Experimental Investigation of the effect of super-plasticizer additive on the concrete-steel bond strength using pull-out test

Document Type : Research Paper

Authors

1 MSc. Student, Islamic Azad University, Khormouj Branch

2 Assistant Professor, Islamic Azad University, Khormuj Branch

Abstract

The bond between concrete and reinforcing steel is essential for the composite action in reinforced concrete structures. In the present study, the effects of super-plasticizer additive on the steel-concrete bond strength is experimentally investigated. A total of 18 pullout samples are prepared in two concrete mix design cases, including ordinary and high-strength concrete. The used steel bars are of diameters 8, 10 and 12 mm, which are embedded inside the concrete in a length five times the rebar diameter. The steel-concrete bond strength is evaluated using direct pullout test method with the universal testing machine. Besides preparing the pullout specimens, 5 standard cube samples of concrete are casted to examine the concrete compressive strength and dimensions of the hardened concrete cubes. The specimens are tested at the 42-day ages and the slip-force curves are obtained using the pullout test. The maximum force and the corresponding slip, bond stress and other important parameters are determined and discussed for the different studied conditions. The results indicate that the rebar-concrete bond strength decreases by increasing the rebar diameter and the super-plasticizer additive has an important effect on the bond strength. For instance, the average bond strength for the concrete mix containing superplasticizer is 2.3 time of that for the normal concrete.

Keywords


[1] Orangun CO, Jirsa IO, Breen JE, “A re-evaluation of test data on development length and splices”, ACI Journal, 74 (3), 114–122, 1977.
[2] Robert P, Thomas P, “Reinforced Concrete Structures”, John Wiley & Sons, New York, 1975.
[3] Mousa MI, “Effect of bond loss of tension reinforcement on the flexural behaviour of reinforced concrete beams”, HBRC Journal, 12, 235–241, 2016.
[4] Mousavi SS, Dehestani M, Mousavi KK, “Bond strength and development length of steel bar in unconfined self-consolidating concrete”, Eng. Struct., 131, 587–98, 2017.
[5]. Chu S H, Kwan A K H, “A new method for pull out test of reinforcing bars in plain and fiber reinforced concrete”, Engineering Structures, 164, 82–91, 2018.
[6] Looney T J, Arezoumandi M, Volz J, and Myers J, “An Experimental Study on Bond Strength of Reinforcing Steel in Self-Consolidating Concrete”, International Journal of Concrete Structures and Materials, 6(3),187–197, 2012.
[7] Ahmed MD, Hafez E, Elyamany, Mostafa AH, Hazem MA, “Bond behavior and assessment of design ultimate bond stress of normal and high strength concrete”, Alexandria Engineering Journal, 53, 355–371, 2014.
[8] E‌s‌f‌a‌h‌a‌ni MR, H‌a‌k‌e‌m‌I A, “Bond strength of reinforcing bars in self-consolidating concrete (SCC) made with recycled aggregates‌”, Sharif journal of civil engineering, 2-27 (2), 93-99, 2011.
[9] Foroughi-Asl A, Dilmaghani S, Famili H, “Bond strength of reinforcement steel in self-compacting concrete”, International Journal of Civil Engineering, 6(1), 24–33, 2008.
[10] Hassan A, Hossain K, Lachemi M, “Bond strength of deformed bars in large reinforced concrete members cast with industrial self-consolidating concrete mixture”, Journal of Construction and Building Materials, 24(4), 520–530, 2010.
[11] Turk K, Benli A, Calayir Y, “Bond strength of tension lap-splices in full scale self-consolidating concrete beams”, Turkish Journal of Engineering and Environmental Sciences, 32, 377–386, 2008.
[12] Castel A, Vidal T, Francois R, "Bond and cracking properties of self-consolidating concrete”, Journal of Construction and Building Materials, 24(7), 1222–1231, 2010.
[13] Bilek V, Bonczková S, Hurta J, Pytlík D, Mrovec M, “Bond Strength Between Reinforcing Steel and Different Types of Concrete”, Procedia Engineering, 190, 243 – 247, 2017.
[14] Nematinejad M, Eskandari-Naddaf H, Tadayonfar G, Saghi, H, “ANN Prediction of bond strength between steel rebar and concrete containing micro-silica, nano-silica and fibers”, Concrete research, 10(2), 47-57, 2017.
[15] Hadi M., Bond of high strength concrete with high strength reinforcing steel, The Open Civil Engineering Journal, 2, 143-147, 2008.
[16] Kabir R, Islam M, “Bond stress behavior between concrete and steel rebar: Critical investigation of pull-out test via Finite Element Modeling”, International journal of civil and structural engineering, 5(1), 80-90, 2014.
[17] Sureshbabu N. and Mathew G. Influence of temperature on bond–slip characteristics of concrete
containing fly ash, Asian Journal of Civil Engineering, https://doi.org/10.1007/s42107-020-00258-8.
[18] Dybeł P., Effect of casting direction on bond of reinforcement in High Performance Self-Compacting Concrete (HPSCC), MATEC Web of Conferences 262, 06004. 2019.
[19] Tepfers R and De Lorenzis L., “Bond of FRP reinforcement in concrete”, Journal of Mechanics of Composite Materials, 39(4), 447-496, 2003.
[20] Tepfers R, “Bond clause proposal for FRPbars/rods in concrete based on CEB/FIP Model Code 90. Part 1: design bond stress for FRP reinforcing bars”, Struct Concrete, 7(2), 47-55, 2006.
[21] Hao QD, Wang YL, Zhang ZC, “Bond strength improvement of GFRP rebars with different rib geometries”, J Zhejiang Univ Sci A, 8(9): 1356-1365, 2007.