عمل آوری داخلی بتن های خودتراکم با استفاده از پلیمرهای سوپرجاذب بر پایه سدیم و پتاسیم

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشجوی دکتری سازه، دانشکده عمران، دانشگاه علم و فرهنگ، تهران، ایران

2 دانشیار، دانشکده عمران، دانشگاه علم و فرهنگ، تهران، ایران

3 استادیار، دانشکده عمران، دانشگاه علم و فرهنگ، تهران، ایران

چکیده

یکی از پارامترهای تاثیرگذار در مقاومت نهایی و دوام بتن‌های خودتراکم، عمل‌آوری پس از ساخت می‌باشد. عمل‌آوری با استفاده از آب-رسانی و پوشش‌های حافظ رطوبت به صورت خارجی و سطحی، با در نظر داشتن محدودیت‌ این روش‌ها، به طور معمول مورد استفاده قرار می‌گیرند. عمل‌آوری داخلی به عنوان یکی از مباحث اساسی، در اجرای سازه‌های بتن‌آرمه و بتن حجیم، با محدودیت‌های بسیار کمتر به خصوص در بتن‌های ویژه و با مقاومت‌های بالا مطرح می‌باشد. بررسی تاثیر عمل‌آوری داخلی بتن خودتراکم با استفاده از پلیمرهای سوپرجاذب، بر روی مشخصات مکانیکی و دوام بتن، هدف این تحقیق می‌باشد. پلیمرهای سوپرجاذب مقداری از آب را به خود جذب کرده و طی فرآیند هیدراسیون به تدریج آن را آزاد می‌نمایند. با استفاده از این روش، فرآیند عمل‌آوری، نه تنها در سطح بلکه در عمق المانهای بتنی نیز به نحو موثرتری انجام می‌شود. دو نوع پودر پلیمر سوپرجاذب برپایه سدیم و پتاسیم با دو مقدار مختلف در این تحقیق مورد استفاده قرار گرفته است. نمونه‌های بتن در سنین 7 و 28 روز تحت آزمایش‌های مقاومت فشاری، مقاومت الکتریکی، نفوذپذیری آب، چرخه ذوب-یخبندان و آزمایش‌های بررسی ریزساختار از جمله SEM،XRD وXRF قرار گرفتند. مقاومت فشاری نمونه‌ها با عمل‌آوری داخلی نسبت به نمونه‌های شاهد به میزان 11.4% افزایش داشته است. از منظر پارامترهای دوام نیز نمونه-ها با عمل‌آوری داخلی، کاهشی بیش از 100% در میزان نفوذپذیری آب و 16.7% بهبود در مقاومت الکتریکی نشان می‌دهند. با بررسی نتایج آزمایش‌های ریزساختار، بهبود تکامل فرآیند هیدراسیون به میزان حداقل 2.4% و حداکثر 8.3% در اثر عمل‌آوری داخلی مشاهده گردید.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Internal Curing of Self-Compacting Concrete Using Superabsorbent Polymers Based on Sodium and potassium

نویسندگان [English]

  • Morteza Mehrvand 1
  • Hossein Parastesh 2
  • mohamadhossein Mobini 3
1 Ph.D. Candidate, dept. of Civil Engineering, University of Science and Culture, Tehran, Iran
2 Associate Professor, dept. of Civil Engineering, University of Science and Culture, Tehran, Iran
3 Assistant Professor, dept. of Civil Engineering, University of Science and Culture, Tehran, Iran
چکیده [English]

One Of the effective parameters in the final strength and durability of self-compacting concrete is post-fabrication curing. External Curing with water Supply and moisture retaining coating are commonly used despite the limitation of these methods. Internal curing is one of the main issues in the implementation of reinforced concrete and bulk concrete structures with much less restrictions, especially in high performance concrete. The aim of this study was to investigate the effect of internal curing of self-compacting concrete using superabsorbent polymers on mechanical properties and durability of concrete. These polymers absorb some water and gradually release it during the hydration process. Using this method, the curing process is performed more efficiently, not only on the surface but also in the depth of concrete elements. Two types of superabsorbent polymer powders based on sodium and potassium with two different amounts have been used in this research. Concrete samples at 7 and 28 days of age were subjected to compressive strength, electrical resistance, water permeability, thaw-freeze cycle and microstructure tests including SEM, XRD and XRF. Compressive strength of samples with internal curing increased by 11.4% compared to control samples. In terms of durability parameters, the samples with internal curing show a reduction of more than 100% in water permeability and 16.7% improvement in electrical resistance. The result of microstructural experiments showed an improvement in evolution of the hydration process by at least 2.4% and at most 8.3% due to internal curing.

کلیدواژه‌ها [English]

  • Internal curing
  • Self-compacting concrete
  • Superabsorbent polymers
  • Microstructure
  • SEM
  • XRD
  • XRF
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