Bond Performance of Near-Surface-Mounted FRP Bars
Publication: Journal of Composites for Construction
Volume 15, Issue 1
Abstract
Near-surface-mounted (NSM) reinforcement has become a well-known method for strengthening existing concrete structures. The bond between the NSM reinforcing bars and concrete is the key factor in the NSM technique. In the NSM technique, there are two bond interfaces: one between the NSM bar and the adhesive, and the other between the adhesive and the concrete. For this technique to perform efficiently, these two interfaces need to be investigated. On the other hand, concrete structures that require rehabilitation are often exposed to aggressive environments. Many of these environments are related to cold-climate conditions as can be found in Canada. Environmental factors including freeze/thaw action, exposure to deicing salts, and sustained low temperatures combine to attack the integrity of repaired structures. Consequently, repair materials for the Canadian infrastructure must be able to withstand these harsh conditions for prolonged periods of time. A total of 80 NSM-fiber-reinforced polymer (FRP) bars installed in C-shaped concrete specimens were tested in pull-out setup to failure. Sixty specimens were tested at normal room temperature, while the remaining 20 specimens were tested after conditioning in an environmentally controlled chamber for 200 freeze/thaw cycles. The dimensions of the specimens were designed, upon a preliminary phase of testing, to ensure that no transverse cracking would occur in the specimen before bond failure of the NSM bar. The results are presented in term of failure load, average bond stress, strains in FRP bar, end slip, and mode of failure. A bond-slip model was proposed for the used FRP bars.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The writers would like to express their special thanks and gratitude to the Natural Science and Engineering Research Council of Canada (NSERC), ISIS Canada, Pultrall Inc. (Thetford Mines, Québec), Hilti Inc. (Montréal, Québec), and the technical staff of the structural lab in the Department of Civil Engineering at the University of Sherbrooke.
References
American Concrete Institute (ACI). (2004). “Guide test methods for fiber-reinforced polymers (FRPs) for reinforcing or strengthening concrete structures.” ACI 440.3R-04, ACI Committee 440, Farmington Hills Mich.
Asplund, S. (1949). “Strengthening bridge slabs with grouted reinforcement.” ACI Struct. J., 20(6), 397–406.
Barros, J., and Fortes, A. (2005). “Flexural strengthening of concrete beams with CFRP laminates bonded into slits.” Cem. Concr. Compos., 27(4), 471–480.
Canadian Standard Association (CSA). (2006). “Canadian high-way bridges design code.” CAN/CSA-S6-06, Canadian Standard Association, Rexdale, Ont., Canada.
De Lorenzis, L., Lundgren, K., and Rizzo, A. (2004). “Anchorage length of near-surface mounted fiber-reinforced polymer bars for concrete strengthening—Experimental investigation and numerical modelling.” ACI Struct. J., 101(2), 269–278.
De Lorenzis, L., and Nanni, A. (2001). “Characterization of FRP rods as near-surface mounted reinforcement.” J. Compos. Constr., 5(2), 114–121.
De Lorenzis, L., and Nanni, A. (2002). “Bond between NSM fiber-reinforced polymer rods and concrete in structural strengthening.” ACI Struct. J., 99(2), 123–132.
De Lorenzis, L., Nanni, A., and La Tegola, A. (2000). “Strengthening of reinforced concrete structures with near surface mounted FRP rods.” Proc., Bibl. Int. Meeting on Composite Masterials, PLAST 2000, 8.
De Lorenzis, L., Rizzo, A., and La Tegola, A. (2002). “A modified pull-out test for bond of near-surface mounted FRP rods in concrete.” Composites, Part B, 33(8), 589–603.
de Sena-Cruz, J. M., and Barros, J. A. O. (2004). “Bond between near surface mounted carbon fiber reinforced polymer laminate strips and concrete.” J. Compos. Constr., 8(6), 519–527.
Focacci, F., Nanni, A., and Bakis, C. (2000). “Local bond-slip relationship for FRP reinforcement in concrete.” J. Compos. Constr., 4(1), 24–31.
Green, M., Bisby, L., Beaudoin, Y., and Labossiere, P. (2000). “Effect of freeze-thaw cycles on the bond durability between fibre reinforced polymer plate reinforcement and concrete.” Can. J. Civ. Eng., 27(5), 949–959.
Hassan, T., and Rizkalla, S. (2003). “Investigation of bond in concrete structures strengthened with near surface mounted carbon fibber reinforced polymer strips.” J. Compos. Constr., 7(3), 248–257.
Hassan, T., and Rizkalla, S. (2004). “Bond mechanism of near-surface-mounted fiber reinforced polymer bars for flexural strengthening of concrete structures.” ACI Struct. J., 101(6), 830–839.
Hilti Inc. (2007). “Product technical guide.” ⟨http://www.ca.hilti.com⟩ (2007).
Kotynia, R. (2007). “Analysis of the flexural response of NSM FRP-strengthened concrete beams.” Proc., FRPRCS-8, 10.
La Tegola, A., and Micelli, F. (2003). “Environmental effect on RC beams with near surface mounted FRP rods.” Proc., 6th Int. Symp. on FRP Reinforcement for Concrete Structures (FRPRCS-6).
Lundqvist, J. (2007). “Numerical analysis of concrete elements strengthened with carbon fiber reinforced polymers.” Ph.D. thesis, Luleå Univ. of Technology, Luleå, Sweden.
Pultrall Inc. (2007). “Product technical specifications.” ⟨http://www.Pultrall.com⟩ (2007).
Rosenboom, O., Hassan, T., and Rizkalla, S. (2007). “Flexural behaviour of aged prestressed concrete girders strengthened with various FRP systems.” Constr. Build. Mater., 21(4), 764–776.
Seracino, R., Saifulnaz, R., and Oehlers, D. (2007). “Generic debonding resistance of EB and NSM plate-to-concrete joints.” J. Compos. Constr., 11(1), 62–70.
Soliman, S. M., El-Salakawy, E. F., and Benmokrane, B. (2007). ”Bond properties of near surface mounted (NSM) carbon FRP bars in concrete.” Proc., Annual General Meeting and Conf. Canadian Society of Civil Engineering.
Soliman, S. M., El-Salakawy, E. F., and Benmokrane, B. (2008a). “Effectiveness of using NSM CFRP bars in flexural strengthening of reinforced concrete beams.” Proc., Annual General Meeting and Conf., CSCE, Quebec City.
Soliman, S. M., El-Salakawy, E. F., and Benmokrane, B. (2008b). “Flexural behaviour of concrete beams strengthened with near surface mounted FRP bars.” Proc., 4th Int. Conf. on FRP Composites in Civil Engineering (CICE2008).
Taljsten, B., and Carolin, A. (2007). “CFRP strengthening of concrete beams—Testing in sub-zero temperature.” Int. J. Mater. Prod. Technol., 28(1/2), 29–45.
Teng, J. G., De Lorenzis, L., Wang, B., Li, R., Wong, T. N., and Lam, L. (2006). “Debonding failures of RC beams strengthened with near surface mounted CFRP strips.” J. Compos. Constr., 10(2), 92–105.
Information & Authors
Information
Published In
Copyright
© 2011 ASCE.
History
Received: Jun 9, 2009
Accepted: Jun 16, 2010
Published online: Jun 18, 2010
Published in print: Feb 2011
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.