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

مهندسی عمران فردوسی

Article 8, Volume 35, Issue 1 - Serial Number 37, June 2022, Pages 13-30   

Document Type: Original Article

DOI: 10.22067/jfcei.2022.74568.1111

Authors

Peyman Imani Jajarmi¹; mohamad reza Tavakkolizadeh^{* 1}; Abbas Youssefi²

¹Department of Civil Engineering, Ferdowsi University of Mashhad.

²Par-e-Tavous Research Institute

Abstract

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.

Keywords

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

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