به کارگیری آزمون‌های پیچش و کشیدن از سطح جهت بررسی تاثیر الیاف پلی‌پروپیلن بر چسبندگی ملات با بتن و ارزیابی مقاومت فشاری درجای آن‌ها

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دکتری سازه، دانشکده فنی و مهندسی، دانشگاه بین المللی امام خمینی (ره)، قزوین، ایران،

2 Department of Civil Engineering, Imam Khomeini International University, Qazvin, Iran

چکیده

در صنعت تعمیر بتن، چسبندگی بین لایه تعمیری و بستر بتنی، نقش تعیین کننده‌ای در عملکرد مرکب موفق لایه‌های تعمیری دارد. با توجه به پدیده جمع‌ شدگی و تاثیر آن بر افت چسبندگی، در این مقاله تاثیر الیاف پلی‌پروپیلن بر چسبندگی ملات و بتن مورد بررسی قرار گرفت. برای انجام آزمایشات از آزمون نوین "پیچش" استفاده شد. در تمامی آزمایشات، نتایج حاصل از آزمون "پیچش" با نتایج آزمون استاندارد "کشیدن از سطح" مورد مقایسه قرار گرفت. برای تجزیه و تحلیل بیشتر نتایج به دست آمده، از آزمون‌های XRD (الگوی پراش اشعه ایکس) و SEM (میکروسکوپ الکترونی روبشی) استفاده شد. همچنین تاثیر الیاف بر جمع‌ شدگی و مشخصات مکانیکی ملات‌های تعمیری و رابطه آن بر چسبندگی بین ملات و بتن بررسی گردید. در این خصوص از آزمون‌های درجای "پیچش" و "کشیدن از سطح" به صورت آزمایشگاهی استفاده شد. با بررسی ضریب همبستگی بین نتایج آزمون‌های درجا با آزمون‌های آزمایشگاهی، نمودارهای کالیبراسیون جهت تبدیل قرائت‌های به دست آمده از آزمون‌های "پیچش" و "کشیدن از سطح" به مقاومت فشاری ملات‌ها ارائه شد. نتایج حاصله بیانگر این بود که برای نمونه الیافی، مقدار بیشینه Ca(OH)2 یا هیدروکسیدکلسیم دچار کاهش شد که منتج به تولید بیشتر سیلیکات کلسیم هیدراته یا ژل C-S-H می‌شود که نتیجه آن بهبود خواص نهایی ملات و افزایش چسبندگی بود. همچنین به طور میانگین مقاومت چسبندگی برشی و کششی 90 روزه حاصل از آزمون‌های "پیچش" و "کشیدن از سطح" با افزودن الیاف به ترتیب به مقدار 49/5 و 43/1 درصد افزایش داشته است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Using "twist-off" and "pull-off" tests to investigate the effect of polypropylene fibers on the bond of mortar/concrete and to evaluate their in-situ compressive strength

نویسندگان [English]

  • Ali Saberi Vaezaneh 1
  • Mahmood Naderi 2
1 Ph.D Department of Civil Engineering, Imam Khomeini International University, Qazvin, Iran
2 Department of Civil Engineering, Imam Khomeini International University, Qazvin, Iran
چکیده [English]

In the concrete repair industry, the adhesion between the repair layer and the concrete plays a decisive role in the successful composite performance of the repair layers. Due to the shrinkage and its effect on adhesion loss, in this paper, the effect of polypropylene fibers on the adhesion between mortar/concrete has been investigated. A new "twist-off" test has been used to perform the experiments. In all experiments, the results of the "twist-off" test were compared with the results of the "pull-off" test. X-ray diffraction patterns and scanning electron microscopy tests were used to further analyze the results. Also, the effect of fibers on shrinkage and mechanical properties of mortars and its relationship to adhesion between mortar and concrete were investigated. In this regard, the tests of "twist-off" and "pull-off" were used in the laboratory and compared with the outputs of computer modeling. Also, by examining the correlation coefficient between the results of in-situ tests and laboratory tests, calibration diagrams were presented to convert the readings obtained from the "twist-off" and "pull-off" tests into the compressive strength of mortars. The results indicate that for the fibrous sample, the peak intensity of Ca (OH)2 or calcium hydroxide is reduced, resulting in the production of more hydrated calcium silicate or C-S-H gel, which results in improved final properties of the mortar and increased adhesion. Also, on average, the shear and tensile bond strength of 90 days obtained from "twist-off" and "pull-off" tests with the addition of fibers increased by 49.5% and 43.1%, respectively.

کلیدواژه‌ها [English]

  • "Twist-off"
  • "Pull-off"
  • Adhesion
  • Mortar
  • Concrete

مراجع

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نشریه مهندسی عمران امیرکبیر
دوره 54، شماره 5
مرداد 1401
صفحه 1675-1690

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