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This chapter presents the development of a new remote monitoring technique for the evaluation of corrosion on reinforced concrete structures, which uses embeddable variations of known ASTM standards and telecommunication technologies as a new way to estimate the rate of loss of the steel used as a component of rebar, since such phenomenon is the main cause of deterioration and degradation of the civil infrastructure. The adaptation of the technique was carried out to obtain an electrochemical half-cell that can be embedded indefinitely into the concrete, which provides the measurements corresponding to the corrosive state and allows calculating indirectly the rate of corrosion through the linear polarization resistance. The adaptation is based on a reference electrode of copper/copper sulphate, a segment of the same steel of the studied structure as working electrode and an auxiliary electrode made from pure graphite, all covered by mortar.

Introduction Corrosion of concrete rebar has been established as the main factor of the premature deterioration of reinforced concrete structures. The occurrence of such phenomena represents mostly the durability problems of the material, especially when the structure is subjected to the chloride ions presence (in marine or high salinity enviroment) and large amounts of carbon dioxide (CO2 ), processes known as chloride penetration and carbonation respectively[1,2,3]. Once the corrosión process has appeared in rebar, these begin to generate large stresses on the layer of concrete around them (due to the iron oxides that accumulate around the transversal area) which over time can generate microcracks, cracks and failure on the general structure[4]. Given the importance of preserving civil structures, is evident the strong necessity of obtaining a system with great flexibility to perform the estimation in situ of the corrosive state, capable to dispose the information for immediate consultation anywhere with minimum internet access. Therefore, the present work shows the development and implementation of a system for in situ monitoring of corrosion, for any reinforced concrete structure based on ASTM C876-91[5] standard for measuring half-cell potential, with which it is possible to determine the corrosion probability of rebar in reinforced concrete structures. Also, the equipment performance is presented by using different reference electrodes as Copper / Copper Sulfate (Cu -CuSO4 ), silver / silver chloride (Ag / AgCl) and Zinc / Zinc Sulfate (Zn -ZnSO4 ). Experiments and Results It was obtained a system for in situ monitoring of corrosion for reinforced concrete, that allows to estimate the corrosion probability on rebar, where the user send a text message, to start the test in the system and in return, via GPRS (General Packet Radio Service), the equipment disposes the data trend on a graphic trough a web server on an internet domain (figure 1). The system was tested on a building of the University complex, where its performance was evaluated using three different reference electrodes, obtaining an error over the measurement, between the standard and the system, of 6.62% (figure 2). References (1) ROA-RODRIGUEZ, G., APERADOR, W., DELGADO, A. Calculation of Chloride Penetration Profile in Concrete Structures. International Journal of Electrochemical Science. v. 8, p. 5022-5035, Apr. 2013 (2) HA WONG, S., VELI, S. Corrosion Monitoring of Reinforced Concrete Structures - A Review. International Journal of Electrochemistry Science, v. 2, p. 1 – 28, Jan. 2007. (3) SATHIYANARAYANAN, S., PANJALI NATARAJAN, K., SARAVANAN, S., SRINIVASAN, G. Corrosion monitoring of steel in concrete by galvanostatic pulse technique. Cement & Concrete Composites, v. 28, p. 630-637, May. 2006. (4) SHAMSAD, A., Reinforcement corrosion in concrete structures, its monitoring and service life prediction––a review. Cement & Concrete Composites, v. 25, p. 459 – 471, May. 2003 (5) ASTM Standard C876-09, 1991, Standard Test Method for Corrosion Potentials of Uncoated Reinforcing Steel in Concrete. ASTM International, West Conshohocken, PA, 2003, DOI: 10.1520/C0876-09.