Abstract—The objective of this work is to study the influence of the properties of the substrate on the retrofit (thin repair) of damaged concrete elements, with the SCC. Fluidity, principal characteristic of the SCC, would enable it to cover and adhere to the concrete to be repaired. Two aspects of repair are considered, the bond (Adhesion) and the tensile strength and the cracking. The investigation is experimental; It was conducted over test specimens made up of ordinary concrete prepared and hardened in advance (the material to be repaired) over which a self compacting concrete layer is cast. Three alternatives of SC concrete and one ordinary concrete (comparison) were tested. It appears that the self-compacting concrete constitutes a good material for repairing. It follows perfectly the surfaces’ forms to be repaired and allows a perfect bond. Fracture tests made on specimens of self-compacting concrete show a brittle behaviour. However when a small percentage of fibres is added, the resistance to cracking is very much improve. Keywords—Adhesion; Concrete; Experimental; Repair; Self compacting I. INTRODUCTION ELF-COMPACTING concrete SCC is a material known in fresh state for its workability and stability and it can be set up without any vibration. This characteristic is distinguished in order to use the SCC as a material of repair. The investigation is experimental; tests are carried out in order to repair a concrete beam by a coating of SCC put over the surface of the concrete beam to be repaired, without using any reinforcement. This type of repairing is named retrofit. The work was conducted over test specimens made up of ordinary concrete prepared and hardened in advance (substrate = the material to be repaired) over which a self compacting concrete layer is cast. II.EXPERIMENTAL PROCEDURE A. Materials and Specimens Specimens were made in two phases. At first the substrates were manufactured with ordinary concrete OC (concrete to be repaired). Later, the repair material (SCC) was cast on the substrate [1]. Substrates were streamed 5 months before the test. The concrete substrate composition is presented in table 1 and the F. Kharchi is with the University of Sciences an Technology Houari Boumediene USTHB, Research lab LBE, Algeria (phone: +213 555 416043; fax:-+213 21 247224, e-mail: kharchifcong@ yahoo.fr). O. Bouksani, is with the University of Médéa, Algeria (e-mail: omarbouksani@ yahoo.fr). M.Benhadji was with the University of Médéa, Algeria (e-mail: mlbenhadji@ yahoo.fr). repair materials in Table II. The compressive strength of the substrate material is 20Mpa. For the repair material, three alternatives of SCC were considered in addition to an ordinary concrete for comparison [2] [3]. Therefore, the following variations are investigated: SCC SCC+SF, SCC with silica fume, SCC+ Fibre: SCC with synthetic fibres, OC: ordinary concrete. The compressive and tensile strength for the repair materials are shown in figures 1 and 2. The results are not surprising, the SCC, in general, was more resilient because the cement mix exceeds that of the OC. By comparing the various SCC, we note the positive result of the silica fume, and fibres. F. Kharchi, M. Benhadji, and O. Bouksani Repair of Concrete Structures with SCC S TABLE I SUBSTRATE COMPOSITION Constituents OC Cement (kg/m3) Water (l/m3) Sand 0-5 mm (kg/m3) Gravels (kg/m3) 392 159 752 938 TABLE II REPAIR CONCRETE COMPOSITIONS OC Weight (kg) SCC weight (kg) SCC+10%SF weight (kg) SCC+10%SF + synthetic fibber weight (kg) Sand 0/3 630 831.6 831.6 831.6 Gravel 3/8 261 410.4 410.4 410.4 Gravel 8/15 851 399.6 399.6 399.6 Cement 350 540 540 540 Water 200 216 216 216 Superplastizer / 7.56 7.56 7.56 Silica fume / 40 40 40 Synthetic fibber / / / 60 W/C 0.5 / / / G/S 0.891 0.891 0.891 W/L 0.4 0.4 0.4 Flow (mm) 690 690 650 Time flow (s) 4.5 4.5 7.7 World Academy of Science, Engineering and Technology International Journal of Civil and Environmental Engineering Vol:5, No:10, 2011 404 International Scholarly and Scientific Research & Innovation 5(10) 2011 scholar.waset.org/1307-6892/2957 International Science Index, Civil and Environmental Engineering Vol:5, No:10, 2011 waset.org/Publication/2957