© 2017 Portuguese Society of Materials (SPM). Published by Elsevier España, S.L.U. All rights reserved. http://dx.doi.org/10.1016/j.ctmat.2016.07.008 Ciência & Tecnologia dos Materiais 29 (2017) e187–e191 ScienceDirect Available online at www.sciencedirect.com http://ees.elsevier.com/ctmat Special Issue “Materiais 2015” Use of advanced composite materials in strengthening axially loaded reinforced concrete columns M. Cheikh-Zouaoui a, * , N. Chikh b a Department of Civil Engineering, Laboratory LABETAP, University of Saad Dahlab, BP 270, Blida, 09000, Algeria b LMDC, Department of Civil Engineering, University of Constantine 1, Route Ain El-Bey, Constantine, 25000, Algeria Abstract The present study deals with the analysis of experimental results, regarding of load carrying capacity and strains, obtained from tests on reinforced concrete (RC) columns, strengthened with external carbon fibre reinforced polymer (CFRP) sheets. The experimental parameters include: number of wrap layers, slenderness of the columns (L/a or L/D) and section geometry (circular or square). A total of 48 specimens were subjected to axial compression. All test specimens were loaded to failure. Compressive stress, both axial and hoop strains have been recorded to evaluate the stress-strain relationship, ultimate stress, stiffness, and ductility. First, the effects of test parameters are analysed and compared. Results clearly demonstrate that composite wrapping can enhance the structural performance of RC columns in terms of both maximum strength and ductility. © 2017 Portuguese Society of Materials (SPM). Published by Elsevier España, S.L.U.. All rights reserved. Keywords: RC column; composite material; CFRP; confinement; slenderness; section shape; strength; ductility. 1. Introduction * During the last decade, advanced composite materials, such as carbon fibre reinforced polymer (CFRP) sheets or plates, have been successfully used for the rehabilitation of concrete structures throughout the world. Their application in civil engineering structures has been growing rapidly in recent years, and is becoming an effective and promising solution for strengthening deteriorated concrete members because of their high strength-to-weight ratio, good fatigue properties and excellent corrosion resistance. They are also quickly and easily applied, their use minimizes labour costs and can lead to significant savings in overall project costs. Several studies on the performance of FRP wrapped columns have been conducted, using both * Corresponding author. E-mail address: czmustapha@yahoo.fr (Cheikh-Zouaoui) experimental and analytical approaches [1-6]. This strengthening technique has proved to be very effective in enhancing column ductility and axial load capacity. Most of the available experimental data regarding FRP-confined columns have been generated from tests on small-scale concrete cylinders with standard strength. The data available for columns with square or rectangular cross sections have increased over recent years but are still limited [7-9]. Also the validation of these results and their applicability to large-scale reinforced concrete (RC) columns is of great practical interest. Published work in this field is relatively scarce [10,11]. More research on this subject is needed to study the effect of slenderness for concrete columns with higher strength. This study presents a comprehensive experimental investigation on the behaviour of axially loaded circular and square reinforced columns strengthened with CFRP wrap. A total of 48 concrete specimens were tested under axial compression. The data recorded included the compressive loads, axial strains, © 2017 Portuguese Society of Materials (SPM). Published by Elsevier España, S.L.U. All rights reserved.