ارزیابی تأثیر دما و الیاف بر خواص مکانیکی بتن خودمتراکم سبک

نوع مقاله : مقاله پژوهشی

نویسندگان

1 تهران - لویزان - دانشگاه شهید رجایی - دانشکده عمران

2 کارشناس ارشد مهندسی سازه، دانشکده مهندسی عمران، دانشگاه تربیت دبیر شهید رجایی، تهران، ایران

چکیده

مزایای بتن خودمتراکم سبک باعث استفاده روزافزون آن در صنعت ساخت ‌و ساز شده است. استفاده از الیاف مختلف در این نوع بتن سبب مشکلاتی نظیر کاهش کارایی و حساسیت به دما می‌شود که نوع و نحوه استفاده از الیاف را به چالش می‌کشد. از این‌ رو در این تحقیق، اثرات دما و الیاف­ شیشه و بازالت بر روی خصوصیات بتن خود­متراکم سبک مورد بررسی قرار گرفته است. در همین راستا 12 طرح اختلاط از این نوع بتن شامل طرح­های اختلاط تکی حاوی 0/25%،0/5 %، 0/75%و 1% حجمی هر کدام از الیاف‌­ها و نمونه­‌های ترکیبی شامل 0/25% الیاف ­بازالت و 0/75% الیاف ­شیشه، 0/5% الیاف ­بازالت به همراه0/5% الیاف ­شیشه، و 0/75% الیاف ­بازالت با0/25% الیاف ­شیشه ساخته ‌شده است. خواص خودمتراکمی در این بتن توسط آزمایش‌­های جریان اسلامپ، 500T، قیف­V و حلقه ­J سنجیده شده است. آزمایش‌­های مقاومت فشاری، کششی و خمشی جهت تعیین ویژگی­‌های مکانیکی بتن در دمای 20 درجه سلسیوس، همچنین دماهای 100 و 300 درجه سلسیوس انجام گرفتند. در نهایت نتایج آزمایش­‌های بتن تازه نشان دادند که بتن خود­متراکم سبک حاضر قابلیت­‌های گذرندگی، پر­شوندگی و مقاومت در برابر جداشدگی را پوشش داده‌­اند. همچنین مشخص شد افزایش الیاف موجب کاهش مقاومت فشاری و افزایش مقاومت‌­های کششی، خمشی و همچنین انرژی شکست می­‌شود. علاوه بر این استفاده از الیاف به‌ صورت ترکیبی در مقایسه با الیاف به ‌صورت تکی خواص مکانیکی بتن را بهبود بیشتری بخشیده‌­اند. بهترین طرح اختلاط­ حاوی ترکیبی از 0/75% الیاف ­شیشه و 0/25% الیاف ­بازالت بوده است که خواص قابل قبولی از بتن تازه و سخت­ شده و همچنین مقاومت در دماهای بالا را ارائه کرده ­است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Evaluating the influence of temperature and fiber type on the mechanical properties of self-compacting lightweight concrete

نویسندگان [English]

  • Moosa Mazloom 1
  • Sajjad Lotfi Ahangar Kolaee 2
2 M.Sc., Civil Engineering Department, Shahid Rajaee Teacher Training University, Tehran, Iran
چکیده [English]

The advantages of self-compacting lightweight concrete have led to its increasing use in the construction industry. The use of different fibers in this type of concrete causes problems such as reduced flowability and sensitivity to temperature, which challenges the type and method of using fibers. In the present study, the effects of glass and basalt fibers (GF and BF) and temperature on the properties of self-compacting lightweight concrete (SCLC) have been investigated. For this aim, the fresh and hardened properties of 12 SCLC mixes have been investigated that contained monotype and hybrid fibers. The self-compacting properties of SCLC were assessed using slump flow, T500, V-funnel, and J-ring. After 28 days of curing, the compressive, splitting tensile and flexural strengths tests were performed to characterize the mechanical properties of SCLC at room temperature of 20 °C and high temperatures of 100 and 300 °C. The test results of fresh concrete showed that all the mixes could be defined as SCLC with good flowability, viscosity, and passing ability. Hardened test results indicated that the addition of the fibers reduced the compressive strength and increased the tensile strength, flexural strength, and fracture energy. Moreover, compared to monotype fibers, the hybrid ones effectively enhanced the mechanical behaviors of SCLC.

کلیدواژه‌ها [English]

  • self-compacting lightweight concrete
  • Fiber-reinforced concrete
  • glass fiber
  • Basalt fiber
  • high temperature
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