بررسی اثر دمای بستر و اپوکسی در هنگام نصب بر روی مقاومت چسبندگی ورق‌های GFRP با استفاده از دو آزمون جدا کردن با کشش (Pull-off) و با پیچش (Twist-off)

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی دانشگاه فردوسی مشهد.

2 دانشکده مهندسی، دانشگاه فردوسی مشهد

3 لعاب مشهد - پرطاووس

چکیده

 استفاده از ورق‌های پلیمر مسلح با الیاف (FRP) به‌دلیل مزایای بسیار زیاد آن‌ها به‌عنوان یکی از پر کاربردترین مصالح به‌سازی سازه‌های بتنی شناخته ‌شده‌است. هدف از انجام این پژوهش، بررسی اثر دمای سطح بستر و هم‌چنین اپوکسی در بازۀ 5 تا 80 درجۀ سانتی‌گراد برروی مقاومت چسبندگی ورق‌های FRP با الیاف شیشه‌ای به بستر پایه‌سیمانی است. به همین منظور، از دو آزمون نیمه‌مخرب جدا کردن تحت کشش (Pull-off Test: POT) و جدا کردن تحت پیچش (Twist-off Test: TOT) بهره‌ گرفته شده‌است. نتیجه‌های این پژوهش براساس تحلیل و بررسی داده‌های 288 آزمونه از 32 نمونۀ ساخته‌شده گزارش شده‌است. به‌منظور درک بهتر اثر دمای سطح بستر و چسب اپوکسی و هم‌چنین برهم‌کنش آن‌ها، برروی مقاومت چسبندگی ورق‌های GFRP، نتایج به‌دست‌آمده بااستفاده از نرم‌افزار SPSS مورد تحلیل واریانس نیز (ANOVA) قرار گرفت. براساس این پژوهش، بیشترین مقاومت چسبندگی مربوط به نمونه‌هایی با دمای سطحی و اپوکسی 50 درجۀ سانتی‌گراد بود که نسبت‌به نمونۀ مبنا (دمای سطحی و اپوکسی 25 درجۀ سانتی‌گراد)، برای روش POT و TOT به‌ترتیب، 36 و 24 درصد افزایش را نشان ‌داد. هم‌چنین، نتیجه‌ها نشان داد، اثر منفی دمای سطح بستر را می‌توان تاحدی با افزایش دمای اپوکسی جبران کرد. افزون بر این، تحلیل درون‌یابی غیرخطی انجام‌شده برروی نتیجه‌ها حاکی از وجود یک رابطۀ نمایی بین مقاومت‌های چسبندگی به‌دست‌آمده از دو روش POT و TOT بود.

کلیدواژه‌ها

عنوان مقاله [English]

Effect of Substrate and Epoxy Temperature on the Bond Strength of GFRP Laminates Using Pull-off and Twist-off Tests

نویسندگان [English]

  • Peyman Imani Jajarmi 1
  • mohamad reza Tavakkolizadeh 2
  • Abbas Youssefi 3
1 Department of Civil Engineering, Ferdowsi University of Mashhad.
2 Department of Civil Engineering, Ferdowsi University of Mashhad.
3 Par-e-Tavous Research Institute
چکیده [English]

In recent years Fiber Reinforced Polymers (FRPs) increasingly used as an efficient way to repair and retrofit concrete structures. Performance of FRP systems depends on environmental, chemical and mechanical conditions. This study was carried out to investigate the effect of substrate and epoxy temperature at the time of installation (5 to 80°C) on bond strength between GFRP and cement-based mortar substrate using pull-off (POT) and twist-off (TOT) tests. A total of 288 tests has been performed and the gathered data were analyzed. The results showed the specimen with 50°C substrate and epoxy temperature had the highest bond strength. In this case, comparing to the control specimen, the bond strength increased up to 36 and 24% for POT and TOT, respectively. Besides, the reduction of the substrate surface temperature caused a decrease in bond strength. Upon increasing the substrate temperature beyond Tg, a significant loss in POT and TOT strength was observed. It was noted that the negative effect of low substrate temperature can be reduced by increasing epoxy temperature. A logarithmic correlation between POT and TOT bond test was observed. Results of the analysis of variance revealed that substrate surface temperature and epoxy temperature significantly affect the adhesion of the two materials and bond strength.

کلیدواژه‌ها [English]

  • Bond strength
  • Substrate surface temperature
  • Epoxy temperature
  • Pull-off
  • Twist-off

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