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

Document Type : Original Article

Authors

Peyman Imani Jajarmi ¹

mohamad reza Tavakkolizadeh ¹

Abbas Youssefi ²

¹ Department of Civil Engineering, Ferdowsi University of Mashhad.

² Par-e-Tavous Research Institute

10.22067/jfcei.2022.74568.1111

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

20.1001.1.27832805.1401.35.1.2.1

---

References

1. Saadatmanesh, H., and Malek, A. M., "Design Guidelines for Flexural Strengthening of RC Beams with FRP Plates", Journal of Composites for Construction, 2, No. 4, pp. 158-164, (1998).
2. Mostofinejad, D., and Hosseini, S. J., "Simulating FRP Debonding from Concrete Surface in FRP Strengthened RC Beams: A Case Study", Scientia Iranica, International Journal of Science and Technology, Transactions A, Civil Engineering, 24, No. 2, pp. 452-456, (2017).
3. Khorasani, A. M., Esfahani, M. R., and Sabzi, J., "The Effect of Transverse and Flexural Reinforcement on Deflection and Cracking of GFRP Bar Reinforced Concrete Beams", Composites Part B: Engineering, 161, No. 3 ,pp. 530-546, (2019).
4. Blackburn, BP., Tatar, J., Douglas, EP., and Hamilton, HR., "Effects of Hygrothermal Conditioning on Epoxy Adhesives Used in FRP Composites", Construction and Building Materials, 96, No. 10, pp. 679-689, (2015).
5. Djouani, F., Connan, C., Delamar, M., Chehimi, MM., and Benzarti, K., "Cement Paste-Epoxy Adhesive Interactions", Construction and Building Materials, 25, No. 2, pp. 411-423, (2011).
6. Stewart, A., "Study of Cement-Epoxy Interfaces, Accelerated Testing, and Surface Modification", PHD Dissertation, University of Florida, Gainesville, FL, (2012).
7. Chen, C., Li, X., Zhao, D., Huang, Z., Sui, L., and Xing, F., "Mechanism of Surface Preparation on FRP-Concrete Bond Performance: A Quantitative Study", Composites Part B: Engineering, 163, No. 4, pp. 193-206, (2019).
8. Varun, N., Sudarshan, G., Shivaraj, A., and Sridevi, G., "Rehabilitation and Retrofitting of Structural Elements Using Various Fibers", Resilient Infrastructure, 202, No. 1, pp. 187-193, (2022).
9. Chothe, O.K. and Agrawal, V. M., "An Experimental Investigation on Applications of Fiber-Reinforced Composites for Rehabilitation of Concrete Beams", Resilient Infrastructure, 202, No. 1, pp. 415-425, (2022).
10. Zhang, P., Lv, X., Zhang, H., Liu, Y., Chen, B., Gao, D., and Sheikh, SA., "Experimental Investigations of GFRP-Reinforced Columns with Composite Spiral Stirrups under Concentric Compression", Journal of Building Engineering, 46, No. 4, pp. 103768, (2022).
11. ACI Committee 440., "Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures (ACI 440. 2R-17)", American Concrete Institute, Farmington Hills, MI, (2017).

 

12. AASHTO-FRPS-1., "Guide Specifications for Design of Bonded FRP Systems for Repair and Strengthening of Concrete Bridge Elements", American Association of State Highway and Transportation Officials, Washington D.C., (2010).
13. fib Bulletin 14., "Externally Bonded FRP Reinforcement for RC Structures. Technical Report on the Design and Use of Externally Bonded Fiber Reinforced Polymer Reinforcement (FRP EBR) for Reinforced Concrete Structures", International federation for structural concrete (fib), Lausanne, Switzerland, (2001).

 

