ارزیابی عملی استفاده از بتن های سبک خودتراکم در احداث سازه های بتن آرمه

نوع مقاله : علمی - پژوهشی

نویسندگان

1 عضو هیات علمی گروه عمران، واحد فومن و شفت، دانشگاه آزاد اسلامی، فومن، ایران

2 دانشیار، دانشگاه گیلان، رشت، ایران

3 کارشناس ارشد مهندسی سازه، دانشگاه آزاد اسلامی واحد تهران جنوب، تهران، ایران

4 دانشکده فنی، دانشگاه گیلان

چکیده

به عقیده بسیاری، بتن خود تراکم یا SCC را می‌توان بتن آینده دانست. مهمترین قابلیت بتن خودتراکم، توانایی جریان یافتن تحت وزن خود، پرکردن فضای موردنیاز و یا قالب به طور کامل، و ایجاد یک مخلوط چگال و به مقدار کافی همگن در بین میلگردهای اعضای بتن‌آرمه، بدون نیاز به ویبره می‌باشد. اما روانی بیش از حد این بتن، فشار وارد بر قالب بندی را افزایش می‌دهد، به طوری‌که در لحظات اول بتن ریزی، فشار قابل توجهی بصورت هیدرواستاتیکی بر جدار قالب وارد می‌شود. لذا کاهش وزن بتن‌های خودتراکم می-تواند یکی از روش‌های کاهش فشار وارد بر قالب بندی باشد. همچنین واضح است که کاهش چگالی بتن، اثر محسوسی بر کاهش وزن سازه داشته و به کاهش ابعاد اعضای سازه‌ای خواهد انجامید. اما از سوی دیگر همواره نگرانی‌هایی در خصوص جداشدگی سبک‌دانه‌ها در هنگام حمل و یا بتن‌ریزی وجود دارد. در این پژوهش، قابلیت حفظ همگن بودن مخلوط و مشخصات مکانیکی بتن سبک خودتراکم LWSCC ساخته شده با سبک دانه‌های رایج در کشور شامل اسکوریا ، لیکا و پومیس در صورت استفاده کاربردی از آن در ستون‌های بتن‌آرمه، به کمک روش‌های نیمه‌مخرب و غیرمخرب بررسی می‌شود. برای رسیدن به این هدف، ستون‌های بتن‌مسلح ساخته شده با بتن سبک خودتراکم، به کمک آزمایش نیمه مخرب مغزه‌گیری به منظور تعیین مقاومت فشاری و نفوذناپذیری و آزمایش غیر مخرب التراسونیک در ارتفاع‌های مختلف ستون‌ها، مورد بررسی قرار گرفته‌اند. نتایج نشان داد که سبکدانه اسکوریا در مقایسه با سایر سبکدانه-های مورد بررسی در این تحقیق، در مجموع عملکرد بهتری در بتن سبک خودتراکم داشته است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Practical Evaluation of Using Lightweight Self-Compacting Concrete in Reinforced Concrete Constructions

نویسندگان [English]

  • hamed pourahmadi sefat arabani 1
  • Ali Sademomtazi 2
  • miralimohammad mirgozar langaroudi 1
  • morteza amooei sarajari 3
  • reza kohani khoshkbijari 4
1 Faculty of Civil Engineering, Fouman and Shaft Branch, Islamic Azad University, Fouman, Iran
2 Associate professor, Civil Engineering Dept, University of Guilan, Rasht, Iran
3 M.Sc. of Structural Engineering, Islamic Azad University South Tehran Branch, Tehran, Iran
4 PhD in Civil Engineering, Faculty of Engineering, University of Guilan, Rasht, Iran
چکیده [English]

Self-compacting concrete or SCC can be considered as the concrete of the future. The most important feature of self-compacting concrete is flowing under its own weight to fill the mould or framework completely, and also to create a dense and sufficiently homogeneous mix between the bars, without any need for vibration. But the excessive Liquidity of this concrete increases the hydrostatic pressure on the frameworks. So, decrease in the weight of self-compacting concrete could be lead to reducing the pressure on frameworks. It is also clear that decreasing the density of concrete has a significant effect on the reduction of the structure’s weight and will lead to decrease in the size of structural elements. On the other hand, there are general concerns about the segregation of lightweight aggregates during transportation or placing. In this research, the ability of maintaining the homogeneity of the mixture and the mechanical properties of lightweight self-compacting concrete (LWSCC) made with common lightweight aggregates in the country including Scoria, Leca and Pumice, has been investigated on concrete columns, using the Semi-destructive and non-destructive methods. To do this, reinforced concrete columns made by self-compacting concrete were investigated using a semi-destructive core test to determine the compressive strength and impermeability. Non-destructive ultrasonic test at different heights of the columns was also conducted. The results showed that Scoria aggregate had generally better performance in self-compacting concrete compared to other lightweight aggregates.

کلیدواژه‌ها [English]

  • Reinforced concrete column
  • Lightweight self-compacting concrete
  • Compressive strength
  • Ultrasonic test
  • Core test
  • Impermeability test
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