دوام ملات‌های پوششی با پایه سیمانی و ژئوپلیمری در برابر تهاجم اسید سولفوریک

نوع مقاله : مقاله پژوهشی

نویسندگان

424 Hafez Ave

چکیده

حمله اسید سولفوریک یکی از مکانیزم‌های خرابی سازه‌های بتنی شایع در تونل‌های انتقال آب بوده که نیاز به تعمیرات اساسی و پرهزینه برای مقابله با آن را دو چندان کرده است. یکی از راه‌های تعمیر این قبیل سازه‌ها اجرای لایه پوششی محافظ بر روی سطح بتن داخل تونل‌ها می‌­باشد. بخش عمده‌ای از پوشش‌های محافظ را ملات‌های با پایه سیمانی تشکیل می‌دهند، اما در چند سال اخیر با توجه به اهمیت آثار زیست ‌محیطی و همچنین در راستای کاهش مصرف انرژی ناشی از تولید سیمان، ملات‌های ژئوپلیمری نیز مورد توجه قرار گرفته‌اند. در این پژوهش به منظور مقایسه ملات­های پایه سیمانی و ژئوپلیمری، 7 مخلوط شامل 5 طرح ملات پایه سیمانی با جایگزینی سرباره کوره آهن‌گدازی و پوزولان طبیعی و 2 طرح ملات ژئوپلیمری بر پایه سرباره کوره آهن‌گدازی حاوی دوده سیلیس، به‌ عنوان طرح‎‌های مورد استفاده انتخاب شده و جهت بررسی ویژگی‌های مکانیکی آن‌ها آزمایشات تعیین مقاومت فشاری و مقاومت چسبندگی کششی (Tensile Adhesive Strength) در سنین مختلف صورت پذیرفته است. همچنین جهت ارزیابی دوام آن‌ها نیز آزمایشات جذب آب موئینگی و تغییرطول، افت مقاومت فشاری و افت وزن پس از قرارگیری در محلول اسید سولفوریک با pH برابر با 1 انجام شده است. بر اساس نتایج به دست آمده، استفاده از مواد جایگزین سیمان (سرباره و پوزولان طبیعی‌) سبب کاهش 25 درصدی مقاومت فشاری، افزایش 50 درصدی مقاومت چسبندگی و کاهش تغییر طول و افت وزن و مقاومت فشاری نمونه‌­های قرار گرفته در معرض اسید سولفوریک شده است. همچنین استفاده از ملات‌های ژئوپلیمری در سنین اولیه عملکرد مناسب تری در محیط­های اسیدی نسبت به ملات­‌های پایه سیمانی داشته است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Durability of cementitious and geopolymer coating mortars against sulfuric acid attack.

نویسندگان [English]

  • faramarz moodi
  • Aliakbar Ramezanianpor
  • Farhad Farhadian
  • Pouria Dashti
Amirkabir University of Technology
چکیده [English]

 Successive deterioration in concrete structures which is caused by the acid attack, has increased the need for substantial and costly repairs to deal with the destruction of concrete structures. Common devastation of water transfer tunnels is due to sulfuric acid attack. One of the ways of maintenance of such structures is to perform the protective coating of the cementitious and geopolymer coating mortars, in which the different features of this coating layer should be studied. In this study, the mechanical properties and durability of geopolymer and cementitious coating mortars containing granulated blast furnace slag and natural pozzolan have been compared. Five cementitious mortar mixtures were prepared with water to binder ratio of 0.32, binder content of 450 kg/m3, and replacement of Portland cement (PC) with 20 and 40% slag and natural pozzolan. 2 geopolymer mortar mixtures with KOH and NaOH as activator were designed. To evaluate their mechanical properties, Compressive strength and tensile adhesion strength were carried out. Also, in order to investigate their durability features against sulfuric acid attack, mortar specimens length Change, compressive strength loss, and weight loss were investigated. According to the results, the use of cement substitute materials (furnace slag and natural pozzolan) reduced the compressive strength by 25%, increased the adhesion strength by 50%, and reduced the length change, weight loss and compressive strength loss of the samples exposed to sulfuric acid. Also, the use of geopolymer mortars had the better performance than the control sample, so that more than 40% increase in compressive strength, about 150% increase in adhesion resistance and approximately 50% decrease in length change and weight loss and compressive strength loss compared to control sample in the sulfuric acid environment. In general, the test results show the proper performance of geopolymer repair mortars in aggressive acidic environments compared to cement-based mortars.

کلیدواژه‌ها [English]

  • Durability
  • Sulfuric Acid Attack
  • Furnace slag
  • Natural Pozzolan
  • Geopolymer mortar
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