14. Aiello, M., Frigione, D., and Acierno, D., "Effects of Environmental Conditions on Performance of Polymeric Adhesives for Restoration of Concrete Structures", Journal of Materials in Civil Engineering, Vol. 14, No. 2, pp. 185-189, (2002).
15. Banea, M., Silva, LFM., and Campilho, R., "Effect of Temperature on Tensile Strength and Mode I Fracture Toughness of a High Temperature Epoxy Adhesive", Journal of Adhesion Science and Technology, 26, No. 7, pp. 939-953, (2012).
16. Nguyen, T., Bai, Y., Zhao, X., and Al-Mahaidi, R., "Mechanical Characterization of Steel/CFRP Double Strap Joints at Elevated Temperature", Composite Structure, 93, No. 6, pp. 1604-1612, (2011).
17. Leone, M., Matthys, S., and Aiello, MA., "Effect of Elevated Service Temperature on Bond between FRP EBR Systems and Concrete", Composites Part B, 40, No. 1, pp. 85-93, (2009).
18. Blontrock, H., Taerwe, L., and Vanwalleghem, H., "Bond Testing of Externally Glued FRP Laminates at Elevated Temperature", international conference on bond in concrete-from research to standard, Budapest, Hungary, (2002).
19. Attari, B., and Tavakkolizadeh, M., "An Experimental Investigation on Effect of Elevated Temperatures on Bond Strength between Externally Bonded CFRP and Concrete", Steel and Composite Structures, 32, No. 5, pp. 559-569, (2019).
20. Imani Jajarmi, P., Tavakkolizadeh, MR., and Youssefi, A., "Effect of Temperature and Moisture on the Bond Strength between FRP Laminates and Cement-Based Mortar Substrates", Structural Concrete, 22, No. 6, pp. 1-23, (2022).
21. Myers, , and Ekenel, M., "Effect of Environmental Conditions on Bond Strength between CFRP Laminate and Concrete Substrate", Center for Infrastructure Engineering Studies (CIES), Special Publication, Vol. 230, No. 1, pp. 1571-1592, (2005).
22. Al-Shawaf, A., Al-Mahaidi, R., and Zhao, X., "Study on Bond Characteristics of CFRP/Steel Double Lap Shear Joints at Subzero Temperature Exposure", 3^rd international conference on FRP composites in civil engineering (CICE), Miami, FL, (2006).
23. Kim, Y., Hossain, M., and Yoshitake, I., "Cold Region Durability of a Two-Part Epoxy Adhesive in Double-Lap Shear Goints: Experiment and Model Development", Journal of Construction and Building Materials, 36, No. 11, pp. 295-304, (2012).
24. Malhotra, V.M., and Carino, N.J., "Non-Destructive Testing of Concrete", Boca Raton, New York, Washington D.C. 2^nd Edition, CRC Press LLC, (2004).
25. ASTM Standard D4541-17., "Standard Test Method for Pull-Off Strength of Coatings Using
    Portable Adhesion Testers, West Conshohocken, PA, (2017).
26. ASTM Standard D7522-15., "Standard Test Method for Pull-Off Strength for FRP Laminate
    Systems Bonded to Concrete Substrate, West Conshohocken, PA, (2015).
27. ASTM Standard D7234-19., "Standard Test Method for Pull-Off Adhesion Strength of
    Coatings on Concrete Using Portable Pull-Off Adhesion Testers", West Conshohocken, PA,
    (2019).
28. CNR-DT 200., "Guide for the Design and Construction of Externally Bonded FRP Systems for
    Strengthening Existing Structures", National Research Council, Italy, (2004).
29. BS EN 1542., "Products and Systems for the Protection and Repair of Concrete Structures. Test
    Measurement of Bond Strength by Pull-Off", British Standard Institution, (1999).
30. Naderi, M., "New Twist-Off Method for the Evaluation of In-Situ Strength of Concrete",
    Journal of Testing and Evaluation, 35, No. 6, pp. 602-608, (2007).
31. Shrestha, J., Ueda, T., and Zhang, D., "Durability of FRP Concrete Bonds and its Constituent
    Properties under the Influence of Moisture Conditions", Journal of Materials in Civil Engineering, 27, No. 2, pp. 201-215, (2015).
32. Ouyang, Z., and Wan, B., "Experimental and Numerical Study of Water Effect on Bond between FRP and Concrete in Moist Environments", Journal of Reinforced Plastics and Composites, 27, No. 2, pp. 205-223, (2008).
33. Carbas, RJC., Marques, EAS., Da Silva, LFM. and Lopes, AM., "Effect of Cure Temperature on the Glass Transition Temperature and Mechanical Properties of Epoxy Adhesives", The Journal of Adhesion, 90, No. 1, pp. 104-119, (2014).
34. Ekenel, M., Myers, J. and Khataukar, A., "Effect of Environmental Conditions During Installation Process on Bond Strength between CFRP Laminate and Concrete Substrate", 3^rd international conference composites in construction, Lyon, France, (2005).