بررسی خواص رئولوژی و زمان گیرش مخلوط های بتن خودتراکم توسط روش صفحه

نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار دانشکده مهندسی عمران، دانشگاه علم و صنعت ایران

2 دانشگاه علم و صنعت ایران

چکیده

زمان گیرش و تغلیظ‌ پذیری مخلوط‌ های بتن خود تراکم دو پارامتر بسیار مهم می‌باشند که در ساعات اولیه بتن‌ریزی حائز اهمیت هستند. برای تعیین این دو پارامتر روش‌هایی وجود دارد که دارای مزایا و معایب از جمله دقت پایین و یا هزینه بالای آزمایش می‌باشند. هدف از این تحقیق ارائه یک روش ارزان و در عین حال با دقت مناسب برای تعیین زمان گیرش و تغلیظ‌ پذیری مخلوط‌ های بتنی می‌باشد که این روش به نام روش صفحه معرفی شده است. روش مذکور شامل اندازه‌گیری تغییرات وزن یک صفحه زبر، در بازه زمانی انجام آزمایش می‌باشد که درون مصالح برپایه سیمان قرار می‌گیرد. جهت اعتبارسنجی روش صفحه، چندین نوع مخلوط بتن خودتراکم حاوی افزودنی‌های سرباره و دوده سیلیس در آزمایشگاه ساخته شده و نتایج زمان گیرش دستگاه صفحه با نتایج بدست آمده از روش استاندارد مقاومت در برابر نفوذ مقایسه شده است. علاوه بر انجام آزمایش صفحه، در این تحقیق سعی شد با اندازه‌گیری تغییرات دمای مخلوط‌ ها، تأثیر پدیده‌های متفاوتی که در حالت تازه رخ می‌دهند، تشریح گردد. با توجه به آزمایش‌های انجام شده، نتایج تغلیظ‌ پذیری دستگاه صفحه با دستگاه رئومتر مقایسه شد. اختلاف نتایج برای مخلوط‌ های مورد آزمایش، از حداقل %3/71 تا حداکثر %10/74 نسبت به نتایج رئومتر بدست آمد. همچنین اختلاف زمان گیرش بدست آمده از روش صفحه نسبت به روش مقاومت در برابر نفوذ حداکثر برابر 9 %بود. این نتایج نشان از دقت قابل قبول این روش در تعیین زمان گیرش و تغلیظ‌‌ پذیری دارد و جهت تعیین این پارامترها پیشنهاد می‌شود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Evaluating the Rheology Properties of Self-Consolidating Concrete Using the Plate Test Method

نویسندگان [English]

  • ali akbar shirzadi javid 1
  • Parviz Ghoddousi 2
  • mohammad jaberizadeh 2
  • behnam bozorgmehr 2
1 assistant professor, school of civil engineering, iran university of science and technology
2 iran university of science and technology
چکیده [English]

Setting time and thixotropy of self-consolidating concrete (SCC) mixtures are two important parameters that affect the early age properties. In order to determine these parameters, there are traditional methods that have advantages and disadvantages such as low accuracy or high cost of testing. The aim of this study is introducing an acceptable method (called plate test) of determining setting time and thixotropy of SCC mixtures. The proposed method is including a rough plate immersed in fresh mixture from one side and attached to the accurate scale from another side. In this study the thixotropy of different self-consolidating concrete mixtures (SCC) containing silica fume and slag were tested. Results of the thixotropy obtained from the plate test were compared with the results obtained from penetration resistance and rheometer respectively. Results showed that the mixture containing slag produced the less temperature comparing with the mixture containing silica fume. It was also shown that the amount of thixotropy obtained from the plate test had a difference of 4% up to 10% in comparison with the rheometer and the results of the setting time had also shown a maximum difference of 9% compared with the results of penetration resistance test. The results proved that the plate test has an acceptable accuracy and can be recommended.

کلیدواژه‌ها [English]

  • Self-Compacting Concrete
  • rheology
  • Thixotropy
  • Plate Test Method
  • Resistance to Penetration
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