New technique to protect RC slabs against explosions using CFRP as externally bonded reinforcement Azer Maazoun, Royal Military Academy, Civil and Materials Engineering Department, (azer.maazoun@ugent.be) Stijn Matthys 2 , Bachir Belkassem 3 , David Lecompte 3 , John Vantomme 3 2 Ghent University, Magnel Laboratory for Concrete Research, Belgium 3 Royal Miliatry Academy,Civil and Materials Engineering Department, Belgium Abstract In recent years, numerous explosions related to industrial accidents and terrorist attacks causing loss of life and severe damage to infrastructures have occurred all over the world. However, existing reinforced concrete (RC) structures are not designed to resist to blast loads and could collapse after the incident. As a consequence, the emerging challenge of critical infrastructure protection has been recognized and nowadays there is a desire to upgrade the blast resistance of existing RC structures. The present paper provides an experimental and numerical analysis of the efficiency of using carbon fiber reinforced polymer (CFRP) as externally bonded reinforcement (EBR) on RC slabs under blast loads in order to increase the flexural resistance of the structure. Moreover, the effect of the propagation of the blast wave within the retrofitted specimens and how it affects the bond interface between the CFRP strip and concrete during the blast loading is discussed. Keywords: Carbon fiber reinforced polymer; Blast loading; Experimental analysis; Numerical simulation; INTRODUCTION Several experimental studies under blast loading report difficulties in getting reliable experimental results because of the generated light and the smoke of the explosion and generally experimental results yielded by these tests are qualitative in nature. In order to avoid this problem, an experimental setup using an explosive driven shock tube (EDST), digital image correlation (DIC) measurement and strain gauges is developed to record the maximum deflection, the evolution of strain in the steel reinforcement, concrete and CFRP strips simultaneously during the explosion. A detailed numerical model is developed to predict the blast response of the non-retrofitted and retrofitted RC slabs. After the validation of the finite element (FE) model, a parametric study with respect to CFRP width and thickness is performed in order to evaluate their effect on the blast response of the RC slabs. EXPERIMENTAL ANALYSIS An experimental program is performed in order to investigate the feasibility of strengthening RC slabs for blast loading by means of EBR and to study the blast response of the strengthened RC slabs. Five simply supported slabs with a span of 2 m between the axis of the supports are tested under an explosive charge. One of the slabs is used as a reference specimen and the remaining slabs were strengthened in flexure with different ratios of carbon fiber reinforced polymer (CFRP). Five specimens were casted in laboratory conditions with the following dimensions: length 2.3 m, width 0.3 m and thickness 0.06 m. Figure 1 shows the slab dimensions and reinforcement details