پایش آزمایشگاهی مقاومت الکتریکی بتن

نوع مقاله : یادداشت فنی

نویسندگان

1 رئیس مرکز تحقیق و توسعه سیمان تهران

2 استادیار مرکز تحقیقات راه، مسکن و شهرسازی

چکیده

روش‌های رایج کنترل گیرش، سخت‌شدگی، روند کسب مقاومت بتن، آزمایش‌های تعیین زمان گیرش ملات ISIRI 392 و بتن ISIRI 6046 و تعیین مقاومت فشاری بتن ISIRI 3206 می‌باشد. به نظر می‌رسد این روش‌های فیزیکی و مکانیکی با چارچوب عملی معین و قراردادی، بطور کامل رفتار بتن و روند تغییرات حالات فازها طی فرآیند هیدراته شدن را نمایش نمی‌دهد؛ لیکن با روش کنترل مقاومت الکتریکی بتن، امکان این پایش میسر می‌باشد. از این‌رو در این مطالعه به این موضوع بطور بومی پرداخته شد و یک عملیات آزمایشگاهی گسترده طراحی گردید. در مرحله اول 11 نمونه سیمان تهیه شدند که مقادیر فازهای آنها تنوع داشتند، اما به واسطه سیمان‌سازی آزمایشگاهی، نرمی و دانه‌بندی آنها شرایط تقریبا یکسانی داشت. آنالیز فیزیکی و شیمیائی نمونه‌های سیمان صورت گرفت. در مرحله بعد 22 مخلوط‌ بتنی با 11 نمونه سیمان تهیه گردید، بطوریکه 11 مخلوط با عنوان شاهد (فاقد افزودنی) و 11 مخلوط با مقدار ثابت افزودنی فوق روان کننده (بر پایه پلی کربوکسیلات) بودند. بر روی مخلوط‌های بتنی آزمایش‌های تعیین مقاومت فشاری بتن سخت شده 7، 28 و 90 روزه انجام شد. همچنین آزمایش تعیین مقاومت الکتریکی انجام شد که از زمان تماس سیمان با آب تا 31 روز بعد بطور مرتب قرائت‌ها صورت گرفت. نتایج حاصله، نشان داد که حداقل سه قله 8، 16 و 23 روز در منحنی مقاومت الکتریکی طی مرور زمان آزمایش دیده می‌شود. تقریباً در همه نمونه‌ها مقاومت الکتریکی تا حدود 3 ساعت کاهش یافته است که زمان گیرش بتن را نشان می‌دهد. بر اساس نتایج این مطالعه، روابطی ارائه شد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Laboratory Monitoring of Electrical Resistance of Concrete (Research Note)

نویسندگان [English]

  • Ali Akbar Kafash Bazari 1
  • Mehdi Chini 2
1 Chief of Laboratory of research and development of Tehran cement Co
2 Assistant Professor of Road, Housing and Urban Development Research Centre
چکیده [English]

Common methods of controlling setting, hardness, process of strength concrete are tests for determining the setting time of mortar (ISIRI 392) and concrete (ISIRI 6046) and determining the compressive strength of concrete (ISIRI 3206). Since these physical and mechanical methods do not fully reflect the behavior of concrete and also it is time and money consuming, application of electrical resistance of concrete has been investigated. Therefore, in this study, an extensive laboratory operation was designed. In the first stage, 11 samples of cement were prepared, the phases of which varied, but due to laboratory cementation, their fineness and grading were almost the same. Physical and chemical analysis of cement samples were performed. In the next step, 22 concrete mixtures with 11 cement samples were prepared, so that 11 mixtures with the title of control (without additives) and 11 mixtures with constant dosage of commercial super plasticizer (based on poly carboxylate). Compressive strength tests has been performed at ages of 7, 28 and 90 days. Also, an electrical resistance test was performed, which was performed regularly from the time of cement contact with water until 31 days later. The results showed that at least three peaks of 8, 16 and 23 days in the electrical resistance curve are seen along the test time. In almost all samples, the electrical resistance is reduced to about 3 hours, which indicates the setting time of the concrete. Based on the results of this study, formula was presented

کلیدواژه‌ها [English]

  • Electrical resistance
  • cement
  • Concrete
  • additives
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  • تاریخ دریافت: 06 بهمن 1400
  • تاریخ بازنگری: 12 اردیبهشت 1401
  • تاریخ پذیرش: 22 خرداد 1401
  • تاریخ اولین انتشار: 22 خرداد 1401