ultra-high performance fiber reinforced concrete specimens exposed to two different curing regimes, a 23°C limewater tank, and a 70°C hot-water tank. Then, the compressive and flexural strength and the electrical behavior of specimens were evaluated. Mechanical strength at the age of 28 days and six months were measured, in order to in conjunction with durability-related properties offer an overall view of UHPFRC characteristics. Results showed that the PVA fiber affected the mechanical strengths by preventing the propagation of cracks and by increasing the total porosity of the matrix. Moreover, its influence on resistivity was highly dependent on the concentration of silica fume particles.

کلیدواژه‌ها [English]

  • Ultra-high performance concrete
  • PVA fibers
  • Silica Fume
  • Microstructure
  • Electrical Resistivity
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