Steel rebars corrosion investigation with strain gages

The presentation of a new laboratory, non-destructive method of detection and checking the corrosion of steel rebars in mortar specimens is discussed in this paper. The method uses extensive meter sensors, such as the well known strain gages (SG) and is based on the phenomena of tension state, in which the mortar mass Comes near the rebar area, after the formation of corrosion products. The SG are embedded in reinforcing mortar specimens during casting. Specimens are immersed in a 3.5 wt% NaCl solution and a constant potential is applied between steel rebar and graphite electrode in order to obtain fast corrosion conditions. As the embedded SG are affected by volume changes, caused not only by corrosion products, all other disturbing parameters have been compensated for by the measurement method described. The method was applied in different types of mortar specimens in order to have test and verification results. The reliability of the technique was evaluated by measuring: (a) the gravimetric weight loss of the reinforcing steel bars; (b) the electrical charge flow through specimens; and (c) the porosity of mortar mass. The test results obtained indicate that the method is reliable and suitable for the laboratory study of the corrosion factors and the influence of concrete admixtures in corrosion protection. (C) 1999 Elsevier Science Ltd. All rights reserved.