INTERFACE SHEAR STRENGTH OF CONCRETE-TO-CONCRETE BOND WITH AND WITHOUT PROJECTING STEEL REINFORCEMENT
DOI:
https://doi.org/10.11113/jt.v75.3707Keywords:
Surface texture, interface shear strength, projecting steel reinforcement, friction, concrete cohesionAbstract
Composite concrete consists of two elements cast at different times which are the concrete base and concrete topping. To achieve composite action, interface shear strength must be sufficient to resist the sliding motion between the two concrete surfaces in contact. The interface shear strength is mainly depended on concrete cohesion, friction and dowel action. A total of 36 “push-off†tests were performed to study the interface shear strength and to assess the influence of surface texture and steel reinforcement crossing the interface. Three different concrete base surfaces are prepared which include smooth or “left as-castâ€, roughened by wire-brushing in the transverse direction and steel reinforcement projecting from the concrete base. Eurocode 2 provides design equations for determining the interface shear strength with different surface textures and also the one where projecting steel reinforcement crosses the interface. The experimental results show that the transverse roughened surface produced the highest interface shear strength of 1.89 N/mm2 (σn = 0 N/mm2), 4.69 N/mm2 (σn = 0.5 N/mm2), 5.97 N/mm2 (σn = 1.0 N/mm2) and 6.42 N/mm2 (σn = 1.5 N/mm2) compared with the other surface textures. This proves that the increase in the degree of roughness contributes to higher concrete cohesion and friction coefficient. However, for the surface with projecting steel reinforcement, the failure is not sudden as experienced by the surface without one. This is due to the contribution of the clamping stress from the dowel action of the steel reinforcements. Meanwhile, for specimens without any projecting steel reinforcements, the interface shear strength depended solely on friction and concrete cohesion of the surface textures. The interface shear strength of surface with and without the projecting steel reinforcement can be predicted using the Mohr-Coulomb failure envelope. This paper also proposed design expressions for concrete-to-concrete bond on surfaces provided with and without projecting steel reinforcement that can be adopted in Eurocode 2.
References
P. M. D. Santos and E. N. B. S. Júlio. 2012. A State-of-the-art Review on Shear-friction. Engineering Structures. 45: 435-448.
J. A. Hofbeck, I. O. Ibrahim, and A. H. Mattock. 1969. Shear Transfer in Reinforced Concrete. ACI Journal Proceedings.
P. W. Birkeland and H. W. Birkeland. 1966. Connections in Precast Concrete Construction. ACI Journal Proceedings.
A. H. Mattock. 1974. Shear Transfer in Concrete Having Reinforcement at an Angle to the Shear Plane. ACI Special Publication.
M. I. Baldwin and L. A. Clark. 1997. Push-off Shear Strength with Inadequately Anchored Interface Reinforcement. Magazine of Concrete Research. 49: 35-43.
M. A. Mansur, T. Vinayagam, and K. H. Tan. 2008. Shear Transfer Across a Crack in Reinforced High-Strength Concrete. ASCE Journal of Materials in Civil Engineering. 20: 294-302.
E. N. B. S. Júlio, D. Dias-da-Costa, F. A. B. Branco, and J. M. V. Alfaiate. 2010. Accuracy of Design Code Expressions for Estimating Longitudinal Shear Strength of Strengthening Concrete Overlays. Engineering Structures. 32: 2387-2393.
Model Code 2010. 2010. Case Postale 88, CH-1015 Lausanne, Switzerland: Comité Euro-International du Béton, Secretariat Permanent, 2010, First complete draft. 1: 318.
EN 1992-1-1. Eurocode 2. 2004. Design of Concrete Structures, Part 1: General Rules and Rules for Buildings. European Committee for Standardization, Avenue Marnix 17, B-1000 Brussels, Belgium. 225 (with corrigendum of 16th January 2008).
ACI Committee 318. 2008. Building Code Requirements for Structural Concrete (ACI 318M-08) and Commentary. ed. Farmington Hills, MI: American Concrete Institute. 473.
L. F. Kahn and A. D. Mitchell. 2002. Shear Friction Tests with High-strength Concrete. ACI Structural Journal.
PCI Design Handbook. 2010. Precast/Prestressed Concrete Institute. 7th Edition.
AASHTO LRFD Bridge Design Specifications. 2007. American Association of State Highway and Transportation Officials, 4th edition, SI units edition. 1526.
P. M. D. Santos and E. N. B. S. Júlio. 2014. Interface Shear Transfer on Composite Concrete Members. Aci Structural Journal. 111: 113-121.
M. E. Mohamad, I. S. Ibrahim, R. Abdullah, A. B. Abd. Rahman, A. B. H. Kueh, and J. Usman. 2015. Friction and Cohesion Coefficients of Composite Concrete-to-Concrete Bond. Cement and Concrete Composites. 56: 1-14.
J. Scott. 2010. Interface Shear Strength in Lightweight Concrete Bridge Girders. Master thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA.
R. C. K. Wong, S. K. Y. Ma, R. H. C. Wong, and K. T. Chau. 2007. Shear Strength Components of Concrete Under Direct Shearing. Cement and Concrete Research. 37: 1248-1256.
J. A. Wallenfelsz. 2006. Horizontal Shear Transfer for Full-depth Precast Concrete Bridge Deck Panels. Master thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA.
D. S. Santos, P. M. D. Santos, and D. Dias-da-Costa. 2012. Effect of Surface Preparation and Bonding Agent on the Concrete-to-Concrete Interface Strength. Construction and Building Materials. 37: 102-110.
M. Gohnert. 2003. Horizontal Shear Transfer Across a Roughened Surface. Cement & Concrete Composites. 25: 379-385.
I. S. Ibrahim. 2008. Interface Shear Strength of Hollow Core Slabs with Concrete Toppings. PhD Thesis, The University of Nottingham.
Downloads
Published
Issue
Section
License
Copyright of articles that appear in Jurnal Teknologi belongs exclusively to Penerbit Universiti Teknologi Malaysia (Penerbit UTM Press). This copyright covers the rights to reproduce the article, including reprints, electronic reproductions, or any other reproductions of similar nature.
